Engineering subarachnoid trabeculae with electrospun poly(caprolactone) (PCL) scaffolds to study leptomeningeal metastasis in medulloblastoma

Leptomeningeal metastasis (LM) occurs when cancer cells infiltrate the subarachnoid space (SAS) and metastasize to the fibrous structures that surround the brain and spinal cord. These structures include the leptomeninges (i.e., the pia mater and arachnoid mater), as well as subarachnoid trabeculae, which are collagen-rich fibers that provide mechanical structure for the SAS, support resident cells, and mediate flow of cerebrospinal fluid (CSF). Although there is a strong expectation that the presence of fibers within the SAS influences LM to be a major driver of tumor progression and lethality, exactly how trabecular architecture relates to the process of metastasis in cancer is poorly understood. This lack of understanding is likely due in part to the difficulty of accessing and manipulating this tissue compartment in vivo. Here, we utilized electrospun polycaprolactone (PCL) to produce structures bearing remarkable morphological similarity to native SAS fiber architecture. First, we profiled the native architecture of leptomeningeal and trabecular fibers collected from rhesus macaque monkeys, evaluating both qualitative and quantitative differences in fiber ultrastructure for various regions of the CNS. We then varied electrospinning parameters to produce a small library of PCL scaffolds possessing distinct architectures mimicking the range of fiber properties observed in vivo. For proof of concept, we studied the metastasis-related behaviors of human pediatric medulloblastoma cells cultured in different fiber microenvironments. These studies demonstrated that a more open, porous fiber structure facilitates DAOY cell spread across and infiltration into the meningeal mimic. Our results present a new tissue engineered model of the subarachnoid space and affirm the expectation that fiber architecture plays an important role in mediating metastasis-related behaviors in an in vitro model of pediatric medulloblastoma.

Abstract 2417: Elucidating the role of SMARCB1 in bladder cancer progression and metastasis

Bladder cancer (BLCA) is the second most common urological malignancy in the US and is usually not curable at an advanced stage. The transcriptomic profiling data of bladder cancer revealed that 64% of BLCA patients have frequent dysregulation of the components of the SWI/SNF, a chromatin remodeling complex. Alterations in chromatin remodeling genes have been previously implicated in human oncogenesis. SMARCB1/INI1 is one of the critical core components of the SWI/SNF complex. In this study, we demonstrate that primary BLCA patients harboring SMARCB1 loss strongly associate with worse survival. Specifically, the biallelic inactivation of the SMARCB1 (SMARCB1 knockout (KO)) in BLCA cell lines resulted in the emergence of aggressive tumor growth leading to soft tissue metastasis to lungs, liver, kidney, and intestine in vivo. Mechanistic studies revealed that IL-6- STAT3 axis is upregulated in SMARCB1 KO BLCA cells. Our data suggest that the STAT3 specific inhibitor, inhibits invasive potential of SMARCB1 KO cells suggesting potential therapeutic efficacy for STAT3 inhibitor to treat subsets of BLCA harboring SMARCB1 loss. In addition, we identified a unique transcriptional signature activated upon SMARCB1 loss, which is predictive of poor patient outcome in BLCA, and hence may be clinically valuable. Bladder cancer (BLCA) is the second most common urological malignancy in the US and is usually not curable at an advanced stage. The transcriptomic profiling data of bladder cancer revealed that 64% of BLCA patients have frequent dysregulation of the components of the SWI/SNF, a chromatin remodeling complex. Alterations in chromatin remodeling genes have been previously implicated in human oncogenesis. SMARCB1/INI1 is one of the critical core components of the SWI/SNF complex. In this study, we demonstrate that primary BLCA patients harboring SMARCB1 loss strongly associate with worse survival. Specifically, the biallelic inactivation of the SMARCB1 (SMARCB1 knockout (KO)) in BLCA cell lines resulted in the emergence of aggressive tumor growth leading to soft tissue metastasis to lungs, liver, kidney, and intestine in vivo. Mechanistic studies revealed that IL-6- STAT3 axis is upregulated in SMARCB1 KO BLCA cells. Our data suggest that the STAT3 specific inhibitor, inhibits invasive potential of SMARCB1 KO cells suggesting potential therapeutic efficacy for STAT3 inhibitor to treat subsets of BLCA harboring SMARCB1 loss. In addition, we identified a unique transcriptional signature activated upon SMARCB1 loss, which is predictive of poor patient outcome in BLCA, and hence may be clinically valuable.

