Use of a physiological model of gentamicin pharmacokinetics for individual dosage of the antibiotic]

A new approach to fixing the initial doses of gentamicin (GM) for its intramuscular administration (the most commonly used anyway) is discussed. The approach is based on the physiological model reproducing the individual patterns of GM concentration change in patient's blood. Such parameters of the model as blood flow velocity and actual average volume of specific tissues as well as the tissue to the blood partition coefficient (Kp) are constant. They were used to calculate the volume of distribution in the body specific organs (Vs). The apparent distribution volume (Vd) and total clearance (Cl) are individual parameters. The Vd value was calculated individually for every particular patient depending on the body weight by the known equations. The difference between Vd and Vs was used to calculate the individual Kp for the organs and tissues which were not specially examined. When calculating Cl of GM, the patient's sex, age, weight and creatinine concentrations were taken into account. To evaluate the local velocity of blood flow after antibiotic intramuscular administration, it was important to consider the patient's sex and age. The approach was used to reproduce the individual patterns of GM concentration change after the initial administration of the antibiotic, 80 mg, to 19 male patients (age range, 21 to 73 years; weight range, 50 to 94 kg; blood creatinine concentration, 0.4 to 1.6 mg/dl). The GM concentrations attained with the use of the model were afterwards compared to the data on FPIA. (TDx, Abbott) by measuring the GM concentrations in the blood of the patients 0.5, 1, 5 and 7 hours after the administration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Characteristics of pharmacokinetics of liposome-incorporated rifampicin in rats after intratracheal administration]

Pharmacokinetics of rifampicin after its single intratracheal administration in the form of the liposome-encapsulated drug and its aqueous solution was studied on rats. It was shown that after the exposure to the liposome-incorporated rifampicin (10 mg/kg) the concentration-time curve in the blood and lungs was sigmoid with the retarded decrease in the blood drug concentration within 9 hours. The plateau segment of the curve provided at least a 4-fold longer maintenance of the rifampicin concentration in the blood and lungs at 3 to 4 micrograms/ml. The use of the liposome-incorporated antibiotic induced 2- and 1.5-fold increases in the AUC in regard to the lungs and blood, respectively.     

A rendezvous with the queen of ion channels: Three decades of ion channel research by David T Yue and his Calcium Signals Laboratory

David T. Yue was a renowned biophysicist who dedicated his life to the study of Ca²⁺ signaling in cells. In the wake of his passing, we are left not only with a feeling of great loss, but with a tremendous and impactful body of work contributed by a remarkable man. David's research spanned the spectrum from atomic structure to organ systems, with a quantitative rigor aimed at understanding the fundamental mechanisms underlying biological function. Along the way he developed new tools and approaches, enabling not only his own research but that of his contemporaries and those who will come after him. While we cannot hope to replicate the eloquence and style we are accustomed to in David's writing, we nonetheless undertake a review of David's chosen field of study with a focus on many of his contributions to the calcium channel field.     

An Evaluation of High-Throughput Approaches to QTL Mapping in Saccharomyces cerevisiae

Dissecting the molecular basis of quantitative traits is a significant challenge and is essential for understanding complex diseases. Even in model organisms, precisely determining causative genes and their interactions has remained elusive, due in part to difficulty in narrowing intervals to single genes and in detecting epistasis or linked quantitative trait loci. These difficulties are exacerbated by limitations in experimental design, such as low numbers of analyzed individuals or of polymorphisms between parental genomes. We address these challenges by applying three independent high-throughput approaches for QTL mapping to map the genetic variants underlying 11 phenotypes in two genetically distant Saccharomyces cerevisiae strains, namely (1) individual analysis of >700 meiotic segregants, (2) bulk segregant analysis, and (3) reciprocal hemizygosity scanning, a new genome-wide method that we developed. We reveal differences in the performance of each approach and, by combining them, identify eight polymorphic genes that affect eight different phenotypes: colony shape, flocculation, growth on two nonfermentable carbon sources, and resistance to two drugs, salt, and high temperature. Our results demonstrate the power of individual segregant analysis to dissect QTL and address the underestimated contribution of interactions between variants. We also reveal confounding factors like mutations and aneuploidy in pooled approaches, providing valuable lessons for future designs of complex trait mapping studies.     

