Assessment of ATP metabolism to adenosine by ecto-nucleotidases carried by tumor-derived small extracellular vesicles.

Immunosuppression is a hallmark of cancer progression. Tumor-derived small extracellular vesicles (sEV), also known as TEX, produce adenosine (ADO) and can mediate tumor-induced immunosuppression.Here, the ATP pathway of ADO production (ATP →  ADP →  AMP →  ADO) by ecto-nucleotidases carried on the sEV surface was evaluated by a method using N6-etheno-ATP (eATP) and N6-etheno-AMP (eAMP) as substrates for enzymatic activity. The "downstream" N6-etheno-purines (ePurines) were measured by high performance liquid chromatography with fluorescence detection (HPLC-FL).Human melanoma cell-derived TEX (MTEX) metabolized eATP to N6-etheno-ADP (eADP), eAMP and N6-etheno-Adenosine (eADO) more robustly than control keratinocyte cell-derived sEV (CEX); due to accelerated conversion of eATP to eADP and eADP to eAMP. MTEX and CEX similarly metabolized eAMP to eADO. Blocking of the ATP pathway with the selective CD39 inhibitor ARL67156 or pan ecto-nucleotidase inhibitor POM-1 normalized the ATP pathway but neither inhibitor completely abolished it. In contrast, inhibition of CD73 by PSB12379 or AMPCP abolished eADO formation by both MTEX and CEX, suggesting that targeting CD73 is the preferred approach to eliminating ADO produced by ecto-nucleotidases located on the sEV surface.The noninvasive, sensitive, and specific assay assessing ePurine metabolism ± ecto-nucleotidase inhibitors in TEX enables the personalized identification of ecto-nucleotidase activity primarily involved in ADO production in patients with cancer. The assay could guide precision medicine by determining which purine is the preferred target for inhibitory therapeutic interventions.

Urinary markers/metabolites of exposure to chemical carcinogens - New possibilities in preventive oncology.

Centuries have passed without tobacco medical evaluation, and similar catastrophes have happened from the Roman Empire to now. We are not aware when, how and how much our body is exposed to chemical carcinogens every day. As a result of such exposure, millions of people fall ill with malignant diseases every year. The objectives of this work are: 1) Determination of the main urinary markers of exposure to the most dangerous chemical carcinogens; 2) Globally raising awareness about necessity of scientific testing chemicals before widespread human use; 3) Introducing the public about ubiquity of: As, Ni, Cr(VI), Cd, Be, and necessity of maximal reducing people's exposure to them. There are well known causal relations between the most dangerous chemical carcinogens and different types of human malignant diseases. Population based studies may determine persons with high concentrations of the urinary markers/metabolites of the most dangerous chemical carcinogens. Then, such selected persons should be removed from such circumstances and/or regularly checked. Better solution is to find out the source(s) of incriminated chemical cancerogens and eliminate or mitigate their emission. These are a kind of (pre)screening (primordial prevention) for persons with high risk of developing malignant diseases causally related to the most dangerous chemical carcinogens.

Untargeted Maternal Plasma Metabolomics in Hirschsprung Disease: A Pilot Study.

Background and Aims: Hirschsprung disease (HSCR) is a congenital disorder of unknown etiology affecting the enteric nervous system (ENS). Since the early gestational development of the ENS is dependent on the prenatal maternal metabolic environment, the objective of this pilot study was to explore the role of specific maternal plasma metabolites in the etiology of HSCR. Methods: In this cross-sectional study, postnatal (as a surrogate for prenatal) plasma samples were obtained from mothers of children diagnosed with HSCR (n = 7) and age-matched mothers of normal children (n = 6). The plasma metabolome was analyzed by ultra-high-pressure liquid chromatography and mass spectrometry. Metabolites were identified by mzCloud using Compound Discoverer software. Using an untargeted metabolomics workflow, metabolites with case versus control group differences were identified. Results: A total of 268 unique plasma metabolites were identified and annotated in maternal plasma. Of these, 57 were significantly different between case and control groups (P < 0.05, t-test). Using a false discovery rate corrected cutoff of 10% to adjust for multiple comparisons, 19 metabolites were significantly different in HSCR cases, including carnitines, medium-chain fatty acids, and glutamic acid. Pathways affected were for amino acid and lipid metabolism. Conclusion: Disordered prenatal metabolic pathways may be involved in the etiopathogenesis of HSCR in the developing fetus. This is the first study to assess maternal plasma metabolomics in HSCR.

