Activity of the lipoxygenase inhibitor 1-phenyl-3-pyrazolidinone (phenidone) and derivatives on the inhibition of adhesion molecule expression on human umbilical vascular endothelial cells

Leukocyte adhesion contributes to perfusion abnormalities and tissue damage during trauma, shock or overwhelming inflammation. This study was performed to determine whether the lipoxygenase inhibitor phenidone and derivatives decrease the expression of adhesion molecules on tumor necrosis factor-alpha (TNF-alpha) stimulated endothelial cells and attenuate leukocyte-endothelial interactions under flow in vitro. TNF-alpha stimulated human umbilical venous endothelial cells (HUVECs) were incubated with phenidone, 4-methyl-phenidone, 4-4-dimethyl-phenidone, 5-methyl-phenidone, 5-phenyl-phenidone, and 5-methyl-1,(2,5-di-chloro-phenyl)-3-pyrazolidone. We tested the inhibition of adhesion molecule expression at different inhibitor concentrations before, during, and after the stimulation of HUVECs. The inhibition of endothelial cell expression on HUVECs was measured by flow cytometry. Rolling and firm adhesion of leukocytes to pretreated endothelium was examined in a parallel plate flow chamber. Phenidone inhibited the expression of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and endothelial-leukocyte adhesion molecule-1 on HUVECs when added prior to HUVEC stimulation. The inhibitory effect of phenidone was still observed when added simultaneously, but not when added after HUVEC stimulation. 4-4-dimethyl-phenidone and 5-phenyl-phenidone inhibited the expression of adhesion molecules more effectively than phenidone. The attenuation of leukocyte rolling under flow conditions was also significantly more effective with 4-4-dimethyl-phenidone than with phenidone. Lipoxygenase inhibitors might be of therapeutically interest for the treatment of overwhelming systemic inflammation during shock, trauma, and sepsis.

A pilot open-label study of the efficacy of subanesthetic isomeric S(+)-ketamine in refractory CRPS patients

OBJECTIVE

Complex regional pain syndrome (CRPS) is a severe neuropathic pain state that is often disproportionate to the initial trauma. Associated features are autonomic dysregulation, swelling, motor dysfunction, and trophic changes to varying degrees. Despite a multitude of treatment modalities, a subgroup of CRPS patients remain refractory to all standard therapies. In these patients, the disease may spread extraterritorially, which results in severe disability. A critical involvement of N-methyl-D-aspartate receptors (NMDARs) has been demonstrated both clinically and by animal experimentation. NMDA antagonists may be effective in many neuropathic pain states. In long-standing, generalized CRPS, we investigated the effects of S(+)-ketamine on pain relief and somatosensory features, assessed by quantitative sensory testing (QST).

METHODS

Four refractory CRPS patients received continous S(+)-ketamine-infusions, gradually titrated (50 mg/day-500 mg/day) over a 10-day period. Pain intensities (average, peak, and least pain) and side effects were rated on visual analogue scales, during a 4-day baseline, over 10 treatment days, and 2 days following treatment. QST (thermo-, mechanical detection, and pain thresholds) was analyzed at baseline and following treatment.

RESULTS

Subanesthetic S(+)-ketamine showed no reduction of pain and effected no change in thermo- and mechanical detection or pain thresholds. This procedure caused no relevant side effects. The lack of therapeutic response in the first four patients led to termination of this pilot study.

CONCLUSION

S(+)-ketamine can be gradually titrated to large doses (500 mg/day) without clinically relevant side effects. There was no pain relief or change in QST measurements in this series of long-standing severe CRPS patients.

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.

Effect of hydroxyethyl starch on vascular leak syndrome and neutrophil accumulation during hypoxia

OBJECTIVE

Several studies have suggested that intravenous hydroxyethyl starch treatment may dampen acute inflammatory responses. It is well documented that limited oxygen delivery to tissues (hypoxia) is common in acute inflammation, and numerous parallels exist between acute responses to hypoxia and to inflammation, including the observation that both are associated with increased vascular leakage and neutrophil infiltration of tissues. Therefore, we compared functional influences of hydroxyethyl starch on normoxic or posthypoxic endothelia.

