Advanced breast conservation and partial breast reconstruction - a review of current available options for oncoplastic breast surgery

Breast cancer is the most common cancer affecting one in three women with new cancer diagnosis in England. Breast-conserving surgery is the primary surgical option in a vast majority of these patients. Use of oncoplastic techniques in breast conservation surgery has significantly improved the aesthetic outcomes without compromising the oncological safety of cancer resections. Oncoplastic breast-conserving surgery (OPBCS) has transformed the specialty with a paradigm shift in ideology and the recognition that aesthetic and oncological resections are synonymous when planning surgical intervention for patients with breast cancer. The two main options for OPBCS are therapeutic mammoplasty and partial beast reconstruction using pedicle-based flaps. This review aims to highlight key concepts in OPBCS demonstrating an overview of these surgical techniques, their safety, outcomes and the emergence of extreme oncoplastic breast surgery.

Clinical frailty and its effect on the septuagenarian population after emergency laparotomy

INTRODUCTION

The UK has an ageing population with an increased prevalence of frailty in the over 70s. Emergency laparotomy for acute intra-abdominal pathology is increasingly offered to this population. This can challenge decision making and information given to patients should not only be based on mortality outcomes but on relative expected quality of life and change to frailty syndromes.

MATERIALS AND METHODS

This was a single site National Emergency Laparotomy Audit (NELA)-based retrospective cohort audit for consecutive cases in the septuagenarian population assessing mortality, length of stay outcome and subjective postoperative functioning. Follow-up was conducted between one and two years postoperatively to determine this.

RESULTS

Some 153 patients were identified throughout the single site NELA database. Median age was 79 years with a ratio of 1.7 men to women. Median rate of all-cause mortality was 35.3% at the median follow-up of 19 months. Median time from admission to death was 120 days. Of those who had died by the time of follow-up, significant preoperative indicators included clinical frailty scale (p < 0.0001), preoperative P-POSSUM (mortality). At follow-up, 35% responded to a quality of life follow-up. This revealed a decline in mid-term physical functioning, lower energy, higher fatigue and reduction in social functioning. There was also an increase in pre- and postoperative clinical frailty scale score.

CONCLUSION

In the septuagenarian-plus population it is important to consider not only risk stratification with mortality scoring (P-POSSUM or NELA-adjusted risk), but to take into account frailty. Postoperative rehabilitation and careful recovery is paramount. Where possible, during the counselling and consent for emergency laparotomy, significant postoperative long-term deterioration in physical, emotional and social function should be considered.

Determination of Pesticide Residues in Foods by Acetonitrile Extraction and Partitioning with Magnesium Sulfate: Collaborative Study

A collaborative study was conducted to determine multiple pesticide residues in fruits and vegetables using a quick, simple, inexpensive, and effective sample preparation method followed by concurrent analysis with gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). For short, the method is known as QuEChERS, which stands for quick, easy, cheap, effective, rugged, and safe. Twenty representative pesticides were fortified in 3 matrixes (grapes, lettuces, and oranges) at 3 duplicate levels unknown to the collaborators ranging from 10 to 1000 ng/g. Additionally, 8 incurred pesticide residues were determined. Thirteen laboratories from 7 countries provided results in the study, and a variety of different instruments were used by collaborators. The QuEChERS procedure simply entails 3 main steps: (1) a 15 g homogenized sample is weighed into a 50 mL centrifuge tube to which 15 mL acetonitrile containing 1 HOAc is added along with 6 g MgSO4 and 1.5 g NaOAc, and the tube is shaken and centrifuged; (2) a portion of the extract is mixed with 3 + 1 (w/w) MgSO4primary secondary amine sorbent (200 mg/mL extract) and centrifuged; and (3) the final extract is analyzed by GC/MS and LC/MS/MS. To detect residues &lt;10 ng/g in GC/MS, large-volume injection of 8 L is typically needed, or the extract can be concentrated to 4 g/mL in toluene, in which case 2 L splitless injection is used. In the study, the averaged results for data from 713 laboratories (not using internal standardization) for the 18 blind duplicates at the 9 spiking levels in the 3 matrixes are as follows [%recovery and reproducibility relative standard deviation (RSDR, %)]: atrazine, 92 (18); azoxystrobin, 93 (15); bifenthrin, 90 (16); carbaryl, 96 (20); chlorothalonil, 70 (34); chlorpyrifos, 89 (25); cyprodinil, 89 (19); o, p-DDD, 89 (18); dichlorvos, 82 (21); endosulfan sulfate, 80 (27); imazalil, 77 (33); imidacloprid, 96 (16); linuron, 89 (19);methamidophos, 87 (17); methomyl, 96 (17); procymidone, 91 (20); pymetrozine, 69 (19); tebuconazole, 89 (15); tolylfluanid (in grapes and oranges), 68 (33); and trifluralin, 85 (20). For incurred pesticides, kresoxim-methyl (9.2 3.2 ng/g) and cyprodinil (112 18) were found in the grapes; permethrins (112 41), -cyhalothrin (58 11), and imidacloprid (12 2) were determined in the lettuces; and ethion (198 36), thiabendazole (53 8), and imazalil (13 4) were determined in the oranges. Chlorpyrifosmethyl (200 ng/g) was used as a quality control standard added during sample homogenization and yielded 86% recovery and 19% RSDR. Intralaboratory repeatabilities for the method averaged 9.8% RSD for all analytes. The results demonstrate that the method is fit-for- purpose to monitor many pesticide residues in fruits and vegetables, and the Study Director recommends that it be adopted Official First Action.

