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At least 883 records · Page 49Linked to original sources
PubMed2001

Molecular properties in cell adhesion: a physical and engineering perspective.

The past several years have seen accelerating growth in research directed towards the understanding and control of cell adhesion processes, from a spectrum of disciplinary approaches including molecular cell biology, biochemistry, biophysics and bioengineering. Consequently, our understanding of the mechanisms involved in cell adhesion has increased substantially. Corresponding quantitative analysis and modeling of the key molecular properties governing their action in regulating dynamic cell attachment and detachment events is crucial for advancing conceptual insight along with technological applications.

Cell Adhesion↗
PubMed2001

The Virtual Cell: a software environment for computational cell biology.

The newly emerging field of computational cell biology requires software tools that address the needs of a broad community of scientists. Cell biological processes are controlled by an interacting set of biochemical and electrophysiological events that are distributed within complex cellular structures. Computational modeling is familiar to researchers in fields such as molecular structure, neurobiology and metabolic pathway engineering, and is rapidly emerging in the area of gene expression. Although some of these established modeling approaches can be adapted to address problems of interest to cell biologists, relatively few software development efforts have been directed at the field as a whole. The Virtual Cell is a computational environment designed for cell biologists as well as for mathematical biologists and bioengineers. It serves to aid the construction of cell biological models and the generation of simulations from them. The system enables the formulation of both compartmental and spatial models, the latter with either idealized or experimentally derived geometries of one, two or three dimensions.

Biology↗
PubMed1999

Production of ginseng and its bioactive components in plant cell culture: current technological and applied aspects.

Ginseng (the root of Panax ginseng CA Mayer) is a valuable oriental herb, which has been used in traditional Chinese medicine for thousands of years, both as a disease-healing drug and a general tonic. The medicinal value of ginseng is now also widely recognized in the west and the world ginseng market is expanding. The current supply of ginseng depends mainly on field cultivation, which is a slow and laborious process. Plant cell and tissue culture methods have been explored as potentially more efficient alternatives for the mass production of ginseng and its bioactive components. Research into ginseng cell and tissue cultures started in the early 1960s and commercial applications have been underway since the late 1980s. The ginseng cell culture has continued to attract considerable research and development effort in recent years as scientists seek to understand and optimize the culture conditions. In this paper, we review recent studies on ginseng cell culture processes, focusing on the physiological and bioengineering factors affecting the productivity of ginseng biomass and useful metabolites (e.g. ginseng saponin and polysaccharide) and the progress and concerns in large-scale applications.

Bioreactors↗
PubMed1999

In vivo efficacy and safety of skin electroporation.

This article reviews the studies on skin electroporation carried out in vivo in animals and emphasizes its potential therapeutic applications for transdermal and topical drug delivery. In agreement with in vitro studies, transport across skin due to high-voltage pulses in vivo was shown to increase by orders of magnitude on a timescale of minutes. Increased transdermal transport was measured by systemic blood uptake and/or pharmacological response, and demonstrated for calcein, a fluorescent tracer, fentanyl, a potent analgesic and flurbiprofen, an antiinflammatory drug. Combined electroporation with iontophoresis was shown to provide rapidly responsive transdermal transport of luteinizing hormone releasing hormone ex vivo as well. These data underline the potential of skin electroporation for improving the delivery profile of existing conventional transdermal patches, but also for replacing the injectable route.High-voltage pulses can increase drug permeation within and across skin but are also an efficient tool to permeabilize the membrane of cells of the cutaneous or subcutaneous tissue. This was shown beneficial for targeting cutaneous cells with oligonucleotides or genes and might open new opportunities for gene therapy and DNA vaccination.The safety of the application of high-voltage pulses on skin was assessed in vivo, using histological and visual scores, and bioengineering methods. While changes in skin barrier and function were observed, the irritation was mild and short-lived. Further optimization of the electrode configuration for improved targeting of the stratum corneum should still improve tolerance and levels of sensation.

Journal Article↗
PubMedDate not supplied

Measurement of Clostridium perfringens beta-toxin production by surface plasmon resonance immunoassay.

A rapid and sensitive assay using surface plasmon resonance (SPR) immunoassay has been developed for the detection of Clostridium perfringens beta-toxin. The SPR immunoassay was conducted off-line by passing fermentation broth by a sensor chip coated with a monoclonal antibody specific for C. perfringens beta-toxin. Quantitation of toxin using SPR immunoassay was achieved by mass transport analysis; results were obtained within 20 min. The SPR immunoassay was compared with an ELISA and the traditional bioassay for C. perfringens beta-toxin. The SPR immunoassay and ELISA detected at least twofold differences in toxin levels at 95% confidence over a broad range of toxin concentrations. The traditional bioassay did not produce the resolution observed with the immunoassays. The SPR immunoassay allows for real-time monitoring of beta-toxin accumulation during production and permits the bioengineer to harvest C. perfringens fermentations when toxin is most concentrated. The SPR methodology may be applied to other fermentations to enhance and optimize toxin yields.