DESIGN

Laboratory study.

SETTING

University hospital.

SUBJECTS

Cultured human microvascular endothelial cells and mice (C57BL/6/129 svj).

INTERVENTIONS

We measured functional influences of hydroxyethyl starch on normoxic or posthypoxic endothelia.

MEASUREMENTS AND MAIN RESULTS

Studies to assess endothelial barrier function in vitro indicated that the addition of hydroxyethyl starch promotes endothelial barrier in a dose-dependent fashion and hydroxyethyl starch-barrier effects are increased following endothelial hypoxia exposure (human microvascular endothelial cells, 48 hrs, 2% oxygen). Treatment of human microvascular endothelial cells with hydroxyethyl starch resulted in a dose-dependent increase in 157-phosphorylated vasodilator-stimulated phosphoprotein, a protein responsible for controlling the geometry of actin-filaments. Neutrophil adhesion was decreased in the presence of physiologically relevant concentrations of hydroxyethyl starch in vitro, particularly after endothelial hypoxia exposure. Using a murine model of normobaric hypoxia, increases in vascular leakage and pulmonary edema associated with hypoxia exposure (4 hrs at 8% oxygen) were decreased in animals treated with intravenous hydroxyethyl starch. Increases of tissue neutrophil accumulation following hypoxia exposure were dampened in hydroxyethyl starch-treated mice.

CONCLUSIONS

Taken together, these results indicate that hypoxia-induced increases in vascular leakage and acute inflammation are attenuated by hydroxyethyl starch treatment.

Dose-dependent influence of barbiturates but not of propofol on human leukocyte phagocytosis of viable Staphylococcus aureus

OBJECTIVE

Deep sedation with barbiturates or propofol is a standard therapy for patients with critically elevated intracranial pressure. Such patients are prone to infectious complications, especially to pneumonias, which are most commonly caused by Staphylococcus aureus. Although various immunomodulatory effects of barbiturates have been described in vitro, their influence on the phagocytosis of viable S. aureus has yet to be investigated. Therefore, we examined the effects of thiopentone, methohexitone, and propofol on the phagocytosis of viable S. aureus.

DESIGN

Laboratory study.

SETTING

University laboratory.

PATIENTS

Ten healthy volunteers aged 32.5 +/- 7 yrs.

INTERVENTIONS

Blood sampling.

MEASUREMENTS AND MAIN RESULTS

Whole blood samples were preincubated with different concentrations of thiopentone, methohexitone, and propofol, which is an isopropylphenol derivate. After viable S. aureus was added, phagocytosis was stopped at different time points. Leukocytes were then stained with monoclonal antibodies for flow cytometric analysis of granulocyte recruitment (ratio of ingesting granulocytes) and phagocytosis activity (fluorescence intensity of ingested bacteria). Both barbiturates inhibited granulocyte recruitment and phagocytosis activity in a dose-dependent manner, whereas propofol did not affect any of the investigated variables. At concentrations higher than 7.6 x 10(-3) M (for thiopentone, p < .008) and 1.1 x 10(-3) M (for methohexitone, p < .04), granulocyte recruitment and phagocytosis activity were significantly inhibited. The calculated inhibitory concentrations (IC50) of thiopentone for granulocyte recruitment and for phagocytosis activity were 1.3 x 10(-2) M and 1.1 x 10(-2) M, respectively. The corresponding values for methohexitone were 3.6 x 10(-3) M and 1.1 x 10(-3) M.

CONCLUSIONS

Our in vitro model points at substantially different effects of barbiturates and propofol on phagocytosis of S. aureus, which is one of the most important pathogens in patients who need neuroprotective therapy. The inhibitory effects of both barbiturates demonstrate a strong dose-dependency, with more pronounced effects for methohexitone. Impairment of phagocytosis activity was more pronounced than granulocyte recruitment.

Einfluss verminderter Scherkräfte auf Entzündungsreaktionen in vitro

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.