Determination of Chlormequat and Mepiquat in Foods by Liquid Chromatography/Mass Spectrometry or Liquid Chromatography/Tandem Mass Spectrometry: Interlaboratory Study

Interlaboratory validation studies have been performed on 2 methods for the determination of chlormequat (CLQ) and mepiquat (MPQ). Both methods used identical extraction procedures and stable isotope internal standardization but differed in the use of liquid chromatography/mass spectrometry (LC/MS) or LC/tandem mass spectrometry (LC/MS/MS) for the determination, the amount of internal standard used, and the expected limit of detection. After addition of deuterated internal standards, CLQ and MPQ were extracted with methanol–water and determined by LC/MS or LC/MS/MS with positive electrospray ionization. Eight European laboratories participated in the LC/MS method study, analyzing mushroom, pear, wheat flour, and fruit puree with residues of CLQ in the range 0.040–1.19 mg/kg and of MPQ in the range 0.041–0.39 mg/kg. For CLQ, the Horwitz ratio (HoRat) values for individual test materials/levels were in the range 0.85–1.13 with amean of 1.00, showing good method performance. For MPQ, the Ho values for mushroom, pear (both levels), and wheat flour were in the range 0.83–0.94, again indicating good method performance. For the determination of MPQ in infant food (fruit puree) at 0.041 mg/kg, the Ho was 1.7 when a value of 0 reported by one participant was excluded. In the LC/MS/MS study, in which 11 laboratories participated, a separate sample set was analyzed with residues of CLQ in the range 0.007–1.03 mg/kg and of MPQ in the range 0.008–0.72 mg/kg. Ho values for CLQ were in the range 0.27–1.36 and for MPQ in the range 0.51–2.10, all corresponding to acceptable method performance.

Applicability of Gradient Liquid Chromatography with Tandem Mass Spectrometry to the Simultaneous Screening for About 100 Pesticides in Crops

A method was developed for screening crops for a range of pesticide residues by liquid chromatography/tandem mass spectrometry (LC/MS/MS). A complete set of LC, electrospray ionization (ESI), and tandem MS acquisition parameters was established for the determination of 108 analytes; these parameters were used for the simultaneous acquisition of 98 analytes in the positive ESI mode and 10 analytes in an additional MS/MS method in the negative ESI mode. The entire procedure involves extraction of residues with methanol–water and partition into dichloromethane. The utility of the method is demonstrated by the analysis of crops of 5 matrix types (water-containing, acidic, dry, sugar-containing, and fatty). Of 108 pesticides/metabolites tested, 104 showed sufficient stability in most matrixes for determination by LC/MS/MS. These analytes belong to 20 chemical classes, which demonstrate the general applicability of the method for multiclass analysis. By using matrix-matched standards, 67 compounds could be determined in most matrixes with recoveries of 70–120% and a relative standard deviation of ≤25% at the 0.01 mg/kg level.

Estimation of Measurement Uncertainty in Pesticide Residue Analysis

Proficiency test results from 5 countries involving 61 separate interlaboratory proficiency tests for pesticide residues were examined in this study. A total of 24 different matrixes and 869 relative standard deviations of the mean (or median) pesticide residue concentration were statistically evaluated in relation to the Horwitz function. The aim was to determine whether or not the concentration-dependent relationship described by Horwitz would hold for the much narrower range of chemicals and concentrations covered in routine pesticide residue analysis. Although for fatty (animal-derived) matrixes the variability increased as the concentration decreased in line with the Horwitz equation, the between-laboratories relative standard deviations for nonfatty matrixes (fruit, vegetables, and grain) remained at 25% over the entire concentration range of 1 μg/kg to 10 mg/kg for the pesticides studied. Given these findings, the Horwitz equation remains valid for calculating uncertainties involving pesticide residues in fatty matrixes. However, for pesticide residue analyses involving nonfatty matrixes, a constant relative standard deviation of 25% is more appropriate for calculating uncertainties, particularly when a reported result is assessed against a regulatory limit.

Development of a QuEChERS-Based Method for the Simultaneous Determination of Acidic Pesticides, Their Esters, and Conjugates Following Alkaline Hydrolysis

An analytical procedure was developed allowing the simultaneous determination of acidic pesticides and their conjugates by addition of an alkaline hydrolysis step into the European Union (EU) version of the QuEChERS method. The procedure resulted additionally in hydrolysis of most esters of phenoxy acids. On the basis of information from metabolism studies and the hydrolytic conditions employed in supervised field trials as well as results on the influence of physical and chemical parameters (temperature, time, type of solvent, type of matrix), alkaline hydrolysis for 30 min at 40 °C was deemed a good compromise for the determination of residues of 2,4-D, dichlorprop, fluazifop, haloxyfop, MCPA, and MCPB. The applicability of the proposed method was tested by analyzing food samples with incurred residues in six German laboratories not involved in method development. Up to 6 times higher residues are measured by using the QuEChERS extraction procedure with the newly developed alkaline hydrolysis step.

