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Biomedical subjects

S Mordon

Publications and source records attributed to S Mordon.

At least 37 records · Page 2Linked to original sources
PubMed2000

In vivo experimental evaluation of skin remodeling by using an Er:Glass laser with contact cooling.

BACKGROUND AND OBJECTIVE: Selective dermal remodeling consists of inducing collagen tightening, neocollagen synthesis, or both, without damage to the overlying epidermis. This experimental study aimed to evaluate an Er:Glass laser emitting at 1.54 micrometer combined with contact cooling to target the upper dermis while protecting the epidermis. STUDY DESIGN/MATERIALS AND METHODS: Male hairless rats were used for the study. Different fluences (26-30 J/cm(2)) by using single 3-ms pulse irradiation or pulse train irradiation (1.1 J, 3 Hz) and different cooling temperatures (+5 degrees C, 0 degrees C, -5 degrees C) were screened with clinical examination and histologic evaluation at 1, 3, and 7 days after laser irradiation. RESULTS: The clinical effects were clearly dose and temperature cooling dependent. It seemed that single pulse irradiation led to epidermal whitening in most cases, whatever the cooling temperature. Conversely, pulse train irradiation showed reproducible epidermal preservation and confinement of the thermal damage into the dermis. New collagen synthesis was confirmed by a marked fibroblastic proliferation, detected in the lower dermis at day 3 and clearly seen in the upper dermis at day 7. CONCLUSION: This new laser seems to be a promising new tool for the treatment of skin laxity, solar elastosis, facial rhytides, and mild reduction of wrinkles.

Animals↗
PubMed2000

Early vascular changes in Crohn's disease: an endoscopic fluorescence study.

BACKGROUND AND STUDY AIMS: Early recurrent lesions occurring after surgery in Crohn's disease may be the result of localized vasculitis. The aim of this study was use fluorescence endoscopy to evaluate the mucosal microcirculation of the neoterminal ileum in relation to endoscopic recurrence in patients who had undergone ileocolonic resection for Crohn's disease. PATIENTS AND METHODS: Ten patients were prospectively enrolled in an endoscopic follow-up study one year after surgery. Recurrence was assessed using routine and fluorescence endoscopy. Biopsies were taken from fluorescent and nonfluorescent sites to look for inflammation and mucosal vascular lesions using standard histological and immunohistochemical methods. RESULTS: Endoscopic recurrence was found in eight patients. At fluorescence endoscopy, the mucosa displayed a heterogeneous pattern, with fluorescent areas corresponding to aphthoid ulcerations; fluorescent rims surrounding dark zones, corresponding to stellar deep ulcers; and small bright spots distributed singly in the mucosa, which appeared normal on routine endoscopy. Histology revealed inflammatory changes with evidence of vascular involvement in 79% of the biopsies taken from the fluorescent spots. CONCLUSIONS: Endoscopic recurrence in Crohn's disease is associated with fluorescent aspects that may reflect vasodilation associated with inflammation, or genuine microvascular lesions. Correlation with the histological findings suggests that these early vascular lesions were secondary to the inflammatory process.

Adult↗
PubMed2000

Hair removal with an Athos Nd:YAG 3.5 ms pulse laser: a 3-month clinical study.

INTRODUCTION/OBJECTIVE: This study aimed to evaluate the safety and efficacy of a 3.5 ms Nd:YAG laser for the removal of hair in subjects with Fitzpatrick skin types I-IV. Thanks to a pulse shorter than the hair Thermal Relaxation time (TRT), photothermolysis was thus achieved. METHODS: This study assessed the percentage of hair reduction at 1 month and at 3 months after a single Nd:YAG laser treatment (Athos; Quantel Médical, France); 3.5 ms pulse, single shot to 3 Hz, a maximum fluence of 80 J/cm2, 4 mm spot, no cooling system, no anaesthesia. The treatment sites consisted of three adjacent squares (optimum fluence, no treatment, -20% optimum fluence). Computerized hair counting was realized on digital pictures. The phototype, pain, side effects and patient's satisfaction were noted. Biopsies were performed 15 min after treatment. The enrolment consisted of 17 women, 22-60 years old, phototypes I-IV, with a follow-up at 1 month and 3 months of 25 sites. RESULTS: Counting at 1 month and at 3 months revealed a significant hair reduction compared with the control sites: 60% at 1 month (P < 0.001) and 24% at 3 months (P < 0.05) for optimal fluence (25-80 J/cm2), compared with 31% and 0% on the control sites; values similar to those published for Nd:YAG or diode lasers. There were no adverse effects at all. Biopsies showed lesions from necrosis coagulation of the root sheaths and hair disruption to isolated apoptotic cells in the outer root sheath, depending on the fluence applied. CONCLUSION: Results from this study show that the Athos Nd:YAG is efficient and safe for removing pigmented hair in phototypes I-IV.

