Isolation, stages of differentiation, and long term maintenance of adult rat myocytes

Although a variety of techniques have been developed to isolate myocytes from adult hearts, the long term viability of such cells has only recently been investigated. In addition, relatively little is known about the stages of differentiation such cells proceed through following isolation. In the present study myocytes were isolated using two techniques, one involving retrograde perfusion via the aorta, and the other involving mechanical "shearing." In addition, several modifications were made to minimize the trauma normal associated with isolating myocytes from adult hearts. Both techniques yielded a high percentage of rod-shaped, quiescent myocytes, although myocytes isolated using the "shearing" method were less likely to remain viable for more than 24 hours. With both techniques those cells which remained viable for more than 24 hours proceeded through an identical pattern of differentiation leading to stable, attached cells which remained viable for up to four weeks. These results demonstrate that with the appropriate isolation techniques it is possible to maintain adult myocardial cells in culture for lengthy periods of time.     

Management of a post-radiotherapy xerostomic patient--a case report

doi: 10.1111/j.1741‐2358.2011.00519.x Management of a post‐radiotherapy xerostomic patient – a case report Objective: The objective of the study was to fabricate complete denture with palatal reservoir filled with artificial saliva for a post radiotherapy edentulous patient. Background: Xerostomia is a subjective complaint rather than a disease. It is caused by irradiation, medication, Sjogren's syndrome & neurological factors such as stress. Radiotherapeutic treatment of head and neck cancer patients often causes long term dysfunction involving their salivary function, swallowing capabilities & taste. All three of these domains are affected by radiation‐ induced damage to the salivary glands. This in turn results in poor retention of complete denture, frequent trauma to alveolar ridge & other oral infections. All these events drastically affects quality of life of ageing patients. Material and Method: A complete denture in heat cure acrylic resin was fabricated in which a palatal reservoir was made on the palatal side. Results: Problems arising due to xerostomia were reduced to a great extent. Conclusion: Prosthodontic management of Xerostomic patient include several techniques. This paper presents a case report of post radiotherapy edentulous patient in which complete denture with palatal reservoir filled with artificial saliva was fabricated.     

The Natural Experiment

Many of you, reading the title of this report, probably felt a certain confusion about this new, unusual term natural experiment. To dispel this quite natural confusion, let me say immediately that I am proposing this term to designate special investigatory techniques situated somewhere between external, objective observation, on the one hand, and a man-devised laboratory experiment (at present referred to as a psychological experiment), on the other. These original techniques, different from both the first and the second, are actually not completely new and unusual but, on the contrary, are well known to every one of you in their rudimentary form. Considered in more detail, they might perhaps be of considerable interest both theoretically and practically. It is for this reason that I decided to propose a new term to designate them. One cannot, of course, in such a brief report attempt to outline all the possible applications of this method to all the phenomena to which it could be applied; hence, I shall focus on an area that is more familiar to me and, moreover, seems to be especially suited for conducting a natural experiment, namely, research on personality or individuality.     

Ecological thresholds and regime shifts: approaches to identification

There is an apparent gap between the prominence of present theoretical frameworks involving ecological thresholds and regime shifts, and the paucity of efforts to conduct simple tests and quantitative inferences on the actual appearance of such phenomena in ecological data. A wide range of statistical methods and analytical techniques are now available that render these questions tractable, some of them even dating back half a century. Yet, their application has been sparse and confined within a narrow subset of cases of ecological regime shifts. Our objective is to raise awareness on the range of techniques available, and to their principles and limitations, to promote a more operational approach to the identification of ecological thresholds and regime shifts.     

MINLP models for the synthesis of optimal peptide tags and downstream protein processing

The development of systematic methods for the synthesis of downstream protein processing operations has seen growing interest in recent years, as purification is often the most complex and costly stage in biochemical production plants. The objective of the work presented here is to develop mathematical models based on mixed integer optimization techniques, which integrate the selection of optimal peptide purification tags into an established framework for the synthesis of protein purification processes. Peptide tags are comparatively short sequences of amino acids fused onto the protein product, capable of reducing the required purification steps. The methodology is illustrated through its application on two example protein mixtures involving up to 13 contaminants and a set of 11 candidate chromatographic steps. The results are indicative of the benefits resulting by the appropriate use of peptide tags in purification processes and provide a guideline for both optimal tag design and downstream process synthesis.     