Effect of intravenous hydroxyethyl starch on the accuracy of measuring hemoglobin concentration

STUDY OBJECTIVE

To determine if intravenous hydroxyethylstarch (HES) affects the accuracy of hemoglobin (Hb) measurements, as artificial colloids are known to increase red blood cell sedimentation rates.

DESIGN

Prospective, randomized study.

SETTING

Tertiary-care academic medical institution.

PATIENTS AND INTERVENTIONS

We randomized 40 surgical American Society of Anesthesiologists (ASA) physical status I and II patients undergoing preoperative autologous blood donation before elective orthopedic surgery. Patients were randomized to receive volume replacement with 500 mL of 6% HES 200,000/0.5 or 500 mL of electrolyte solution. Measurements of Hb concentration and leukocyte count were performed using an analyzer with a suction needle sampling from the bottom of the test tube. Measurements were performed after mixing and repeated after a 10-minute period of upright positioning of the tube (at rest).

MAIN RESULTS

In the study group that received HES, Hb levels were increased above baseline after resting (mean increase to 151% of baseline values, P < .01), whereas the leukocyte count was decreased (mean decrease to 39% of baseline values, P < .01). No difference between baseline and resting measurements were observed in patients who received intravenous crystalloids. In addition, we repeatedly measured the Hb concentration in an unstirred tube with and without the addition of HES. In blood samples containing HES, the Hb concentration was increased above baseline after 2.5 minutes of resting, compared with 30 minutes without HES addition (P < .05).

CONCLUSIONS

Mixing of test tube contents before sampling is critical for accurate measurement of the Hb concentration in the blood of patients who received intravenous HES.

Effects of Intraoperative Blood Salvage on Leukocyte Recruitment to the Endothelium

Background

The contamination of salvaged wound blood with activated leukocytes has been suspected to play a role in leukocyte-mediated tissue injury by increased adhesion to the endothelium. To verify this hypothesis, the authors performed a clinical study to examine the effects of blood salvage on leukocyte-endothelial interactions.

Methods

Expression of L-selectin, CD18, and CD11b and leukocyte adhesion to activated endothelium from human umbilical veins were measured in 25 patients undergoing major orthopedic surgery. Adhesion of fluorescently labeled leukocytes was examined in a flow chamber at shear rates of 50-1,600 s. Comparisons were made between samples from venous blood and from processed salvaged wound blood (SWB).

Results

At 30% hematocrit, SWB contained 2,162 +/- 147 leukocytes/microl. In comparison with venous blood, CD11b was up-regulated in SWB 1.3- to 3.6-fold on monocytes and neutrophils, whereas L-selectin and CD18 decreased on monocytes by 53% and 15%, respectively (P &lt; 0.05). Despite up-regulation of CD11b, firm adhesion was significantly reduced by 74-76% in SWB. Rolling fractions and rolling velocities were significantly higher in SWB, and their relation to shear rate was markedly altered (P &lt; 0.01). In addition, adherent leukocytes from SWB were significantly less resistant to increments of shear rate than leukocytes from venous blood (P &lt; 0.01).

Conclusions

Despite up-regulated CD11b, integrin-mediated adhesion is markedly impaired in salvaged blood. Therefore, the effect of blood salvage cannot be predicted from cell surface expression but rather from functional assays. The former hypothesis, that leukocytes from SWB aggravate leukocyte-mediated tissue injury by increased adhesion, may not be as great a concern as previously suggested.

Influence of a Long-Term, High-Dose Volume Therapy with 6% Hydroxyethyl Starch 130/0.4 or Crystalloid Solution on Hemodynamics, Rheology and Hemostasis in Patients with Acute Ischemic Stroke

BACKGROUND

This study was performed to investigate the clinical effects of a 4-day volume therapy with a newly developed, 6% hydroxyethyl starch (HES) 130/0.4 versus crystalloid solution, with particular regard to systemic and cerebral hemodynamics, rheology and safety.

METHODS

In a randomized, double-blind study, 40 patients suffering from an acute ischemic stroke received either 6% HES 130/0.4 or crystalloid solution as continuous infusion over 4 days with a total dose of 6.5 liters. Efficacy parameters studied included hemodynamics (cardiac output, blood pressure, flow velocity with transcranial Doppler) and rheology (hematocrit and plasma viscosity). Safety parameters examined included laboratory, hemostaseology (including factor VIII) and an adverse event questionnaire (including pruritus).