Citation Format: Chandra Sekhar Amara, Karthik Reddy Reddy, Yuntao Yang, Badrajee Waduge Danthasinghe, Allison Bellman, Andrea B. Apollo, David J. Shih, Leomar Ballester, Pavlos Msaouel, Wenjin J. Zheng, Matthew J. Ellis, Seth P. Lerner, Arun Sreekumar, Shyam M. Kavuri, Nagireddy Putluri. Elucidating the role of SMARCB1 in bladder cancer progression and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2417.

TERT Immunohistochemistry Expression as a Surrogate of TERT Promoter Mutations in Infiltrating Gliomas

Introduction/Objective

Genomic alterations are critical for the diagnosis of infiltrating gliomas. Mutations in the telomerase reverse transcriptase promoter (TERTp) are sufficient for a diagnosis of glioblastoma in some cases, independent of histologic features. Although DNA sequencing is the preferred method for evaluating TERTp mutations, there are limitations with regards to turn-around-time, accessibility, and cost. In this study, we evaluated the efficacy of using TERT immunohistochemistry (IHC) as a surrogate marker for the identification of TERTp mutations in infiltrating gliomas.

Methods/Case Report

The study cohort consisted of 31 infiltrating gliomas diagnosed following the 2016 WHO classification of CNS tumors by a board-certified neuropathologist. Each case was evaluated by immunohistochemistry (anti-TERT monoclonal antibody) and with a targeted next-generation sequencing (NGS) panel. A systemic literature search was conducted to examine reports of TERT antibody as a surrogate marker of TERTp mutations. TERTp mutation detected by sequencing was considered the gold standard.

Results (if a Case Study enter NA)

TERT immunohistochemistry demonstrated a sensitivity of 61.1% and specificity of 69.2%. Cases were divided into IDH-WT and IDH-mutant infiltrating gliomas. Among the IDH-WT group, 84% contained the TERTp mutation with a sensitivity of 62.5% and specificity of 33.3% for the TERTp IHC. IDH-mutant gliomas showed a 16.2% TERTp mutation rate, and immunohistochemistry had a sensitivity of 50% and 80% specificity. The probability of TERT immunohistochemistry in diagnosing TERTp mutations exhibited a poor likelihood ratio for both the positive and negative test. Literature review included 5 studies with an overall sensitivity and specificity remaining consistently low (<80%), with 2 of these studies evaluating CNS related tumors giving rise to similar diagnostic performance.

Conclusion

TERT IHC has suboptimal sensitivity and specificity for identifying TERTp mutations in IDH-WT and IDH- mutant infiltrating gliomas.

Invasive Mold Infections (IMIs) of the Central Nervous System (CNS) in Patients with Hematologic Cancer (HC) (2000–2016): Uncommon but Deadly

Background

There is paucity of data regarding IMIs of the CNS in patients with HC or stem cell transplantation (SCT).

Methods

Review of the records of patients with HC and/or SCT recipients who were diagnosed with CNS IMIs at MD Anderson Cancer Center (1/1/2000–5/31/2016). IMIs were classified as proven or probable (EORTC/MSG criteria). We excluded patients with mixed CNS infections. Risk factors for survival at day 42 post diagnosis (dx) were assessed. A multivariate logistic regression analysis was performed to identify independent predictors of mortality.