Determination of Free Histidine in Complex Hair Care Products with Minimum Sample Preparation Using Cation-Exchange Chromatography and Post Column Derivatization.

In this communication, we describe the first analytical method for the determination of free histidine in hair care products (shampoos and conditioners). Cation-exchange chromatography combined with postcolumn derivatization and fluorimetric detection enabled the accurate (recovery: 83.5-114.8%) and precise (2.4-5.6% RSD) determination of free histidine without matrix interferences at concentration levels down to 1.5 mg kg-1. Real commercially available samples were found to contain the amino acid at levels ranging between 70 and 535 mg kg-1.

Therapeutic drug monitoring of Amikacin in hospitalized patients: A pilot study.

Background: Amikacin, an aminoglycoside, is a widely used parenteral antibiotic. Therapeutic drug monitoring (TDM) is recommended for aminoglycosides to avoid toxicity. However, the lack of infrastructure at most places precludes it. This pilot and novel study attempt to estimate the real-world serum levels of Amikacin in hospitalised patients. Methods: Thirty admitted patients, given Amikacin injections, were included in the study. In addition, 15 clinical specimens isolated with gram-negative bacteria were tested for minimum inhibitory concentration (MIC) value of Amikacin. Trough and peak serum levels of Amikacin were estimated by high-pressure liquid chromatography (HPLC). Results: The average MIC value of Amikacin estimated in our laboratory was 3.92 mcg/mL. Peak and trough serum levels of Amikacin ranged from 12.1 to 66.4 mcg/ml and 1.1 to 20.7 mcg/ml, respectively. More than 83% of our patients achieved peak Amikacin levels of 15 mcg/mL, and 37% had trough levels above 5 mcg/mL. These levels are desirable watersheds as per available literature. Conclusion: Trough levels of Amikacin in all cases and a review of dosing according to MIC values are recommended to achieve drug safety and therapeutic efficacy.

Dynamics of gliotoxin and bis(methylthio)gliotoxin production during the course of Aspergillus fumigatus infection.

As recently described, fungal secondary metabolism activates during infection in response to a hostile host environment. Gliotoxin and bis(methylthio)gliotoxin are two recognized secondary metabolites produced by Aspergillus fumigatus with differential cytotoxicity and involved in virulence. We sought to describe the temporal dynamics of gliotoxin and bis(methylthio)gliotoxin during A. fumigatus progression to further explore their role in the infection. First, we optimized the production of the mycotoxins under different in vitro growth conditions and then specifically measured them using an UHPLC/PDA method. The analytical conditions were selected after testing different parameters such as extraction procedures, column type, and mobile phase composition. We found that gliotoxin and bis(methylthio)gliotoxin are differentially excreted to the extracellular media during the course of A. fumigatus infection regardless of the growth format tested. Dynamic profiles show an early production of gliotoxin, which, after reaching a maximum, decreases coinciding with the increase in the production of the inactive derivative bis(methylthio)gliotoxin. Presence of gliotoxin may indicate an early phase of fungal development, whereas detection of bis(methylthio)gliotoxin may correspond to a more advanced stage of infection. Our chromatographic method successfully characterizes these secondary metabolites. Thus, it may potentially be used to further understand Aspergillus infection. LAY SUMMARY: Aspergillus fumigatus secondary metabolites may contribute to fungal survival. A new chromatographic method was applied to simultaneously characterize two relevant metabolites. Presence of toxic gliotoxin may indicate an early phase of development, whereas the detection of the inactive derivate may represent an advanced infection stage.

Preparative isolation of antioxidative furanocoumarins from Dracocephalum heterophyllum and their potential action target.

Traditional Tibetan medicine has extensively documented the health benefits of Dracocephalum heterophyllum. However, there are few reports on the chemical composition of furanocoumarins, probably because of their complicated isolation and purification procedures. In this study, four antioxidative furanocoumarins were isolated from Dracocephalum heterophyllum by medium- and high-pressure liquid chromatography in combination with on-line high-performance liquid chromatography-1,1-diphenyl-2-picrylhydrazyl recognition. Crude samples were sequentially pretreated by medium-pressure liquid chromatography using silica gel, MCI GEL CHP20P, and diol as stationary phases, whereas on-line high-performance liquid chromatography-1,1-diphenyl-2-picrylhydrazyl system was used to recognize antioxidant peaks in target fractions. Thereafter, the antioxidative peaks were separated and purified through high-pressure liquid chromatography to obtain four furanocoumarins with purities greater than 95%; namely isodemethylfuropinarine, demethylfuropinarine, alloimperatorin, and alloisoimperatorin. Finally, the antioxidant capacity of the isolated furanocoumarins was determined using in vitro experiments (1,1-diphenyl-2-picrylhydrazyl assays, molecular docking, and cellular validation) and it was concluded that nuclear factor erythroid 2-related factor 2 protein is a potential target of these compounds for their antioxidation effects. Thus, the proposed methodology exhibits excellent efficacy for the preparative isolation of high-purity antioxidative furanocoumarins from extracts of Dracocephalum heterophyllum and it can be efficiently utilized for isolating antioxidants from other natural products.

