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At least 757 records · Page 42Linked to original sources
PubMed2005

Selenium uptake, translocation, assimilation and metabolic fate in plants.

The chemical and physical resemblance between selenium (Se) and sulfur (S) establishes that both these elements share common metabolic pathways in plants. The presence of isologous Se and S compounds indicates that these elements compete in biochemical processes that affect uptake, translocation and assimilation throughout plant development. Yet, minor but crucial differences in reactivity and other metabolic interactions infer that some biochemical processes involving Se may be excluded from those relating to S. This review examines the current understanding of physiological and biochemical relationships between S and Se metabolism by highlighting their similarities and differences in relation to uptake, transport and assimilation pathways as observed in Se hyperaccumulator and non-accumulator plant species. The exploitation of genetic resources used in bioengineering strategies of plants is illuminating the function of sulfate transporters and key enzymes of the S assimilatory pathway in relation to Se accumulation and final metabolic fate. These strategies are providing the basic framework by which to resolve questions relating to the essentiality of Se in plants and the mechanisms utilized by Se hyperaccumulators to circumvent toxicity. In addition, such approaches may assist in the future application of genetically engineered Se accumulating plants for environmental renewal and human health objectives.

Animals↗
PubMed2025

Engineered Lactiplantibacillus plantarum and Levilactobacillus brevis utilizing ribonucleoprotein-mediated editing for inactivation of hemolysin gene.

Lactiplantibacillus plantarum and Levilactobacillus brevis are widely used probiotics with significant potential as chassis organisms for probiotic engineering. However, their bioengineering remains underdeveloped compared to that of other probiotic bacteria due to the limited availability of genetic tools. Although CRISPR-Cas systems have shown promise for genome editing in Lactobacillus species, strain- or site-specific targeting challenges must be overcome to enhance their broader applicability. This study aimed to develop a novel editing system with reduced dependency on plasmids and antibiotics in L. plantarum WCFS1, L. plantarum SPC 72 - 1 and L. brevis SPC-SNU 70 - 2 using a Cas9-gRNA ribonucleoprotein (RNP) complex. Although the hlyIII gene has been annotated as a hemolysin-related gene in several Lactobacillus genomes, no functional hemolytic activity has been definitively demonstrated to date. In this study, hlyIII was selected as a target to evaluate genome editing efficiency and to assess its potential relevance to strain safety. To construct ΔhlyIII strains, the RNP complex targeting hlyIII was separately transformed with recombinase RecE/T and double-stranded donor DNA. As a result, ΔhlyIII mutants were obtained under optimized electroporation conditions. Sequencing analysis revealed a 50 bp deletion and the introduction of a stop codon in hlyIII across all mutant strains. The hemolytic activity test showed a reduction in free hemoglobin levels in the ΔhlyIII strains compared to the wild type: 27.0%, 74.3%, and 5.0% in L. plantarum WCFS1, L. plantarum SPC 72 - 1, and L. brevis SPC-SNU 70 - 2, respectively. These results suggest strain-dependent differences in hemolytic activity and indicate that inactivation of hlyIII may contribute to reduced hemolysis, although further validation is needed to clarify its functional role. In conclusion, the hlyIII gene was successfully edited in L. plantarum and L. brevis using Cas9-gRNA ribonucleoprotein-mediated editing, demonstrating the feasibility of this genome editing platform for application in probiotic strains.

Gene Editing↗
PubMed2006

Gene therapy to create biological pacemakers.

Old age and a variety of cardiovascular disorders may disrupt normal sinus node function. Currently, this is successfully treated with electronic pacemakers, which, however, leave room for improvement. During the past decade, different strategies to initiate pacemaker function by gene therapy were developed. In the search for a biological pacemaker, various approaches were explored, including beta(2)-adrenergic receptor overexpression, down regulation of the inward rectifier current, and overexpression of the pacemaker current. The most recent advances include overexpression of bioengineered ion channels and genetically modified stem cells. This review considers the strengths and the weaknesses of the different approaches and discusses some of the different viral vectors currently used.

Adenoviridae↗
PubMed2026

Advancing insect research through cell line transcriptomics.

This review emphasizes the significance of insect cell lines in transcriptomic research, highlighting their role as vital tools for uncovering cellular and molecular mechanisms of insect physiology, immune responses, and adaptation to environmental stressors. Cell lines derived from tissues such as the midgut, fat body, nervous system, and reproductive organs enable researchers to examine gene expression changes in a controlled setting, making discoveries that are difficult to achieve through whole-organism studies. High-throughput sequencing and single-cell RNA sequencing (scRNA-seq) have identified genes linked to detoxification, stress response, development, and immune defense, offering valuable insights for future applications in agriculture, pest control, and biotechnology. To organize this information clearly, we have summarized key findings in a table, providing an accessible overview of each cell line's important roles in transcriptomic research. This method not only highlights the adaptability of insect cell lines in functional genomics but also underscores their usefulness as model systems in pest management, virology, and bioengineering. Through utilizing transcriptomics, insect cell lines continue to advance our understanding of insect biology and foster the development of innovative strategies for sustainable crop protection and biotechnological use.