Animals↗
PubMed2001

Biomechanics of the cervical spine Part 3: minor injuries.

Minor injuries of the cervical spine are essentially defined as injuries that do not involve a fracture. Archetypical of minor cervical injury is the whiplash injury. Among other reasons, neck pain after whiplash has been controversial because critics do not credit that an injury to the neck can occur in a whiplash accident. In pursuit of the injury mechanism, bioengineers have used mathematical modelling, cadaver studies, and human volunteers to study the kinematics of the neck under the conditions of whiplash. Particularly illuminating have been cinephotographic and cineradiographic studies of cadavers and of normal volunteers. They demonstrate that externally, the head and neck do not exceed normal physiological limits. However, the cervical spine undergoes a sigmoid deformation very early after impact. During this deformation, lower cervical segments undergo posterior rotation around an abnormally high axis of rotation, resulting in abnormal separation of the anterior elements of the cervical spine, and impaction of the zygapophysial joints. The demonstration of a mechanism for injury of the zygapophysial joints complements postmortem studies that reveal lesions in these joints, and clinical studies that have demonstrated that zygapophysial joint pain is the single most common basis for chronic neck pain after injury.

Accidents, Traffic↗
PubMed2002

Toxicological evaluation of chemical mixtures.

This paper addresses major developments in the safety evaluation of chemical mixtures during the past 15 years, reviews today's state of the art of mixture toxicology, and discusses challenges ahead. Well-thought-out tailor-made mechanistic and empirical designs for studying the toxicity of mixtures have gradually substituted trial-and-error approaches, improving the insight into the testability of joint action and interaction of constituents of mixtures. The acquired knowledge has successfully been used to evaluate the safety of combined exposures and complex mixtures such as, for example, the atmosphere at hazardous waste sites, drinking water disinfection by-products, natural flavouring complexes, and the combined intake of food additives. To consolidate the scientific foundation of mixture toxicology, studies are in progress to revisit the biological concepts and mathematics underlying formulas for low-dose extrapolation and risk assessment of chemical mixtures. Conspicuous developments include the production of new computer programs applicable to mixture research (CombiTool, BioMol, Reaction Network Modelling), the application of functional genomics and proteomics to mixture studies, the use of nano-optochemical sensors for in vivo imaging of physiological processes in cells, and the application of optical sensor micro- and nano-arrays for complex sample analysis. Clearly, the input of theoretical biologists, biomathematicians and bioengineers in mixture toxicology is essential for the development of this challenging branch of toxicology into a scientific subdiscipline of full value.

Air Pollutants↗
PubMed2001

Heparin in the treatment of burns: a review.

Burns are difficult to treat, wounds with complex local and systemic pathology and high mortality, that often heal slowly with scars and contractures. Glycosaminoglycans (GAGs) have been used in parenteral and topical application studies. These studies have uncovered anticoagulative, antiinflammatory and neoangiogenic properties, which may stimulate tissue repair and reepithelializing effects. The endogenous GAGs utilized in treating burns are heparin, dermatan sulfate, heparan sulfate, keratin sulfate, chondroitin-4- and chondroitin-6-sulfate, and hyaluronic acid. Heparin, the most sulfated and acidic GAG, has been used parenterally, topically, by inhalation, in pellet, and in bioengineered membranes. Heparin relieved pain, inhibited clotting and inflammation, restored blood flow, and enhanced healing. Heparin effects that improved and reduced burn care were time, dose, pH, site, source and duration related in studies. Potential adverse effects with heparin use are bleeding, thrombocytopenia and allergy. Heparin preserved lung and improved function. Heparin preserved intestinal integrity and reduced bacterial translocation. Collagen restoration was enhanced. The healed skin was smooth. Heparin reduced needs for pain medicine, topical antibiotics, resuscitation fluids, blood, water baths, debridement, surgery and grafts. Cost of treatments were reduced. Although not as yet fully substantiated, topical heparin therapy of burns may be a useful addition to the range of available treatments for burn wounds.

Administration, Topical↗
PubMed2002

Lithium and antidepressants: inhibiting eicosanoids, stimulating immunity, and defeating microorganisms.