HPLC Determination of Colistin in Human Urine Using Alkaline Mobile Phase Combined with Post-Column Derivatization: Validation Using Accuracy Profiles.

In this study, the development, validation, and application of a new liquid chromatography post-column derivatization method for the determination of Colistin in human urine samples is demonstrated. Separation of Colistin was performed using a core-shell C18 analytical column in an alkaline medium in order (i) to be compatible with the o-phthalaldehyde-based post-column derivatization reaction and (ii) to obtain better retention of the analyte. The Colistin derivative was detected spectrofluorometrically (λext/λem = 340/460 nm) after post-column derivatization with o-phthalaldehyde and N-acetyl cysteine. The post-column derivatization parameters were optimized using the Box-Behnken experimental design, and the method was validated using the total error concept. The ß-expectation tolerance intervals did not exceed the acceptance criteria of ±15%, meaning that 95% of future results would be included in the defined bias limits. The limit of detection of the method was adequate corresponding to 100 nmol·L-1. The mean analytical bias (expressed as relative error) in the spiking levels was suitable, being in the range of -2.8 to +2.5% for both compounds with the percentage relative standard deviation lower than 3.4% in all cases. The proposed analytical method was satisfactorily applied to the analysis of the drug in human urine samples.

High-Performance Reversed-Phase Flash Chromatography Purification of Peptides and Chemically Modified Insulins.

Preparative reversed-phase HPLC is the established method for the purification of peptides, but has significant limitations. We systematically investigated the use of high-performance reversed-phase flash chromatography (HPFC) to rapidly purify laboratory-scale quantities of crude, synthetic peptides and chemically modified insulins. We demonstrated these methods for a diverse set of peptides, including short, medium, and long peptides. Depending on the purity profile of the peptide, HPFC can be used either as the sole purification method, or as a pre-purification method prior to final HPLC purification. Furthermore, HPFC is suitable for the purification of peptides that are not fully in solution. We provide guidelines for the HPFC of synthetic peptides and small proteins, including the choice of columns, eluents, and gradients. We believe that HPFC is a valuable alternative to HPLC purification of peptides and small proteins.

Fast, inexpensive, and reliable HPLC method to determine monomer fractions in poly(3-hydroxybutyrate-co-3-hydroxyvalerate).

The determination of the monomer fractions in polyhydroxyalkanoates is of great importance for research on microbial-produced plastic material. The development of new process designs, the validation of mathematical models, and intelligent control strategies for production depend enormously on the correctness of the analyzed monomer fractions. Most of the available detection methods focus on the determination of the monomer fractions of the homopolymer poly(3-hydroxybutyrate). Only a few can analyze the monomer content in copolymers such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate), which usually require expensive measuring devices, a high preparation time or the use of environmentally harmful halogenated solvents such as chloroform or dichloromethane. This work presents a fast, simple, and inexpensive method for the analysis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with high-performance liquid chromatography. Samples from a bioreactor experiment for the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with Cupriavidus necator H16 were examined regarding their monomer content using the new method and gas chromatography analysis, one of the most frequently used methods in literature. The results from our new method were validated using gas chromatography measurements and show excellent agreement.Key points∙ The presented HPLC method is an inexpensive, fast and environmentally friendly alternative to existing methods for quantification of monomeric composition of PHBV.∙ Validation with state of the art GC measurement exhibits excellent agreement over a broad range of PHBV monomer fractions.

Correlation between enzyme multiplied immunoassay technique and high-performance liquid chromatography in the quantification of voriconazole in a paediatric population.

