Resistance gelatin queues: The gel strength of the leather tails can range from 40 to 4000g Double Bloom, but is usually between 100 and 300 g. The tails of bones have traditionally covered the range of 40-150g. Preserving the quality of the glue: Viscosity and gel strength of the tail are not completely stable properties and can worsen if the solutions are handled improperly. It is said that the tail is degraded, which taken literally means that quality is reduced from higher to a lower. The degradation is caused by prolonged heating or by bacteria and microorganisms. Therefore you should avoid all unnecessary heating. Usually it is as undesirable as unnecessary heat tail solutions above 600C, at this temperature the viscosity and the resistance of the gelatin can decrease by 0.2-1.0% per hour, depending on quality and bacterial enzymes present. At 800C the rate of degradation is about is about four times higher than 600C. In boiling solutions is very rapid degradation.

At temperatures near 400C thermal degradation is very slow, but the degradation may be rapid if there are still bacteria. The modern lines usually contain preservatives that prevent bacterial growth, although there are still variations in the rate of degradation between the tails of the same quality, due to the presence of bacterial enzymes, which can cause degradation even when it inhibits the subsequent bacterial growth. It is advisable not to rely entirely on the work of the condoms and whenever possible, prepare the queues in separate series, in order not to mix a new queue with old and potentially contaminated materials. Animals with the tail surfaces can be joined, if they are likely to be wet with water and if one is permeable to water. The animal glue has certain disadvantages in comparison with some synthetic glues that can be used for the same purpose.

The solidification is slower at high temperatures. In wet conditions are considerably weakened joints and can break easily when subjected to stress, but a structure can resist the actions of the intersperse if glued joints are located deep enough to be protected. For example, animal glues were used successfully for the assembly of window frames before they were known synthetic glues. Moreover, the tail has some advantages animal synthetic glue. Rarely used as hardeners, prepared solutions of animal glue-time employment have long and useful indefinite duration storage in comparison with synthetic glues. The quality animal glues not shatter into a thick line of glue. The dry line is not as harsh as the tail phenolic and urea-formaldehyde and is detrimental to emboss cutting tools.

The most important property of the animal's tail, however, power gel and its main advantage lies in the exploitation of this property. The fast initial solidification a glue joint, produced by gelation, it is useful in the assembly of structures in which the union is difficult or inconvenient. The rapid emergence of adhesion in animal glues when solidified in gel form makes them useful in applications such as gluing fabric or wood, bookbinding books, manufacture of cartons in high-speed machines in the manufacture of gummed paper. The role of collagen in the maintenance of the physico-chemical and mechanical properties of the dermis leads us to believe that their use of cosmetics may alleviate a deficit by encouraging: Maintenance of deep hydration: The collagen hydration effect is attributed to its ability to retain water. The native soluble collagen used at concentrations of 0.05% with a comparable moisturizing power to 10% of a wetting agent such as urea or sorbitol. This effect can be assessed by different methods:

1. Insensible water loss from the skin.
2. Measuring the electrical or thermal impedance of the stratum corneum.
3. Measuring the viscoelastic properties of the stratum corneum.

Skin Relief: The application of collagen causes an effect of "smoothing" of the skin surface structures, which translates into a smoother skin. The influence of collagen on the skin topography is exercised at two levels:

1. When the skin condition is altered due to a chemical treatment or by bad weather, collagen has the power to restore the initial organization of the surface.
2. On a healthy skin, application of collagen leads to a reduction of the amplitudes of the cutaneous relief without affecting its complexity.

In the case of fibrous collagen (lyophilized) used as a facial mask, the effect of "smoothing" is visible in a single application. This property is due to the presence of soluble collagen. This activity on the cutaneous relief reflects moisturizing and film forming properties of colla -

Skin Elasticity

The mechanical properties of skin are defined in terms of robustness, extensibility, stiffness or elasticity. In the study of the influence of a cosmetic treatment with soluble collagen was determined that it involved a decrease in the value of breaking strength and improved elasticity.

Stimulation of cell growth: In cell cultures has been identified as substrates of collagen can maintain living cells. The collagen chains have chemotactic properties on fibroblasts, which can partly explain its role in healing.