Results

We identified 40 patients (16 proven; 40%). Most patients were white (29; 73%) and male (33; 83%). Median age was 58 years. The most common HC was acute leukemia (23; 58%). Seventeen patients (43%) were SCT recipients; 13 (76%) had GVHD. Most patients had active HC and neutropenia at dx (38; 95% and 21; 53%, respectively). Twenty-seven patients (68%) were in the ICU at dx. Aspergillus sp. (13; 33%) and Mucorales (8; 20%) accounted for >50% of cases. CNS IMIs were deemed to be secondary to direct extension or hematogenous spread in 9 (23%) and 31 (77%) patients, respectively. In the latter group, 28/31 (90%) had fungal pneumonia. Of the 27 and 9 patients who had Aspergillus galactomannan antigen tested from serum and CSF, respectively, 18 had positivity in serum (66%) and 3 in CSF (33%). Most patients (30; 75%) had exposure to mold-active agents within 30d of dx. Most patients (34; 85%) received lipid AMB and were treated with combination therapy (33; 83%). Most CNS lesions presented as ring-enhancing abscesses radiographically (26; 65%). Absence of giant cells and granulomas in the pathologic examination of the brain lesions were associated with increased 42 days mortality (0% vs. 70%, P = 0.01 and 0% vs. 60% in those who survived, P = 0.03, respectively). In multivariate analysis, co-infection at the time of dx was associated with increased mortality (OR: 16.5, 95% CI: 1.4–198.3, P = 0.03) while steroid tapering was associated with decreased mortality (OR: 0.06, 95% CI: 0.01–0.53, P = 0.01). There was a trend towards protective role of surgical drainage (ORn = 0.18, 95% CI = 0.03–1.14, P = 0.07).

Conclusion

CNS IMIs occur in ill patients with active HC who are often pre-exposed to antifungals. Immune response in pathology, steroid tapering and possibly surgical drainage are associated with improved outcome.

Disclosures

D. P. Kontoyiannis, Pfizer: Research Contractor, Research support and Speaker honorarium. Astellas: Research Contractor, Research support and Speaker honorarium. Merck: Honorarium, Speaker honorarium. Cidara: Honorarium, Speaker honorarium. Amplyx: Honorarium, Speaker honorarium. F2G: Honorarium, Speaker honorarium

Influence of the CO2 Quality in the Antioxidant Activity of Rosemary Extracts Dearomatized by Supercritical Fluid Extraction

The effect of the CO2 quality (mainly related to CO2 content) in the antioxidant activity of rosemary extracts deodorized by using a supercritical fluid extraction process is analyzed. A Taguchi experimental design was used to study the influence of the CO2 quality on the antioxidant activity of the rosemary dearomatized extracts. The antioxidant activity of the rosemary extracts obtained in optimal conditions was tested with sunflower oil.

Lateral diffusion, function, and expression of the slow channel congenital myasthenia syndrome αC418W nicotinic receptor mutation with changes in lipid raft components

Lipid rafts, specialized membrane microdomains in the plasma membrane rich in cholesterol and sphingolipids, are hot spots for a number of important cellular processes. The novel nicotinic acetylcholine receptor (nAChR) mutation αC418W, the first lipid-exposed mutation identified in a patient that causes slow channel congenital myasthenia syndrome was shown to be cholesterol-sensitive and to accumulate in microdomains rich in the membrane raft marker protein caveolin-1. The objective of this study is to gain insight into the mechanism by which lateral segregation into specialized raft membrane microdomains regulates the activable pool of nAChRs. We performed fluorescent recovery after photobleaching (FRAP), quantitative RT-PCR, and whole cell patch clamp recordings of GFP-encoding Mus musculus nAChRs transfected into HEK 293 cells to assess the role of cholesterol and caveolin-1 (CAV-1) in the diffusion, expression, and functionality of the nAChR (WT and αC418W). Our findings support the hypothesis that a cholesterol-sensitive nAChR might reside in specialized membrane microdomains that upon cholesterol depletion become disrupted and release the cholesterol-sensitive nAChRs to the pool of activable receptors. In addition, our results in HEK 293 cells show an interdependence between CAV-1 and αC418W that could confer end plates rich in αC418W nAChRs to a susceptibility to changes in cholesterol levels that could cause adverse drug reactions to cholesterol-lowering drugs such as statins. The current work suggests that the interplay between cholesterol and CAV-1 provides the molecular basis for modulating the function and dynamics of the cholesterol-sensitive αC418W nAChR.