Infection-emerging, reemerging, antibiotic-resistant, and bioengineered-increasingly threatens mankind. It is widely assumed that immunostimulating agents, were they to exist, would be ideal in battling microorganisms. Various investigators have established lithium and antidepressants as immunostimulants and antimicrobials and they have identified the mechanisms involved. Eicosanoids both depress immunity and activate microorganisms and lithium and antidepressants oppose eicosanoids. Such philosophers of science as Paul Feyerabend have argued that special interests invariably oppose revolutionary paradigms.

Adjuvants, Immunologic↗
PubMed1997

The elusive local factor in atherosclerosis.

Recent evidence confirms that local haemodynamic stresses account for the initiation, topographical localization and complications of atherosclerosis. These causative stresses are vibratory and associated with pulse pressure and the lesser vibrations of greater frequency generated by blood flow at predilection sites. This bioengineering fatigue hypothesis is further substantiated by analogous effects of repetitive stresses on erythrocytes and in the musculoskeletal system. The mechanism underlying fatigue is cumulative molecular scissions of the mural constituents which ultimately result in failure of the wall as a whole. Free radicals and oxidation products are by-products of this molecular scission in atherogenesis. This theory which explains the progressive inexorable loss of mural cohesion, its pathogenesis and complications is completely substantiated by the iatrogenic and experimental reproduction of the disease by haemodynamic means.

Animals↗
PubMed1998

Silicon and matrix macromolecules: new research opportunities for old diseases from analysis of potential mechanisms of breast implant toxicity.

An understanding of the normal and essential integration of the element silicon in biosystems, as well as knowledge of its fundamental chemistry, are crucial to understanding its role in health and disease. Modern organosilicon chemistry, based in part on the artificial silicon-carbon bond, coincided with the emergence of the biomaterials and bioengineering fields fifty years ago, and was thought to be a fortunate coincidence according to conventional wisdom that high-molecular-weight polymeric siloxanes were chemically and biologically inert. These concepts have been challenged by reports of silicone migration and degradation following insertion of gel-filled breast implants, claims of a novel systemic illness appearing in many breast implant recipients, and investigations implicating varied and permeating immunotoxic mechanisms of disease causation by breast devices. The present study develops additional potential pathogenetic ideas based on alterations of cell biochemistry by silicon-containing compounds, and offers correlation of the patients' diverse clinical features with plausable disruption of basic biological processes. This in turn raises new questions concerning everyday environmental exposure, has broad implications for multiple other diseases, can provide alternative directions for future investigative research, and may contribute to the ongoing redefinition of immune dysfunction and inflammation.

Biocompatible Materials↗
PubMed2000

Effect of surfactants on human stratum corneum: electron paramagnetic resonance study.

Electron paramagnetic resonance (EPR) spectra of nitroxide spin probes are useful for studying biological membranes and chemical-membrane interactions. Recently, we established a stripping method to remove stratum corneum (SC) for this purpose. To assess this stripping method with EPR and correlate with standard methods, we quantified the irritant effects of three types of surfactants by measurements of visual score and transepidermal water loss (TEWL), SC hydration and chromametry and studied EPR spectra measurements of surfactant-treated cadaver SC (C-SC) and stripped off SC (S-SC) on patch tested sites. 5-Doxyl stearic acid was the spin label. The order parameter S obtained from the spectra of S-SC correlated with those of C-SC and TEWL values. The results suggest that this method is capable of evaluating the fluidity of SC and correlates with the above bioengineering parameters.

Adult↗
PubMed2000

An in vivo investigation of the rabbit skin responses to transdermal iontophoresis.

To optimize the benefits of transdermal iontophoresis, it is necessary to develop a suitable animal model that would allow for extensive assessments of the biological effects associated with electro-transport. Rabbit skin responses to iontophoresis treatments were evaluated by visual scoring and by non-invasive bioengineering parameters and compared with available human data. In the current density range 0.1-1.0 mA/cm(2) applied for 1 h using 0.9% w/v NaCl and 0.5 mA/cm(2) for up to 4 h, no significant irritation was observed. 2 mA/cm(2) applied through an area of 1 cm(2) for 1 h resulted in slight erythema at both active electrode sites but without significant changes in transepidermal water loss (TEWL) and laser Doppler velocimetry (LDV). A value of 4 mA/cm(2) under similar conditions caused moderate erythema at the anode and cathode with TEWL and LDV being significantly elevated at both sites; 1 mA/cm(2) current applied for 4 h, caused moderate erythema at both anode and cathode; and 1 mA/cm(2) applied for 1 h caused no irritation when the area of exposure was increased from 1 to 4.5 cm(2). When significant irritation and barrier impairment occurred, the erythema was resolved within 24 h with barrier recovery complete 3-5 days post-treatment. Rabbit skin thus shows promise as an acceptable model for iontophoresis experiments.

