Dead Space Models Research Articles

In vivo models for assesment of wound healing potential: A systematic review

Abstract Introduction The wound is defined as an injury of a living tissue, arose due to either an accidental injury like cut of the cells or skin or sometime, maybe broken the tissue, which may cause the anomalies in the cellular ability to exhibit the protective mechanism. Wound healing is process of regaining the integrity of cell structure and layers of the skin. The normal healing process of wounds are categorized in 4 phases which includes hemostatic, inflammatory, fibrolastic and maturation. Purpose The present manuscript embarks on up to date information on different methods being used for wound healing assessment including incision, excision, burn wound and dead space models. The biochemical parameter which acts as wound healing markers are collagen estimation (hydroxyproline), hexosamine, DNA estimation, total protein estimation, wound Index, contraction area, epithelization period and tensile strength etc. Histologic evaluations is also an integral part of wound healing evaluation which, help in evaluating the cellular and matrix detail within the wound. Conclusion At present, molecular approaches are important to heal the wound. For assessment of potential of any herbal drug/synthetic compound, incision wound model, excision wound model, burn wound model and dead space model and their parameter are used.

Evaluation of the wound healing efficacy of chemical and phytogenic silver nanoparticles.

Wound healing requires a series of cellular events and a cascade of co-ordinated and systemic biochemical events. Silver nanoparticles possess many beneficial properties for wound management including antibacterial, anti-inflammatory and pro-healing properties. In this study, the authors investigated the wound healing properties of Cinnamomum verum extract mediated nanosilver (CENS) particles in comparison with 1% povidone iodine, citrate mediate NS and CE treatments. The topical application of CENS showed good antibacterial activity and accelerated wound healing with complete epithelialisation and normal re-growth of hair in all three models of study: namely, excision, incision and dead space models in rats compared with all other treatments. CENS was also found to promote collagen synthesis, stabilise wound besides countering oxidative stress and stimulating cellular proliferation CENS could be a novel therapeutic agent for wound management.

Characterization and Modeling of Breakdown Probability in Sub-Micrometer CMOS SPADs

This paper presents the characterization of two different single-photon avalanche diodes fabricated in a standard 0.15 μm CMOS process and the modeling of their breakdown probability. The first device is based on a p+/nwell abrupt junction, while the second one has a pwell/n-iso diffused junction. Breakdown voltage and breakdown probability are modeled using both local and dead-space models. While the two models are in agreement for the prediction of breakdown voltage, it is shown that the local model largely underestimates the breakdown probability with respect to experimental results. On the contrary, the voltage and wavelength dependence of breakdown probability can be correctly predicted using the dead-space model.

OPTIMAL RESPIRATORY CONTROL SIMULATION AND COMPARATIVE STUDY OF HYPERCAPNIC VENTILATORY RESPONSES TO EXTERNAL DEAD SPACE LOADING

There has been considerable research effort regarding ventilatory responses to breathing with an imposed external dead space, and inhalation of fixed levels of CO 2 by human subjects. A human respiratory control model incorporating the optimality hypothesis can successfully demonstrate ventilatory responses to both chemical stimuli and muscular exercise. In this study, to verify the model behavior of the optimal chemical–mechanical respiratory control model, we simulated the ventilatory control under dead space loading and CO 2 inhalation. The simulation was provided by a LabVIEW® based human respiratory control simulator and signal monitoring system. The dead space measurement was described with two distinct models, derived from Gray and Coon, and predicted behaviors with corresponding ventilatory responses were investigated and compared with experimental findings. While both dead space models produced satisfactory predictions on simulated optimal [Formula: see text] versus Pa CO 2, [Formula: see text] versus Pa CO 2, F versus PI CO 2, VT versus PI CO 2, VD-total versus VT, VD- total /VT versus VT, [Formula: see text] versus VT and [Formula: see text] versus VT relationships, Gray's model provided better correlation and more consistent results throughout most of the ventilatory responses. The study of relative behavior of respiratory signals and comparative relationship of the ventilator responses between dead space loading during rest and CO 2 inhalation will certainly provide valuable understanding of increases in central respiratory motor command output of human respiratory control, which is also associated with Dyspnea on exertion, and give potential clinical perspective to realize the impaired ability to excrete CO 2 in patients diagnosed with acute respiratory distress syndrome.

Embelin accelerates cutaneous wound healing in diabetic rats

This study reports the effect of embelin (1) on cutaneous wound in streptozotocin (STZ)-induced diabetic rats. The effect was studied using excision, incision, and dead space models. In diabetic rats, topical application of embelin 5% (w/w) ointment showed a significant increase in wound contraction and better epithelialization, thereby facilitating the healing. Embelin was also active by the oral route (25 and 50 mg/kg) in the incision and dead space wound models. In incision wound model, wound granulation tissues were removed on 8th post-wounding day, and the hydroxyproline, hexosamine, total protein, and DNA contents were determined. In STZ diabetic rats, topical and oral applications of embelin showed an increase in hydroxyproline, hexosamine, total protein, and DNA contents. It also showed a significant increase in wound breaking strength. Embelin significantly increased granuloma tissue weight and breaking strength in dead space model. These results indicated that embelin accelerated wound healing in diabetic rat.

