Use of multiple pharmacodynamic measures to deconstruct the Nix-TB regimen in a short-course murine model of tuberculosis.

A major challenge for tuberculosis (TB) drug development is to prioritize promising combination regimens from a large and growing number of possibilities. This includes demonstrating individual drug contributions to the activity of higher-order combinations. A BALB/c mouse TB infection model was used to evaluate the contributions of each drug and pairwise combination in the clinically relevant Nix-TB regimen [bedaquiline-pretomanid-linezolid (BPaL)] during the first 3 weeks of treatment at human equivalent doses. The rRNA synthesis (RS) ratio, an exploratory pharmacodynamic (PD) marker of ongoing Mycobacterium tuberculosis rRNA synthesis, together with solid culture CFU counts and liquid culture time to positivity (TTP) were used as PD markers of treatment response in lung tissue; and their time-course profiles were mathematically modeled using rate equations with pharmacologically interpretable parameters. Antimicrobial interactions were quantified using Bliss independence and Isserlis formulas. Subadditive (or antagonistic) and additive effects on bacillary load, assessed by CFU and TTP, were found for bedaquiline-pretomanid and linezolid-containing pairs, respectively. In contrast, subadditive and additive effects on rRNA synthesis were found for pretomanid-linezolid and bedaquiline-containing pairs, respectively. Additionally, accurate predictions of the response to BPaL for all three PD markers were made using only the single-drug and pairwise effects together with an assumption of negligible three-way drug interactions. The results represent an experimental and PD modeling approach aimed at reducing combinatorial complexity and improving the cost-effectiveness of in vivo systems for preclinical TB regimen development.

[On the quality of the external post-mortem examination in cases of fatal head trauma : A comparison of death certificate and forensic autopsy]. / Zur Qualität der ärztlichen Leichenschau bei todesursächlichem Schädel­Hirn­Trauma : Ein Vergleich von Todesbescheinigung und gerichtlicher Obduktion.

BACKGROUND: In Germany it is required by law that basically every type of physician needs to be capable of executing a correct external post-mortem examination of a corpse. In recent years, numerous investigations on external post-mortem examinations repeatedly reported systematic mistakes and erroneous procedures in various clinical and medicolegal case groups. Accordingly, the completion of death certificates is frequently performed incorrectly. As one of the typical unnatural death cases, decedents dying from fatal head trauma (FHT) represent a special autopsy case group, which is expected to be correctly recognized during the primary external post-mortem examination because the external injuries are mostly obvious. OBJECTIVE: The present study aimed at investigating the quality of the external post-mortem examination in medicolegal FHT cases by means of comparison of death certificates and autopsy reports from a 10-year period. MATERIAL AND METHODS: In a retrospective study design all autopsy cases from the Institute of Legal Medicine of the University Hospital Münster in the years 2006-2015 (n = 3611) were analyzed as to the presence of FHT. A total of 328 cases with FHT and the concomitant presence of a death certificate filled out before the autopsy were identified. Subsequently, the cause of death according to the death certificate was compared with the cause of death according to the autopsy. The degree of agreement was classified into six different categories from I to VI. While category I represented a complete lack of agreement, category VI was assigned to cases with full agreement. RESULTS: In 58.5% of the cases (category VI) FHT was identified correctly during the external post-mortem examination. In 1.5% of the cases, a completely different cause of death was determined during the external post-mortem examination (category I). In 19.2% of the cases, no cause of death or the statement "unclear" was given as the cause of death in the death certificate (categories II and III). Cross-analyses and intuitive heatmap visualization were generated to identify case constellations with an increased risk for discrepancies. These analyses revealed that among all discrepant cases (categories I-V), falls were found significantly more often than in the nondiscrepant cases (p < 0.01), especially falls of women older than 57 years (median age of women) or falls considered as accidents by the examiner. In addition, traffic-associated FHT of men older than 44.5 years (median age of men) was identified more frequently in the external post-mortem examination. CONCLUSION: Despite the fact that FHT should be a cause of death that is comparably easy to identify during external post-mortem examination, more than one third of the cases were not sufficiently recognized. Therefore, special attention must still be paid to certain case constellations during the external post-mortem examination. Typical examples of such cases are burned bodies, cases of advanced putrefaction and falls.

