An ultrasonic system for measurement of absolute myocardial thickness using a single transducer

1995 ◽  
Vol 268 (3) ◽  
pp. H1358-H1367 ◽  
Author(s):  
K. F. Pitsillides ◽  
J. C. Longhurst
Keyword(s):  
Wall Thickness ◽  
Piezoelectric Transducer ◽  
Animal Studies ◽  
Wall Motion ◽  
Myocardial Function ◽  
Error Signal ◽  
Myocardial Wall Motion ◽  
Myocardial Wall

We have developed an ultrasonic instrument that can measure absolute regional myocardial wall motion throughout the cardiac cycle using a single epicardial piezoelectric transducer. The methods in place currently that utilize ultrasound to measure myocardial wall thickness are the transit-time sonomicrometer (TTS) and, more recently, the Doppler echo displacement method. Both methods have inherent disadvantages. To address the need for an instrument that can measure absolute dimensions of myocardial wall at any depth, an ultrasonic single-crystal sonomicrometer (SCS) system was developed. This system can identify and track the boundary of the endocardial muscle-blood interface. With this instrument, it is possible to obtain, from a single epicardial transducer, measurement of myocardial wall motion that is calibrated in absolute dimensional units. The operating principles of the proposed myocardial dimension measurement system are as follows. A short duration ultrasonic burst having a frequency of 10 MHz is transmitted from the piezoelectric transducer. Reflected echoes are sampled at two distinct time intervals to generate reference and interface sample volumes. During steady state, the two sample volumes are adjusted so that the reference volume remains entirely within the myocardium, whereas half of the interface sampled volume is located within the myocardium. After amplification and filtering, the true root mean square values of both signals are compared and an error signal is generated. A closed-loop circuit uses the integrated error signal to continuously adjust the position of the two sample volumes. We have compared our system in vitro against a known signal and in vivo against the two-crystal TTS system during control, suppression (ischemia), and enhancement (isoproterenol) of myocardial function. Results were obtained in vitro for accuracy (> 99%), signal linearity (r = 0.99), and frequency response to heart rates > 450 beats/min, and in vivo data were acquired for end-systolic dimension (r = 0.99), end-diastolic dimension (r = 0.99), and percent wall thickness (r = 0.99). Both in vitro and in vivo tests indicate that the SCS functions identically to the two-crystal TTS. Use of the SCS allows measurement of absolute wall thickness and hence myocardial function, for both acute and chronically instrumented animal studies, with minimal or no trauma to myocardium.

Decellularized bone extracellular matrix in skeletal tissue engineering

2020 ◽  
Vol 48 (3) ◽  
pp. 755-764
Author(s):  
Benjamin B. Rothrauff ◽  
Rocky S. Tuan
Keyword(s):  
Tissue Engineering ◽  
Bone Regeneration ◽  
Tissue Regeneration ◽  
Animal Studies ◽  
Tumor Resection ◽  
Regenerative Capacity ◽  
Skeletal Tissue ◽  
Large Bone

Bone possesses an intrinsic regenerative capacity, which can be compromised by aging, disease, trauma, and iatrogenesis (e.g. tumor resection, pharmacological). At present, autografts and allografts are the principal biological treatments available to replace large bone segments, but both entail several limitations that reduce wider use and consistent success. The use of decellularized extracellular matrices (ECM), often derived from xenogeneic sources, has been shown to favorably influence the immune response to injury and promote site-appropriate tissue regeneration. Decellularized bone ECM (dbECM), utilized in several forms — whole organ, particles, hydrogels — has shown promise in both in vitro and in vivo animal studies to promote osteogenic differentiation of stem/progenitor cells and enhance bone regeneration. However, dbECM has yet to be investigated in clinical studies, which are needed to determine the relative efficacy of this emerging biomaterial as compared with established treatments. This mini-review highlights the recent exploration of dbECM as a biomaterial for skeletal tissue engineering and considers modifications on its future use to more consistently promote bone regeneration.

