Helicobacter pylori in patients can be killed by visible light.
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BACKGROUND: Helicobacter pylori colonizes the mucus layer of the human stomach and may cause peptic ulcer and adenocarcinoma. Novel antimicrobial approaches are sought due to the occurrence of antibiotic resistance and consequent treatment failure. We report here that H. pylori is susceptible to inactivation by blue light. STUDY DESIGN/MATERIALS AND METHODS: A controlled, prospective, blinded, trial of endoscopically delivered blue light to eradicate H. pylori in regions of the gastric antrum, in 10 patients between the ages of 21 and 80 who tested positive for H. pylori. Light (405 nm) (40 J/cm2) was delivered to a 1-cm diameter spot in the gastric antrum via optical fiber passed through the endoscope and weighed biopsies were taken from treated and control spots and colonies quantitatively cultured. RESULTS: Blue light killed 5 logs of bacteria in vitro. The mean reduction in H. pylori colonies per gram tissue between treated and control spots was 91% (7.4+/-4.8 x 10(6) vs. 8.1+/-1.9 x 10(7), two-tailed P < 0.0001). Some patients had reductions approaching 99%. No differences were observed on histological examination of light-treated and control gastric tissue. CONCLUSION: Blue light phototherapy may represent a novel approach to eradication of H. pylori, particularly, in patients who have failed standard antibiotic treatment. (+info)
We have found that broadband light (380 to 520 nm) rapidly and selectively kills oral black-pigmented bacteria (BPB) in pure cultures and in dental plaque samples obtained from human subjects with chronic periodontitis. We hypothesize that this killing effect is a result of light excitation of their endogenous porphyrins. Cultures of Prevotella intermedia and P. nigrescens were killed by 4.2 J/cm2, whereas P. melaninogenica required 21 J/cm2. Exposure to light with a fluence of 42 J/cm2 produced 99% killing of P. gingivalis. High-performance liquid chromatography demonstrated the presence of various amounts of different porphyrin molecules in BPB. The amounts of endogenous porphyrin in BPB were 267 (P. intermedia), 47 (P. nigrescens), 41 (P. melaninogenica), and 2.2 (P. gingivalis) ng/mg. Analysis of bacteria in dental plaque samples by DNA-DNA hybridization for 40 taxa before and after phototherapy showed that the growth of the four BPB was decreased by 2 and 3 times after irradiation at energy fluences of 4.2 and 21 J/cm2, respectively, whereas the growth of the remaining 36 microorganisms was decreased by 1.5 times at both energy fluences. The present study suggests that intraoral light exposure may be used to control BPB growth and possibly benefit patients with periodontal disease. (+info)
Phototherapy with narrowband vs broadband UVB.
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Phototherapy with ultraviolet (UV) radiation of wavelengths between 280 and 320 nm (UVB) is a safe and effective treatment for a variety of diseases. In addition to standard broadband UVB (bUVB), narrowband phototherapy with fluorescent bulbs emitting near monochromatic UV around 311 nm (nUVB) has become an important treatment for diseases such as psoriasis, atopic dermatitis and vitiligo. In addition to these indications, the number of diseases for which nUVB phototherapy is reported to be effective is continuously growing. The differential effects of nUVB phototherapy in comparison to other UV wavelengths as well as established and new indications for this treatment modality are reviewed. (+info)
The importance of irradiance and area in neonatal phototherapy.
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BACKGROUND: Despite a long period of development, there are still considerable variations in the spectral output, the levels of irradiance, and irradiated area provided by commercial phototherapy systems. These variations depend on the types and output of the lamps used to produce the phototherapy, along with the design of the systems, and principally on whether the phototherapy is provided from overhead or underneath. OBJECTIVE: To see whether commercially available phototherapy systems produce sufficient irradiance over the surface area of the neonate. METHODS: Surface plots of the output irradiance were made on a number of systems and used to calculate the effective irradiance on the surface of a premature or term baby, using mapped outlines. RESULTS: A 10-fold difference in peak central irradiances was found between the systems tested, with a fourfold to fivefold difference in effective irradiance to the baby surfaces. Although work published over 20 years ago showed that levels of irradiance should reach 2 mW/cm2 to achieve optimal effectiveness, some of the commercial systems tested do not appear to achieve this level. CONCLUSION: Purchasers of neonatal phototherapy systems need to take into account whether the systems will produce sufficient irradiance over the area to ensure maximal effect, to keep the treatment time to a minimum. (+info)
Susceptibility of Streptococcus mutans biofilms to photodynamic therapy: an in vitro study.
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OBJECTIVES: The purpose of this study was to evaluate the antimicrobial effect of toluidine blue O (TBO), in combination with either a helium/neon (HeNe) laser or a light-emitting diode (LED), on the viability and architecture of Streptococcus mutans biofilms. METHODS: Biofilms were grown on hydroxyapatite discs in a constant depth film fermentor fed with artificial saliva that was supplemented with 2% sucrose four times a day, thus producing a typical 'Stephan pH curve'. Photodynamic therapy was subsequently carried out on biofilms of various ages with light from either the HeNe laser or LED using energy densities of between 49 and 294 J/cm(2). RESULTS: Significant decreases in the viability of S. mutans biofilms were only observed when biofilms were exposed to both TBO and light, when reductions in viability of up to 99.99% were observed with both light sources. Overall, the results showed that the bactericidal effect was light dose-dependent and that older biofilms were less susceptible to photodynamic therapy. Confocal laser scanning microscopy images suggested that lethal photosensitization occurred predominantly in the outermost layers of the biofilms. CONCLUSIONS: Photodynamic therapy may be a useful approach in the treatment of dental plaque-related diseases. (+info)
Effect of timed bright light treatment for rest-activity disruption in institutionalized patients with Alzheimer's disease.
