Amputated from the Solarcaine Thread out of mercy (this, originally from Urche's response to Dave's message) Sorry I don't have any data to aid your research. But, an interesting aspect of the sunscreen market is that at least one company (Nanophase) is producing nanoparticle preparations (I think mostly silicon dioxide) for sunscreen manufacturing.Nano-SiO2 would be totally awesome, like, dude!For one thing it'd be totally non-allergenic, as opposed to all the blahphenones and yadda yaddas. I wonder what the effective UVA/UVB rating would be in a formulation?People that go for SPF-197 (waterproof formulation excipients, of course) and spend all day in the sun get what they deserve, and generate lots of business for dermatologists and allergists, and in sad cases, for plastic and burn graft surgeons, and the oncologists.As an example (yes, I know, I lecture), a friend of mine (who worked for Pharmacia) and I went to the NJ shore. All precautions taken. A simple bit of sun and water in Brigantine and then hit Sin City - East for a bit of gambling.Deerfly bite on what probably was the femoral, right leg. Asymptomatic for a couple hours, symptoms rapidly developing. Made it back to "North" Jersey and made ASAP appts. Emerg consult, I had something on hand for pain and immediate antibiotic treatment and topical relief and topical antisepsis and preliminary debris management. Plus I could have him in the best facility in the area in about 8 minutes and admitted fairly quickly thereafter, with the help of a few friends, including a word or two from my internist and someone in one of the departments I worked with.Third degree burns requiring plastic surgery, tops of both feet.( Not the fly's fault.) Massively advancing septicemia, that was the fly's fault, the bloody little nasty bastard; if he'd bitten me, the fly would probably have been MedEvac'ed to the U.S. Department of Interior's EBICU (Endangered Bug Intensive Care Unit), and I'd have been fined or imprisoned for endangering some rare and particularly horrible bloodsucking insect, as though an ample supply are not available in Washington, D.C. But...Why are people so bloody stupid, or do they actually listen when doctors tell them anything? "High dose topical fluorinated topical steroids, avoid any exposure to sunlight to those feet, Son? Or at least not much, not at first." Apparently that patient consult sank in like raindrops on Teflon.We shared the same internist, or else I'd have taken him right to hospital; as it was, the Pt. was okay and on a proper initial regimen as opposed to a 0400 ER admission. The feet were washed with Chlorhexidine or Betadine (I forget which I used) and rinsed and then treated with sterile modified Burrows solution and then wrapped in sterile dressings after being allowed to air dry.As it was, money saved to insurance and the government, a bed free for someone needing it more, less suffering and aggravation to patient.Sorry this is so far off topic. I'm amputating it out of courtesy to Dave and Urche.Pt. treated completely on an outpatient basis for both immediate and subsequent care.Outcome: 100% successful.Cost: $50 (pre-care) An open ER bed: $?RSH.
Just as a thought, I didn't know nanoparticulate sized SiO2 would block UV, but then again thinking about it, it's rather clever. Regular glass (a/k/a "flint glass" or regular window glass), which is mostly SiO2, blocks a lot of UVB and UVA. You have to put additives into the melt, I don't remember offhand; somebody in the Rare Earth series, or Rubidium, I forget, to make the glass they use in hospital solariums and such. Regular glass DOES pass some UV through, of course, but a fraction vs. an open window.But on the other other hand -- mercury vapor lamps, including the ones used for sunlamps, use a quartz tube (the high-pressure types used for face tanning and special medical applications, not the fluorescent-lamp low pressure phosphor coated tubes).And quartz is nearly pure silicon dioxide. So is it just a matter of the intensity of the mercury vapor arc's UVA/UVB emission, that enough escapes along with the visible light? I guess even an 80% blocking would still let enough through; besides, those suckers wouldn't need the Watts they draw, I guess, unless serious attenuation was occuring. 500 - 700 Watts makes a lot of photons in the UVA/UVB range (no, I'm NOT going to do the calculations) in a mercury arc.But anyway, back to the notion of an SiO2 based screen; there are so many people allergic to the agents in current use; SiO2 is chemically and biologically inert. (Unless you breathe in the dust.)RSH.