Modulation of Matrix Metalloproteinases by Plant-Derived Products

2020 ◽  
Vol 20 ◽  
Author(s):  
Nur Najmi Mohamad Anuar ◽  
Nurul Iman Natasya Zulkafali ◽  
Azizah Ugusman
Keyword(s):  
Clinical Trials ◽  
Natural Products ◽  
Matrix Metalloproteinases ◽  
Animal Studies ◽  
Current Knowledge ◽  
In Vitro Models ◽  
In Vivo Studies ◽  
Extracellular Matrix Components

: Matrix metalloproteinases (MMPs) are a group of zinc-dependent metallo-endopeptidase that are responsible towards the degradation, repair and remodelling of extracellular matrix components. MMPs play an important role in maintaining a normal physiological function and preventing diseases such as cancer and cardiovascular diseases. Natural products derived from plants have been used as traditional medicine for centuries. Its active compounds, such as catechin, resveratrol and quercetin, are suggested to play an important role as MMPs inhibitors, thereby opening new insights into their applications in many fields, such as pharmaceutical, cosmetic and food industries. This review summarises the current knowledge on plant-derived natural products with MMP-modulating activities. Most of the reviewed plant-derived products exhibit an inhibitory activity on MMPs. Amongst MMPs, MMP-2 and MMP-9 are the most studied. The expression of MMPs is inhibited through respective signalling pathways, such as MAPK, NF-κB and PI3 kinase pathways, which contribute to the reduction in cancer cell behaviours, such as proliferation and migration. Most studies have employed in vitro models, but a limited number of animal studies and clinical trials have been conducted. Even though plant-derived products show promising results in modulating MMPs, more in vivo studies and clinical trials are needed to support their therapeutic applications in the future.

scholarly journals Occupational Exposure to Carbon Nanotubes and Carbon Nanofibres: More Than a Cobweb

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 745
Author(s):  
Enrico Bergamaschi ◽  
Giacomo Garzaro ◽  
Georgia Wilson Jones ◽  
Martina Buglisi ◽  
Michele Caniglia ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Animal Studies ◽  
Chemical Properties ◽  
Biological Behavior ◽  
Cross Sectional ◽  
Carbon Nanofibres ◽  
Material Entity ◽  
Cross Sectional Design

Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) are erroneously considered as singular material entities. Instead, they should be regarded as a heterogeneous class of materials bearing different properties eliciting peculiar biological outcomes both in vitro and in vivo. Given the pace at which the industrial production of CNTs/CNFs is increasing, it is becoming of utmost importance to acquire comprehensive knowledge regarding their biological activity and their hazardous effects in humans. Animal studies carried out by inhalation showed that some CNTs/CNFs species can cause deleterious effects such as inflammation and lung tissue remodeling. Their physico-chemical properties, biological behavior and biopersistence make them similar to asbestos fibers. Human studies suggest some mild effects in workers handling CNT/CNF. However, owing to their cross-sectional design, researchers have been as yet unable to firmly demonstrate a causal relationship between such an exposure and the observed effects. Estimation of acceptable exposure levels should warrant a proper risk management. The aim of this review is to challenge the conception of CNTs/CNFs as a single, unified material entity and prompt the establishment of standardized hazard and exposure assessment methodologies able to properly feeding risk assessment and management frameworks.

scholarly journals Antidiabetic Properties of Naringenin: A Citrus Fruit Polyphenol

Biomolecules ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 99 ◽  
Author(s):  
Danja J. Den Hartogh ◽  
Evangelia Tsiani
Keyword(s):  
Insulin Resistance ◽  
Animal Studies ◽  
Citrus Fruit ◽  
Epidemiological Studies ◽  
Personal Health ◽  
Current Review ◽  
Vegetables And Fruits

