Canine Smooth Muscle Contraction Model.

Smooth muscle is found extensively in the human body, including in blood vessels, airways, the gastrointestinal tract, and the urinary bladder. Although the contractile proteins of smooth muscle are very similar to those of striated muscle, smooth muscle's contractile mechanism has not been studied as extensively as those for cardiac and skeletal muscle. Previous studies developed a lumped model of muscle contraction and applied it to cardiac muscle and to skeletal muscle.

Improving medical residents' utilisation of integrated mental health in primary care.

Background: Integration of mental health services allows for improved prevention and management of chronic conditions within the primary care setting. This quality improvement project aimed to increase adherence to and functioning of an integrated care model within a patient-centred medical home. Specifically, the project focused on improving collaboration between Primary Care Mental Health Integration (PC-MHI) and the medical resident Patient Aligned Care Teams (PACT) at a Veterans Affairs Medical Center in Northport,New York (VAMC Northport).

Modeling Mouse Soleus Muscle Contraction.

Models of muscle contraction are typically based on a measured force-velocity relation embodied as Hill's contractile element [1]. Adopting a particular force-velocity relation dictates the muscle's mechanical properties. Dynamic crossbridge based models, such as Huxley's [2], typically focus on ultrastructural mechanics.

Targeted De Novo Centromere Formation in Drosophila Reveals Plasticity and Maintenance Potential of CENP-A Chromatin.

Centromeres are essential for accurate chromosome segregation and are marked by centromere protein A (CENP-A) nucleosomes. Mis-targeted CENP-A chromatin has been shown to seed centromeres at non-centromeric DNA. However, the requirements for such de novo centromere formation and transmission in vivo remain unknown.

Functional Requirements of a Mathematical Model of Muscle Contraction.

Muscle modeling has a long history. Models typically belong to the class of lumped models built around Hill's contractile element, or to crossbridge models at the ultrastructure level. Lumped models built on the contractile element are not sufficiently dynamic, since the muscle's contractile properties are set a priori by the force-velocity relation.

Islands of retroelements are major components of Drosophila centromeres.

Centromeres are essential chromosomal regions that mediate kinetochore assembly and spindle attachments during cell division. Despite their functional conservation, centromeres are among the most rapidly evolving genomic regions and can shape karyotype evolution and speciation across taxa. Although significant progress has been made in identifying centromere-associated proteins, the highly repetitive centromeres of metazoans have been refractory to DNA sequencing and assembly, leaving large gaps in our understanding of their functional organization and evolution.

The KAT's Out of the Bag: Histone Acetylation Promotes Centromere Assembly.

Heterochromatin is incompatible with centromeric chromatin assembly and propagation. In this issue of Developmental Cell, Ohzeki et al. (2016) reveal that a critical role of the Mis18 complex is to transiently recruit the lysine acetyltransferase KAT7 to centromeres to facilitate the removal of H3K9me3 and the deposition of CENP-A.

Establishment of Centromeric Chromatin by the CENP-A Assembly Factor CAL1 Requires FACT-Mediated Transcription.

Centromeres are essential chromosomal structures that mediate accurate chromosome segregation during cell division. Centromeres are specified epigenetically by the heritable incorporation of the centromeric histone H3 variant CENP-A. While many of the primary factors that mediate centromeric deposition of CENP-A are known, the chromatin and DNA requirements of this process have remained elusive.

Modeling muscle's nonlinear viscoelastic dynamics.

Muscle's contractile properties are complicated by its viscoelastic properties. Failure of early viscoelastic muscle models led to Hill's force-velocity relation embodied as the contractile element. Adopting a particular force-velocity relation to describe muscle is neither easy, nor unique [1].

Broad geographic analyses reveal varying patterns of genetic diversity and host specificity among echinostome trematodes in New Zealand snails.

Host specificity is a fundamental component of a parasite's life history. However, accurate assessments of host specificity, and the factors influencing it, can be obscured by parasite cryptic species complexes. We surveyed two congeneric species of intertidal snail intermediate hosts, Zeacumantus subcarinatus and Zeacumantus lutulentus, throughout New Zealand to identify the number of genetically distinct echinostome trematodes infecting them and determine the levels of snail host specificity among echinostomes.

Cardiac muscle strip model parameters and muscle elastance.

A recent functional model of the left ventricle as a pressure generator that is time and volume dependent was adapted to describe the mechanical aspects of heart muscle contraction. Muscle's complex dynamics develop from a single equation based on the formation and relaxation of crossbridge bonds. Muscle is modeled as a force generator that is time and length dependent.