Adult↗
PubMed2000

Effects of skin cleaning modes on the condition of collagen and elastin after laser resurfacing.

BACKGROUND: Laser resurfacing is now widely used for the treatment of facial wrinkles, photoaging and acne scars and is usually combined with comparatively aggressive methods of cleaning detritus off the treated area after each laser pass. OBJECTIVE: This study aims to evaluate two different cleaning methods (damp gauze or damp large-tip cotton buds) in order to elucidate their influence on the healing process, if any. The left or right preauricular area, chosen at random on 10 patients undergoing periocular and perioral resurfacing with the same laser system, was cleaned after each laser pass with damp gauze (Group G) and the contralateral side with the large-tip cotton buds (Group C). Post-resurfacing oedema and erythema were observed in the preauricular areas and rated by the same experienced observer immediately after treatment and at 14, 30, 45, 60 and 90 days. RESULTS: Oedema was slightly more noticeable initially in Group G patients, but the erythema was more intense and lasted longer in the gauze-cleaned tissue. The sites were biopsied at 90 days and the samples sent for blinded histological evaluation to assess the degree of collagen and elastin fibre compaction. The histology demonstrated that the tissue from Group G achieved, at 90 days, better compaction of collagen and elastin fibres than that from Group C. CONCLUSIONS: It is suggested that the abrasive action caused by the gauze adds to the existing stimulative inflammatory reaction following CO2 laser resurfacing, which augments the collagen and fibre compaction response in the tissue. Comparatively aggressive cleaning with damp gauze may therefore be preferable to other methods when performing laser resurfacing.

Aged↗
PubMed2000

Inhaled nitric oxide modulates leukocyte kinetics in the mesenteric venules of endotoxemic rats.

OBJECTIVE: to determine whether inhaled nitric oxide (NO) would alter leukocyte kinetics in the septic microvasculature. DESIGN: Randomized, controlled trial. SETTING: Experimental laboratory. SUBJECTS: Male Sprague Dawley rats. INTERVENTIONS: Rats were treated with either saline or endotoxin (10 mg/kg, iv) and then allowed to breathe either air or air plus NO (10 ppm). MEASUREMENTS AND MAIN RESULTS: After a 4-hr period, rolling, firm adhesion, and emigration of leukocytes and endothelial dysfunction were monitored in mesenteric venules by using intravital videomicroscopy. Compared with controls, endotoxemic rats exhibited a profound influx in mesenteric venule rolling leukocytes (55+/-17 vs. 70+/-19 leukocytes/min; p < .05), associated with a reduction of leukocyte rolling velocity (83+/-14 vs. 34+/-3 microm/sec; p < .05). In endotoxemic rats, venular endothelium leukocyte firm adhesion (1.15+/-0.32 vs. 4.08+/-0.96 leukocytes/ 100 microm; p < .05) and emigration (0.84+/-0.47 vs. 4.23+/-1.2 leukocytes/100 microm; p < .05) increased compared with controls. Inhaled NO had no effect on leukocyte kinetics in control rats. Inhaled NO significantly attenuated endotoxin-induced venular endothelium leukocyte adhesion (4.08+/-0.96 vs. 1.86+/-0.76 leukocytes/100 microm; p < .05) and emigration (4.23+/-1.2 vs. 1.68+/-0.72 leukocytes/100 microm; p < .05). Compared with control rats, macromolecular (FITC-dextran) vascular leakage, expressed as the perivenular/intravenular fluorescence intensity ratio, increased in endotoxemic rats (0.56+/-0.02 vs. 0.81+/-0.05; p < .01). Endotoxin-induced macromolecular vascular leakage increases were partially prevented by inhaled NO (0.66+/-0.01 vs. 0.56+/-0.02; p < .05). CONCLUSION: These observations suggest that inhaled NO reduces leukocyte adhesion and the degree of vascular permeability dysfunction in mesenteric venule of endotoxemic rats.

Administration, Inhalation↗
PubMed2000

Escherichia coli endotoxin reduces cytochrome aa3 redox status in pig skeletal muscle.