Use of Multiple Pharmacodynamic Measures to Deconstruct the Nix-TB Regimen in a Short-Course Murine Model of Tuberculosis.

A major challenge for tuberculosis (TB) drug development is to prioritize promising combination regimens from a large and growing number of possibilities. This includes demonstrating individual drug contributions to the activity of higher-order combinations. A BALB/c mouse TB infection model was used to evaluate the contributions of each drug and pairwise combination in the clinically relevant Nix-TB regimen (bedaquiline-pretomanid-linezolid [BPaL]) during the first three weeks of treatment at human equivalent doses. RS ratio, an exploratory pharmacodynamic (PD) marker of ongoing Mycobacterium tuberculosis rRNA synthesis, to-gether with solid culture CFU and liquid culture time to positivity (TTP) were used as PD markers of treatment response in lung tissue; and their time course profiles were mathematically modeled using rate equations with pharmacologically interpretable parameters. Antimicrobial interactions were quantified using Bliss independence and Isserlis formulas. Subadditive (or antagonistic) and additive effects on bacillary load, assessed by CFU and TTP, were found for bedaquiline-pretomanid and linezolid-containing pairs, respectively. In contrast, subadditive and additive effects on rRNA synthesis were found for pretomanid-linezolid and bedaquiline-containing pairs, respectively. Additionally, accurate predictions of the response to BPaL for all three PD markers were made using only the single-drug and pairwise effects together with an assumption of negligible three-way drug interactions. The results represent an experimental and PD modeling approach aimed at reducing combinatorial complexity and improving the cost-effectiveness of in vivo systems for preclinical TB regimen development.

Ion pairing techniques: compatibility with on-line liquid chromatography--mass spectrometry.

The mass spectrometric properties of a series of model ion pairs were examined. In the cases studied it was possible to vaporize the ion pair consituents and to produce spectra corresponding to those of the unpaired materials. These findings offer a convenient means for derivatizing certain ionic compounds and demonstrate the feasibility of analyzing ionic species by on-line liquid chromatography-mass spectrometry.

Understanding Subdural Collections in Pediatric Abusive Head Trauma.

Life-threatening physical abuse of infants and toddlers is frequently correlated with head injuries. A common variant of the abusive head trauma is the shaken baby syndrome. The present review article sheds light on subdural collections in children with abusive head trauma and aims at providing a recent knowledge base for various medical disciplines involved in diagnostic procedures and legal proceedings. To this end, the different subdural collection entities are presented and illustrated. The pathophysiologic background is explained. Differential and age-diagnostic aspects are discussed and summarized by tabular and graphic overviews. Two problematic constellations frequently occurring during initial CT investigations are evaluated: A mixed-density subdural collection does not prove repeated trauma, and hypodense subdural collections are not synonymous with chronicity. The neuroradiologic analysis and assessment of subdural collections may decisively contribute to answering differential diagnostic and forensic questions. In addition to more reference data, a harmonization of terminology and methodology is urgently needed, especially with respect to age-diagnostic aspects.

Capillary electrophoresis.

The past year has seen major advances in capillary electrophoresis in terms of broadening applicability. A variety of successful approaches to peptide/protein and DNA separation and analysis are now available, and techniques for saccharide analysis are developing rapidly. Capillary electrophoresis--mass spectrometry continues to demonstrate its potential as a tool for high-resolution structure analysis.

Subdural hygromas in abusive head trauma: pathogenesis, diagnosis, and forensic implications.

Are subdural hygromas the result of abusive head trauma? CT and MR imaging represent important tools for the diagnosis of abusive head trauma in living infants. In addition, in-depth understanding of the pathogenesis of subdural hygromas is increasingly required by neuroradiologists, pediatricians, and forensic physicians. Therefore, the current knowledge on subdural hygromas is summarized and forensic conclusions are drawn. The most important diagnostic pitfalls, benign enlargement of the subarachnoid space, and chronic subdural hematoma, are discussed in detail. Illustrative cases from forensic practice are presented. Literature analysis indicates that subdural hygromas can occur immediately or be delayed. If other infrequent reasons can be excluded, the presence of subdural hygromas strongly suggests a posttraumatic state and should prompt the physician to search for other signs of abuse. To differentiate subdural hygromas from other pathologies, additional MR imaging of the infant's head is indispensable after initial CT scan.