Animals↗
PubMed2002

Healing the diabetic wound and keeping it healed: modalities for the early 21st century.

The incidence of lower extremity wounds, infections, and amputations continues to increase worldwide. Fortunately, the past decade has seen a surge of activity in research into new modalities in wound healing and, even more recently, prevention. This article discusses the basic physiology of wound healing, with particular attention being paid to current and potential wound healing modalities. These include, among other modalities, discussions of bioengineered skin, hyaluronic acid, subatmospheric pressure therapy, growth factors, and endogenous cytokine stimulation. Emerging concepts targeting prevention through novel methods of patient empowerment, dermal thermometry, and computerized activity monitoring are also discussed.

Diabetes Complications↗
PubMed2001

New trends in the treatment of orthostatic hypotension.

Nonpharmacologic and pharmacologic treatment can significantly attenuate the symptoms of orthostatic hypotension. Some of the interventions that are used to treat orthostatic hypotension have been known for decades. However, several new treatment strategies have been developed in recent years. New knowledge about the pathophysiology of orthostatic syndromes has been gathered that will strongly influence the way treatments are tailored to individual patients. For example, patients with and without residual autonomic function exhibit differential responses to certain treatments. A large subgroup of patients with severe autonomic failure show a profound pressor response to water drinking. This simple effect can be exploited to treat orthostatic and postprandial hypotension in some patients. New bioengineering technologies that attempt to replicate normal baroreflex mechanisms may become available for selected patients with central autonomic dysfunction.

Humans↗
PubMed2003

Tissue engineering in urology: where are we going?

Tissue engineering in urology is a broad term used to describe the development of alternative tissue sources for diseased or dysfunctional native urologic tissue. This article reviews the recently published techniques involving synthetic and natural biodegradable matrices alone, known as "unseeded" scaffolds, and the latest data on "seeded" scaffolds, which are impregnated with cultured cells from urologic organs. Recent discoveries in reporter gene labeling of urologic tissue are discussed as a new method to identify and track the fates of these transplanted cells in vivo. This article also investigates how these bioengineering techniques are applied to synthetic and natural scaffolds, such as polyglycolic acid and porcine small intestine submucosa, to increase bladder capacity, repair urethral strictures, and replace corporal plaques in Peyronie's disease. Furthermore, recently published reports that these materials have been seeded with chondrocytes to create corporal rods for penile prostheses and stents for ureteral and urethral stricture disease are discussed. With these latest developments as a foundation, the future directions of tissue engineering in urology are presented.

Animals↗
PubMed1994

The development of implantable cardioversion defibrillation systems: the clinical chronicle of defibrillation leads.

Clinical experience suggests that there is a significant advantage from both the standpoint of survival and thoracotomy morbidity in the use of cardioverter defibrillator implantation strategies with transvenous and subcutaneous leads. Bioengineering achievements making the latter possible remains somewhat preliminary in comparison with the highly advanced analytic technology from which the leads for bradycardia pacing have issued. Accordingly, a good deal remains to be accomplished in the technology evolution of leads for implantable cardioverter defibrillators (ICDs). While second- and third-generation leads have proved to be clinically useful, their development remains far from complete. To date most lead studies have focused on endocardial shock pathways, waveforms, and the linkage thereof affecting defibrillation thresholds. Experience suggests that asymmetric biphasic waveforms that use dual pathways (versus monophasic unidirectional shocks) yield a greater margin of safety for effective control of arrhythmias with existing ICD systems. The critical mass and region of myocardium encompassed by energy pathways, the simultaneous versus sequential pulsing of ICD antiarrhythmic discharges, as well as electrode combinations, locations, and polarity, remain under study. Although final adjudication of the superiority of endocardial systems that exclude the need for thoracotomy over those that use epicardial electrodes remains to be determined by further observational and randomized trials, it is reasonable to conclude at this juncture that ICDs with endocardial leads are feasible and facile, providing a highly promising alternative to other antiarrhythmic strategies.

Animals↗
PubMed1981

Polyurethane contraceptive vaginal sponge: product modifications resulting from user experience.