Left ventricular model parameters and cardiac rate variability.

A recent functional model of the left ventricle characterizes the ventricle's contractile state with parameters, rather than variables. The ventricle is treated as a pressure generator that is time and volume dependent. The heart's complex dynamics develop from a single equation based on the formation and relaxation of crossbridge bonds within underlying heart muscle.

Functional requirements of a mathematical model of the heart.

Functional descriptions of the heart, especially the left ventricle, are often based on the measured variables pressure and ventricular outflow, embodied as a time-varying elastance. The fundamental difficulty of describing the mechanical properties of the heart with a time-varying elastance function that is set a priori is described. As an alternative, a new functional model of the heart is presented, which characterizes the ventricle's contractile state with parameters, rather than variables.

Amino acid analysis of peptide loading ratios in conjugate vaccines: a comparison of direct electrochemical detection and 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate pre-column derivatization methods.

Amino acid analysis using direct electrochemical detection was compared with precolumn fluorescent derivatization using 6-aminoquinolyl- N-hydroxysuccinimidyl carbamate (AQC) for evaluation of the degree of covalent coupling of peptides to a carrier-protein complex derived from the bacteria Neisseria meningitidis. AQC derivatization was found to give superior sensitivity compared to electrochemical detection, with less interference from sample components such as carbohydrates or buffer salts. Hydrolysis time and temperature were optimized for maximal recoveries of the marker amino acid 6-aminohexanoic acid (epsilon-Ahx) and the unique amino acids S-dicarboxyethyl cysteine (SDCEC) and S-carboxymethyl homocysteine (SCHMC), which are generated upon the hydrolysis of the covalent linkage between the peptide and the carrier protein.

Defining muscle elastance as a parameter.

Functional descriptions of striated muscle are often based on the measured variables force and initial velocity of shortening, embodied as Hill's contractile element. The fundamental difficulty of describing the mechanical properties of muscle with a force-velocity relation that is set a priori, and the practical problem of the act of measurement changing muscle's force-velocity relation or elastance curve, are described. As an alternative, a new model of muscle contraction is presented, which characterizes muscle's contractile state with parameters, rather than variables.

A paradigm for quantifying ventricular contraction.

The left ventricle may be described as a time, volume and flow dependent pressure generator. First, isovolumic pressure is measured at various end-diastolic volumes. Next, pressure is adjusted to account for small changes accompanying ejection, denoted the ejection effect.

Construction of adenoviral vectors.

Recombinant adenovirus vectors have proven to be useful tools in facilitating gene transfer. Construction of such vectors requires a knowledge of the adenovirus genome structure and its life cycle. A commonly used recombinant adenovirus involves deletion of the E1 region; such a recombinant is traditionally produced by overlap recombination after cotransfection of 293 cells with a plasmid shuttle vector and a large right-end restriction fragment of viral DNA.

The changing view of the heart through the centuries.

In human perception, the heart was not always part of the blood circulating system. It was later included as a suction pump until Harvey argued that the heart is actually a compression pump, the central organ of the circulation, and the only organ responsible for the motion of blood. Considered initially as an autonomous pump, the heart gradually became viewed as subservient to the needs of the peripheral organs it perfuses.

Human circulatory system model based on Frank's mechanism.

A new analytical model of the left ventricle as a pump, developed from isolated canine experiments, was adapted to describe each of the four heart chambers in a complete human circulatory system model. Each chamber is embodied as a volume and time dependent isovolumic pressure source, after Otto Frank's classic experiments. Analytical results show that a small set of equations is sufficient to describe the main features of the heart as a pump, including isovolumic and ejecting beats for a wide range of ventricular and circulation conditions.

The left ventricular ejection effect.

A recently developed model of the left ventricle, based on experimental data, has been shown to exhibit the main features of the heart's ability to pump. Two special cases during blood ejection, termed pressure deactivation and hyperactivation, were identified. This study proposes an 'ejection effect' correction to the model that addresses deactivation, hyperactivation and adjusts the shape of the computed ventricular ejection curve in late systole.

A perspective on myocardial contractility.

Myocardial contractile properties form the cornerstone of the heart's ability to pump blood. Efforts have been made to characterize these properties via classic elasticity theory concepts, which can lead to spurious results, as demonstrated by experiments measuring intramyocardial pressure. Two ways out of these difficulties are identified.