Anti-irritant power: Collagen in the form soluble or fibrous possesses the power to reduce the irritation induced by chemicals, when applied simultaneously with them. This protective effect has been studied with respect to the croton oil and various detergents. In this case, it appears that collagen forms a film around the micelles of detergent and thus moderates the action of these products. This protective effect may also be explained by a protection mechanism for absorption of collagen on the outer surface of the stratum corneum. The influence of collagen cosmetic treatment in the aging process has been evaluated with two techniques:

Study of thermal stability of collagen network

The denaturation of collagen, ie the transition from orderly helical structure jelly-like amorphous structure can be measured by a differential calorimeter scheduled. Indeed, this transition causes an endothermic reaction that results in a heat absorption peak, because the surface is proportional to the enthalpy of denaturation of collagen.

To judge the influence of a native collagen cosmetic treatment, a scientist and colleagues applied an emulsion O / W with 0.02% collagen in rat growth period, observing a change in the thermal properties of the collagenous network , appearing as "younger".

Study of the biomechanical properties of skin:

Given that the fibrous network and in particular the collagen fibers are at the skin more important from the standpoint of mechanics, Herbage measured different parameters (elasticity, rupture) in rat skin by applying a emulsion O / W with 0.02% acid soluble collagen compared with a placebo emulsion. After slaughtering the animal, samples were subjected to skin traction dynamometer 1026, until his break. There was a significant decrease in breaking strength and stability.

In conclusion, it appears that in young skin, collagen halted the progression of physical-mechanical parameters and thus slows the aging of the fibrous network.

Cosmetic Use Of Collagen:

Collagen appears as a great hydration factor, an agent capable of promoting skin smoothness and elasticity, which may also slow the evolution of age of physical parameters of the dermis, activated tissue regeneration and reduce skin irritations. Thus, acid-soluble collagen, with or without telopeptides, is used in preparation of milks and creams for treatment. The lyophilized collagen was used as face masks for the same purpose.

Activity on the hair: Collagen and hydrolysates in hair products are introduced as conditioning agents and protectors. Collagen promotes cohesion of the scales of the cuticle. This effect leads to a change in hair porosity and improved surface state.

Moreover, the hair treated with soluble native collagen can be elongated by 6% higher than untreated hair.

Activity as a vehicle: Collagen has a special place as a biomaterial, to possess the ability to obtain reticular collagenous matrices with variable degree of solubility. J. Cotte, H. Dumas, apply the technique to obtain microspheres Pilling imprison insoluble or lipophilic active and depending on the degree of crosslinking may melt and break when applied to the skin giving substances. Resistant areas are also available for use in peels.

Medical Use Of Collagen:

The use of collagen for catgut, was the first step of this material in medical use. Between 1932 and 1944 appeared the work of T. Huzella on the growth of cells on collagen fibers. In 1956 R.L. Ehrmam and G.O. Gey published, "The growth of cells on a transparent gel of reconstituted rat-tail collagen and show the favorable action of collagen on the growth of 29 types of cells and tissue implants (man, rat, frog). After him, many researchers followed the studies confirming the results obtained by other authors, showing that collagen increases cell growth. Following these studies were initiated drug trials in the field of healing. A. Cer showed that collagen determines a remarkable acceleration of the cicatricial process. Struck Nagelschmidt and concluded that concussions and fractures are regenerated so faster with the application of exogenous collagen. More recently, Daniel, Foix and Zaegel performed a remarkable job on a sample of 20 persons suffering from varicose ulcers, obtaining rapid healing in 16 cases, after application, after disinfection, a collagen film. Importantly, the rate of healing (from 8 days to 2 months), ulcers of one month to several years of development in which the normal healing (acetamido acid and Trichlorocarbanilide) provided a very weak or no improvement. The use of collagen in the medical field is based with the following properties:

1. Contribution to improving the mechanical properties of tissue.
2. Power hemostatic: the plates and collagen powders are used in surgery to induce hemostasis.
3. Cell growth: the supports of collagen used as substrate to develop cell cultures. These crops may lead to the formation of new tissues.

Adjuvant healing: collagen in the form of film, is used in the treatment of burns and ulcers. It is biocompatible and biodegradable. Compared with other proteins is somewhat immunogenic and telopeptides of human collagen are very similar to those of bovine collagen. It is essential that the antigenicity is assessed separately for each product type. The main antigenic determinants are localized at the level of the telopeptides. Importantly, denatured collagen is more antigenic, hence the importance of using native collagen for medical applications. The biodegradability of collagen and its derivatives is an important point in its use in the field of implants. In the implants, the number of "Crosslink is an important factor in revascularization, cellular regeneration and persistence of the implant.

The collagen can be implanted in wounds with skin loss in order to prevent shrinkage and to minimize the development of granulation tissue.