A preliminary study of a new contraceptive vaginal sponge containing the spermicide nonoxynol -9 (N-9), was undertaken to assess acceptability of the method among a group of sexually active volunteers in Mexico City. Numerous modifications of the product and its packaging resulted from user experience and feedback to the physicians and bioengineers conducting the study. Although determining efficacy of the sponge was not an objective, it quickly became clear that spermicide is a crucial component of the intravaginal sponge contraceptive system; a high incidence of pregnancies led us to increase the spermicide level from 10% to 20%, then to the current 30% of dry sponge weight, or about 1.0 gram per sponge. (It should be noted that the high pregnancy rates were consistent with our experience using other vaginal contraceptive methods in the same clinic population). This initial evaluation of the contraceptive sponge has resulted in significant modification which should increase its acceptability to a small but important group of contracepting women. The sponge is currently being evaluated by the International Fertility Research Program (IFRP) in multicentered comparative clinical trials to determine use-effectiveness and acceptability in various cultures.

Clinical Trials as Topic↗
PubMed1994

MTT-assay and neutral red release (NRR)-assay: relative role in the prediction of the irritancy potential of surfactants.

A comparative study on the in vitro and in vivo irritancy of anionic, amphoteric and non-ionic surfactants was performed. In vitro ED50 values of the surfactants were determined by two cytotoxicity assays, the dimethylthiazoldiphenyltetrazoliumbromide (MTT) assay and the neutral red release (NRR) assay on serum-free cultured human foreskin keratinocytes. In vivo human irritancy data were obtained by a 24 hour occlusive patch test in volunteers and the irritant skin response quantified by visual scoring, evaporimetry and colorimetry. A close relationship between the evaluation methods of the patch test was observed (r = 0.92 to r = 0.96), confirming that the 'bioengineering' methods, such as evaporimetry and colorimetry are suitable for measuring skin irritation. For six surfactants evaluated we found a good correlation (r = 0.91) between the ED50 values of the MTT assay and the in vivo irritancy data. The NRR assay yielded less satisfactory correlation coefficients with regard to MTT assay (r = 0.42) and in vivo irritancy data (r = 0.46). This can be mainly attributed to a misinterpretation of the amphoteric and non-ionic surfactants by the NRR assay. While the NRR assay may better evaluate the anionic surfactants, the MTT assay seems to be more suitable when testing a broader range of chemically diverse surfactants. Limitations of cell culture systems are noted, although the potential usefulness of cultured human skin cells for skin irritancy testing has been clearly demonstrated.

Adult↗
PubMed1987

Lectin-specific targeting of lysosomal enzymes to reticuloendothelial cells.

The principles and methods used for enzymatic modification of the carbohydrate portion of glucocerebrosidase are similar to those performed by Ashwell and Morell, Stahl, and others. It is difficult to explain the lack of uptake of native enzyme through binding of the high-mannose type glycopeptide to Man/GlcNAc receptors since approximately 20% of the total oligosaccharides on the native enzyme are high mannose type. Possibly a requirement for multiple sites of attachment to the receptor is not met by a single high-mannose type oligosaccharide per molecule. Alternatively, the presence of complex type oligosaccharides on this enzyme, demonstrated by structural studies, may mask the mannose site and thus account for the poor uptake of native enzyme. The ability to successfully deglycosylate any protein or enzyme in order to specifically target a selected cell type requires that there be (1) an available source of pure enzyme; (2) specific exoglycosidases of high specific activity available either commercially or relatively easily purified; (3) chemical or biochemical means available for the testing of the product, preferably at each step; and (4) a means of separating the glycosidases used from the desired enzyme product. The characteristic and unique accumulation of glucocerebroside only in cells of the monocyte- histiocyte series, makes Gaucher's disease an excellent prototype for the study of enzyme replacement therapy. The principles demonstrated for the enzymatic deglycosylation of glucocerebrosidase may be applied to the cell-specific delivery of other glycoproteins as well. Other lysosomal diseases in which storage occurs in multiple cell types may be ameliorated by administration of macrophage-directed enzymes if, by so doing, storage material can be digested during the normal phagocytic turnover of senescent cells. Consideration of the kinetics of degradation and the structural features affecting the stability of enzymes in vivo are prerequisites to improving the bioengineering of targeted lysosomal enzymes. Animal and culture models have been developed for the study of glucocerebrosidase delivery to specific cell types and substrate degradation. Other studies have progressed toward a definition not only of the receptors at the plasma membrane involved in the internalization of exogenous enzyme, but also of internal receptors or properties of the lysosome responsible for intracellular protein trafficking. A complete understanding of the forces acting to direct endogenous or exogenously supplied enzyme to a given subcellular organelle will require a synthesis of experimental results from all areas of glycoprotein research.

Animals↗
PubMed1978

Provisional model for propagation of electrical activity in upper urinary tract.

A theory on the function of the renal pelvis as a pacemaker for ureteral peristalsis is given. The bioengineering "black box" approach is used to describe peristaltic behavior monitored at the ureter and thr renal pelvis, by both peristaltic pressure and electromyographic methods. The model provides a stimulus to further thought on the nature and significance of electrical activity in the upper urinary tract.