RESULTS

In both groups, a small, but not significant increase in cardiac output was observed. There were no significant changes regarding the remaining efficacy or safety parameters, except for the well-known increase in serum alpha-amylase through the infusion of HES.

CONCLUSION

In our study with patients suffering from acute ischemic stroke, continuous infusion (1 ml/min) of HES 130/0.4 or crystalloid solution did not differ regarding safety or hemodynamic efficacy.

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.

Aortokavales Kompressionssyndrom

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.

Influence of long-term volume therapy with hydroxyethyl starch on leukocytes in patients with acute stroke

A repeated administration of hydroxyethyl starch affects hemostasiological and rheological factors such as the concentration of factor VIII/von Willebrand factor, platelet volume and plasma viscosity. An earlier study showed that HES also lowers the concentration of fibronectin, a molecule important in the reticuloendothelial system (RES). RES has a "clearing function" and is a part of the non-immune-specific defense mechanisms of the body. It is involved in the elimination of HES from the blood. Since leukocytes are another important part of the unspecific defense system, the goal of the present study was to investigate whether HES affects leukocytes. After giving their informed consent, 20 patients with cerebral perfusion disorders were randomized and underwent a double-blind 10-day hypervolemic hemodilution with HES 200/0.5/13 or HES 70/0.5/4. The numbers of leukocytes, percentage of lymphocytes, percentage of neutrophilic granulocytes and hemoglobin concentration were measured. The absolute number of leukocytes did not change significantly, but the share of neutrophilic granulocytes increased. The increase in neutrophilic granulocytes reflects an increase in phagocytic activity. HEs 200/0.5/13, which has the larger in vivo molecular weight (MW = 95 kD), caused a larger increase in neutrophilic granulocytes than HES 70/0.5/4, which has an in vivo MW of 58 kD.

Recent developments in European colloid solutions

Coagulopathy resulting from hydroxyethyl starch (HES) administration is well documented for high-molecular-weight, highly substituted HES solutions. These are the only starch-based synthetic colloids approved for volume replacement in the United States. Recent developments in European colloid solutions revolve around designing new starch molecules. By increasing the C2:C6 ratio and decreasing the molar substitution to 0.4, a new HES with a molecular weight of 130,000 was introduced. This solution is without significant influence on coagulation. Actual experimental work is concentrating on modulating the inflammatory response of monocytes and endothelial cells after infusion of colloid solutions. This may help prevent or even correct capillary leak, and the intravascular persistence of infused colloidal might be prolonged.

Local anesthetics impair human granulocyte phagocytosis activity, oxidative burst, and CD11b expression in response to Staphylococcus aureus

BACKGROUND

With invasion of bacteria, the host defense system is activated by a complex cascade of various mechanisms. Local anesthetics previously were shown to interact with diverse components of the immune response, such as leukocyte adherence on endothelial monolayers, oxidative burst, or crosstalk within lymphocyte subset populations. However, effects of newer local anesthetics like bupivacaine and ropivacaine on antibacterial host defense-primarily phagocytosis activity, oxidative burst, or CD11b expression-still remain unclear.

METHODS

Whole blood samples were preincubated with local anesthetics (lidocaine, 9.2, 92.2, and 1,846 microm bupivacaine, 6.1, 61, and 770 microm; ropivacaine, 6.4, 64, and 801 microm). For the oxidative burst and CD11b assay, dihydroethidium was added to the probes. After viable Staphylococcus aureus was added in a 5 to 1 ratio following leukocyte count, phagocytosis was stopped at different times, and staining with monoclonal antibodies was performed for subsequent flow cytometric analysis of phagocytosis activity, oxidative burst, and CD11b expression.

RESULTS

Granulocyte phagocytosis activity, CD11b expression, and generation of reactive oxygen species were significantly reduced by lidocaine (P < 0.0002) and bupivacaine (P < 0.005) in the highest concentration (1,846 microm and 770 microm, respectively). The capability of granulocytes to ingest bacteria was significantly depressed only by lidocaine (P < 0.003). Ropivacaine had no significant effect on any parameter investigated.