Administration, Cutaneous↗
PubMed2002

On computational control of flow in airblast atomisers for pulmonary drug delivery.

Among different approaches to successful pharmacotherapy the pulmonary drug delivery (PDD) mode plays an increasingly important role. In this paper PDD systems based on air-blast atomisation have been analysed mathematically. In order to allow the bioengineer to estimate the degree of effectiveness of a specific system prototype and to lay the basic principles for design, a conservation-law-based mathematical model is discussed. Key control parameters that allow improvement in the efficiency of the system have been identified and main characteristics of the system have been analysed numerically as functions of these parameters.

Aerosol Propellants↗
PubMed2002

Skin permeation enhancement effect and skin irritation of saturated fatty alcohols.

Though the skin permeation enhancement effect of chemical penetration enhancers has been studied extensively, their skin irritation potential has not been adequately investigated. The objective of this study was to evaluate the skin permeation enhancement effect and skin irritation of saturated fatty alcohols using melatonin as a model compound. A saturated solution of melatonin in a mixture of water and ethanol (40:60) containing 5% w/v of saturated fatty alcohol was used in the skin permeation studies using Franz diffusion cells. For skin irritation studies, 230 microl of fatty alcohol solution was applied on the dorsal surface of the hairless rats using Hill top chamber. The skin irritation was evaluated by visual scoring method and bioengineering methods such as measurement of transepidermal water loss (TEWL) and skin blood flow. The flux of melatonin across hairless rat skin was found to be dependent on the carbon chain length of the fatty alcohols, with decanol showing the maximum permeation of melatonin. All fatty alcohols increased the TEWL and skin blood flow significantly compared with the vehicle. The fatty alcohols (decanol, undecanol and lauryl alcohol), which showed greater permeation of melatonin, also produced greater TEWL, skin blood flow and erythema. Tridecanol and myristyl alcohol showed lower permeation enhancement effect but caused greater skin irritation. Octanol and nonanol may be the most useful enhancers for the transdermal delivery of melatonin considering their lower skin irritation and a reasonably good permeation enhancement effect. However, further studies are needed to ascertain their safety as skin penetration enhancers. Skin permeation and skin irritation in experimental animals such as rats are generally higher compared with human skin. Further studies in human volunteers using fatty alcohols at the concentrations of 5% or lower may provide useful information on the utility of these fatty alcohols as permeation enhancers.

Administration, Cutaneous↗
PubMed2002

New therapeutic options for chronic wounds.

Increased research and understanding of acute and chronic wounds has led to the development of new therapies to stimulate and improve healing of difficult wounds. These include various growth factors, animal-derived wound coverings, and bioengineered human skin tissue.

Chronic Disease↗
PubMed2001

Leg ulcer diagnosis and management.

Lower extremity ulcers can be challenging diagnostically and therapeutically. This article, provides an overview of the different kinds of lower extremity wounds typically seen by the medical dermatologist. It also reviews new treatment modalities, including topical growth factors and bioengineered skin. A team approach is emphasized.

Antiphospholipid Syndrome↗
PubMed2003

Yeast cell adhesion on oligopeptide modified surfaces.

Self-assembling oligopeptides are novel materials with potential bioengineering applications; this paper explores the use of one of these oligopeptides, EAK 16 II, for modifying the surface properties of cell-supporting substrates. To characterize the surface properties, thermodynamic measurements of liquid contact angle and surface free energy were correlated to atomic force microscopy (AFM) observations. A critical concentration of 0.1 mg/ml was found necessary to completely modify the surface properties of the substrate with EAK 16 II. Adhesion of a yeast cell, Candida utilis, was modified by the coating of EAK 16 II on both hydrophobic (plastic) and hydrophilic (glass) surfaces: Cell coverage was slightly enhanced on the glass substrate, but decreased significantly on the plastic substrate. This indicates that the yeast cell adhesion was mainly determined via hydrophobic interactions between the substrate and the cell wall. However, on the EAK 16 II modified glass substrate, surface roughness might be a factor in causing a slightly larger cell adhesion than that on bare glass. The morphology of adhered cells was also obtained with AFM imaging, showing a depression at the center of the cell on all substrates. Small depressions on the oligopeptide-coated surfaces and plastic substrate may indicate good water-retaining ability by the cell. There was no apparent difference in cell adhesion and morphology among cells obtained from lag, exponential and stationary growth phases.

Candida↗