Determination of Glyphosate Levels in Breast Milk Samples from Germany by LC-MS/MS and GC-MS/MS

This study describes the validation and application of two independent analytical methods for the determination of glyphosate in breast milk. They are based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS), respectively. For LC-MS/MS, sample preparation involved an ultrafiltration followed by chromatography on an anion exchange column. The analysis by GC-MS/MS involved an extraction step, cleanup on a cation exchange column, and derivatization with heptafluorobutanol and trifluoroacetic acid anhydride. Both methods were newly developed for breast milk and are able to quantify glyphosate residues at concentrations as low as 1 ng/mL. The methods were applied to quantify glyphosate levels in 114 breast milk samples, which had been collected from August to September of 2015 in Germany. The mothers participated at their own request and thus do not form a representative sample. In none of the investigated samples were glyphosate residues above the limit of detection found.

Emerging pesticide metabolites in groundwater and surface water as determined by the application of a multimethod for 150 pesticide metabolites

A recently developed multimethod for the determination of 150 pesticide metabolites was exemplarily applied to 58 samples of groundwater and surface water. 37 of these metabolites were detected in at least two samples with a concentration ≥0.025 μg/L. The detected metabolites were ranked according to their concentration and frequency of detection. Findings are clearly dominated by metabolites of chloroacetanilide herbicides, but metabolites of sulfonylurea and thiocarbamate herbicides and other herbicides (dichlobenil) together with metabolites of some fungicides (tolylfluanid, chlorothalonil, trifloxystrobin) were also prominent. A number of 17 of the ranked metabolites are denoted as emerging metabolites because no reports on their previous detection in groundwater or surface water were found. Most of them, however, were correctly predicted to occur in the summary reports of the European pesticide approval process. Median total concentrations of the analysed pesticide metabolites summed up to 0.62 μg/L in groundwater and 0.33 μg/L in surface waters. While the concentration of the individual metabolites is usually low (<0.1 μg/L) the diversity of metabolites found in one sample can be large; between two and six metabolites were detected most frequently (maximum of 12 metabolites). Runoff from urban surfaces was investigated in this study and also here previously undetected pesticide (biocide) metabolites were detected. The emerging pesticide metabolites detected in environmental water samples in this study require more extended monitoring.

The influence of electrospray ion source design on matrix effects

This study investigates to which extent the design of electrospray ion sources influences the susceptibility to matrix effects (MEs) in liquid chromatography-tandem mass spectrometry (LC-MS/MS). For this purpose, MEs were measured under comparable conditions (identical sample extracts, identical LC column, same chromatographic method and always positive ion mode) on four LC-MS/MS instrument platforms. The instruments were combined with five electrospray ion sources, viz. Turbo Ion Spray, Turbo V(TM) Source, Standard ESI, Jet Stream ESI and Standard Z-Spray Source. The comparison of MEs could be made at all retention times because the method of permanent postcolumn infusion was applied. The MEs ascertained for 45 pesticides showed for each electrospray ion source the same pattern, i.e. the same number of characteristic signal suppressions at equivalent retention times in the chromatogram. The Turbo Ion Spray (off-axis geometry), Turbo V(TM) Source (orthogonal geometry) and the Standard Z-Spray Source (double orthogonal geometry) did not differ much in their susceptibility to MEs. The Jet Stream ESI (orthogonal geometry) reaches a higher sensitivity by an additional heated sheath gas, but suffers at the same time from significantly stronger signal suppressions than the comparable Standard ESI (orthogonal geometry) without sheath gas. No relation between source geometry and extent of signal suppression was found in this study.

Suitability of an orbitrap mass spectrometer for the screening of pesticide residues in extracts of fruits and vegetables

For about 500 pesticides, the sensitivity of a benchtop high-resolution mass spectrometer using the Orbitrap for mass separation was compared to that of a widely used (low-resolution) tandem mass spectrometer. Both instruments were coupled to LC and used electrospray ionization. The selectivity of the Orbitrap in the full-scan acquisition mode without fragmentation was evaluated at a resolution of 100 000 full width at half maximum for all pesticides detectable with sufficient sensitivity. For this purpose, quasimolecular ions were extracted within 5 ppm windows from total ion chromatograms of two types of extracts of cucumber, lemon, wheat flour, raisin, and tea. In each of the obtained reconstructed ion chromatograms (individual chromatograms for 500 pesticides, each pesticide in 10 different extracts) the sum of signals not arising from the analyte was used to get a measure on selectivity. In addition, the target analyte list was checked for ions of similar mass. The influence of matrix on the ability to detect low concentrations of fortified pesticides was also studied, with the help of spiked extracts. This part of the survey tested whether analyte peaks were lost because of insufficient mass resolution or an early closing C-Trap (used to control the ion current into the Orbitrap). Finally, the stability of the ion ratio [M+H]+/[M+Na]+ was tested, which may be helpful to confirm the identity of an analyte.

Targeted pesticide residue analysis using triple Quad LC-MS/MS

The determination of pesticide residues by HPLC-MS/MS requires decisions on a multitude of analytical parameters. This includes the selection of eluents, columns and ion sources, but also the optimization of the tandem mass spectrometer for the selected target analytes. Another aspect is the use of the restricted acquisition time between two chromatographic data points. An appropriate selection of all these parameters as well as the measures to avoid interference by cross talks and wrong quantitative results by matrix effects is discussed in this chapter.