CONCLUSIONS

Local anesthetic dose and structure dependently inhibit inflammatory and immunologic parameters of granulocyte functions. Ropivacaine shows low interference with granulocyte immunologic and inflammatory functions.

Penetration of intravenous hydroxyethyl starch into the cerebrospinal fluid in patients with impaired blood-brain barrier function

Hypovolemic patients with impairment of the blood-brain barrier may receive IV hydroxyethyl starch (HES) to stabilize cardiovascular function and to increase cerebral perfusion pressure. It is not known whether HES can penetrate into the cerebrospinal fluid (CSF) under those conditions. We investigated plasma and CSF levels of HES after IV infusion in patients with suspected disturbance of the blood-brain barrier. Eight adult patients were studied who were being treated for head trauma or subarachnoid hemorrhage, with an external CSF drain in place. All patients exhibited radiographic signs of blood-brain barrier impairment diagnosed by cerebral computed tomography. After IV infusion of 500 to 1000 mL of HES 200,000/0.5, plasma HES levels were measured. Additionally, all CSF that was drained within 8 h after the HES infusion was collected, and HES concentrations were measured. All patients had detectable HES plasma concentrations (3.41 to 9.95 mg/mL). In contrast, no HES could be detected in the CSF of any patient. These data indicate that IV HES 200,000/0.5 does not penetrate into the CSF in patients with disturbed blood-brain barrier function after subarachnoid hemorrhage or head trauma. Further study is required to determine whether HES penetrates into the intracranial interstitium, despite the absence of HES in the CSF.

IMPLICATIONS

Patients may receive IV hydroxyethyl starch (HES) after head trauma or subarachnoid hemorrhage. The results of the present study indicate that in patients with suspected blood-brain barrier impairment, HES does not penetrate from the plasma into the cerebrospinal fluid.

Effects of magnetic cell separation on monocyte adhesion to endothelial cells under flow

Studies on monocyte adhesion are frequently limited by spontaneous changes of CD11b and CD62L during cell purification. Most isolation protocols for flow cytometric analysis that overcome this problem cannot be used when large numbers of living cells are needed for functional adhesion assays. This study investigated whether magnetic cell separation of monocytes with a paramagnetic bead against CD33 is a feasible method combining high yield with a low degree of spontaneous activation. As determined by flow cytometry, isolation of magnetically tagged monocytes at 4 degrees C did not alter the expression of CD11b and CD62L when compared to whole blood controls. Warming the cells slowly to room temperature immediately before starting the adhesion assay in a parallel plate flow chamber at 37 degrees C prevented further upregulation of adhesion molecules due to rewarming. When adhesion of magnetically tagged monocytes was compared with untouched monocytes that had been isolated via depletion of contaminating leukocytes, videomicroscopy showed that labelling CD33 neither affected rolling nor firm adhesion to human umbilical venous endothelial cells under flow. Finally, the subsequent upregulation of tissue factor expression on adherent monocytes indicates that magnetically separated monocytes responded properly to activating stimuli during cell adhesion. We conclude that magnetic cell separation via CD33 represents a feasible method for cell separation whenever large numbers of non-activated monocytes are needed for adhesion assays under flow.

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.

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.

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.

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.

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.

Pharmacokinetics of meropenem in critically ill patients with acute renal failure treated by continuous hemodiafiltration

The pharmacokinetics of meropenem were studied in nine anuric critically ill patients treated by continuous venovenous hemodiafiltration. Peak levels after infusion of 1,000 mg over 30 min amounted to 103.2 +/- 45.9 microgram/ml, and trough levels at 12 h were 9.6 +/- 3.8 microgram/ml. A dosage of 1,000 mg of meropenem twice a day provides plasma drug levels covering intermediately susceptible microorganisms. Further reductions of the dosage might be appropriate for highly susceptible bacteria or when renal replacement therapies with lower clearances are applied.