Electromyography↗
PubMed1994

Suited crewmember productivity.

Analysis of the extravehicular activity (EVA) sortie experience gained in the former Soviet Union and physiologic hygienic aspect of space suit design and development shows that crewmember productivity is related to the following main factors: -space suit microclimate (gas composition, pressure and temperature); -limitation of motion activity and perception, imposed by the space suit; -good crewmember training in the ground training program; -level of crewmember general physical performance capabilities in connection with mission duration and intervals between sorties; -individual EVA experience (with accumulation) at which workmanship improves, while metabolism, physical and emotional stress decreases; -concrete EVA duration and work rate; -EVA bioengineering, including selection of tools, work station, EVA technology and mechanization.

Astronauts↗
PubMed1991

Design of two immobilized cell catalysts by entrapment on gelatin: internal diffusion aspects.

Experimental results obtained during the design of two immobilized cell catalysts by entrapment on gelatin are presented. Strong diffusional limitations are found and explained with the usual parameters and models, introducing an empirical correlation between substrate concentration and effectiveness factor. The effect of particle size, enzyme load, and specific activity in the system is discussed in terms of cooperation between bioengineers and geneticists.

Catalysis↗
PubMed1988

Biomechanical highlights--the personal miscellany of a decade.

Developments of the past decade, primarily in biomechanics, are characterized through personal recollections. Topics covered include pressure treatment of hypertrophic scars, laser eradication of tattoos, amputation stump and artificial limb interactions, elbow arthoplasty, disability rehabilitation and training for sports performance, functional electrical stimulation and joint goniometry. The review is prefaced by comments on the present day context and resource environment of bioengineering research and ends by discussing the anticipated advent of health maintenance oriented community care as the activity of first priority for the future.

Biomechanical Phenomena↗
PubMed1995

Defensins.

Defensins are a family of small cationic, antibiotic peptides that contain six cysteines in disulfide linkage. The peptides are abundant in phagocytes and small intestinal mucosa of humans and other mammals and in the hemolymph of insects. They contribute to host defense against microbes and may participate in tissue inflammation and endocrine regulation during infection. Bioengineered defensins are potentially useful as prophylactic and therapeutic agents in infections.

Amino Acid Sequence↗
PubMed1987

Trematode eggshells: Novel protein biopolymers.

In the past few years recombinant DNA technology has somewhat serendipitously shed new light on the formation of trematode eggshells, with the publication of the sequences of highly expressed female-specific genes encoding protein components of the schistosome eggshell and with the isolation of DOPA-rich proteins and one of the corresponding genes from Fasciola. These proteins and other structural polypeptides with repetitive structures were the subject of a recent meeting Bioengineering for Material Applications (sponsored by the Office of Naval Research in Bethesda, USA, June 1987). In this article, based on that meeting, John Cordingley explains how the structure of trematode eggshells appears to show features common to several other biopolymers.

Journal Article↗
PubMed1995

In vitro method for quantifying the effectiveness of the longitudinal arch support mechanism of a foot orthosis.

The purpose of this investigation was to develop a technique to quantify the effectiveness of the longitudinal arch support mechanism of a foot orthosis. The experimental model was based on the following principle of foot biomechanics: as the foot is subjected to a load, a proportion of the load is experienced as tension by the plantar aponeurosis. A differential variable reluctance transducer was implanted into the plantar aponeuroses of cadaveric lower limb feet through which the strain was calculated in three conditions, specimen barefoot, specimen with shoe, and specimen with shoe and orthosis. Each donor limb was mounted in an electromechanical test machine that applied a load of 900 N to the tibia. Time, load, and strain data were collected and analysed at four load levels (225, 450, 675, 900 N). In addition the measurements and test design were evaluated for reliability. Strain in the plantar aponeurosis decreased significantly in the specimen with shoe and orthosis compared to the specimen with shoe only. There was a significant increase in the time to load data in the specimen with shoe and orthosis condition in contrast to the barefoot measurements. There were no significant differences in strain between the barefoot tests and those of the shoe, indicating that the shoe tested provided minimal support to the foot's longitudinal arch. RELEVANCE: One of the most common foot pathologies that patients seek medical attention for is plantar fasciitis. The primary cause of this condition is excessive tension in the plantar aponeurosis. A foot orthosis is often prescribed for treatment, relying on its longitudinal arch support mechanism to relieve the strain in the plantar aponeurosis. Quantifying the amount of strain experienced by the plantar aponeurosis is needed to identify how effective foot orthoses are in providing support to the foot's longitudinal arches. Such information is of importance to the medical practitioner who is involved with orthotic clinical recommendations. The described method will also be useful to bioengineers concerned with the arch support component of running shoes.

Journal Article↗