Compensation of matrix effects by postcolumn infusion of a monitor substance in multiresidue analysis with LC-MS/MS

This study systematically compares matrix effects in liquid chromatography (LC) coupled by electrospray ionization (ESI) in the positive mode with tandem mass spectrometry (MS/MS) for 129 pesticides in 20 plant matrixes. In total, 2388 analyte/matrix combinations were evaluated. Permanent postcolumn infusion (PCI) of analyte standards was used to quantify matrix effects over the whole chromatographic run time. This allowed the analyte signal suppression or enhancement, by different coeluting matrix components, to be assessed throughout the duration of an entire chromatographic run, i.e., independent of a specific retention time. Matrix effects occurring at a certain retention time in one matrix were surprisingly similar for different analytes with diverse physicochemical properties. On the basis of this finding, a new approach for matrix effect compensation in multiresidue analysis was developed in which one single monitor substance is permanently added postcolumn. Signal intensities of all analytes obtained by LC-MS/MS analysis of sample extracts are then corrected for the matrix effect recorded by the monitor substance. With the use of this approach, strong matrix effects could be reduced and apparent recoveries increased from 45% to 85% on average. With dependence on the particular sample matrix, between 69% and 100% of the analytes showed recoveries between 60% and 140% after correction. Thus this approach may significantly reduce the number of cases in which standard addition is required to confirm violations of maximum residue levels.

Residue analysis of 500 high priority pesticides: better by GC-MS or LC-MS/MS?

This overview evaluates the capabilities of mass spectrometry (MS) in combination with gas chromatography (GC) and liquid chromatography (LC) for the determination of a multitude of pesticides. The selection of pesticides for this assessment is based on the status of production, the existence of regulations on maximum residue levels in food, and the frequency of residue detection. GC-MS with electron impact (EI) ionization and the combination of LC with tandem mass spectrometers (LC-MS/MS) using electrospray ionization (ESI) are identified as techniques most often applied in multi-residue methods for pesticides at present. Therefore, applicability and sensitivity obtained with GC-EI-MS and LC-ESI-MS/MS is individually compared for each of the selected pesticides. Only for one substance class only, the organochlorine pesticides, GC-MS achieves better performance. For all other classes of pesticides, the assessment shows a wider scope and better sensitivity if detection is based on LC-MS.

Determination of chlormequat and mepiquat in foods by liquid chromatography/mass spectrometry or liquid chromatography/tandem mass spectrometry: interlaboratory study

Interlaboratory validation studies have been performed on 2 methods for the determination of chlormequat (CLQ) and mepiquat (MPQ). Both methods used identical extraction procedures and stable isotope internal standardization but differed in the use of liquid chromatography/mass spectrometry (LC/MS) or LC/tandem mass spectrometry (LC/MS/MS) for the determination, the amount of internal standard used, and the expected limit of detection. After addition of deuterated internal standards, CLQ and MPQ were extracted with methanol-water and determined by LC//MS or LC/MS/MS with positive electrospray ionization. Eight European laboratories participated in the LC/MS method study, analyzing mushroom, pear, wheat flour, and fruit puree with residues of CLQ in the range 0.040-1.19 mg/kg and of MPQ in the range 0.041-0.39 mg/kg. For CLQ, the Horwitz ratio (HoRat) values for individual test materials/levels were in the range 0.85-1.13 with a mean of 1.00, showing good method performance. For MPQ, the Ho values for mushroom, pear (both levels), and wheat flour were in the range 0.83-0.94, again indicating good method performance. For the determination of MPQ in infant food (fruit puree) at 0.041 mg/kg, the Ho was 1.7 when a value of 0 reported by one participant was excluded. In the LC/MS/MS study, in which 11 laboratories participated, a separate sample set was analyzed with residues of CLQ in the range 0.007-1.03 mg/kg and of MPQ in the range 0.008-0.72 mg/kg. Ho values for CLQ were in the range 0.27-1.36 and for MPQ in the range 0.51-2.10, all corresponding to acceptable method performance.

The ECHO technique--the more effective way of data evaluation in liquid chromatography-tandem mass spectrometry analysis

The aim of this study was to evaluate the applicability of ECHO technique in pesticide residue analysis using LC/MS/MS instruments with atmospheric pressure chemical (APCI) and electrospray (ESI) ionization. The technique is based on simultaneous injections of reference standards and samples in one run. First and second injections are made ahead and behind a precolumn, respectively, thus resulting in a short difference of retention times between standard and sample peak. The obtained couple of peaks were applied to the easy detection of pesticides and simultaneous estimation of the residue content in real samples in a single run. If residues were not observed, the second sample peak did not occur and the ECHO peaks were used to demonstrate instrument performance in each run and for each analyte. Another advantage of ECHO technique is its potential to compensate matrix effects. The occurrence and compensation of matrix effects using APCI was tested with four matrix types (water containing, acidic, dry and sugar containing) and 22 pesticides. The same matrix types but 58 pesticides were used tests with electrospray ionization. Most often matrix effects had been observed with lemon. The percentage of pesticides showing significant matrix effects did not differ between APCI and ESI. But these effects caused signal enhancement in APCI measurements and signal suppression, when ESI was used. The ECHO technique was able to compensate many matrix effects in measurements with both types of ion sources.

