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Low Fluence (low + fluence)

Distribution by Scientific Domains

Medical Sciences	60%
Life Sciences	40%

Selected Abstracts

Treatment of post-inflammatory hyperpigmentation using 1064-nm Q-switched Nd:YAG laser with low fluence: report of three cases

JOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 10 2009
SB Cho
[source]

Photodynamic Effects of Antioxidant Substituted Porphyrin Photosensitizers on Gram-positive and -negative Bacteria,

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2003
Helena Ashkenazi
ABSTRACT Photodynamic treatment of the gram-negative bacteria Escherichia coli B and Acinetobacter baumannii and the gram-positive bacterium Staphylococcus aureus was performed using two newly devised and synthesized antioxidant carrier photosensitizers (antioxidant carrier sensitizers-2 [ACS-2] and antioxidant carrier sensitizers-3 [ACS-3]), which are butyl hydroxy toluene and propyl gallate substituted haematoporphyrins, respectively. It was found that ACS-2 is less reactive than other photosensitizers previously used for the same purpose, whereas ACS-3 is very effective against the multidrug-resistant bacterium A. baumannii, causing its complete eradication at a low fluence (,7.5 J/cm) of blue light (407,420 nm) and a low concentration (10 ,M). At a higher fluence (,37.5 J/cm) complete eradication of E. coli B can be obtained under the same conditions. Furthermore, X-ray microanalysis and ultrastructural changes indicate that ACS-3, especially in the case of photodynamic treatment of A. baumannii, interferes with membrane functions and causes the inactivation of the bacterium. ACS-3 may be suggested as a specific photosensitization agent for photoinactivation of gram-negative bacteria. [source]

Modulation by phytochrome of the blue light-induced extracellular acidification by leaf epidermal cells of pea (Pisum sativum L.): a kinetic analysis

THE PLANT JOURNAL, Issue 5 2000
J. Theo M. Elzenga
Summary Blue light induces extracellular acidification, a prerequisite of cell expansion, in epidermis cells of young pea leaves, by stimulation of the proton pumping-ATPase activity in the plasma membrane. A transient acidification, reaching a maximum 2.5,5 min after the start of the pulse, could be induced by pulses as short as 30 msec. A pulse of more than 3000 ,mol m,2 saturated this response. Responsiveness to a second light pulse was recovered with a time constant of about 7 min. The fluence rate-dependent lag time and sigmoidal increase of the acidification suggested the involvement of several reactions between light perception and activation of the ATPase. In wild-type pea plants, the fluence response relation for short light pulses was biphasic, with a component that saturates at low fluence and one that saturates at high fluence. The phytochrome-deficient mutant pcd2 showed a selective loss of the high-fluence component, suggesting that the high-fluence component is phytochrome-dependent and the low-fluence component is phytochrome-independent. Treatment with the calmodulin inhibitor W7 also led to the elimination of the phytochrome-dependent high-fluence component. Simple models adapted from the one used to simulate blue light-induced guard cell opening failed to explain one or more elements of the experimental data. The hypothesis that phytochrome and a blue light receptor interact in a short-term photoresponse is endorsed by model calculations based upon a three-step signal transduction cascade, of which one component can be modulated by phytochrome. [source]

Near Painless, Nonablative, Immediate Skin Contraction Induced by Low-Fluence Irradiation with New Infrared Device: A Report of 25 Patients

DERMATOLOGIC SURGERY, Issue 5 2006
JAVIER RUIZ-ESPARZA MD
BACKGROUND Nonablative radiofrequency (NARF) has been the only method for producing noninvasive skin tightening. Nevertheless, significant pain during the procedure is an important downside of this technology. A new nonablative medical device, Titan (Cutera, Inc., Brisbane, CA, USA), capable of fluences much lower than those possible with NARF, was tested as a less painful alternative. OBJECTIVES To produce skin contraction leading to lifting of eyebrows and/or improvement of lower face and neck skin laxity using fluences below pain levels. PATIENTS AND METHODS Twenty-five patients were treated. Standardized photographs were obtained preoperatively, after a few days, a few weeks, and up to 12 months after the procedure. RESULTS Immediate changes were obtained in 22 of 25 patients. Examination of photographs revealed that the initial improvement was maintained throughout the follow-up period. CONCLUSION Immediate true skin contraction persisting through the immediate, intermediate, and long-term follow-up was found in the vast majority of patients in this group. Edema as an artifact simulating immediate improvement was excluded by serial photographs taken during the follow-up period. Skin contraction occurred at low fluences, below the threshold of pain. This, to the best of our knowledge, has not been previously described in the medical literature. [source]

Treatment of Striae Rubra and Striae Alba With the 585-nm Pulsed-Dye Laser

DERMATOLOGIC SURGERY, Issue 4 2003
Gloria P. Jimeénez MD
BACKGROUND The treatment of striae distensae has recently been reported with various lasers such as the 585-nm pulsed dye laser. At lower fluences (2.0 to 4.0 J/cm2), this laser has been purported to increase the amount of collagen in the extracellular matrix. OBJECTIVE To determine whether the 585-nm pulsed dye laser is effective in both striae rubra and striae alba after two treatments and, in addition, to determine whether there is a net effect on collagen density in treated samples. METHODS Twenty patients (skin types II to VI) with either striae rubra (9) or striae alba (11) were treated at baseline and at week 6. The total length of the study was 12 weeks. Untreated striae on the same patient were used as control subjects. Striae clinical parameters such as color and area were measured before the first and after the last treatment by an independent examiner using a visual analog scale. A hydroxyproline assay was used to measure collagen changes in two of the striae quantitatively. RESULTS The 585 nm had a moderate beneficial effect in reducing the degree of erythema in striae rubra. There was no apparent clinical change on striae alba. Total collagen per gram of dry weight of sampled tissue increased in striae treated with pulsed dye laser versus control subjects. CONCLUSION We recommend the use of the 585-nm pulsed dye laser for striae rubra in patients skin types II to IV. Extreme caution or avoidance should be observed in pulsed dye laser treatments for patients with phototypes V to VI even with the use of low fluences. Tissue collagen changes measured may be an early change, which precedes significant clinical improvement. [source]