The enzyme multiplied immunoassay technique (EMIT) is a new method for determining the plasma concentration of voriconazole (VRZ). This study aimed to investigate the correlation between EMIT and high-performance liquid chromatography/ultraviolet rays (HPLC/UV) in determining the plasma VRZ trough concentration in children, in China. A total of 419 blood samples were collected, and plasma VRZ concentrations were detected by the EMIT and HPLC methods. The results of 304 samples were analysed after excluding samples that were undetectable or beyond the quantification limit. A test result value of 0 was defined as undetectable, while concentrations outside the detection range (0.2 - 20.0 µg/ml for HPLC and 0.5 - 16.0 µg/ml for EMIT) were defined as beyond the quantification limit. Results from both methods were compared using the Passing Bablok regression, Bland-Altman plot analysis, and paired Wilcoxon test. The plasma VRZ concentrations determined by EMIT and HPLC showed a strong linear correlation through the linear regression equation YEMIT = 1.310 × HPLC +0.149 (R2 = 0.9082). The Bland-Altman plot analysis showed poor level consistency as measured by the two methods. The paired Wilcoxon-test showed a significant difference between the two methods (p < .0001). Compared to EMIT, HPLC accurately detected plasma VRZ concentration, making it suitable for VRZ therapeutic drug monitoring. The numerical values of the EMIT-measured levels were higher than those of HPLC, which may be related to VRZ metabolites interference and co-administrated drugs.

Determination of residue of diflufenican in wheat and soil by ultra-high-pressure liquid chromatography and mass spectrometry conditions.

BACKGROUND: In order to clarify whether the application of diflufenican in the wheat field will produce residues in wheat plants and soil. In this experiment, ultra-high-pressure liquid chromatography was used to determine the residues of diflufenican in wheat plants, grains, and soil, which provided a new theoretical basis and technical guidance for the safe production of wheat. RESULTS: The results showed that the average diflufenican recovery per added level in wheat and soil were in the range of 85.7% to 91.3%, relative standard deviations were all in a range of 2.43% to 6.00%, and the minimum detectable amount of diflufenican was 1.0 × 10-10 g kg-1 . With the increase of wheat growing days and soil layers, the residues of diflufenican in wheat plants and soil became lower. The order of residual amount of diflufenican in the growth period were heading period, flowering period, filling period and maturing period. The order of residual amount of diflufenican in different soil layers was 0-20, 20-40, 40-60, 60-80 and 80-100 cm respectively from the top to the bottom. In addition, with the increase of the dosage of diflufenican, the residual amount of diflufenican becomes higher. Thus, the residual amount of diflufenican after 2.0 times applied amount was higher than the 1.0 time applied amount. CONCLUSION: The residual amounts of diflufenican in wheat and soil were very small, far below the value of the maximum residue limit (MRL) on wheat provided by China. Under the applied amount administered in this experiment, a single spray of diflufenican in wheat trifoliate is safe for wheat, humans and livestock. © 2020 Society of Chemical Industry.

[Determination of five phenolic compounds in workplace air by composite sampling tube-high performance liquid chromatography].

Objective: To develop a method for simultaneous determination of Dydroquinone, Resorcinol, Pyrocatechol, 4-Nitrophenol and 2, 4-Dinitrophenol in workplace air by high performance liquid chromatography. Methods: Air samples were collected by composite tube (front end glass fiber filter membrane, back section silica gel) , 10% methanol was desorbed, separated by C18 chromatographic column, detected by photo-diode array (PDA) detector, and quantitatively determined by external standard method at the wave-length of 230 nm. Results: The linear relationship of 5 phenolic compounds was good (r>0.999) . The detection limit of glass fiber filtration membrane and silica gel adsorbent were 0.13-0.41 g/ml and 0.16-1.04 g/ml respectively. The quantitative limit of glass fiber filtration membrane was 0.44-1.36 g/ml, and the silica gel adsorbent was 0.52-3.46 g/ml. The average desorption efficiency of glass fiber membrane and silica gel adsorbent were 97.5%-100.1% and 86.9%-100.3%, respectively. In and between batches, the precision glass fiber filtration membrane was 0.71%-4.88%, 0.91%-4.82%, silica gel adsorbent was 0.47%-4.62%, 0.76%-5.52%. Samples can be stored for at least 30 days at -20 ℃. The possible co-existing interferences of aniline, phenol, p-nitrochlorobenzene, o-nitrophenol and trinitrophenyl did not interfere with the determination. Conclusion: The sensitivity, precision, accuracy and linear range of this method all meet the requirements of the specification. The collection and preservation of samples can also meet the requirements of the limits. It is suitable for the simultaneous determination of hydroquinone, resorcinol, hydroquinone, hydroquinone, hydroquinone, p-nitrophenol and 2, 4-dinitrophenol in the air of the workplace.