Extraction of microsporidial DNA from modified trichrome-stained clinical slides and subsequent species identification using PCR sequencing

Molecular techniques involving polymerase chain reaction (PCR) and sequencing provide a relatively simple and objective means of identifying microsporidia to species level. We modified previously described methods of DNA extraction and PCR conditions for identification of microsporidia from museum slides, clinical specimens and environmental samples and successfully identified Vittaforma corneae in 11 out of 13 cases of microsporidial infection from used trichrome-stained slides of corneal scrapings from HIV-negative patients with keratoconjunctivitis.     

Characterization of human passive muscles for impact loads using genetic algorithm and inverse finite element methods

The objective of this study is to identify the dynamic material properties of human passive muscle tissues for the strain rates relevant to automobile crashes. A novel methodology involving genetic algorithm (GA) and finite element method is implemented to estimate the material parameters by inverse mapping the impact test data. Isolated unconfined impact tests for average strain rates ranging from 136 s⁻¹ to 262 s⁻¹ are performed on muscle tissues. Passive muscle tissues are modelled as isotropic, linear and viscoelastic material using three-element Zener model available in PAMCRASH^TM explicit finite element software. In the GA based identification process, fitness values are calculated by comparing the estimated finite element forces with the measured experimental forces. Linear viscoelastic material parameters (bulk modulus, short term shear modulus and long term shear modulus) are thus identified at strain rates 136 s⁻¹, 183 s⁻¹ and 262 s⁻¹ for modelling muscles. Extracted optimal parameters from this study are comparable with reported parameters in literature. Bulk modulus and short term shear modulus are found to be more influential in predicting the stress-strain response than long term shear modulus for the considered strain rates. Variations within the set of parameters identified at different strain rates indicate the need for new or improved material model, which is capable of capturing the strain rate dependency of passive muscle response with single set of material parameters for wide range of strain rates.     

A review of biomechanical models

This paper surveys biomechanical models of the nonimpact type, involving the musculo-skeletal system. Models of bones, joints and body segments, including human gait and motion of the whole body are discussed. In particular, stress analysis of bone, calculation of ligament and muscle forces across joints and the kinetics and kinematics of locomotion are discussed. The models are described in terms of the method of formulation, the method of solution and the realism of the results obtained. There is a need for more data on material properties of various body tissues and more experimental research to develop techniques for validating many of the models. Further work on the selection of appropriate objective functions for indeterminate problems is also required.     

A flexible state-space approach for the modeling of metabolic networks I: development of mathematical methods

We introduce a novel, flexible, optimization-based mathematical framework for the modeling of arbitrarily complex metabolic networks: topological metabolic analysis (TMA). The framework is adapted from state-space approaches used by Manousiouthakis and co-workers for the representation of complex heat- and mass-exchanger networks. We offer a thorough discussion of the mathematics and general theory underlying the framework, and discuss certain mathematical advantages of our modeling representation in comparison with other commonly used techniques (MFA and FBA). We employ a novel aggregate objective function for use with our basic constraint model, including a generalized least-squares term (for fitting available experimental measurements) and a linear design term (for representing biological or engineering goals). Using a case-study taken from recent literature (McKinlay et al., 2007), we demonstrate (among other benefits) the ability of this objective to identify alternate distinct-yet-equally optimal solutions for a given modeling problem. We also show that these solutions, obtained using only external metabolite uptake and secretion measurements, provide useful biological insights and compare favorably with solutions obtained on the basis of (13)C isotope-tracing data.     

Physiology and electrical activity of uterine contractions

Presently, there is no effective treatment for preterm labor. The most obvious reason for this anomaly is that there is no objective manner to evaluate the progression of pregnancy through steps leading to labor, either at term or preterm. Several techniques have been adopted to monitor labor, and/or to diagnose labor, but they are either subjective or indirect, and they do not provide an accurate prediction of when labor will occur. With no method to determine preterm labor, treatment might never improve. Uterine electromyography (EMG) methods may provide such needed diagnostics.     

Silica xerogel/aerogel-supported lipid bilayers: Consequences of surface corrugation

The objective of this paper was to review our recent investigations of silica xerogel and aerogel-supported lipid bilayers. These systems provide a format to observe relationships between substrate curvature and supported lipid bilayer formation, lipid dynamics, and lipid mixtures phase behavior and partitioning. Sensitive surface techniques such as quartz crystal microbalance and atomic force microscopy are readily applied to these systems. To inform current and future investigations, we review the experimental literature involving the impact of curvature on lipid dynamics, lipid and phase-separated lipid domain localization, and membrane-substrate conformations and we review our molecular dynamics simulations of supported lipid bilayers with the atomistic and molecular information they provide.     

