But although millions of babies have now been born by IVF , the technique can offer no help to couples eager to have a child that is genetically theirs but who lack the eggs or sperm to make it: men whose testes produce no sperm, say, or women who have undergone surgery for ovarian cancer. Some opt for donor eggs or sperm, but an alternative may be on the way. Scientists are making steady progress towards creating human eggs and sperm — the so-called gametes that combine in fertilisation — artificially in a petri dish. The feasibility of such an extraordinary transformation of our flesh has only been recognised for 11 years.
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- How to Safely Get Vitamin D From Sunlight
- What is rose wine and how is it made?
- What Is Sebum and Why Does It Build Up on Skin and Hair?
- Experts Say This Is The Best Way To Boost Your Collagen Production
- Leather production processes
- Vitamin D and your health: Breaking old rules, raising new hopes
- Vitamin D: The “sunshine” vitamin
How to Safely Get Vitamin D From SunlightVIDEO ON THE TOPIC: Mass production of 3D carbon fiber skin tutorial
There is a clinical need for skin substitutes to replace full-thickness skin loss. Our group has developed a bilayered skin substitute produced from the patient's own fibroblasts and keratinocytes referred to as Self-Assembled Skin Substitute SASS.
After cell isolation and expansion, the current time required to produce SASS is 45 days. We aimed to optimize the manufacturing process to standardize the production of SASS and to reduce production time.
The new approach consisted in seeding keratinocytes on a fibroblast-derived tissue sheet before its detachment from the culture plate. Four days following keratinocyte seeding, the resulting tissue was stacked on two fibroblast-derived tissue sheets and cultured at the air—liquid interface for 10 days.
The resulting total production time was 31 days. An alternative method adapted to more contractile fibroblasts was also developed. It consisted in adding a peripheral frame before seeding fibroblasts in the culture plate. SASSs produced by both new methods shared similar histology, contractile behavior in vitro and in vivo evolution after grafting onto mice when compared with SASSs produced by the day standard method.
In conclusion, the new approach for the production of high-quality human skin substitutes should allow an earlier autologous grafting for the treatment of severely burned patients. The standard surgical treatment for the permanent closure of large full-thickness skin wounds that can occur following acute trauma or surgical intervention consists in replacing tissue loss with skin autografts harvested from an uninjured donor site on the patient.
Progress in tissue engineering has led to the development of technologies, allowing the production of skin substitutes. These substitutes can be either epidermal or dermal substitutes or bilayered skin substitutes. Tissue-engineered bilayered skin substitutes are composed of both a dermis and an epidermis. The ideal bilayered skin substitute should be easy to handle, must permanently ensure the skin barrier function, and should not induce a host immune rejection.
Some models of bilayered skin substitutes produced in the laboratory have been reported to allow permanent coverage of full-thickness wound, to reduce the need for harvesting autografts, and are indicated as an adjunct treatment for massive burns. The self-assembly approach developed at the LOEX 4 , 5 allows for the reconstruction of a fully autologous bilayered skin substitute. This method is based on the capability of cells to form an organized three-dimensional tissue without using any exogenous scaffold or biomaterial.
The resulting skin tissue shares many properties with native human skin and minimizes the host response after transplantation. The self-assembly method generates a highly functional and mechanically stable skin substitute 6 preserving epithelial stem cells, 7 which is suitable for autologous grafting in humans.
The first published self-assembly method involves a day production period that includes the fabrication of the dermal component 28 days , the seeding of keratinocytes followed by a 7-day submerged culture period, and maturation at the air—liquid interface for an additional 10 days. The aim of the present study was to reduce the production time of Self-Assembled Skin Substitute SASS and to standardize the manufacturing protocol for clinical production purposes.
The new method only requires a day production period. The resulting SASSs are equivalent in terms of histological properties, contractility, and in vivo evolution compared with SASSs produced with the day reference method.
The study was approved by the institutional animal care and use committee and by the institutional committee for the protection of human subjects. The procedures followed were in accordance with the Helsinki Declaration of Human keratinocytes and dermal fibroblasts were isolated from 1 newborn and 11 adult 18 to 46 years old human skin samples as previously described.