In Silico Derived Small Molecules Bind the Filovirus VP35 Protein and Inhibit Its Polymerase Cofactor Activity

The Ebola virus (EBOV) genome only encodes a single viral polypeptide with enzymatic activity, the viral large (L) RNA-dependent RNA polymerase protein. However, currently, there is limited information about the L protein, which has hampered the development of antivirals. Therefore, antifiloviral therapeutic efforts must include additional targets such as protein–protein interfaces. Viral protein 35 (VP35) is multifunctional and plays important roles in viral pathogenesis, including viral mRNA synthesis and replication of the negative-sense RNA viral genome. Previous studies revealed that mutation of key basic residues within the VP35 interferon inhibitory domain (IID) results in significant EBOV attenuation, both in vitro and in vivo. In the current study, we use an experimental pipeline that includes structure-based in silico screening and biochemical and structural characterization, along with medicinal chemistry, to identify and characterize small molecules that target a binding pocket within VP35. NMR mapping experiments and high-resolution x-ray crystal structures show that select small molecules bind to a region of VP35 IID that is important for replication complex formation through interactions with the viral nucleoprotein (NP). We also tested select compounds for their ability to inhibit VP35 IID–NP interactions in vitro as well as VP35 function in a minigenome assay and EBOV replication. These results confirm the ability of compounds identified in this study to inhibit VP35–NP interactions in vitro and to impair viral replication in cell-based assays. These studies provide an initial framework to guide development of antifiloviral compounds against filoviral VP35 proteins.     

Nanogap Dielectric Spectroscopy for Aptamer-Based Protein Detection

Among the various label-free methods for monitoring biomolecular interactions, capacitive sensors stand out due to their simple instrumentation and compatibility with multiplex formats. However, electrode polarization due to ion gradient formation and noise from solution conductance limited early dielectric spectroscopic measurements to high frequencies only, which in turn limited their sensitivity to biomolecular interactions, as the applied excitation signals were too fast for the charged macromolecules to respond. To minimize electrode polarization effects, capacitive sensors with 20 nm electrode separation were fabricated using silicon dioxide sacrificial layer techniques. The nanoscale separation of the capacitive electrodes in the sensor results in an enhanced overlapping of electrical double layers, and apparently a more ordered “ice-like” water structure. Such effects in turn reduce low frequency contributions from bulk sample resistance and from electrode polarization, and thus markedly enhance sensitivity toward biomolecular interactions. Using these nanogap capacitive sensors, highly sensitive, label-free aptamer-based detection of protein molecules is achieved.     

Mitotic recombination in haematological malignancy

The role of mitotic recombination in cancer has been difficult to study since prior knowledge of likely mutation targets was usually required.Here we have reviewed the recent advances in haematological malignancies. In particular we have dealt with acquired uniparental disomy and homozygosity, homozygous versus heterozygous mutations, transgenic animal models of MR and homozygous mutations, clonal evolution, mitotic recombination versus non-disjunction and the mechanism of mitotic recombination, breakpoints of mitotic recombination.     

Hormonal regulation of placental nitric oxide and pathogenesis of pre-eclampsia

The placenta is central to foetal growth and development in mammalian pregnancy. Compromised placental function (as found in pre-eclampsia) often results in life-threatening situations for both mother and foetus. The nitric-oxide (NO) signalling cascade is important for placental function, in particular for the development of the vascular network and for maintaining vascular tone. This pathway seems to be regulated by multiple hormonal signals. Emerging evidence suggests that pathogenic mechanisms that are involved in abnormal placental function target specific molecules, such as hormone receptors, that regulate NO release and have subsequent dramatic consequences. Here, we discuss the current knowledge of NO function in the placenta, its hormonal regulation in normal pregnancy and in the pathophysiology of pre-eclampsia, its potential pathogenic mechanisms and possible use as a therapeutic target.