Hydroxyethyl starch antibodies in humans: incidence and clinical relevance

Hydroxyethyl starch (HES) is a plasma expander used for perioperative i.v. fluid management, as well as for resuscitation from trauma and shock. HES is very well tolerated, and the incidence of anaphylactic reactions is lower than with dextran or gelatin. Dextran anaphylaxis is caused by circulating dextran-reactive antibodies (ABs) of the immunoglobin G (IgG) class found in most adults. Histamine release from mast cells induces adverse reactions after gelatin infusion. The cause of adverse reactions due to HES is not yet clear. To investigate AB formation due to HES, we collected sera of 1004 patients at least 14 days after starch administration. Using a highly sensitive enzyme-linked immunoabsorbent assay technique, we found one patient with a low 1:10 titer of HES-reactive ABs (immunoglobin M [IgM] class). Despite repeated HES infusions, no clinical reaction could be detected in this patient. On the basis of a binomial distribution, a one-tailed confidence interval (99%) was used to calculate the percentage of the occurrence of ABs in general with maximum of 33 in 10,000 persons (IgM) and 23 in 10,000 persons (IgG). We suggest that HES-reactive ABs are extremely rare and that they do not necessarily induce anaphylaxis. Other mechanisms may be responsible for adverse reactions due to HES.

IMPLICATIONS

The frequency of antibody formation due to hydroxyethyl starch, a commonly used plasma expander, was prospectively investigated in 1004 patients. Only one patient showed transient antibody formation, which was not harmful to the patient. This low antigenicity could explain the excellent tolerance of hydroxyethyl starch compared with other plasma expanders.

Blood transfusion-modulated tumor recurrence: first results of a randomized study of autologous versus allogeneic blood transfusion in colorectal cancer surgery

PURPOSE

Allogeneic blood transfusions have reportedly been associated with a poor prognosis in patients with curatively resected cancer. To control for immunosuppression induced by a speculatively causal allogeneic blood transfusion, we designed a randomized study in which the control group received autologous blood transfusions not related to any condition of immunosuppression.

PATIENTS AND METHODS

One hundred twenty patients with potentially curative resectable colorectal cancer and the capability to predeposit autologous blood were randomly selected to receive either standard allogeneic blood transfusion or predeposited autologous blood.

RESULTS

In curatively resected cancer patients, the number who needed allogeneic blood transfusions was reduced from 60% in the allogeneic blood group to 33% in the autologous blood group (P = .009). After a median follow-up duration of 22 months (range, 8 to 48) tumor recurrence was observed in 28.9% of the allogeneic blood group and 16.7% of the autologous blood group. Life-table analysis established a tendency toward a shorter tumor-free survival for the allogeneic blood group (log-rank P = .11). The problem with this analysis was the strong association of allogeneic blood transfusions with tumor recurrence, which interfered in 33% of patients in the autologous blood group who required additional allogeneic blood transfusions. Multivariate analysis of established risk factors for tumor recurrence and surgery-related variables reflecting potential immunosuppressive conditions showed that only pT stage (relative risk, 6.61; 95% confidence interval [CI], 1.82 to 23.99; P = .004), pN stage (relative risk, 8.39; 95% CI, 3.15 to 22.33; P < .001), and the need for allogeneic blood (relative risk, 6.18; 95% CI, 2.20 to 17.37; P < .001) were independent predictors of tumor recurrence. Subgroup analysis of patients who received a transfusion of < or = 2 U blood found a significantly higher risk of tumor recurrence in the allogeneic blood group (relative risk, 5.16; 95% CI, 1.13 to 23.62; P = .034), which was reduced to borderline significance (relative risk, 3.54; 95% CI, 0.76 to 16.51; P = .107) by adjustment for tumor (T) and node (N) stage.

CONCLUSION

As indicated by these first results, the blood transfusion modality has a significant effect on tumor recurrence after surgical treatment of colorectal cancer. A change in the practice of blood transfusion might thus potentially surpass the impact of any recent adjuvant treatment strategies.