Keratinocytes were grown on a feeder layer of irradiated human fibroblasts 11 and cultured in keratinocyte medium Dulbecco—Vogt modified Eagle medium: Ham's F12, ratio , For tissue production, cells were used at passage three for keratinocytes and passage two to six for fibroblasts. In this study, tissue-engineered skin substitutes produced by three adaptations of the SASS-1 method were compared: the method referred to as SASS-2 reference method, previously presented in Ref.
Each proposed method was performed 6—10 times in triplicate using different combinations of fibroblasts and keratinocytes, of which four combinations were donor matched.
Tissue surrounding the frame is folded thereon. The frame is grasped with forceps, and the tissue is carefully detached and stacked on a subsequent tissue sheet. Surrounding tissue is again folded onto the frame, and the second tissue sheet is detached. The procedure is repeated with a third fibroblast-derived tissue sheet. The resulting skin substitute is referred to as SASS The total production time is 45 days Fig. The method SASS-3 consists in seeding 0.
The tissue adheres to the frame. Both extremities of the frame are grasped with forceps, and the tissue is progressively raised.
Once detached, the tissue is stacked onto a day fibroblast-derived tissue sheet. Surrounding tissue is folded onto the frame without covering the inside tissue, and the second tissue sheet is detached. The total production time is 31 days Fig. According to the patient's cells, dermal fibroblasts can sometimes induce contraction of unanchored tissue sheets when keratinocytes were added on the sheet. To circumvent this problem, an alternative approach referred to as method SASS-4 was developed.
Then, 0. After 4 days, the tissue is carefully detached and stacked with two other anchored fibroblast tissue sheets. The remaining steps are identical to those of the method SASS The total production time is 38—45 days Fig. The structural stability of the skin substitutes was assessed at the end of the culture period after 10 days of culture at the air—liquid interface by measuring tissue contraction with the method of agar-gelled substrate as described.
The experiment was repeated twice using newborn or adult cells each time in triplicate. Six mice per condition were grafted. Fusenig's silicone chambers were removed after 21 days. For each condition, mice were sacrificed 21 3 mice and 90 3 mice days after grafting. Skin substitute samples before grafting, 21 and 90 days after grafting were processed for histological and immunofluorescence analysis.
Five micrometer-thick sections were stained with Masson's trichrome using Weigert's hematoxylin, fuchsin-ponceau, and aniline blue.
Grimaud, Pasteur Institute, Lyon, France. Samples were processed and pictures were acquired as described.
All three types of substitutes have been successfully produced with most keratinocyte and fibroblast populations tested, except with cells from a year-old female donor where only SASS-2 and SASS-4 have been successfully produced. In this case, the addition of the donor-matched keratinocytes onto the unanchored fibroblast-derived sheet SASS-3 induced contraction resulting in unusable shrunk tissue.
Surface uniformity varied between cell donors. Areas appearing denser or brighter were observed Fig. Macroscopic and histological analysis of SASS produced in vitro. Arrows point out squame accumulation. Representative histological aspect of an area appearing brighter macroscopically D and an epithelial cell inclusion E. The four typical layers of human epidermis stratum basale , spinosum, granulosum, and corneum were observed in denser areas of SASS, indicating a fully differentiated epidermis Fig.
For less homogeneous SASS, areas that appeared brighter macroscopically were typically associated with a lower number of keratinocyte layers and the absence of a stratum corneum Fig. Some of these structures were in contact with the epidermis forming invaginations data not shown. Analysis of skin markers and of the ultrastructure of SASS matured in vitro. Representative transmission electron microscopy observations M, N.
Cell nuclei were stained in blue with Hoechst reagent A—L. Dotted line indicates the dermoepidermal junction. Red arrows point to collagen fibers M, N. Hd, hemidesmosomes; ll, lamina lucida ; ld, lamina densa. Keratin K 19 immunostaining was performed to evaluate the persistence of stem cells and confirmed the presence of a small subset of basal keratinocytes expressing K19 Fig. Basal cells expressed K14 and integrin alpha-3 data not shown , whereas K10 expression was restricted to the suprabasal layers Fig.
Filaggrin, a protein associated to the cornified envelope, was detected in the upper cell layers of the epidermis Fig. The final SASS surface area available for grafting depends on the contraction of the tissue after detachment from the peripheral anchorage at the end of the culture.