A 2D HPLC-MS/MS method for several antibiotics in blood plasma, plasma water, and diverse tissue samples.

An analytical method using 2D high-performance liquid chromatography followed by tandem mass spectrometry for the quantification of the beta-lactam antibiotics amoxicillin, flucloxacillin, piperacillin, benzylpenicillin, the beta-lactamase inhibitors clavulanic acid, and tazobactam, as well as the macrolide antibiotic clindamycin, is presented. All analytes were measured in human plasma, while amoxicillin, clavulanic acid, flucloxacillin, and clindamycin were also analyzed in human tissue samples. Because of its high-protein binding, additionally, the free fraction of flucloxacillin was measured after ultrafiltration. As internal standards, deuterated forms of the beta-lactams were used. Sample preparation for all matrices was protein precipitation followed by online extraction on a TurboFlow MAX column, while sample separation was performed on an Accucore XL C18 column. Calibration curves were linear over 0.2-25 mg/kg for the tissue samples and 0.05-20 mg/l for the free fraction of flucloxacillin. In plasma, the calibration curves for amoxicillin and piperacillin were linear over 3.125-125 mg/l, for clavulanic acid and tazobactam over 1-40 mg/l, for benzylpenicillin 0.25-40 mg/l, and for flucloxacillin and clindamycin over 1.5-60 mg/l and 0.05-8 mg/l respectively. In plasma and plasma ultrafiltrate, inaccuracy and imprecision for any analyte were always less than 15%. In tissue, the accuracy and precision varied up to 16%, respectively, 20%, when various tissues were analyzed using a calibration in water. Graphical abstract.

Rapid identification of chemical compositions in callicarpa kwangtungensis Chun by ultra-high-performance liquid chromatography with Q Exactive hybrid quadrupole orbitrap high-resolution accurate mass spectrometry.

Callicarpa kwangtungensis Chun is a traditional Chinese medicine that has various therapeutic effects. Despite its wide use in Chinese medicine, the study is still quite limited, especially its chemical compositions. In this research, an ultra-high-pressure liquid chromatography coupled with Q Exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry tandem mass spectrometry method was utilized to analyze its chemical compositions for the first time. As a result, a total of 124 compounds, including 20 phenylethanoid glycosides, 31 flavonoids, 36 organic acids, 26 terpenoids and 11 phenols, were identified or tentatively characterized in 30 min. Among them, 49 compounds, including 5 phenylethanoid glycosides, 12 flavonoids, 16 organic acids, 12 terpenoids, and 4 phenols, were identified in Callicarpa kwangtungensis Chun for the first time. Besides, the fragmentation pathways were also discussed. This research established a rapid and reliable method to analyze the chemical compositions of complicated herb without the process of isolation, and provide abundant information on the chemical material basis for further bioactivity and quality control studies.

Measurement of drug concentration and bacterial contamination after diluting morphine for intrathecal administration: an experimental study.

BACKGROUND: Low concentrations of morphine are required for safe dosing for intrathecal injections. Sometimes, manual dilution of morphine is performed to achieve these low concentrations, but risks dilution errors and bacterial contamination. The primary goal was to compare the concentrations of morphine and bupivacaine between four groups of syringes. The secondary goal was to investigate the difference in contamination rate between these groups. METHODS: Twenty-five experienced anesthesia providers were asked to prepare a mixture of bupivacaine 2.0 mg/ml and morphine 60 µg/ml using 3 different methods as clean and precise as possible. The fourth method used was the aspiration of ampoules prepared by the pharmacy. The concentrations of morphine and bupivacaine were measured by High-Pressure Liquid Chromatography (HPLC). The medication was cultured for bacterial contamination. RESULTS: Group 1 (median 60 µg/ml; 95% CI: 59-110 µg/ml) yielded 3 outliers above 180 µg/ml morphine concentration. Group 2 (76 µg/ml; 95% CI: 72-80 µg/ml) and 3 (69 µg/ml; 95% CI: 66-71 µg/ml) were consistently higher than the target concentration of 60 µg. The group "pharmacy" was precise and accurate (59 µg/ml; 95% CI: 59-59 µg/ml). Group 2 and "pharmacy" had one contaminated sample with a spore-forming aerobic gram-positive rod. CONCLUSION: Manually diluted morphine is at risk for deviating concentrations, which could lead to increased side-effects. Medication produced by the hospital pharmacy was highly accurate. Furthermore, even when precautions are undertaken, contamination of the medication is a serious risk and appeared to be unrelated to the dilution process.