No evidence for the existence of preformed antibodies against hydroxyethyl starch in man

Using the highly sensitive ELISA technique for detecting anti-hydroxyethyl starch (HES) antibodies in man sera from 1,056 patients were analyzed. Patients of both sex, who had never had any prior contact with HES, were included in the study. In none of the cases could any titer of HES-reactive antibodies be detected. These data suggest that in man preformed HES-reactive antibodies do not exist or are extremely rare. In any case, unlike dextran-reactive antibodies, they should not have a high clinical importance. The mechanism behind the very rarely observed anaphylactoid reactions after HES application is still unknown.

Medical equipment ordinance and lack of personnel: two contrary factors influencing anesthesia patient safety

In January 1986, West German legislators enacted the Medical Equipment Ordinance (MedGV) to define specific regulations for both manufacturers and operators of medical equipment and to offer a measure of safety to patients. We describe the history of MedGV, its regulations, and the mechanisms developed to enforce those regulations. We also evaluate its impact on clinical practice in light of the current staff shortages in anesthesia practice and research in Germany. Finally, we focus our discussion on the distinction between improved equipment as a minor factor in critical-incidents and the inadequate manpower as a major factor in anesthesia mishaps. It is unclear what will develop after 1993, when the national states in Europe form a common market.

[Hypovolemic-hemorrhagic shock. Pathophysiology and therapy]

The common features of all different kinds of circulatory shock are a disturbance of the microcirculation and an imbalance between cellular oxygen demand and supply. The pathophysiology is discussed by the example of hypovolemic-hemorrhagic shock, including macrocirculation, humoral regulatory mechanisms, the role of vascular endothelium, and cellular dysfunction. The first aim of therapeutic efforts is the rapid restitution of a normal circulatory volume as a basic requirement for the normalisation of the microcirculation. Actual concepts of volume substitution and transfusion therapy are presented.

The prophylactic activity of amoxycillin/clavulanate and cefoxitin in vascular surgery--a randomized clinical study

In a randomized clinical study, 141 patients who had to undergo operations on the aorta or the main arteries received either amoxycillin/clavulanate or cefoxitin perioperatively for prophylaxis. As no wound infection occurred amoxycillin/clavulanate and cefoxitin were found to be equal in effectiveness.

Lung tissue concentrations of ciprofloxacin following intravenous administration in patients

Serum and corresponding lung tissue concentrations of ciprofloxacin (Ciprobay) were investigated in 25 patients undergoing open lung surgery for pulmonary malignancies. Drug levels were measured at various times (50-240 min) after completion of a single i.v. dose of 200 mg by bioassay and HPLC. Lung tissue concentrations peaked within one hour after dosing (bioassay: 3.2 micrograms/g, HPLC: 4.5 micrograms/g). Tissue levels exceeded corresponding serum level 3- to 4fold throughout the observation period. The results demonstrate excellent penetration properties of this new antimicrobial compound into lung tissue. Ciprofloxacin was concentrated in the lung and thus by far exceeded known minimum inhibitory concentrations for most nosocomial respiratory pathogens.

Interstitial handling of aminoglycoside antibiotics and radiographic contrast media in the kidney

Lymphatics of the mammalian kidney originate in the loose connective tissue around large blood vessels. This paravasal tissue drains the interstitum. The intarenal lymphatic system consists of interlobular, arcuate, and interlobar vessels according to the architecture of the arterial system. The interlobar vessels drain into the hilar lymph vessels. Capsular lymphatics are connected with the interlobular lymphatics inconsistantly. The renal medulla is drained by the venous vasa recta exclusively--there are no lymphaties in the medulla. Lymphatic fluid is mainly formed along the small renal veins as vascular transudate. After i.v. bolus injection concentrations of aminoglycosidic antibiotics in renal lymph reflect plasma values closely. Radiographic contrast media in renal lymph also showed a close correlation with plasma values with some indication of tubular secretion.