The structural stability of the skin substitutes after detachment from the anchorage was evaluated in vitro over a period of 2 days. Results showed that the contraction kinetic displayed the characteristic exponential decay profile of tissue-engineered skin produce by self-assembly, 6 independently of the method used for fabrication Fig.
Contractile behavior of SASS matured in vitro. SASS-2 blue curve , SASS-3 red curve , and SASS-4 green curve were placed on an agar substrate, and the surface area of the skin substitutes was measured over time to obtain contraction kinetic curves.
N: number of independent experiments performed in triplicate. Complete take of all grafts to the wound bed was observed.
The epithelium was present on all grafts for the entire duration of the experiment, indicating the preservation of functional epithelial stem cells within the skin substitute and long-term epithelial regeneration.
The arrow pointing toward the junction between mouse and human epithelium. Cell nuclei were stained in blue with Hoechst reagent. In this study, alternative methods to produce high-quality autologous human skin substitutes suitable for the permanent coverage of full-thickness skin wounds were proposed.
The three designs derive from the self-assembly approach originally presented by our team for blood vessels, 5 followed by skin in Method SASS-3 should be prioritized because it allows the production of skin substitutes in 31 days, which is 2 weeks less than the previous 45 days required for SASS-2, while SASS-4 method manages contractile fibroblasts.
Intrinsic contractile properties of fibroblasts as well as their ability to secrete extracellular matrix vary between donors personal observation. It happens that unanchored fibroblast-derived tissue sheets spontaneously detached from the culture plate after being in culture.
Also, the addition of keratinocytes onto an unanchored fibroblast sheet sometimes induces contraction of the sheet followed by their spontaneous detachment and further tissue shrinkage. The SASS-4 method was designed to circumvent this problem by adding a peripheral anchorage to limit spontaneous tissue contraction.
Our results are consistent with the limited tissue contraction observed with anchored adipose tissue sheets or myofibroblast-derived tissue sheets. For SASS production to treat a patient, fibroblasts are used from passage 2. To determine the potential of fibroblasts to generate tissues that resist to manipulation and contraction, a dozen of fibroblast-derived tissue sheets can be prepared from passage 1 fibroblasts to anticipate the behavior of cells, to adjust the optimal culture time, and to orient the choice of the production method to use thereafter.
The quality of the basement membrane and its adequate ultrastructure in SASS may allow for the stem cell preservation since the basement membrane is involved in the maintenance of epithelial stem cells.
Gelatin is a protein substance derived from collagen, a natural protein present in the tendons, ligaments, and tissues of mammals. It is produced by boiling the connective tissues, bones and skins of animals, usually cows and pigs. Gelatin's ability to form strong, transparent gels and flexible films that are easily digested, soluble in hot water, and capable of forming a positive binding action have made it a valuable commodity in food processing, pharmaceuticals, photography, and paper production. As a foodstuff, gelatin is the basis for jellied desserts; used in the preservation of fruit and meat, and to make powdered milk, merinque, taffy, marshmallow, and fondant. It is also used to clarify beer and wine. Gelatin's industrial applications include medicine capsules, photographic plate coatings, and dying and tanning supplies.
What is rose wine and how is it made?
Elsevier Health Sciences Bolero Ozon. Concept Maps in the disorders chapters help you visualize difficult material, and illustrate how a disorder's multiple symptoms, treatments, and side effects relate to each other. Nursing Care Plans with critical thinking questions provide a clinical scenario and demonstrate application of the nursing process with updated NANDA-I nursing diagnoses to individual patient problems. Anatomy and physiology content in each body system overview chapter provides basic information for understanding the body system and its disorders, and appears along with Focused Assessment boxes highlighting the key tasks of data collection for each body system.
What Is Sebum and Why Does It Build Up on Skin and Hair?
Rankings are based on the combined production of two types of leather: heavy leather typically sole, belting, strap, and mechanical leathers made from unsplit hides and light leather used in most other applications: bags, coats, shoes, etc , as well as two main categories of raw materials: bovine cow and bison hides, and sheep and goat skins. Producing nearly 1. Russia takes fourth position with just over 1. Russia produces mainly light leather from bovine animals 1. In third place is Italy, the undisputed European leader in leather production, with over 1. Of the 1. Overall, the Chinese leather industry produces nearly 4 billion square feet of leather per year - more than doubling the production of 2nd place Brazil.