Simultaneous measurement of nineteen binding constants of peptides to vancomycin using affinity capillary electrophoresis-mass spectrometry.

On-line affinity capillary electrophoresis-electrospray ionization-mass spectrometry (ACE-MS) was used for the simultaneous measurement of multiple binding constants of an all-D-tetrapeptide library to the model receptor, vancomycin. Determination of Kd values for the 19 peptides of the form Fmoc-DXYA is demonstrated. The data are compared with the results obtained for individual compounds using ACE-UV, and good correlation between the two detection methods is shown. Simultaneous determination of multiple Kd values by ACE-MS is achieved in one set of experiments, whereas only one Kd value can be obtained by ACE-UV during the same time. ACE-MS measures multiple binding constants in solution in a fast and reliable manner using femtomole amounts of samples.

DNA sequencing by capillary electrophoresis using short oligonucleotide primer libraries.

Two strategies for DNA sequencing by primer walking using short oligonucleotide primer libraries have been successfully employed along with capillary electrophoresis using replaceable polymer solutions of linear polyacrylamide and fluorescence detection. A 3.5-kb stretch of the single-stranded M13mp18 template was sequenced with T7 PRISM dye-terminator/Sequenase chemistry. An in-house base-calling program offered read lengths of roughly 450 bases with an average of 97.8% accuracy.

Use of zwitterionic detergents for the separation of closely related peptides by capillary electrophoresis.

Capillary electrophoresis incorporating hydrophobic selectivity is shown to be a powerful technique for separating closely related peptide species. In this work, hydrophobic interaction was induced through the addition of suitable amounts of a zwitterionic detergent (N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate) and further modified with organic solvents. A neutral, hydrophilic-coated capillary was used to minimize electroosmotic flow. Two test solutes, Met15- and Leu15-gastrin, were employed to probe hydrophobic selectivity with various electrophoretic conditions. The nature and concentration of the detergent and the organic modifier were varied to adjust the selectivity. Operation near the critical micelle concentration of the zwitterionic detergent in the presence of acetonitrile or various alcohols produced the highest hydrophobic selectivity among the conditions studied. The zwitterionic detergent approach was also briefly compared to the use of non-ionic detergents for hydrophobic selectivity.

Analysis of protein fractions by micropreparative capillary isoelectric focusing and matrix-assisted laser desorption time-of-flight mass spectrometry.

In this study, the use of capillary isoelectric focusing (cIEF) as a micropreparative tool for protein analysis by matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) is demonstrated. A newly designed, automated, collection interface equipped with a fiber-optic UV detector and a sheath flow connection was employed for collection of protein fractions. Multiple fractions were collected during a single cIEF run and further analyzed by MALDI-TOF-MS for mass assignment. The feasibility of the method was tested with a mixture of model proteins with different isoelectric points and molecular masses, and with variants of human hemoglobins differing in pI, but with negligible difference in M(r). Some practical considerations of the collection procedure and subsequent TOF analysis are presented.

Capillary electrophoretic examination of underivatized oligosaccharide mixtures released from immunoglobulin G antibodies and CTLA4Ig fusion protein.

A procedure is presented for the separation of underivatized oligosaccharides by capillary electrophoresis (CE) with a phytic acid-borate buffer system. The presence of the phytic acid ion-pairing agent greatly increases resolution between oligosaccharides in the complex mixtures studied, which was demonstrated by the separation of oligosaccharides originating from various immunoglobulin G antibodies and CTLA4Ig, a biologic fusion protein. The conditions also resolve neutral oligosaccharides, usually a major CE limitation. High-performance anion-exchange chromatography with pulsed amperometric detection, a standard technique for oligosaccharide and sugar analysis, is used as a reference method to analyze some of the complex oligosaccharide mixtures.

Capillary electrophoresis for the detection of known point mutations by single-nucleotide primer extension and laser-induced fluorescence detection.