Polymorphic ventricular tachycardia and KCNJ2 mutations

We sought to identify the electrophysiologic basis of life-threatening events associated with polymorphic ventricular tachycardia (PVT) in young patients with heterozygous KCNJ2 mutations. PVT describes a beat-to-beat alternating QRS axis and morphology during ventricular tachycardia. PVT may be well tolerated and even asymptomatic in young patients without other heart disease, but an association with syncope, cardiac arrest, or sudden death has long been known. Little is known of the basis of life-threatening events associated with PVT in this setting. We identified heterozygous KCNJ2 mutations (R67W and C101R respectively) in 2 adolescents with PVT (cycle length > 375 ms, < 160 beats/minute). Biophysical properties of wild-type and mutant KCNJ2 channels were characterized during heterologous expression in Xenopus oocytes. Despite a large tachycardia burden, neither patient experienced symptoms during electrocardiographic documentation of PVT. One patient had a history of cardiac arrest, but neither had other evidence of heart disease. Both patients were treated with an implantable cardioverter-defibrillator (ICD). In one patient, ICD interrogation identified rapid ventricular tachycardia (cycle length of 190 to 270 ms), terminated with a single 29-J asynchronous shock, as the cause of 2 syncopal episodes occurring 19 months apart. Biophysical characterization of KCNJ2-C101R demonstrated a loss-of-function and a dominant-negative effect on Kir2.1. Similar effects were previously observed for KCNJ2-R67W. Heterozygous mutations in KCNJ2 can cause life-threatening ventricular arrhythmias. Arrhythmia documented during cardiac arrest is rapid ventricular tachycardia; ICD is effective therapy for cardiac arrest in patients with PVT due to KCNJ2 mutation.

FKBP binding characteristics of cardiac microsomes from diverse vertebrates

FK506 binding protein (FKBP) is a cytosolic receptor for the immunosuppressive drug FK-506. The common isoform, FKBP12, was found to be associated with the calcium release channel (ryanodine receptor 1) of different species of vertebrate skeletal muscle, whereas 12.6, a novel FKBP isoform was found to be associated with canine cardiac ryanodine receptor (ryanodine receptor 2). Until recently, canine cardiac sarcoplasmic reticulum was considered to be the prototype for studying heart RyR2 and its interactions with FKBP. In this study, cardiac microsomes were isolated from diverse vertebrates: human, rabbit, rat, mice, dog, chicken, frog, and fish and were analyzed for their ability to bind or exchange with FKBP isoforms 12 and 12.6. Our studies indicate that RyR2 from seven out of the eight animals contain both FKBP12 and 12.6. Dog is the exception. It can now be concluded that the association of FKBP isoforms with RyR2 is widely conserved in the hearts of different species of vertebrates.

A simple method for isolating human and rabbit polymorphonuclear neutrophils (PMNs)

We report the successful application to human venous blood of a novel method developed to purify rabbit polymorphonuclear neutrophils (PMNs) from whole blood. Human PMNs were separated from whole blood after sedimentation with dextran and histopaque density gradient centrifugation. 3.92 +/- 0.26 x 10(6) PMNs per ml of blood was harvested. The purity of the preparation was 92.00 +/- 1.10%. The PMNs isolated were capable of generating a high amount of reactive oxygen species (ROS) and elastase after stimulation with phorbol 12-myristate 13-acetate (PMA): 13.43 +/- 0.3 microM of O2-, 9.62 +/- 0.15 microM of H2O2 and 5.48 +/- 0.01 microM of elastase. This method gives equivalent yield and viability when applied to isolating human or rabbit PMNs, in comparison with standard methods used to isolate human PMNs. Our method could be usefully exploited for comparative studies of rabbit and human PMNs with a cellular model of inflammatory oxidative stress in which the monitoring parameters are ROS and elastase. Thus, the results of animal (rabbit) studies can be extended to human diseases.