But anyway, back to the notion of an SiO2 based screen; there are so many people allergic to the agents in current use; SiO2 is chemically and biologically inert. (Unless you breathe in the dust.)RSH. ************************************************************************Hi RSHIt is Zinc Oxide used in sunblock .http://www.forbes.com/global/2001/0205/084_2.htmlsnipThe only publicly traded nanotech pure play with measurable sales is Nanophase Technologies in Romeoville, Illinois, which probably lost more than $4 million on $4.2 million in sales last year. Its initial successes are in some rather mundane products, including zinc oxide, the goopy white sunblock that looks attractive only on a lifeguard's nose. The traditional method for making zinc oxide is to grind it into crystals about 200 nanometers wide. Nanophase can make them as small as 50 nanometers wide, which renders the zinc oxide transparent—no more white goop—since each crystalline particle is small enough to allow harmless light to pass through. Sunburn-causing ultraviolet light, with its shorter wavelengths, bounces off the particles and never makes it to the skin. Nanophase produces these particles by first vaporizing zinc rods in a 1,600-degree plasma-arc reactor, essentially a giantblowtorch. Clusters of zinc atoms then mix with a reactive gas, usually oxygen, and cool to a solid. Some 900 million of these zinc oxide crystals can fit in a single layer on the head of a pin. The company shipped 250 tons of zinc oxide powder last year. Customers include BASF (for use in sunblocks) and Dr. Scholl's (for use as an antifungal agent in foot powder). " regards ;o)
Geez, where did I get my wires crossed? (Don't answer that!)Well, I treated everyone to an erudite but totally irrelevant rumination on SiO2, anyway. :)ZnO2 of course already is widely used in total sunblock products but as I said eariler, the lifeguard and surfer type dudes and dudettes look like they have toothpaste on their noses. Then came a clever idea with the introduction of "Zink" or something like that, which comes in different colors, so you can look like a Native American about to go to war.A practically colloidal, well I guess it's larger than colloidal, but in any case small enough to be transparent and yet retain its UV blocking ability is astonishing; I'd labored under the misimpression for years that Zn02 ointment USP, as it originally was prosaically sold, blocked UV by simply being like paint and blocking everything.200 nm.. hmm, that's 2000 Angstrom, right? The stuff has to block wavelengths above 2000 A (I don't know how to make the little circle above the A so forget it), to arounsd the upper end of 2000 and into 3000 I think, to block UVB; I forget the wavelengths for UVA, UVB, and "longwave" (non-burning / non-tanning UV used in "black lights" if anyone remembers those).It'd be nice if the particle size had a bearing on what is filtered/bounced off, so that products could be "tuned", say, to totally block all UVA & UVB, i.e. a "sunblock", or to permit UVA and block UVB. Or ideally (but if particle size is directly related to what gets in, then a mixture of two different sizes would be needed), something that allowed 5% UVB and all UVA through. (Real tanning type dudes know that a small amount of UVB seems to perk up melaninogenesis (if I spelled that right, I'll be amazed).)I don't do the sun thing for my looks; improving that would need an act of God. But I do find tanning beds in the wintertime help perk me up; I probably have mild SAD; and also, maintaining a mild tan helps control my oily skin; it's a little embarassing being 44 and buying Stri-Dex.So in the process, I've become rather an obsessive nut on the subject, like I have about lawn grubs and aquariums, What are Raccoons' Favorite Foods, etc.RSH.
"I don't do the sun thing for my looks; improving that would need an act of God. But I do find tanning beds in the wintertime help perk me up; I probably have mild SAD"************************************************************************Hi RSHSince i did not know what SAD was when i first read above,i did a little Googleling to educate myself.I rather doubt you have have SAD(seasonal affective disorder).Treatment of SAD is not done by use of tanning machines.With your background i am sure you are fully aware of dangers of tanning machines and will say no more. Treatment of SADTreatment studies of light therapy have shown increasingly rigorous methodology with larger sample sizes, less diagnostic heterogeneity, longer treatment periods, and parallel instead of crossover designs. Wavelength of light used in light therapy was examined in two studies. In one study, the ultraviolet (UV) spectrum did not add to the therapeutic efficacy of light therapy [14*]. Because of the potential harmful effects of long-term W exposure, light therapy devices should have W filters that block wavelengths below 400 nm. In a comparison light box study, cool-white fluorescent lights were as effective as full-spectrum fluorescent lights , adding evidence to other studies showing that various light sources (including incandescent lights) are effective for treating SAD. Devices other than light boxes were also studied for light therapy. Two recent studies, with the largest sample sizes in light therapy studies to date, used a light visor [16*,17*]. In both studies, there was no relationship between the intensity of light and various measures of response to treatment, despite the fact that very low intensity light (60 lux) was used. This contrasts to most light box studies where a dear intensity-response relationship is found. Several explanations may explain this discrepancy. The proximity of the visor light source to the eye may increase the amount of light that reaches the retina, as compared to a light box. Lux, a unit of illumination, may also not be the best measure of the biologic or therapeutic effect of light. There is increasing evidence that even low illumination can affect biologic parameters , so that for some patients, light as low as 100 lux may be therapeutically effective. Finally, although the response rate was high in both studies (over 60% by strictly defined criteria), a non-specific (placebo) effect of light therapy must also be considered. In this regard, a light box study by Eastman and associates [19**] using a non-light control condition (a negative ion generator that, unknown to subjects, was turned off), found no differences between the control condition and bright light treatment (7000 lux for 1 hour in the morning). However, the response rate for the bright light condition (29%) was unusually low compared to other treatment studies. The selection criteria and unusually sunny weather during the course of their study may have excluded more light-responsive patients. Thus, the issue of placebo effects in light therapy remains