All rights reserved. Body organs aren't all internal like the brain or the heart. There's one we wear on the outside. Skin is our largest organ—adults carry some 8 pounds 3. This fleshy covering does a lot more than make us look presentable. In fact, without it, we'd literally evaporate. Skin acts as a waterproof, insulating shield, guarding the body against extremes of temperature, damaging sunlight, and harmful chemicals. It also exudes antibacterial substances that prevent infection and manufactures vitamin D for converting calcium into healthy bones. Skin additionally is a huge sensor packed with nerves for keeping the brain in touch with the outside world. At the same time, skin allows us free movement, proving itself an amazingly versatile organ.
Experts Say This Is The Best Way To Boost Your Collagen Production
Back to Healthy body. Vitamin D is essential for healthy bones. Find out how to get enough without risking sun damage.
Best served chilled, rose gives you savoury flavours resembling fruits like blackberries, plums and cherries. Neither a white nor of the red variety, the rose is a pink wine produced from red grapes with minimal skins contact, almost similar to the white wine process. As a matter of fact, winemakers are not allowed to produce it that way — not if the wine is to be labelled as rose. Rose wine is, in fact, made exclusively from the same blue grapes as the red wines are made of. These blue grapes almost always have a light, often colourless juice and so the obvious question arises: Where does the dark red colour come from? The release of the pigments from the mash during red winemaking typically occurs over a few weeks and, if this process is interrupted after just a few hours, only a little colouring will have been released from the grape skins. The rose winemaker takes advantage of this and assumes total control over the colour of the wine. Once the juice has taken on a slight red hue, it is pressed and transferred to another tank where it continues to ferment without the skins. It will eventually be bottled as rose wine. So, in the strict sense, rose wines are fermented red wines that have had only minimal contact with the grape skins. Of course!
Leather production processes
See the Skin Health Overview article. The antioxidant properties of vitamin C ascorbic acid and its role in collagen synthesis make vitamin C a vital molecule for skin health. Dietary and topical ascorbic acid have beneficial effects on skin cells, and some studies have shown that vitamin C may help prevent and treat ultraviolet UV -induced photodamage. However, the effects of vitamin C in the skin are not well understood due to limited research. This article discusses the potential roles of vitamin C in the skin and summarizes the current knowledge about vitamin C in skin health. Vitamin C is a normal skin constituent that is found at high levels in both the dermis and epidermis 1, 2. The vitamin C content of the epidermis is higher than the dermis, although the vitamin C concentrations in both layers are approximately equal to that of other water-soluble antioxidants , including uric acid and glutathione Aging, however, causes a decline in vitamin C content in both the epidermis and dermis 2.
Vitamin D and your health: Breaking old rules, raising new hopes
The skin, along with hair and nails, is the protective covering of the body. In addition, the skin prevents germs from entering the body and damaging internal organs. Skin supports the life of all other body parts and plays a role in maintaining the immune system. Skin also helps to regulate body temperature through the sweat glands. When the body becomes overheated, sweat glands give off moisture perspiration , which cools the body as it evaporates. As the body part responsible for the sense of touch, the skin works with the nervous system to alert the body to potential dangers by detecting pressure, pain, heat, and cold.
Vitamin D: The “sunshine” vitamin
Vitamin D was discovered in , culminating the long search for a way to cure rickets, a painful childhood bone disease. Within a decade, the fortification of foods with vitamin D was under way, and rickets became rare in the United States. But solving the problem of rickets was only the beginning of research into vitamin D. Research results suggest that vitamin D may have a role in other aspects of human health.
It coats, moisturizes, and protects your skin. So, what exactly is sebum made up of? If you have very oily skin, your body may be producing an excess amount of the mixture of lipids fat-like molecules that make up sebum.
Experience the magic of biology in your own home lab. This hands-on introduction includes more than 30 educational and fun experiments that help you explore this fascinating field on your own. Perfect for middle- and high-school students and DIY enthusiasts, this full-color guide teaches you the basics of biology lab work and shows you how to set up a safe lab at home. The Illustrated Guide to Home Biology Experiments is also written with the needs of homeschoolers firmly in mind, as well as adults who are eager to explore the science of nature as a life-long hobby.
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