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BACKGROUND: Disturbances in rest-activity rhythm are prominent and disabling symptoms in Alzheimer's disease (AD). Nighttime sleep is severely fragmented and daytime activity is disrupted by multiple napping episodes. In most institutional environments, light levels are very low and may not be sufficient to entrain the circadian clock to the 24-hour day. METHOD: The purpose of this randomized clinical trial was to test the effectiveness of timed bright light therapy in reducing rest-activity (circadian) disruption in institutionalized patients with AD. The experimental groups received either morning (9.30-10.30 am) or afternoon (3.30-4.30 pm) bright light exposure ( > or = 2500 lux in gaze direction) Monday through Friday for 10 weeks. The control group received usual indoor light (150-200 lux). Nighttime sleep, daytime wake, and rest-activity parameters were determined by actigraphy. Repeated measures analysis of variance was employed to test the primary study hypotheses. RESULTS: Seventy institutionalized subjects with AD (mean age 84) completed the study. No significant differences in actigraphy-based measures of nighttime sleep or daytime wake were found between groups. Subjects in either experimental light condition evidenced a significantly (p < 0.01) more stable rest-activity rhythm acrophase over the 10-week treatment period compared to the control subjects whose rhythm phase delayed by over two hours. CONCLUSIONS: One hour of bright light, administered to subjects with AD either in the morning or afternoon, did not improve nighttime sleep or daytime wake compared to a control group of similar subjects. However, exposure to one-hour of bright light in either the morning or afternoon may provide sufficient additional input to the circadian pacemaker to facilitate entrainment to the 24-hour day. (+info)
Effect of morning bright light treatment for rest-activity disruption in institutionalized patients with severe Alzheimer's disease.
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BACKGROUND: Disturbances in rest-activity rhythm are prominent and disabling symptoms in Alzheimer's disease (AD). Nighttime sleep is severely fragmented and daytime activity is disrupted by multiple napping episodes. In most institutional environments, light levels are very low and may not be sufficient to enable the circadian clock to entrain to the 24-hour day. The purpose of this randomized, placebo-controlled, clinical trial was to test the effectiveness of morning bright light therapy in reducing rest-activity (circadian) disruption in institutionalized patients with severe AD. METHOD: Subjects (n = 46, mean age 84 years) meeting the NINCDS-ADRDA (National Institute of Neurological and Communicative Disorders and Stroke--the Alzheimer's Disease and Related Disorders Association) AD diagnostic criteria were recruited from two large, skilled nursing facilities in San Francisco, California. The experimental group received one hour (09:30-10:30) of bright light exposure (> or = 2500 lux in gaze direction) Monday through Friday for 10 weeks. The control group received usual indoor light (150-200 lux). Nighttime sleep efficiency, sleep time, wake time and number of awakenings and daytime wake time were assessed using actigraphy. Circadian rhythm parameters were also determined from the actigraphic data using cosinor analysis and nonparametric techniques. Repeated measures analysis of variance (ANOVA) was used to test the primary study hypotheses. RESULTS AND CONCLUSION: Although significant improvements were found in subjects with aberrant timing of their rest-activity rhythm, morning bright light exposure did not induce an overall improvement in measures of sleep or the rest-activity in all treated as compared to control subjects. The results indicate that only subjects with the most impaired rest-activity rhythm respond significantly and positively to a brief (one hour) light intervention. (+info)
Profile of clinical efficacy and safety of topical tacalcitol.
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Several topical treatments such as ointments, keratolytics, dithranol, tar, corticosteroids and Vitamin D3 analogues are commonly used in the treatment of mild and/or moderate psoriasis. These treatments can be associated with a variety of local and systemic side effects, as well as to very often unsatisfactory results. The purpose of this critical review of the literature is to evaluate the efficacy and tolerability of the synthesis of new analogues of the Vitamin D3 Tacalcitol, which is formulated in ointment form at a concentration of 4 microg/g, for the treatment of mild and/or moderate psoriasis (involvement of <20% of the surface of the skin) and to evaluate whether this drug can be used in the treatment of other skin conditions. Based on existing data in the literature, Tacalcitol is an effective drug for the topical treatment of psoriasis and is also able to ensure that the effects last over time, even after treatment has stopped. Tacalcitol is also well tolerated because the onset of side effects, such as local irritation, pruriginous or burning sensations, were reported in only a small percentage of the subjects who were treated. Lastly, the marked regulatory effects it has on the proliferation and differentiation of keratinocytes, as well as on the immunocompetent cells, has led to suggestions that Tacalcitol may be used in other keratinisation disorders and in some hyperproliferative skin diseases. Evaluation of the effective indications to use in these conditions still requires further data confirming its effectiveness, opening the way to wider use of this molecule in dermatology. (+info)