Regrow New Skin
Indeed, after a period of great enthusiasm, during which septic shock was considered the prototypic cytokine-mediated disease, most of the big pharmaceutical companies became daunted by the complexity of this pathological condition, which is associated with other diseases such as cancer, trauma, or burn injury. Some attempts have been toward a narrower definition of the component of septic shock, including acute respiratory distress syndrome (ARDS) and multiple organ failure (MOF), in which cytokines play an important role. In 1992 the American College of Chest Physicians and the Society of Critical Care Medicine Consensus Conference introduced the term systemic inflammatory response syndrome (SIRS) (3). Despite these difficulties, the scientists working in the field of cytokines and inflammation have continued using the models of lipopolysaccharide (LPS) toxicity as a means of inducing a systemic inflammatory response (to stick to the above definition).
As might be expected, there is a significant difference between nonsurgical and surgical laser treatments. For the most part, nonsur-gical laser treatments have a more limited effect on the skin because the laser energy is absorbed by a targeted skin component. Only the unwanted skin components, such as blood vessels, pigmented cells or hair follicles, are damaged. With nonsurgical laser treatments pain is mild usually no anesthesia is required. In contrast, surgical laser treatments are nonspecific and affect all skin components equally. In laser resurfacing, entire layers of skin are removed and significant healing must take place because new skin must grow to replace the removed skin. Incisional laser surgery requires stitches to close the wound.
To overcome such difficulties in studying human epidermal wound healing, we have developed a new skin organ culture model, which involves the complete removal of the epidermis from the central portion of a skin disk. The viability and efficiency of such models has been previously demonstrated in various studies investigating complex aspects of cutaneous dendritic cell
The pain of standard injections is partially, if not wholly, the result of direct mechanical stimulation of the ATP cascade. Work of Burnstock and others suggest that during tissue damage, adenosine triphosphate (ATP) is released from damaged cells. ATP is a ubiquitous cellular energy storage compound, which when released extracellularly potentiates input nociceptors (pain receptors) via direct stimulation of purinergic neurons. The effect appears to provide a local signal for tissue destruction, which in turn stimulates remedial physiological responses such as inflammation, etc. Pain may also result from tissue distension caused by drug injection, skin damage (and ATP release), or direct damage to nerves. Researchers are approaching the challenge of pain reduction by several techniques that are linked by one unifying strategy limiting the extent of mechanical insult to skin to the first 50 microns of tissue. force to breach skin (as in needle penetration), and has made sensation-free...
There is a limit to how much heat can be safely imparted to the skin by the CO2 laser. Generally, three or four passes are the limit. Too many passes may desiccate the skin and result in excessive heat generation with subsequent laser passes. Such excessive heating can result in a burn injury with resultant scar formation or pigmentary alteration. Care must be taken to use less laser energy in certain areas of the face where the skin is thinner so that not too much of the dermis is affected. Reduced laser energy is also necessary on the eyelids because too much skin contraction of the lower eyelid can result in permanent ectropion (a pulling down of the lid that causes the white of the eye to be overly visible).
And a wavelength that was highly absorbed by hemoglobin (relative to other skin chromophores) could be used. Pulse duration had to be shorter than thermal relaxation time so that heat would not build up excessively within the blood vessel and then be conducted to surrounding dermal tissue, causing a burn injury (with resultant scarring).
The respiratory complications of burns (inhalation injury) can result in significant morbidity and mortality in those initially surviving a fire. Respiratory tract injury results from the inhalation of products of combustion, which may be numerous, and has an even greater impact on mortality than the two important factors in burn injury of patient age and surface area involved.
Figure 15.2 Rabies virus infection of the animal body. After entering the body through damaged skin a virion infects a neurone via the nerve endings and is transported to the cell body, where virus replication takes place. The infection spreads to other neurones and to salivary gland cells, which shed virions into the saliva.
Occurs at three different physical levels. The most superficial and visible level is the skin. The preponderance of sun damage is in the skin and is easily removed by surgical procedures such as laser resurfacing. With healing, entirely new layers of skin replace the sun-damaged skin, essentially reversing the aging process.
Infection with rabies virus normally occurs as a result of virus in saliva gaining access to neurones through damaged skin. The infection spreads to other neurones in the central nervous system, then to cells in the salivary glands, where infectious virus is shed into the saliva (Figure 15.2).
The exact process of clearance of tattoo ink appears to involve shattering of the ink particles. The pulverized fragments are ingested by macrophages (a type of white blood cell), and the tattoo ink actually disappears from the skin. The incidence of scarring or skin damage is extremely low with Q-switched laser treatment for tattoos this is thus a nonsurgical treatment. In contrast, surgical treatments for tattoos invariably result in significant scarring.
Resurfacing of facial skin is the most common surgical laser treatment. These treatments are effective because they remove whole layers of sun-damaged skin with healing, completely new skin actually replaces what was removed. Unwanted textural features such as wrinkles are smoothed out and, because the epidermis is entirely removed with resurfacing, age spots and splotchy pigmentation are also removed. The erbium YAG laser has an extremely high affinity for water almost all of this laser's energy is absorbed by water, resulting in immediate and complete vaporization of thin layers of skin. The fraction of laser energy not absorbed by water produces a small amount of residual heat in adjacent (lower) layers of skin. In contrast, the CO2 laser has a lower affinity for water in addition to vaporizing skin cells, this laser leaves a zone of heated skin below the vaporized skin layers. This residual heat is generally below the threshold to cause damage (that is, the skin does not suffer a...
Advances in cosmetic laser surgery have made possible the safe removal of a wide variety of skin imperfections including excess hair, enlarged blood vessels, and pigmented lesions. Laser resurfacing, although a more invasive surgical procedure, can produce remarkable improvement in wrinkled and sun damaged skin. (In fact, the more wrinkled and sun damaged the skin, the more dramatic will be the likely improvement.) Incisional laser surgery, especially blepharoplasty, produces the same results as conventional surgery, only with much less bruising and a much faster recovery. The laser is not a magic wand, but in the hands of a skilled surgeon this instrument can produce remarkable cosmetic improvement.
Aging causes subtle structural and biochemical changes in the skin independently of environmental factors. The most obvious and characteristic changes, however, are largely the result of many years of sun exposure. How old one looks (especially in the face) is much more a function of how much sun damage he or she has suffered than it is of his or her chronological age. The sun produces a great deal of UV radiation, which is largely responsible for the skin damage. The damage ranges from an acute injury such as sunburn to the chronic structural changes that we associate with aging skin, including splotchy pigmentation (age spots) and wrinkles. Most skin cancers are attributable to UV damage to skin cells' genetic material deoxyribonucleic acid (DNA). Protection from sun exposure is by far the most effective measure anyone can take to prevent aging of the skin as well as potentially serious health problems such as skin cancer. Even artificial Aged epidermis may demonstrate rough and...