Delocalized TCNQ stacks in nickel and copper tetraazamacrocyclic systems

New derivatives of formula [M(dieneN4)](TCNQ)3, M = Ni or Cu and dieneN4 = cis- or trans-hexamethyltetraazacyclotetradecadiene, have been obtained. The TCNQ units show electronic delocalization and formation of 1D stacks, with no direct interactions with the metal cations. The stack is not uniform and can be seen as formed by trimeric dianions (TCNQ)3(2-). The electronic delocalization favors the conductivity in these materials, which behave as good semiconductors. The crystal structures of the trans derivatives have been solved: [Ni(transdieneN4)](TCNQ)3, triclinic, P-1, a = 8.809(2) A, b = 10.896(2) A, c = 13.727(2) A, alpha = 103.04(1) degrees, beta = 101.23(2) degrees, gamma = 109.37(2) degrees, Z = 1; [Cu(trans-dieneN4)](TCNQ)3: triclinic, P-1, a = 7.872(1) A, b = 9.840(1) A, c = 14.819(1) A, alpha = 92.32(1) degrees, beta = 95.05(1) degrees, gamma = 95.66(1) degrees, Z = 1.

Reduced ammonium chloride haemolysis time enhances the number of isolated functional rabbit polymorphonuclear neutrophils

In the present study we compared seven different methods for isolating rabbit polymorphonuclear neutrophils (PMNs) with a view to assessing viability, lymphocyte contamination and isolation yield. The two methods offering the best isolation yield and functional PMNs were retained. Leukocyte-containing plasma fraction was obtained after erythrocyte sedimentation with dextran. First, PMNs were isolated from this fraction, using hypotonic ammonium chloride haemolysis followed by Histopaque density gradient centrifugation (Method-A). Second, PMNs were obtained from leukocyte-containing plasma after centrifugation on two Percoll layers (Method-B). These processes resulted in a high cellular yield: 2.66x10(6)+/-0.22 PMNs per ml of blood (Method-A) and 1.87x10(6)+/-0.37 PMNs per ml of blood (Method-B). In both cases the PMNs isolated were of high purity and viability. In comparison, when using the standard techniques for rabbit - consisting of ammonium chloride haemolysis taking at least four times as long--fewer PMNs were isolated. The PMNs isolated by Method-A and -B were able to generate a high amount of reactive oxygen species (ROS) after stimulation with phorbol 12-myristate 13-acetate (PMA). These methods to separate PMNs are recommended for in vitro studies.

High-performance liquid chromatographic determination of naltrexone in plasma of hemodialysis patients

A simple, sensitive, selective and reliable reversed-phase high-performance liquid chromatographic (HPLC) method with UV detection is described for the determination of naltrexone in plasma samples. Naltrexone and the internal standard, naloxone, were isolated from plasma either with a liquid-liquid extraction method using ethyl acetate or with a solid-phase extraction method using Sep-Pack C18 cartridge before chromatography. The extracts were dried under a stream of nitrogen and the samples were reconstituted in the mobile phase, then 20 microL were injected on a Waters Symmetry C18 column (5 microm particle size, 4.6 x 150 mm). The mobile phase consisted of 0.06% triethylamine (pH 2.8)-acetonitrile (92:8, v/v) pumped at 1 mL/min. The peak-area ratio versus plasma concentration was linear over the range of 10-500 ng/mL and the detection limit was less than 8 ng/mL. Quantification was by ultra-violet detection at 204 nm. The present method was applied to the determination of the plasma concentration of naltrexone in dialyzed patients. Patients (n = 8) with severe generalized pruritus received 50 mg of naltrexone orally per day for 2 weeks. The variability in the therapeutic response in treated patients required plasma concentration investigations of this opioid antagonist.