Electron microscopy of retinal tapetum (Caiman crocodilus)

The distribution and ultrastructure of the retinal tapetum lucidum in Caiman crocodilus is described. In the light adapted eye the tapetum is recognized in the superior half of the fundus. It consists of guanine containing crystalline platelets which are spread almost over the entire retinal pigment epithelial cells which can be divided into different layers: 1. The basal surface facing the choriocapillary vessels is differentiated into numerous densely packed true microfolds which are commonly described as "basal infoldings". 2. A remarkable high content of mitochondria as well as a great number of lipid droplet-like spherical bodies is observed. 3. In the nuclear zone a Golgi apparatus and all stages of phagocytosis are found. 4. Within the level of intercellular junctions, crystalline platelets are arranged mainly perpendicularly to the long axis of the neighbouring receptor cells, whereas 5. platelets in large pigment epithelial cell processes extending from the apical cell surface between the photoreceptors are oriented parallel to the receptor axis. 6. Heavy pigmentation of the apical tips of pigment cell processes by melanosomes is observed, but only within the lower half of the fundus. The functional significance of the tapetum of Caiman crocodilus is discussed.

Cell death in the mosaic epididymis of sex reversed mice, heterozygous for testicular feminization

Sex reversed mice heterozygous for testicular feminization are genetic females which are converted to males by the autosomal Sxr ("sex reversed") mutation, thus imitating the Y-chromosome. They carry on one of their X-chromosomes the mutation for testicular feminization. Then, X-inactivation leads to the formation of a mosaic of androgen insensitive XTfm and androgen sensitive X+ cells. In the epididymis the Tfm cells are maintained into adulthood as undifferentiated flat cells. There are however, always less Tfm cells than expected from random X-inactivation. Therefore, in the present study the role of cell death in the modification of the original mosaic is investigated before and after castration. It is shown that survival or elimination of Tfm cells depends on the structure of the smooth muscle layers around the epididymal duct. In addition to elimination of whole Tfm sections, a steady loss of single cells, not only in the Tfm but also in the wild-type fraction occurs. In the connective tissue distinct necrotic areas are present. After castration massive necroses appear in both cell types. In Tfm sections disintegration of the wall layers again leads to elimination of Tfm cells and to protrusion of epithelial cells in the interstitium which later on may be organized as abnormal sprouts and ducts. The observations indicate that the testosterone dependent trophic principle is based on short-range intercellular interactions and presumably arises in the connective tissue component of the epididymis.

Comparative electron-microscopic studies on the conus papillaris and its relationship to the retina in night and day active geckos

The ultrastructure of the capillary endothelium of the conus papillaris within the vitreous body was studied in night, day, and mixed (night and day) active geckos (Homopholis wahlbergi, Gekko gecko, Pachydactylus bibronii, Tarentola mauritanica, Lygodactylus conraui, Phelsuma guimbeaui, Phelsuma madagascariensis). Capillary endothelial cells were poorly developed in night and mixed active animals, whereas in day active animals they were highly organized. In particular the number and height of the luminal and basal microvilli and the frequency of micropinocytotic vesicles were distinctly increased in day active geckos. It is assumed that these structural mechanisms improve the transendothelial transportation capacity of metabolic substances. When the thickness of the retinal layers was compared, we found that the inner retinal layers of those geckos in which the conus capillaries were poorly developed, were approximately 60% of the thickness of the inner retina in the day active geckos. The results indicate that the structural organization of conal endothelial cells is related primarily to the retinal structure rather than to the animals' daytime behavior. Furthermore, our observations support the theory that the conus papillaris of lizards, like the pecten oculi of birds, has a primary function in the nutrition of the avascular retina and/or is involved in the exchange of fluid in the vitreous.

The ultrastructure of the thin loop limbs of the mouse kidney

The thin limbs of the loops of Henle in the mouse kidney have been investigated by conventional electron microscopy. Resulting from light microscopic investigations, a distinction in the epithelia of short and long loops can be demonstrated. Ultrastructurally, the thin limbs (descending) of short loops are composed of a uniformly thin and simple epithelium. In contrast, long loops (thin descending and ascending) are composed of three different epithelial types which are representative of a distinctly more complex epithelial system. Two epithelial types were observed in the thin descending limbs of long loops and the third type was observed in the ascending thin limbs. Based upon these findings it is suggested that the thin descending limbs of short and long loops of Henle in the mouse kidney cannot perform the same functions in the renal concentrating mechanism.