In 1981 the F.A.D. approved the introduction of collagen in the market. Is required before use, a test of awareness in the forearm to ensure the patient's allergy to this material, and not to its implementation until it has observed the area for a period of four weeks. Collagen injected subcutaneously condenses into a soft dough and consistent contact with body temperature. Generally used as a replacement or filler for the correction of certain defects in the dermis. The most common indications for use are:

1. Collagen plates obtained by lyophilization of a native collagen gel used as:
2. Quick hemostatic.
3. Strong epithelializing.
4. Favoring the fixation and adhesion of grafts and flaps.
5. Can be used as a collagen implant in drinks, in a phosphate buffered saline and lidocaine.
6. Correction risk lines, glabellar, and vertical frown, corners nasolabial folds, chin, etc. and acne scarring or trauma.

The collagen sponge matrix serves temporarily to the cells that form a web of collagen used as substrate for the mineral deposit and bone formation. Collagen sponges are also used as drug reservoirs or vaginal contraceptives. The tanning collagen threads are used as surgical suture. Collagen tubes are used as drug reservoirs implants. After this brief review we can conclude collagen biomaterial noting that despite being known for many years continues to form an active part in high cosmetic formulations to be little affected by this market fads that usually suffers. This indicates that their effectiveness and properties are not easy to replace, but perhaps is in the world of dermatology and surgery where surprises us with some exceptional qualities and worthy of attention.

Adhesive: It is a material capable of holding two materials together providing strong physical attraction force required between the two surfaces. The material which adheres to the adhesive substrate or adherent is called. Content: The exact nature of the compositions is not spread by the manufacturers, but the following composition is typical of many adhesives: Polymer: Form of the adhesive mass and contributes to its strength in 3 dimensions. Solvent: Must be present to bring the adhesive to a liquid.

Charges: are added to reduce costs or improve certain properties such as fluidity or resistance to takeoff. Adhesive: Substances which contribute to hit while the adhesive is still wet or uncured. Plasticizers: softening the final film of the adhesive and impart flexibility. Other Additives: Inflammation retardants, light stabilizers, colorants and viscosity control agents are the most typical cases. Adhesion molecules: commercial adhesives are complex mixtures of molecules because the compounds are added (components). Viscous molecules that attract and are involved in the sup. united are organic polymers. These molecules (polymers) contain carbon and hydrogen and oxygen atoms, nitrogen, silicon, chlorine.

The atoms of a molecule can be linked adhesive in different ways, but most have in common sig. characteristics: Atoms held together by shared electrons, this is a covalent bond, and then the adhesive has limited stability when heated and usually not water soluble (very few) are a typical vinyl queues. Polymers are very large molecules containing thousands of atoms. The molecules of the adhesive can have a linear arrangement of atoms or may be branched polymers.

The shared electrons are free to move between atoms that bind them together and suspended in this volume and the attraction of the positive atomic nucleus exerts on them. As the molecules are electronically loaded adhesives adhere to surfaces. The constant fluctuation of positive and negative centers in a molecule indicates that the net charge on the molecule is zero. There will always be attraction between molecules, however, can be aligned internally uneven loads in the vicinity of the molecules, the attraction resulting from this uneven distribution of electrons is called Van der Waals force. These forces are applied to both adherent surfaces (adhesion forces) and adjacent molecules (cohesive forces). The range of these forces is considerably lower if the adhesive is in intimate contact with the areas to be joined, due to surface roughness of the sup. there is always treated mechanically. This is the reason that the adhesive has fully penetrate the surface roughness and spray the entire surface. The resistance of the adhesive force depends, for this reason, the degree of wet (to maximize intermolecular exchange) and on the other side of the bonding capacity of the surface.

Wetting: The term refers to the adhesive coating in intimate contact with the surface. When the adhesive to flow and find a valley it will flow into the valley (good wet) or have a bridge over it (bad wet). Adhesives with high attractive force for themselves, will be more viscous and tend to form a bridge over the valley taking result in reduced contact area between the adhesive and substrate, reducing the resistance of the gluing.

A special problem occurs when the adhesive is applied dissolved in solvent, the solvent can flow into the sup. the valley faster than the adhesive, so it keeps the adhesive layer floating on the solvent. When the adhesive is cured, the solvent is lost by evaporation and a vacuum between the adhesive and substrate. The cleaning process can be evaluated with the "ultimate test of water droplets" by applying several drops of water on a sup. improperly cleaned, the spherical shape of the drop is fairly, but if the water runs, the wet is satisfactory (the face of union is sufficiently clean)

• Written by Rajinder Soni.
• In category Medicine & Surgery.
• 15 years ago.

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