Expression vectors for human adenosine deaminase gene therapy

Somatic gene transfer offers a possible new approach for treatment of human genetic disease. Defects affecting blood-forming tissues are candidates for therapies involving transfer of genetic information into hematopoietic stem cells. Adenosine deaminase (ADA) deficiency is being used as a model disease for which gene transfer techniques can be developed and evaluated. We describe here the construction and testing of 20 retroviral vectors for their ability to transfer and express human ADA in vitro and in vivo via a mouse bone marrow transplantation model. After infection of primary bone marrow with one fo these vectors (p delta NN2ADA), human ADA was detected in 60-85% of spleen colonies at day 14 and maintained long term in the blood of fully reconstituted mice. This system offers the opportunity to assess methods for increasing efficiency of gene transfer, for regulation of expression of foreign genes in hematopoietic progenitors, and for long-term measurement of the stability of expression in these cells.     

Review. Studying cumulative cultural evolution in the laboratory

Cumulative cultural evolution is the term given to a particular kind of social learning, which allows for the accumulation of modifications over time, involving a ratchet-like effect where successful modifications are maintained until they can be improved upon. There has been great interest in the topic of cumulative cultural evolution from researchers from a wide variety of disciplines, but until recently there were no experimental studies of this phenomenon. Here, we describe our motivations for developing experimental methods for studying cumulative cultural evolution and review the results we have obtained using these techniques. The results that we describe have provided insights into understanding the outcomes of cultural processes at the population level. Our experiments show that cumulative cultural evolution can result in adaptive complexity in behaviour and can also produce convergence in behaviour. These findings lend support to ideas that some behaviours commonly attributed to natural selection and innate tendencies could in fact be shaped by cultural processes.     

Regulation of polypeptide growth factor synthesis and growth factor-related gene expression in the rat and mouse uterus before and after implantation

It is apparent that the uterus is a rich source of growth factors, the synthesis of which may be induced by female sex steroids. These growth factors appear to be involved in complex autocrine/paracrine regulatory circuits which in turn interact with steroid hormones. With the exception of CSF-1, however, detailed studies of the appearance of these growth factors and their receptors during pregnancy and under different hormonal regimens have yet to be performed. Furthermore, causative roles have not been established for any of these growth factors in uterine biology and pregnancy. In the near future we can expect that, by using in-situ techniques, the producing and responding cells will be identified. Cell culture models will also have to be established to investigate specific growth factor-induced functions. In the longer term, once more is known about the regulation of uterine growth factors, imaginative new experiments need to be designed, perhaps involving transgenic animals, to establish causative roles for growth factors in uterine biology.     

A short review of model selection techniques for radiation epidemiology

A common type of statistical challenge, widespread across many areas of research, involves the selection of a preferred model to describe the main features and trends in a particular data set. The objective of model selection is to balance the quality of fit to data against the complexity and predictive ability of the model achieving that fit. Several model selection techniques, including two information criteria, which aim to determine which set of model parameters the data best support, are reviewed here. The techniques rely on computing the probabilities of the different models, given the data, rather than considering the allowed values of the fitted parameters. Such information criteria have only been applied to the field of radiation epidemiology recently, even though they have longer traditions of application in other areas of research. The purpose of this review is to make two information criteria more accessible by fully detailing how to calculate them in a practical way and how to interpret the resulting values. This aim is supported with the aid of some examples involving the computation of risk models for radiation-induced solid cancer mortality fitted to the epidemiological data from the Japanese A-bomb survivors. These examples illustrate that the Bayesian information criterion is particularly useful in concluding that the weight of evidence is in favour of excess relative risk models that depend on age-at-exposure and excess relative risk models that depend on age-attained.     

A short review and critique of methodology used in fish growth and nutrition studies

A number of the techniques commonly employed in fish growth and nutrition studies are evaluated and limitations imposed by their use are indicated. Total and digestible energy values of dietary formulations should be measured directly and the use of caloric conversion coefficients and assumed digestibility values may lead to serious error. There is considerable misunderstanding relating to the term metabolizable energy and metabolizable energy has been estimated in a number of ways, all of which are unreliable. In view of this, it is suggested that there is a good case to be made for ceasing to use the term.     