Capillary electrophoresis (CE) with laser-induced fluorescence (LIF) was used to detect known point mutations using the method of single-nucleotide primer extension (SNuPE). Three different point mutations in human mitochondrial DNA associated with Leber's hereditary optic neuropathy (LHON) were detected by annealing a primer immediately 5' to the mutation on the template and extending the primer by one fluorescently labeled dideoxy terminator complementary to the mutation. By using two or more differently labeled terminators, both the mutant and wild type could be simultaneously detected. The advantages of using CE-LIF for detecting SNuPE reactions include speed and ease of analysis, absence of radioactivity, and potential for automation.

Characterization and performance of a neutral hydrophilic coating for the capillary electrophoretic separation of biopolymers.

Polyvinylmethylsiloxanediol (50% vinyl) was synthesized and combined with a cross-linker for static coating onto fused-silica columns. After cross-linking and binding to the surface, linear polyacrylamide was grafted to the double bonds of the siloxanediol; subsequently, this linear polymer matrix was cross-linked with formaldehyde. The grafted neutral polymeric layer provided suppression of electroosmotic flow and minimized adsorption. This combination yielded successful open tube and polymer network separations of proteins, peptides and DNA molecules. Very high efficiencies (ca. 1 x 10(6) plates/m) were achieved for open tube protein separations, and hundreds of consecutive runs were performed with minimal change in migration times.

Liquid chromatographic and capillary electrophoretic examination of intact and degraded fusion protein CTLA4Ig and kinetics of conformational transition.

Methods have been developed for the CE and HPLC analysis of CTLA4Ig, an immunoglobulin fusion protein. Two different LC approaches, size-exclusion (SEC) and "mixed-mode" ion-exchange (ABx), were developed along with a CE method that uses a micellar electrokinetic chromatographic buffer consisting of borate ions, sodium dodecyl sulfate and acetonitrile. These assays measure the presence of several CTLA4Ig-related species, and the observed changes resulting from multiple modes of degradation. In an attempt to identify possible degradation products, collections were taken from the ABx and SEC liquid chromatographic systems and further analyzed by matrix-assisted laser desorption time-of-flight (MALDI TOF) mass spectrometry. Multiple species were detected covering a wide molecular mass range. In addition, the CE method was used to study conformational kinetics between two forms of CTLA4Ig and to estimate the activation energy of the conformer-conformer transition. Pseudo-first-order reaction kinetics were demonstrated for CTLA4Ig samples stressed with papain, H2O2, and sodium dodecyl sulfate/heat.

Examination of capillary zone electrophoresis, capillary isoelectric focusing and sodium dodecyl sulfate capillary electrophoresis for the analysis of recombinant tissue plasminogen activator.

The microscale techniques of CZE, cIEF and SDS capillary electrophoresis have been evaluated for the analysis of a complex glycoprotein, recombinant tissue plasminogen activator (rtPA). A series of omega-amino acid buffers (pH approximately 5) was found suitable for the CZE separation of rtPA on coated capillaries. rtPA could be resolved into a series of major and minor peaks in an epsilon-aminocaproic acid buffer containing 0.01% (v/v) Tween 80. For cIEF, a two step method with pressure mobilization was utilized. Using a commercial instrument, either a polymer solution with a 50 microns I.D. capillary or narrow bore capillaries without a polymer solution (25 microns I.D.) were employed. rtPA was resolved into at least eight species within a pI range of 6.4-9.2 using Ampholine 3.5-10. Migration time precision for the major peaks ranged from 0.2% for CZE to < or = 2-3% R.S.D. for cIEF. Total recovery of rtPA from the capillary was also demonstrated for both methods. Analysis of rtPA, rtPA Type I, rtPA Type II and the desialylated forms resulted in the expected elution profiles. Finally, the potential of SDS capillary electrophoresis using a coated capillary for an rtPA Type I/Type II purity assay was shown.

DNA sequence analysis of Prinker-modified restriction fragments after collection from capillary electrophoresis with replaceable matrices.