The Polyvinyl Alcohol Sponge Model Implantation

Wound healing is a complicated, multistep process involving many cell types, growth factors and compounds1-3. Because of this complexity, wound healing studies are most comprehensive when carried out in vivo. There are many in vivo models available to study acute wound healing, including incisional, excisional, dead space, and burns. Dead space models are artificial, porous implants which are used to study tissue formation and the effects of substances on the wound. Some of the commonly used dead space models include polyvinyl alcohol (PVA) sponges, steel wire mesh cylinders, expanded polytetrafluoroethylene (ePTFE) material, and the Cellstick1,2.Each dead space model has its own limitations based on its material's composition and implantation methods. The steel wire mesh cylinder model has a lag phase of infiltration after implantation and requires a long amount of time before granulation tissue formation begins1. Later stages of wound healing are best analyzed using the ePTFE model1,4. The Cellstick is a cellulose sponge inside a silicon tube model which is typically used for studying human surgery wounds and wound fluid2. The PVA sponge is limited to acute studies because with time it begins to provoke a foreign body response which causes a giant cell reaction in the animal5. Unlike other materials, PVA sponges are easy to insert and remove, made of inert and non-biodegradable materials and yet are soft enough to be sectioned for histological analysis2,5.In wound healing the PVA sponge is very useful for analyzing granulation tissue formation, collagen deposition, wound fluid composition, and the effects of substances on the healing process1,2,5. In addition to its use in studying a wide array of attributes of wound healing, the PVA sponge has also been used in many other types of studies. It has been utilized to investigate tumor angiogenesis, drug delivery and stem cell survival and engraftment1,2,6,7. With its great alterability, prior extensive use, and reproducible results, the PVA sponge is an ideal model for many studies1,2.Here, we will describe the preparation, implantation and retrieval of PVA sponge disks (Figure 1) in a mouse model of wound healing.

The Polyvinyl Alcohol Sponge Model Implantation

Wound healing is a complicated, multistep process involving many cell types, growth factors and compounds1-3. Because of this complexity, wound healing studies are most comprehensive when carried out in vivo. There are many in vivo models available to study acute wound healing, including incisional, excisional, dead space, and burns. Dead space models are artificial, porous implants which are used to study tissue formation and the effects of substances on the wound. Some of the commonly used dead space models include polyvinyl alcohol (PVA) sponges, steel wire mesh cylinders, expanded polytetrafluoroethylene (ePTFE) material, and the Cellstick1,2. Each dead space model has its own limitations based on its material's composition and implantation methods. The steel wire mesh cylinder model has a lag phase of infiltration after implantation and requires a long amount of time before granulation tissue formation begins1. Later stages of wound healing are best analyzed using the ePTFE model1,4. The Cellstick is a cellulose sponge inside a silicon tube model which is typically used for studying human surgery wounds and wound fluid2. The PVA sponge is limited to acute studies because with time it begins to provoke a foreign body response which causes a giant cell reaction in the animal5. Unlike other materials, PVA sponges are easy to insert and remove, made of inert and non-biodegradable materials and yet are soft enough to be sectioned for histological analysis2,5. In wound healing the PVA sponge is very useful for analyzing granulation tissue formation, collagen deposition, wound fluid composition, and the effects of substances on the healing process1,2,5. In addition to its use in studying a wide array of attributes of wound healing, the PVA sponge has also been used in many other types of studies. It has been utilized to investigate tumor angiogenesis, drug delivery and stem cell survival and engraftment1,2,6,7. With its great alterability, prior extensive use, and reproducible results, the PVA sponge is an ideal model for many studies1,2. Here, we will describe the preparation, implantation and retrieval of PVA sponge disks (Figure 1) in a mouse model of wound healing.

The evidence based wound healing activity of Lawsonia inermis Linn.

The ethanol extract of Lawsonia inermis (200 mg/kg/day) was used to evaluate the wound healing activity on rats using excision, incision and dead space wound models. The animals were divided into three groups of six each in the excision model and two groups of six each in the incision model and dead space models. The topical application was made in the case of excision wound model, whereas, oral treatment was done with incision and dead space wound models. The following differences were noted in the group of experimental animals which were treated with an extract of L. inermis when compared with the control and reference standard animals: a high rate of wound contraction (p < 0.001), a decrease in the period of epithelialization (p < 0.001), high skin breaking strength (p < 0.001), a significant increase in the granulation tissue weight (p < 0.001) and hydroxyproline content (p < 0.05). The extract-treated animals showed 71% reduction in the wound area when compared with controls which was 58%. Histological studies of the tissue obtained on day 10 from the extract-treated group showed increased well organized bands of collagen, more fibroblasts and few inflammatory cells when compared with the controls which showed inflammatory cells, scanty collagen fibres and fibroblasts. Enhanced wound contraction, increased skin breaking strength, hydroxyproline and histological findings suggest the use of L. inermis in the management of wound healing.

Wound healing activity of root extracts of Berberis lyceum royle in rats

The wound healing activities of the aqueous and methanol extracts of the root of Berberis lyceum were assessed using incision, excision and dead wound space models of wound repair in rats. After application of both extracts it was observed that the area of epithelialization increased, followed by an increase in wound contraction, skin breaking strength, tissue granulation, dry weight and hydroxyproline content. Histopathological studies of the granulation tissue also indicated that there was an increase in collagen formation in those rats treated with the methanol extract, compared with the control group animals. The methanol extract was more effective than the aqueous extract, but both showed significant results compared with the control.