Type 2 diabetes mellitus (T2DM) is a metabolic disease characterized by insulin resistance and hyperglycemia and is associated with personal health and global economic burdens. Current strategies/approaches of insulin resistance and T2DM prevention and treatment are lacking in efficacy resulting in the need for new preventative and targeted therapies. In recent years, epidemiological studies have suggested that diets rich in vegetables and fruits are associated with health benefits including protection against insulin resistance and T2DM. Naringenin, a citrus flavanone, has been reported to have antioxidant, anti-inflammatory, hepatoprotective, nephroprotective, immunomodulatory and antidiabetic properties. The current review summarizes the existing in vitro and in vivo animal studies examining the anti-diabetic effects of naringenin.

scholarly journals Subinhibitory Antimicrobial Concentrations: A Review of In Vitro and In Vivo Data

1992 ◽  
Vol 3 (4) ◽  
pp. 193-201 ◽  
Author(s):  
George G Zhanel ◽  
Daryl J Hoban ◽  
Godfrey KM Harding
Keyword(s):  
Antimicrobial Activity ◽  
Animal Studies ◽  
Molecular Level ◽  
Bacterial Virulence ◽  
Antibacterial Effects ◽  
Wide Range ◽  
Immune Defences

Antimicrobial activity is not an ‘all or none’ effect. An increase in the rate and extent of antimicrobial action is usually observed over a wide range of antimicrobial concentrations. Subinhibitory antimicrobial concentrations are well known to produce significant antibacterial effects, and various antimicrobials at subinhibitory concentrations have been reported to inhibit the rate of bacterial growth. Bacterial virulence may be increased or decreased by subinhibitory antimicrobial concentrations by changes in the ability of bacteria to adhere to epithelial cells or by alterations in bacterial susceptibility to host immune defences. Animal studies performed in rats, hamsters and rabbits demonstrate decreased bacterial adherence, reduced infectivity and increased survival of animals treated with subinhibitory antimicrobial concentrations compared to untreated controls. The major future role of investigation of subinhibitory antimicrobial concentrations will be to define more fully, at a molecular level, how antimicrobials exert their antibacterial effects.

In vivo assessment of human vaginal oxygen and carbon dioxide levels during and post menses

2005 ◽  
Vol 99 (4) ◽  
pp. 1582-1591 ◽  
Author(s):  
Donna R. Hill ◽  
Marianne E. Brunner ◽  
Deborah C. Schmitz ◽  
Catherine C. Davis ◽  
Janine A. Flood ◽  
...  
Keyword(s):  
Animal Studies ◽  
Pathogenic Bacteria ◽  
Sensor Technology ◽  
Atmospheric Conditions ◽  
Bacterial Virulence Factor ◽  
Carbon Dioxide Levels ◽  
Kinetics Of ◽  
Insertion Process

Previous in vitro and in vivo animal studies showed that O2and CO2concentrations can affect virulence of pathogenic bacteria such as Staphylococcus aureus. The objective of this work was to measure O2and CO2levels in the vaginal environment during tampon wear using newly available sensor technology. Measurements by two vaginal sensors showed a decrease in vaginal O2levels after tampon insertion. These decreases were independent of the type of tampons used and the time of measurement (mid-cycle or during menstruation). These results are not in agreement with a previous study that concluded that oxygenation of the vaginal environment during tampon use occurred via delivery of a bolus of O2during the insertion process. Our measurements of gas levels in menses showed the presence of both O2and CO2in menses. The tampons inserted into the vagina contained O2and CO2levels consistent with atmospheric conditions. Over time during tampon use, levels of O2in the tampon decreased and levels of CO2increased. Tampon absorbent capacity, menses loading, and wear time influenced the kinetics of these changes. Colonization with S. aureus had no effect on the gas profiles during menstruation. Taken collectively, these findings have important implications on the current understanding of gaseous changes in the vaginal environment during menstruation and the potential role(s) they may play in affecting bacterial virulence factor production.

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