Applicability of gradient liquid chromatography with tandem mass spectrometry to the simultaneous screening for about 100 pesticides in crops

A method was developed for screening crops for a range of pesticide residues by liquid chromatography/tandem mass spectrometry (LC/MS/MS). A complete set of LC, electrospray ionization (ESI), and tandem MS acquisition parameters was established for the determination of 108 analytes; these parameters were used for the simultaneous acquisition of 98 analytes in the positive ESI mode and 10 analytes in an additional MS/MS method in the negative ESI mode. The entire procedure involves extraction of residues with methanol-water and partition into dichloromethane. The utility of the method is demonstrated by the analysis of crops of 5 matrix types (water-containing, acidic, dry, sugar-containing, and fatty). Of 108 pesticides/metabolites tested, 104 showed sufficient stability in most matrixes for determination by LC/MS/MS. These analytes belong to 20 chemical classes, which demonstrate the general applicability of the method for multiclass analysis. By using matrix-matched standards, 67 compounds could be determined in most matrixes with recoveries of 70-120% and a relative standard deviation of < or = 25% at the 0.01 mg/kg level.

Estimation of measurement uncertainty in pesticide residue analysis

Proficiency test results from 5 countries involving 61 separate interlaboratory proficiency tests for pesticide residues were examined in this study. A total of 24 different matrixes and 869 relative standard deviations of the mean (or median) pesticide residue concentration were statistically evaluated in relation to the Horwitz function. The aim was to determine whether or not the concentration-dependent relationship described by Horwitz would hold for the much narrower range of chemicals and concentrations covered in routine pesticide residue analysis. Although for fatty (animal-derived) matrixes the variability increased as the concentration decreased in line with the Horwitz equation, the between-laboratories relative standard deviations for nonfatty matrixes (fruit, vegetables, and grain) remained at 25% over the entire concentration range of 1 microg/kg to 10 mg/kg for the pesticides studied. Given these findings, the Horwitz equation remains valid for calculating uncertainties involving pesticide residues in fatty matrixes. However, for pesticide residue analyses involving nonfatty matrixes, a constant relative standard deviation of 25% is more appropriate for calculating uncertainties, particularly when a reported result is assessed against a regulatory limit.

Effect of alpha subunit on allosteric modulation of ion channel function in stably expressed human recombinant gamma-aminobutyric acid(A) receptors determined using (36)Cl ion flux

Inhibitory gamma-aminobutyric acid (GABA)(A) receptors are subject to modulation at a variety of allosteric sites, with pharmacology dependent on receptor subunit combination. The influence of different alpha subunits in combination with beta3gamma2s was examined in stably expressed human recombinant GABA(A) receptors by measuring (36)Cl influx through the ion channel pore. Muscimol and GABA exhibited similar maximal efficacy at each receptor subtype, although muscimol was more potent, with responses blocked by picrotoxin and bicuculline. Receptors containing the alpha3 subunit exhibited slightly lower potency. The comparative pharmacology of a range of benzodiazepine site ligands was examined, revealing a range of intrinsic efficacies at different receptor subtypes. Of the diazepam-sensitive GABA(A) receptors (alpha1, alpha2, alpha3, alpha5), alpha5 showed the most divergence, being discriminated by zolpidem in terms of very low affinity, and CL218,872 and CGS9895 with different efficacies. Benzodiazepine potentiation at alpha3beta3gamma2s with nonselective agonist chlordiazepoxide was greater than at alpha1, alpha2, or alpha5 (P < 0.001). The presence of an alpha4 subunit conferred a unique pharmacological profile. The partial agonist bretazenil was the most efficacious benzodiazepine, despite lower alpha4 affinity, and FG8205 displayed similar efficacy. Most striking were the lack of affinity/efficacy for classical benzodiazepines and the relatively high efficacy of Ro15-1788 (53 +/- 12%), CGS8216 (56 +/- 6%), CGS9895 (65 +/- 6%), and the weak partial inverse agonist Ro15-4513 (87 +/- 5%). Each receptor subtype was modulated by pentobarbital, loreclezole, and 5alpha-pregnan-3alpha-ol-20-one, but the type of alpha subunit influenced the level of potentiation. The maximal pentobarbital response was significantly greater at alpha4beta3gamma2s (226 +/- 10% increase in the EC(20) response to GABA) than any other modulator. The rank order of potentiation for pregnanolone was alpha5 > alpha2 > alpha3 = alpha4 > alpha1, for loreclezole alpha1 = alpha2 = alpha3 > alpha5 > alpha4, and for pentobarbital alpha4 = alpha5 = alpha2 > alpha1 = alpha3.

Identification and characterization of A-105972, an antineoplastic agent

A high-throughput screening assay was designed to select compounds that inhibit the growth of cultured mammalian cells. After screening more than 60,000 compounds, A-105972 was identified and selected for further testing. A-105972 is a small molecule that inhibits the growth of breast, central nervous system, colon, liver, lung, and prostate cancer cell lines, including multidrug-resistant cells. The cytotoxic IC50 values of A-105972 were between 20 and 200 nM, depending on the specific cell type. The potency of A-105972 is similar in cells expressing wild-type or mutant p53. A majority of cells treated with A-105972 were trapped in the G2-M phases, suggesting that A-105972 inhibits the progression of the cell cycle. Using [3H]A-105972, we found that A-105972 bound to purified tubulin. Unlabeled A-105972 competed with [3H]A-105972 binding with an IC50 value of 3.6 microL. Colchicine partially inhibited [3H]A-105972 binding with an IC50 value of approximately 90 microM, whereas paclitaxel and vinblastine had no significant effect. Tumor cells treated with A-105972 were observed to contain abnormal microtubule arrangement and apoptotic bodies. DNA ladder studies also indicated that A-105972 induced apoptosis. A-105972 caused a mobility shift of bcl-2 on SDS-PAGE, suggesting that A-105972 induced bcl-2 phosphorylation. A-105972 treatment increased the life span of mice inoculated with B16 melanoma, P388 leukemia, and Adriamycin-resistant P388. These results suggest that A-105972 is a small molecule that interacts with microtubules, arrests cells in G2-M phases, and induces apoptosis in both multidrug resistance-negative and multidrug resistance-positive cancer cells. A-105972 and its analogues may be useful for treating cell proliferative disorders such as cancer.