Effects of two antihypertensive agents, labetalol and metoprolol, on the production of reactive oxygen species by normal polymorphonuclear leukocytes in vitro

OBJECTIVE

Increased lipid peroxidation is a putative causal factor for preeclampsia. Because oxygen free radicals are involved in inducing the lipid oxidation chain reaction, we evaluated two beta adrenoreceptor blockers, labetalol and metoprolol, currently used for treating hypertension with regard to their ability to inhibit the formation of reactive oxygen species during respiratory burst of human normal polymorphonuclear leukocytes in vitro.

METHODS

We determined whether labetalol or metoprolol have antioxidative activity in a model of polymorphonuclear leukocytes stimulated in vitro with phorbol-12-myristate-13-acetate (PMA) and N-formyl-methionin-leucin-phenylalanin (fMLP). We also studied the scavenging properties of these two drugs using acellular systems.

RESULTS

Labetalol inhibits O2-. production by neutrophils activated by fMLP (IC50 = 17.5 mg/L) and weakly by PMA (43.6% inhibition at 100 mg/L). It also possesses a significant activity on OH. production (IC50 = 65 mg/L) that may depend in part on its ability to interfere with iron in the Fenton reaction. The same assays performed with metoprolol did not show any inhibitory effect on O2.- generation. It decreased weak OH. production by neutrophils, as a result of cellular and scavenging effects.

CONCLUSION

Labetalol shows important antioxidative properties in vitro with regard to normal leukocyte oxidative metabolism.

Serum opioid activity after physical exercise in rats

In order to study the effect of exercise on the total serum opioid activity, female rats were trained for 3 weeks on a motor-driven treadmill and the experiment was ended by a final strenuous run until exhaustion. The serum samples were taken immediately after the final run and were analyzed by radioreceptor assay. Despite considerable interindividual variations, serum opioid activity, expressed in met-enkephalin equivalents (ME eq +/- S.D.), was significantly higher in the exercising group (74.5+/-50.5 pmol ME eq/ml) than in the control group (35.7+/-20.2 pmol ME eq/ml). Because of the much lower molar levels of beta endorphin and met-enkephalin, this result suggests that many other opioid peptides might be involved in that increase.

Evaluation of the effects of Gd complexes used as magnetic resonance imaging contrast agents, on superoxide dismutase: comparison of two methods

Investigations are currently being made into the safety of gadolinium complex contrast agents used in Magnetic Resonance Imaging. Their hyperosmolality or potential Gd3+ release is evoked as a cause of various anaphylactoid reactions to be observed in humans after intravenous injection. An estimation has already been made of their effects on the liberation of reactive oxygen intermediates by neutrophils. The purpose of this study was to find a suitable method to measure SOD activity in the presence of these hyperosmolar solutions, and to evaluate their action on this activity. Two techniques were compared to measure this activity. Results and statistical analysis showed that pyrogallol autoxidation was greatly affected by solution osmolalities, whereas ferricytochrome C reduction was not. Gadopentetate dimeglumine and gadoterate meglumine seemed to activate Cu, Zn SOD in vitro, but did not exhibit any SOD-like activity. Gadodiamide did not interfere with this system of detoxication.

In vitro effects of spiramycin and dirithromycin on IL1 beta production by human LPS-stimulated mononuclear cells

Polymorphonuclear neutrophils are the predominant cells in acute inflammatory lesions and their functions and recruitment are regulated by cytokines, including IL1, TNF and IL8. Antibiotic modulation of inflammatory effects has stimulated investigations of antibiotics for their potential activity as immunomodulators over their primary bactericidal or bacteriostatic activities. This study reports the influence of macrolides, spiramycin and dirithromycin on IL1 beta production. Mononuclear cells, isolated from healthy human volunteers, were preincubated with macrolides (0.1 to 500 micrograms/ml) and stimulated by Escherichia coli lipopolysaccharide. Then, IL1 beta production was detected by western blotting analysis. At therapeutic concentrations, dirithromycin and spiramycin seemed to enhance IL1 beta production by LPS-stimulated cells, with +37 per cent and +28 per cent at 1 microgram/ml respectively. At supratherapeutic concentrations, these drugs seemed to inhibit IL1 beta production through protein kinase C inhibition, with inhibitory concentrations 50 per cent of 378 micrograms/ml for dirithromycin and 234 micrograms/ml for spiramycin. So, macrolides may modulate the host defence system through their influence on cytokine production.