Chronic Administration of Fipronil Heterogeneously Alters the Neurochemistry of Monoaminergic Systems in the Rat Brain.

Fipronil (FPN), a widely used pesticide for agricultural and non-agricultural pest control, is possibly neurotoxic for mammals. Brain monoaminergic systems, involved in virtually all brain functions, have been shown to be sensitive to numerous pesticides. Here, we addressed the hypothesis that chronic exposure to FPN could modify brain monoamine neurochemistry. FPN (10 mg/kg) was chronically administered for 21 days through oral gavage in rats. Thereafter, the tissue concentrations of dopamine (DA) and its metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid; serotonin (5-HT) and its metabolite, 5-hydroxyindoleacetic acid (5-HIAA); and noradrenaline (NA) were measured in 30 distinct brain regions. FPN significantly decreased DA and its metabolite levels in most striatal territories, including the nucleus accumbens and the substantia nigra (SN). FPN also diminished 5-HT levels in some striatal regions and the SN. The indirect index of the turnovers, DOPAC/DA and 5-HIAA/5-HT ratios, was increased in numerous brain regions. FPN reduced the NA content only in the nucleus accumbens core. Using the Bravais-Pearson test to study the neurochemical organization of monoamines through multiple correlative analyses across the brain, we found fewer correlations for NA, DOPAC/DA, and 5-HIAA/5-HT ratios, and an altered pattern of correlations within and between monoamine systems. We therefore conclude that the chronic administration of FPN in rats induces massive and inhomogeneous changes in the DA and 5-HT systems in the brain.

An eco-friendly HPLC-UV method for the determination of risedronate in its bulk and tablet dosage form with application to content uniformity, dissolution and stability testing.

Risedronate is a nitrogen-containing bisphosphonate for the treatment and prevention of postmenopausal osteoporosis. The current work aims to develop a novel green HPLC-UV method for the rapid analysis of risedronate sodium in bulk and tablet formulation. The analyzed samples were separated on Waters Atlantis dC18 (150 mm × 3.9 mm; 5 µm) column using a green mobile phase consisting of potassium phosphate buffer pH 2.9 and potassium edetate buffer pH 9.5 in a ratio of 1:2, the final pH was adjusted to 6.8 with phosphoric acid, the mobile phase was pumped at a rate of 1.0 mL/min, with column temperature set at 30 °C, eluted samples were detected at 263 nm and the chromatographic run time was 3.0 min. The method was found to be linear over the concentration range of 14-140 µg/mL with a correlation coefficient (r2) of 0.9994. Accuracy and precision were evaluated from three QC samples (LQC, MQC and HQC) together with the five calibrators where the percentage accuracy was found to be 101.84%. Processed quality control samples of risedronate sodium were tested for stability at different conditions, short term, long term and freeze- thaw stability. The current method was further extended to study the content uniformity of Actonel® tablets following United States Pharmacopoeia (USP) guidelines. The proposed method was fully validated as per ICH guidelines.

[Exertional dyspnea, myalgia, petechiae of the lower extremities and pronounced gingivitis in a 64-year-old female patient]. / Belastungsdyspnoe, Myalgien und Petechien der unteren Extremitäten sowie ausgeprägte Gingivitis bei einer 64-jährigen Patientin.

A female patient presented with exertional dyspnea, myalgia, a petechial rash of the lower extremities and pronounced gingivitis. The biochemical test results showed the presence of anemia. The patient had a known eating disorder and on questioning about eating habits admitted that she did not eat any fruit or vegetables. This led to the suspicion of a vitamin C deficiency, which was confirmed by high-pressure liquid chromatography. The patient was subsequently treated with 1000 mg ascorbic acid daily for 1 month whereby the clinical symptoms and anemia improved within a few weeks.

Resolving power in liquid chromatography: A trade-off between efficiency and analysis time.

This review describes chromatographic dispersion and different plate-height models frequently used to assess the chromatographic performance of ultra-high-pressure liquid chromatography column technology. Furthermore, different performance indices, including the resolution, the separation impedance, and kinetic plots are discussed allowing to quantify and visualize the resolving power in liquid chromatography. The construction of kinetic plots is explained, and different visualization approaches are highlighted. Finally, key instrument and column-technology developments to advance the kinetic performance limits are discussed and selected state-of-the-art applications are highlighted.