Gamma-aminobutyric acid type B receptors with specific heterodimer composition and postsynaptic actions in hippocampal neurons are targets of anticonvulsant gabapentin action

Gamma-aminobutyric acid (GABA) activates two qualitatively different inhibitory mechanisms through ionotropic GABA(A) multisubunit chloride channel receptors and metabotropic GABA(B) G protein-coupled receptors. Evidence suggests that pharmacologically distinct GABA(B) receptor subtypes mediate presynaptic inhibition of neurotransmitter release by reducing Ca2+ conductance, and postsynaptic inhibition of neuronal excitability by activating inwardly rectifying K+ (Kir) conductance. However, the cloning of GABA(B) gb1 and gb2 receptor genes and identification of the functional GABA(B) gb1-gb2 receptor heterodimer have so far failed to substantiate the existence of pharmacologically distinct receptor subtypes. The anticonvulsant, antihyperalgesic, and anxiolytic agent gabapentin (Neurontin) is a 3-alkylated GABA analog with an unknown mechanism of action. Here we report that gabapentin is an agonist at the GABA(B) gb1a-gb2 heterodimer coupled to Kir 3.1/3.2 inwardly rectifying K+ channels in Xenopus laevis oocytes. Gabapentin was practically inactive at the human gb1b-gb2 heterodimer, a novel human gb1c-gb2 heterodimer and did not block GABA agonism at these heterodimer subtypes. Gabapentin was not an agonist at recombinant GABA(A) receptors as well. In CA1 pyramidal neurons of rat hippocampal slices, gabapentin activated postsynaptic K+ currents, probably via the gb1a-gb2 heterodimer coupled to inward rectifiers, but did not presynaptically depress monosynaptic GABA(A) inhibitory postsynaptic currents. Gabapentin is the first GABA(B) receptor subtype-selective agonist identified providing proof of pharmacologically and physiologically distinct receptor subtypes. This selective agonism of postsynaptic GABA(B) receptor subtypes by gabapentin in hippocampal neurons may be its key therapeutic advantage as an anticonvulsant.

Determination of Q1, an unknown organochlorine contaminant, in human milk, Antarctic air, and further environmental samples

Q1, an organochlorine component with the molecular formula C(9)H(3)Cl(7)N(2) and of unknown origin was recently identified in seal blubber samples from the Namibian coast (southwest of Africa) and the Antarctic. In these samples, Q1 was more abundant than PCBs and on the level of DDT residues. Furthermore, Q1 was more abundant in seals from the Antarctic than the Arctic. To prove this assumption, gas chromatography-electron-capture negative ion mass spectrometry (GC/ECNI-MS), which is sensitive and selective for Q1, allowed for screening of traces of Q1 even in samples with particularly high levels of other organochlorine contaminants. Q1 was isolated by high-performance liquid chromatography (HPLC) from a skua liver sample. A 1:1 mixture with trans-nonachlor in electron-capture detectors (ECDs) was used to determine the relative response factor with ECNI-MS. The ECNI-MS response of Q1 turned out to be 4.5 times higher than that of trans-nonachlor in an ECD. With GC/ECNI-MS in the selected ion-monitoring mode, four Antarctic and four Arctic air samples were investigated for the presence of Q1. In the Antarctic air samples, Q1 levels ranged from 0.7 to 0.9 fg/m(3). In Arctic air samples, however, Q1 was below the detection limit (<0.06 fg/m(3) or 60 ag/m(3)). We also report on high Q1 levels in selected human milk samples (12-230 microg/kg lipid) and, therefore, suggested that the unknown Q1 is an environmental compound whose origin and distribution should be investigated in detail. Our data confirm that Q1 is a bioaccumulative natural organochlorine product. Detection of a highly chlorinated natural organochlorine compound in air and human milk is novel.

Reasons for the decomposition of the fungicide thiram during preparation of fruit and vegetable samples and consequences for residue analysis

The concentration of thiram in aqueous solution decreases by 50-75% within 20 min in the presence of cut pieces of apple, cucumber or celeriac with a section surface area of 160 cm2 each. The decomposition rate is predominantly influenced by the section surface area of the cut fruit and vegetable samples. Denaturing reaction conditions (exchange of the solvent water by methanol; boiling of sample material) will significantly slow down the decomposition rate. It was concluded that the thiram decomposition had been caused by enzymes on the section surface of the fruit and vegetable samples. For a specific determination of thiram, a simple rinsing of the intact fruit and vegetable material was appropriate as extraction method. For the screening of thiram residues, the often used Keppel method, which determines CS2 from thiram or dithiocarbamates seems to be applicable even if samples had been coarsely cut, since decomposition of the CS2-forming intermediates is slower than the breakdown of thiram itself. Therefore, specific determination of thiram is necessary only, if maximum residue limits for dithiocarbamates are not adhered to.