Time and concentration dependent influence of dirithromycin on neutrophils oxidative burst

Dirithromycin is a 14-membered macrolide antibiotic, well known to yield high intragranulocytic levels after several hour exposure. We chose therefore to investigate oxidative metabolism after prolonged incubation periods with neutrophils. Neutrophil generation of reactive oxygen species, represented by superoxide anion, was assessed after fMLP or Staphylococcus aureus-induced activation of the respiratory burst. Cellular uptake of the drug was assessed concurrently, in order to attempt a correlation with time-dependent modifications of the cellular oxidative status. For 1 hour exposure time, a pro-oxidant effect was reported for lower concentrations, achievable during therapeutic administration, whereas the highest ones promoted a potent anti-oxidant effect. After prolonged incubation times, the anti-oxidant effect alone was reported, with time-dependent modifications of IC50 values. These values could be correlated with intracellular accumulation of the drug. The anti-inflammatory activity reported here for high dirithromycin concentrations, could be nevertheless clinically relevant, since dirithromycin cellular uptake extends beyond 4 hours.

In vitro activity of aminoglycosides on the respiratory burst response in human polymorphonuclear neutrophils

In response to phagocytosis of microbes or chemical stimuli, neutrophils generate reactive oxygen species which represent the major bactericidal mechanism of these cells. We have investigated the influence of aminoglycosides (amikacin, gentamicin, netilmicin and tobramycin), antibiotics with a marked concentration-dependent killing effect, on the human neutrophil oxidative burst represented by the release of hydrogen peroxide. This study was performed using time-dependent cellular experiments and a cell-free system. In the cellular model, 2-h incubation with amikacin (ranging from 10 mg/l to 1 g/l), enhanced hydrogen peroxide release by stimulated human neutrophils. At higher concentrations (1 to 5 g/l), hydrogen peroxide production was decreased. No significant effects were observed with the other aminoglycosides at concentrations ranging from 10 mg/l to 2.5 g/l. The pro-oxidant activity of amikacin may be due to a cellular mechanism through oxidative metabolism of human neutrophils as demonstrated in the cell washing experiment, whereas the antioxidant activity observed for higher concentrations may be a result of a scavenging effect as demonstrated in the cell-free system. The enhanced of hydrogen peroxide production observed for therapeutic concentrations of amikacin could be a beneficial effect for neutrophil bactericidal functions.

Stability study of fotemustine in PVC infusion bags and sets under various conditions using a stability-indicating high-performance liquid chromatographic assay

The stability and compatibility of fotemustine, a nitrosourea anticancer agent, in 5% dextrose solution with polyvinyl chloride (PVC) containers and administration sets were studied under different conditions of temperature and light. The drug was diluted to 0.8 and 2 mg ml(-1) in 100 or 250 ml 5% dextrose injection solutions for 1-h simulated infusions using PVC bags and administration sets with protection from light. After preparation in the PVC bags containing 5% dextrose, fotemustine was also prepared at the same concentrations and stored at 4 degrees C for 48 h and at room temperature (22 degrees C) or at sunray exposure ( > 30 degrees C) over 8 h with or without protection from light. The solution samples were removed immediately at various time points of simulated infusions and storage, and stored at -20 degrees C until analysis. The physical compatibility with PVC and chemical stability in solution of fotemustine were assessed by visual examination and by measuring the concentration of the drug in duplicate using a stability-indicating high-performance chromatographic assay. When admixed with a 5% dextrose solution, fotemustine 2 and 0.8 mg ml(-1) was compatible and stable over 1-h of simulated infusion using PVC bags through PVC administration sets with protection from light. On the other hand, in the same diluent, fotemustine was compatible and stable with PVC bags for at least 8 h at 22 degrees C with protection from light and for at least 48 h at 4 degrees C with protection from light. There were no pH variation, no visual change, no color change, no visible precipitation and no loss of the drug. Conversely, when the solutions were exposed to light (ambient or solar), the drug concentration decreased rapidly, leading to the production of a degradation product as shown by mass spectral analysis and a discoloration of the solutions. Finally, in all cases, no DEHP (di-2-ethylhexyl phthalate) was detected in the injection solution.