A review on EEG-based methods for screening and diagnosing alcohol use disorder

The screening test for alcohol use disorder (AUD) patients has been of subjective nature and could be misleading in particular cases such as a misreporting the actual quantity of alcohol intake. Although the neuroimaging modality such as electroencephalography (EEG) has shown promising research results in achieving objectivity during the screening and diagnosis of AUD patients. However, the translation of these findings for clinical applications has been largely understudied and hence less clear. This study advocates the use of EEG as a diagnostic and screening tool for AUD patients that may help the clinicians during clinical decision making. In this context, a comprehensive review on EEG-based methods is provided including related electrophysiological techniques reported in the literature. More specifically, the EEG abnormalities associated with the conditions of AUD patients are summarized. The aim is to explore the potentials of objective techniques involving quantities/features derived from resting EEG, event-related potentials or event-related oscillations data.     

Stabilization of the Bio-membrane by Small Molecules: Interaction of Trehalose with the Phospholipid Bilayer

Abstract

Anhydrobiotic organisms undergo periods of acute dehydration during their life cycle. It is of interest to understand how the biomembrane remains intact through such stress. A di-saccharide, trehalose, which is metabolised during anhydrobiosis is found to prevent disruption of model membrane systems (1). Molecular modelling techniques are used to investigate the possible mode of interaction of trehalose with a model monolayer. The objective is to maximise hydrogen bonding between the two systems. A phospholipid matrix consisting of l,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) is chosen to represent the monolayer. The crystal structure of DMPC (2) reveals that there are two distinct conformers designated as A and B. An expansion of the monolayer, coplanar with its surface, results in the trehalose molecule being accomodated in a pocket formed by four B conformers. One glucose ring of the sugar rests on the hydrophobic patch provided by the choline methyls of an A conformer. Five hydrogen bonds are formed involving the phosphate oxygens of three of the surrounding B conformers. The model will be discussed with reference to relevant experimental data on the interaction.     

Provisional bifurcation stenting

Obstructive coronary lesions involving a branch origin or extending into the branch itself, remain one of the main challenges in the rapidly developing world of interventional cardiology. Acutely, these lesions are prone to the complications resulting in significant residual stenosis or loss of one of the branches. Long-term follow up has also been disappointing with a high incidence of restenosis. Numerous techniques have been developed, aimed at optimizing the acute and long-term results by adapting standard angioplasty hardware, with limited success, particularly in the long term. This article describes a fully dedicated system for bifurcation lesions with stenting of the main vessel to the main branch, yet ensuring side branch patency, with limited risk of branch origin stenosis or stent jailing, allowing for provisional stenting of the branch as dictated by the angiographic outcome.     

Caiman latirostris (broad-snouted caiman) as a sentinel organism for genotoxic monitoring: basal values determination of micronucleus and comet assay.

Caiman latirostris is one of the two crocodilian species that inhabit Argentina. In this country, as a consequence of agricultural frontiers expansion during the last years, many areas of the geographic distribution of the broad snouted caiman overlap with regions of intensive agricultural activity. Contaminants released to the environment may induce genetic alterations in wildlife, which could lead to mutations and/or carcinogenesis. Up to the moment, no studies had been made concerning the possibbility to apply biomarkers of genotoxic evaluation in C. latirostris. The aim of this study was to adapt two widely used genotoxic techniques, the comet assay and the micronucleus test, for their application in C. latirostris and to determine the baseline values in this species, in order to establish its suitability as a sentinel organism for future genotoxic monitoring of environmental pollutants. A total of 41 juvenile caimans of 4 months old (FMO) and 10 months old (TMO) were used. Genotoxic techniques were applied on peripheral blood erythrocytes introducing the necessary modifications required by the material, which are presented here. Our results show that baseline values of DNA damage are quite stable among juvenile caimans (MN: FMO animals 0.87+/-0.74 and TMO animals 1.04+/-0.92; DI: FMO animals 103.40+/-3.36 and TMO animals 120.08+/-11.33), being independent of the nest of origin, sex and size of the animals and confirm the potential value of both short term tests as accurate screening tools for the evaluation of genotoxic agents in C. latirostris. This is the first reference to the application of genotoxic techniques on C. latirostris and the second in crocodilians. Data provided here will be useful for future studies involving the biomonitoring of natural regions where C. latirostris occurs, employing this species as a sentinel organism for genotoxic assessment of environmental pollutants.