Variation of toxaphene indicator compounds in fish from single fishing grounds: conclusions for sampling

The levels of three toxaphene indicator compounds were determined in individual lots of herring, redfish, Greenland halibut and farmed salmon. Concentration levels of the three marine fish species were characterised by a right-skewed frequency distribution whereas residue concentrations in farmed salmon were normally distributed. The toxaphene concentrations in the edible part of redfish, herring and Greenland halibut were found to be positively correlated to the sizes and thus to age. As results show, for representative sampling of a landed catch, not more than 10 individual fishes from typical size classes of a lot are necessary for a pooled sample.

Mass spectrometric characterization of Q1, a C(9)H(3)Cl(7)N(2) contaminant in environmental samples

Q1, a heptachloro component of unknown structure and origin, was recently identified as a major organochlorine contaminant in samples from Africa and the Antarctic. Gas chromatography in combination with low resolution mass spectrometry (LRMS) was applied to establish a molecular weight of m/z 384 including seven chlorine atoms. Three possible molecular formulae (C(11)H(7)Cl(7), C(10)H(3)Cl(7)O, and C(9)H(3)Cl(7)N(2)) were proposed which could not be distinguished by LRMS. In this presentation the molecular composition of Q1 was studied using gas chromatography in combination with high resolution electron impact ionization mass spectrometry. With the option of further heteroatoms (P, S, N, O, F, and Br), 17 molecular formulae were obtained for the molecular weight of 384 u. In the selected ion monitoring (SIM) mode, performed with a resolution of 16,000, highest response was found at 383.812 or C(9)H(3)Cl(7)N(2). 11 fragment ions detected in the low resolution full scan mass spectrum of Q1 were also investigated in the high resolution SIM mode. In every case, the nitrogen-variant showed highest abundance while the other 16 structural variants could be definitely excluded. These investigations revealed that the molecular formula of Q1 is C(9)H(3)Cl(7)N(2). No stable component with this molecular formula has ever been reported in the literature, to our knowledge. Copyright 1999 John Wiley & Sons, Ltd.

Fusacandins A and B; novel antifungal antibiotics of the papulacandin class from Fusarium sambucinum. II. Isolation and structural elucidation

Two novel antifungal compounds of the papulacandin class, named fusacandins A and B, have been isolated from Fusarium sambucinum. Each compound contains two units of galactose and one of glucose, the latter connected as a C-glycoside to an aromatic moiety. Fusacandin A is esterified at two sites with long-chain, unsaturated fatty acids and fusacandin B at only one site. The structures of the fusacandins were elucidated through analysis of mass spectral and 1-D and 2-D homonuclear and heteronuclear NMR data.

Occurrence of 9- and 13-keto-octadecadienoic acid in biological membranes oxygenated by the reticulocyte lipoxygenase

Membranes of intact rabbit reticulocytes and rat liver mitochondrial membranes oxygenated by the pure reticulocyte lipoxygenase contain 13-keto-9Z,11E-octadecadienoic acid and 9-keto-10E,12Z-octadecadienoic acid. In mitochondrial membranes not treated with lipoxygenase and in rabbit erythrocyte membranes these products were not detected. The chemical structure of the compounds has been identified by cochromatography with authentic standards on various types of HPLC columns, by uv and ir spectroscopy and GC/MS. In the membranes of rabbit reticulocytes up to 2% of the linoleate residues are present as its 9- and 13-keto derivatives. Most of the keto compounds (up to 90%) are esterified in the membrane ester lipids, only about 10% were found in the free fatty acid fraction. It is proposed that the keto dienoic fatty acids are formed via decomposition of hydroperoxy polyenoic fatty acids originating from the oxygenation of the membrane lipids by the reticulocyte lipoxygenase.

Occurrence of free and esterified lipoxygenase products in leaves of Glechoma hederacea L. and other Labiatae

Leaves of Glechoma hederacea L. and other Labiatae contain (9S,10E,12Z,15Z)-9-hydroxy-10,12,15-octadecatrienoic acid, (10E,12Z,15Z)-9-oxo-10,12,15-octadecatrienoic acid, (9S,10E,12Z)-9-hydroxy-10,12-octadecadienoic acid and (10E,12Z)-9-oxo-10,12-octadecadienoic acid in a ratio of 71/14/12/3 (by mass), predominantly esterified in the membrane ester lipids. The leaves contain the highest level of these products, whereas only small amounts were found in the stalk and the roots. The chemical structures of these compounds were established by ultraviolet and infrared spectroscopy, by co-chromatography with authentic standards on various types of HPLC columns including chiral-phase HPLC and gas chromatography/mass spectrometry. The stereochemical specificity indicates the enzymatic origin of the products, most probably via a lipoxygenase reaction. Freshly harvested specimens of G. hederacea L. contain only small amounts of hydroxy-polyenoic fatty acids. Air-drying causes a strong increase in the content of free and esterified (9S,10E,12Z,15Z)-9-hydroxy-10,12,15-octadecatrienoic acid. Up to 80% of the hydroxy fatty acids of the total lipid extracts were esterified in the cellular lipids. The data presented indicate that lipoxygenase products occur in the cellular ester lipids of G. hederacea L. and other Labiatae. The results are discussed in the light of a possible involvement of the lipoxygenase pathway in the natural senescence of leaves.