Determination of cyclohexamone after derivatization with 2,4-dinitrophenyl hydrazine in intravenous solutions stored in PVC bags by high performance liquid chromatography

A high performance liquid chromatographic procedure is described for the determination of cyclohexanone leached in intravenous solutions from the poly(vinyl chloride) bags. After derivatization with 2,4-dinitrophenylhydrazine and extraction with pentane, the cyclohexanone derivative was analysed on a C18 BDS Hypersil column using mobile phase mixture of acetonitrile:water (55:45). Ultra-violet detection was performed at 368 nm. The limit of quantification was 30 ng/mL and the assay was linear from 0.05 to 50 micrograms/mL. The recovery was better than 95%. The proposed method is satisfactory in its accuracy and precision with particularly relative standard deviations (RSD) for intra-assay and inter-assay of below 10%. This method has been successfully used for the determination of cyclohexanone in aqueous solutions such as sodium chloride (0.9%) and glucose (5%) stored in PVC containers. The values obtained varied between 2.04 and 44.9 micrograms/mL according to solutions and volume.

Verapamil inhibits elastase release and superoxide anion production in human neutrophils

In response to activation of phagocytic cells and during inflammatory disorders, some proteases and very reactive oxygen species are produced. These proteases and oxidants are involved in many diseases like tissue injury or atherosclerosis. We have shown in vitro that verapamil, a calcium channel blocker, had antielastase and antioxidant properties. This drug inhibited the release of elastase by neutrophils in a dose-dependent manner when these cells were stimulated by phorbol-myristate-acetate (PMA), by N-formyl-methionyl-leucylphenylalanine (fMLP) and by the calcium ionophore A23187 (Ca.I). In addition, verapamil inhibited superoxide anion when human neutrophils were stimulated by PMA, fMLP, dioctanoylglycerol (DiC8), Ca.I or by opsonised zymosan (OZ). Verapamil did not act by scavenging elastase or oxidants as demonstrated in cell-free models which showed no direct antielastase or antioxidant effect involved by verapamil. Superoxide anion and elastase inhibition by verapamil has been considered to the mobilization of cytosolic calcium and inhibition of protein kinase C. The results suggest that verapamil might contribute help the development and progression of atheroma where oxidants and elastase are involved.

Dearomatization of Antioxidant Rosemary Extracts by Treatment with Supercritical Carbon Dioxide

Treatment with supercritical CO(2) is proposed for deodorizing antioxidant rosemary extracts obtained by steam distillation and Soxhlet extraction. The process conditions have been optimized by applying a Taguchi experimental design with the aim of obtaining, at minimum cost, a product with acceptable antioxidant activity as well as minimum rosemary aroma. Variables were selected for their effects on the selective extraction of the compounds responsible for the residual aroma of the rosemary extract. The optimized method allowed 90% dearomatization; no detrimental effects in antioxidant activity or color of the extracts have been observed after supercritical fluid processing.

[Value of esophageal manometry with the methylergometrin maleate test in angina with normal coronarography. The concept of esophageal angina]

22 patients presenting an "angina with normal coronarography" and 5 control subjects were subjected to a manometric exploration of the oesophagus in the basal state and under methylergometrine maleate (MEM) treatment. The MEM test is shown to be a good one for the induction of painful oesophageal dyskinesias, particularly in patients who had suffered in an inexplicable manner when that substance was administered for coronarography.