unresolved. The Seattle group conducted a series of studies investigating dawn simulation in SAD [20,21,22*]. Dawn simulation uses a device that gradually increases illumination exposure, while the patient is sleeping, to simulate a summer dawn during the winter. Significant improvement occurred using dawn simulation compared to various control conditions, despite a final illumination as low as 250 lux. Two groups studying predictors for light therapy found that hypersomnia and hyperphagia predicted clinical response [23*,24,25*]. Another study, however, reported that only high consumption of sweets in the latter half of the day predicted response to treatment [26*]. Of interest is that prospective measures of sleep and eating were used in the latter study, whereas the other studies used global patient self-report. Light therapy has been considered a rather benign treatment with few side effects. A systematic report of side effects to light therapy using a light visor showed that approximately 20% of patients reported mild side effects, including headache, eyestrain, and "feeling wired" . A more controversial topic is the potential for prolonged bright light exposure to produce harmful effects on the retina. The intensities of light used in light therapy regimens are not considered harmful to the human retina based on short term studies, but the retinal effects of long term bright light exposure are not known. Some investigators have called for routine ophthalmologic evaluation prior to starting light therapy because of the small, potential risk of aggravating previously unrecognized retinal conditions (e.g. macular degeneration) [28*]. Others suggest ophthalmologic screening only in patients with a history of pre-existing retinal disease, patients taking highly photosensitizing drugs, and the elderly [29*]. Empiric data are still sparse, but a recently reported five-year prospective study of patients on chronic light therapy has not shown any significant clinical or electrophysiologic changes in the eyes . Finally, antidepressant drugs are also being studied in SAD. An open study showed efficacy of bupropion in treating SAD [31*]. One case-study suggested that citaloprim, a selective serotonin reuptake inhibitor, was as effective as light therapy [321. Fluoxetine was reported to be as effective as light therapy for SAD [33*], and results from at least two double-blind studies of serotonin reuptake inhibitors in SAD will soon be available. What remains a question is whether a combination of medications and light therapy is more effective than either alone. best regards;o)
Delighted,All I can say is that it works for me; perhaps keeping my skin from breaking out and a little tan knocks out my blues.As you can imagine, I've studied SAD at about the same or deeper depth than I usually investigate anything. The special lightboxes for SAD cost a fortune. I don't do well on SSRI's, an understatement to say the least.I do take large amounts of tyrosine a few hours before UV exposure, that might help explain my response, and of course antioxidants every day regardless; it's odd the same metabolic pathway that leads from tyrosine to melanin also leads to neurotransmitters.Perhaps it is all a placebo effect, but as I say, it works for me, and was not suggesting or recommending it for anyone else.I'm also not talking about being tan like George Hamilton, the actor; that all better be some kind of dye or I don't know why that man doesn't have problems.RSH.
I do occasionally make an effort to get some extra sunlight because of my psoriasis. It always helps for me, although I do know there is a small percentage of people with psoriasis who react negatively to sunlight.Phototherapy is very useful for people with severe psoriasis and this is often administered in a dermatologist's office. Some people buy their own phototherapy units for home use, but require a prescription for this and often have to get their units reset after a prescribed number of uses to force the patient to get their skin rechecked by the dermatologist before continuing the potentially carcinogenic therapy.Some will apply topicals like coal tar preparations to sensitize their skin to the phototherapy, but this should of course be done with great care at first until the correct dose is determined. (burning is NOT recommended and may cause a severe flare of Koebner reaction type psoriasis in reaction to the burn, so better to start very, very slowly)Other items will also affect the potency of the phototherapy, such as eating celery, which also sensitizes the skin.Their are prescription drugs that may be taken prior to phototherapy to increase sensitivity as well, such as the PABA used to make for PUVA therapy (the P in PUVA is the drug plus the UVA). Their are also specialized types of phototherapy units that dispense just UVA or UVB light, as well as narrow focused UV units and such. Remember that ANY form of phototherapy can increase the incidence of skin cancers of any form (there are 3 forms). Therefore, anyone who is using phototherapy, whether from natural sunlight or from tanning salons or in a dermatologist's office should always be particularly careful to watch for the usual signs of a skin cancer. (changes in a mole, for example, or irregular edges in a mole, or different colors in a mole, any change in a mole, especially one about the size of a pencil eraser)http://www.dermconsultants.com/articles/solar_damage.htmThe above link will give a good overview of the potential damage that may result from phototherapy from any source and is written for the lay person. The author is a well-respected practicing dermatologist and a friend of mine. He calls tanning booths "tanning coffins". :)Best regards,LadyandyPS: for more information on phototherapy for psoriasis, see the National Psoriasis Foundation ( http://www.psoriasis.org/ )
Their are prescription drugs that may be taken prior to phototherapy to increase sensitivity as well, such as the PABA used to make for PUVA therapy (the P in PUVA is the drug plus the UVA). Their are also specialized types of phototherapy units that dispense just UVA or UVB light, as well as narrow focused UV units and such. Ladyandy,I think the "P" in PUVA stands for Psoralen, not PABA (p-aminobenzoic acid); the even though PUVA is still a commonly used term, the P part usually now is one of the semisynthetic derivatives like oxypsoralen and such. All of which as you note are ferocious photosenitizers.RSH.
Right you are, RSH... thank you for the correction. That's what I get for typing off the top of my head. :)I've had the light box treatments for my psoriasis, but that was before they had the "p" for the psoralens drugs to take prior. That was of course many, many years and lots of changes in treatment ago.Best regards,Ladyandy
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