Lipoxygenase catalyzed oxygenation of hydroxy fatty acids to lipoxins

The pure lipoxygenases from rabbit reticulocytes and soybeans convert a variety of substrates (arachidonic acid, 15-HPETE, 15-HETE, 5-HETE, various DiHETE isomers) to trihydroxy eicosanoids containing a conjugated tetraene system (lipoxins). In general, the methyl esters are better substrates for lipoxin formation than are the free acids. Lipoxygenase inhibitors (5,8,11,14-eicosatetraynoic acid, nordihydroguaiaretic acid) strongly inhibit the lipoxin formation. The complete stereochemistry of the lipoxin B formed from 15S-HETE methyl ester has been established by co-chromatography with authentic standards on various types of HPLC columns, by GC/MS analysis, by gas liquid chromatography of the ozonolysis fragments of the menthoxy carbonyl derivatives and 1H-NMR studies. The molar absorption coefficient of the conjugated tetraenes was measured as epsilon 301 = 53,000. The lipoxins formed from 15-HETE and various DiHETE isomers are formed exclusively via the oxygenation pathway as shown by experiments under an 17O2 atmosphere and/or by anaerobic incubations. Our results indicate that lipoxins can be synthesized via lipoxygenase-catalyzed sequential oxygenation of polyenoic fatty acids and their hydro(pero)xy derivatives.

Formation of lipoxin B by the pure reticulocyte lipoxygenase via sequential oxygenation of the substrate

The pure reticulocyte lipoxygenase converts 15LS-hydroxy-5,8,11,13(Z,Z,Z,E)-icosatetraenoic acid (15LS-HETE) methyl ester to a complex mixture of products containing 5DS,14LR,15LS-trihydro(pero)xy-6E,++ +8Z,10E,12E-icosatetraenoate methyl ester (lipoxin B methyl ester), 5DS,15LS-DiH(P)ETE methyl ester and four 8,15LS-DiH(P)ETE methyl ester isomers [DiH(P)ETE = dihydro(pero)xy-icosatetraenoic acid]. After a short incubation period (15 min) 5DS,15LS-DiH(P)ETE methyl ester was found to be the main product, whereas after a 3-h incubation lipoxin B methyl ester was the predominant product. The reaction shows a remarkable stereoselectivity since only small amounts of other trihydroxy tetraenes are formed. Anaerobiosis, heat inactivation of the enzyme, or incubation in the presence of lipoxygenase inhibitors (icosatetraynoic acid, nordihydroguaiaretic acid) completely abolished the reaction. The complete steric structure of the major tetraene product (lipoxin B methyl ester) was established by ultraviolet spectroscopy, HPLC on four different types of columns, gas chromatography/mass spectrometry, gas/liquid chromatography of the ozonolysis fragments of the menthoxycarbonyl derivatives, and by 400-MHz 1H-NMR. Atmospheric oxygen was incorporated at carbon-5 and carbon-14 into the major product. 5DS,15LS-DiH(P)ETE methyl ester was shown to be an intermediate in the synthesis. Lipoxin B was also formed during the oxygenation of arachidonic acid, 15LS-HETE and 5DS,15LS-DiHETE. The results presented here indicate that lipoxin B can be formed by pure lipoxygenases via a sequential oxygenation of arachidonic acid or its hydro(pero)xy derivatives.

Analysis of the stereochemistry of lipoxygenase-derived hydroxypolyenoic fatty acids by means of chiral phase high-pressure liquid chromatography

A chiral phase HPLC method was developed for the simultaneous determination of the positional and optical isomers of the lipoxygenase-derived hydroxypolyenoic fatty acids. With a Bakerbond chiral phase HPLC column (dinitrobenzoyl phenylglycine as chiral phase) the positional and optical isomers of the reduced dioxygenation products (by triphenylphosphine or borohydride) of linoleic acid and arachidonic acid were separated after methylation of the carboxylic groups. No cumbersome chemical derivatization such as conversion to a diastereomer was necessary. As compared with the methods used up till now chiral phase HPLC proved to be simpler and more sensitive. About 10 pmol of hydroxy fatty acids suffice for an analysis. The chiral phase HPLC can be used for the preparative separation of the optical antipodes of the lipoxygenase products. An optical purity of more than 90% can be reached in one preparative run. The method was applied to the determination of the stereochemistry of the dioxygenation products of polyenoic fatty acids formed by the lipoxygenases from soybeans, reticulocytes, pea seeds (isoenzyme I and II), tomato fruits, by the quasilipoxygenase activity of hemoglobin, and by the methylene blue-mediated photooxidation of arachidonic acid.

[Analysis and stability of propiverine hydrochloride (Mictonorm)]

In acid, neutral and alkaline solution the hydrolytic degradation of the spasmolytic agent Mictonorm (1) was determined. As degradation products ester- and/or ether fragments (2-5), benzophenone (6) and a compound X (7) were identified. In comparison N-Methylpiperidinyl(4)-benzilate (2) and benzilic acid (3) were also investigated in the isothermal quick-assay test. The test showed that the ether bound in 1 was hydrolyzed before the ester group. The compounds 5-7 are formed also direct from 3.

Formation of lipoxin B by the pure reticulocyte lipoxygenase

The pure reticulocyte lipoxygenase converts 5,15-DiHETE via a lipoxygenase reaction to 5,14,15-trihydroxy-6,8,10,12-eicosatetraenoic acid (a lipoxin B isomer) as shown by GC/MS analysis of its trimethylsilyl ether. With arachidonic acid, 15-HETE and 15-HETE methyl ester this lipoxin B isomer was also formed. The results presented here indicate that pure mammalian lipoxygenases are able to form lipoxins via sequential multiple oxygenation of arachidonic acid or its hydroxy derivatives.