This paper demonstrates the procedure of sequencing DNA restriction fragments isolated by a recently developed fraction collector after CE separation. In particular, using pBr 322 plasmid as a model system, a double digest was performed with Eco RI and Pst 1 restriction enzymes to produce two fragments of 749 base pairs (bp) and 3612 bp, both with cohesive ends. Prinkers, specific linkers complementary to the cohesive ends, were then ligated to both fragments (increasing the size by 59 bp each). These Prinker-modified fragments were separated by CE and collected. The success of the collection was demonstrated by reinjection of each isolated fraction with laser-induced fluorescence detection, using ethidium bromide as intercalater. The 808 bp isolated fragment was then polymerase chain reaction-amplified with appropriate primers for the Prinker ends, followed by cycle sequencing. Both strands of the fragment were run on an ABI 373, sequencing 427 bases and 450 bases, respectively, with a read accuracy of 99.3%. This approach with Prinker-modified restriction fragment and automated CE fraction collection can be used as a general procedure for sequencing unknown genomic DNA as well as mutated DNA mixtures.

Automated microanalysis using magnetic beads with commercial capillary electrophoretic instrumentation.

The potential of a new microanalytical method using magnetic beads (MBs) and commercial capillary electrophoresis (CE) instrumentation for performing enzymatic and inhibition assays, as well as for analysis of biological molecules such as antigens, substrates, etc., has been explored. A small quantity of magnetic beads containing immobilized biomolecules was injected into a neutral hydrophilic-coated fused-silica capillary. The short plug (2-3 mm) of beads was held fixed by a magnet placed in the cartridge of the CE system, without the use of frits. The beads could be replaced after each run, eliminating the need to regenerate the solid support. Two protocols were used for analysis: sequential injection (SI) and SI followed by isotachophoretic (ITP) focusing. Alkaline phosphatase (AP) and HIV-protease were used to demonstrate the SI procedure for enzymatic and inhibition assays. The second protocol, SI/ITP, was employed to quantitate an antigen (mouse mAB) using antibodies (sheep IgG towards mouse AB) immobilized on the beads. The MB-CE method, requiring only femtomole (fmol) quantities of material, can potentially be employed in diagnostic and forensic assays, kinetic studies and searching for inhibitors, ligands, receptors, etc.

Separation of DNA fragments by capillary electrophoresis using replaceable linear polyacrylamide matrices.

The use of low percent (1.5-6% T) replaceable linear polyacrylamide (LPA) network matrices for rapid separation of double-stranded DNA fragments was explored. Separations of fragments ranging from 20 to 23,000 base pairs were readily achieved. Typically, 4 x 10(6) theoretical plates/m were obtained in less than 30 min. Short separation times under 2 min were also possible, using the DNA intercalating dye, ethidium bromide, along with high electric fields. The high resolving power of linear polyacrylamide was demonstrated in the separation of two fragments which differ by a single base pair (123/124 base pairs) using 6% T LPA and ethidium bromide intercalation. This LPA composition allowed for the possible single base-pair resolution of dsDNA fragments up to 300 base pairs in length. Several concentrations of the linear polyacrylamide for different ranges of fragment lengths have been employed. In addition, replaceable LPA offers the advantage of a fresh separation matrix for each run, thus overcoming column stability problems and minimizing needs for sample cleanup. Electro-osmotic flow was substantially reduced using stable capillary coatings, which were required for obtaining high efficiencies and good reproducibility.

Use of acidic and basic pH and calcium ion addition in the capillary zone electrophoretic characterization of recombinant human deoxyribonuclease, a complex phosphoglycoprotein.

This paper describes the analysis of recombinant human deoxyribonuclease (rhDNAse), an acidic and complex phosphoglycoprotein, by capillary zone electrophoresis (CZE). Separation performance was found to be dramatically improved by the addition of calcium ions to the CZE running buffer, due to the influence of calcium binding on the charge and the electrophoretic behavior of rhDNAse. The pH dependent calcium binding effects on the electrophoretic separation were demonstrated at both acidic and basic pH, resulting in a two-dimensional (pH 4.8 and 8.0) calcium aided analysis that achieved multipeak resolution of the complex, glycosylation based, charge microheterogeneity of rhDNAse. Two-dimensional investigation of neuraminidase- and alkaline phosphatase-digested protein further demonstrated that the acidic pH resolved acidic charge heterogeneity and that the basic pH discriminated neutral heterogeneity. This work demonstrates the resolving power of CZE for the analysis of a complex microheterogeneous glycoprotein, and emphasizes the importance of employing multiple separation conditions in accordance with known structural characteristics of the protein.