OBJECTIVE: To assess the effect of endotoxin on cytochrome aa3 (Caa3) redox status in a controlled blood flow preparation of pig isolated hindlimb, at a constant oxygen delivery (Do2limb) (constant flow period) and during progressive ischemia (decreasing flow period). DESIGN: Randomized, controlled experimental study. SETTING: University hospital experimental laboratory. SUBJECTS: Ten piglets. INTERVENTIONS: Hindlimb blood flow was restricted to the femoral vessels. The arterial femoral blood flow coming from the carotid artery was controlled by a roller occlusive pump. The femoral venous blood flow was returned to the jugular vein. During the first 100 mins, the hindlimb blood flow was maintained at a normal level and then decreased stepwise. Animals were randomized to receive 150 microg/kg endotoxin lipopolysaccharide (LPS; n = 5) or saline (control; n = 5). MEASUREMENTS AND MAIN RESULTS: Hindlimb muscle Caa3 redox status was monitored by near-infrared spectroscopy. Hindlimb Do2limb and oxygen consumption (Vo2limb) were calculated. In the LPS group, a rapid reduction of Caa3 redox status was observed after LPS administration, whereas the hindlimb blood flow remained normal with no change in Do2limb and Vo2limb. A progressive simultaneous decrease in Do2limb and Vo2limb was observed during the decreasing flow period with no further reduction in Caa3 redox status. In the control group, no change was observed in Caa3, Do2limb, or Vo2limb during the constant flow period. During the decreasing flow period, Caa3 redox status was reduced as Do2limb and Vo2limb decreased. CONCLUSION: Our results suggest that endotoxin may induce a reduction of Caa3 redox status independently of Do2 and Vo2.

Animals↗
PubMed2000

Inhaled NO reduces leukocyte-endothelial cell interactions and myocardial dysfunction in endotoxemic rats.

Inhaled nitric oxide (NO) has been shown to have some protective effect in the peripheral distal inflamed vasculature. The objective of the study was to determine whether inhaled NO would reduce endotoxin-induced leukocyte activation and myocardial contractile dysfunction. Rats were treated with either saline or endotoxin (10 mg/kg iv) and then allowed to breathe (4 h) either air or air plus NO (10 ppm). In endotoxemic rats, mesenteric venular endothelium leukocyte firm adhesion increased compared with control rats (1.15 +/- 0.32 vs. 4.08 +/- 0.96 leukocytes/100 microm; P < 0.05). Inhaled NO significantly attenuated endotoxin-induced venular endothelium leukocyte adhesion (4.08 +/- 0.96 vs. 1.86 +/- 0.76 leukocytes/100 microm; P < 0.05) and FITC-conjugated anti-intercellular adhesion molecule-1 fluorescence intensity. Endotoxin-induced myocardial dysfunction and leukocyte content increases were reduced in inhaled NO-treated rats. These observations suggest that inhaled NO reduces the degree of cardiovascular dysfunction and inflammation in endotoxemic rats.

Administration, Inhalation↗
PubMed1999

Quantitative fluorescein angiography following diode laser retinal photocoagulation.

OBJECTIVE: An in vivo study was done to establish if laser-induced damage of the retina could be quantified using fluorescein angiography. METHOD: This study was carried out on rabbit eyes (n = 6) with an 810 nm diode laser (spot diameter: 500 microm, pulse duration: 1 second, power: 100 mW-400 mW) adapted on a slit lamp. Fluorescence measurements were performed with a fundus camera connected to a fluorescence imaging system. Fluorescence staining of the retina was evaluated by mathematical modeling. Lesions were correlated to laser parameters and to histologic data. RESULTS: Image analysis shows that the laser lesions stained progressively. Fluorescence appears first at the borders of the lesion exhibiting a fluorescent ring. A progressive increase of the fluorescence into the central zone is observed. The maximum fluorescence intensity into the center of the laser spot is obtained after a delay depending on the laser energy. Below 100 +/- 20 mW, lesions are detectable by fluorescence imaging only. A fluorescence plateau appears for a threshold light dose above 200 +/- 20 mW. Mathematical modeling demonstrates that quantitative assessment of laser-induced damage to the retina is feasible using fluorescence imaging. CONCLUSION: The quantification of fluorescence staining in terms of both intensity and time can contribute to a better quantification of laser-induced damage. At last, since laser damage may mimic naturally occurring pathology, this method should also be considered to quantify different types of lesions.

Animals↗
PubMed1999

Treatment of individual café au lait macules with the Q-switched Nd:YAG: a clinicopathologic correlation.

BACKGROUND: Café au lait macules (CALMs) respond variably to treatment with lasers. This study was carried out to identify which individual features of CALMs could predict a good clinical response to treatment. METHODS: Twenty-two patients aged 3-43 years were treated with the frequency-doubled Q-switched Nd:YAG (10 ns, Ø = 3 mm, 2.0 to 3.0 J/cm2). Biopsy specimens of the CALMs were obtained before treatment in 11 patients to achieve the diagnosis of CALMs. Treatment of CALMs usually requires several laser sessions, so the treatment was carried out at 2-month intervals. Clinical follow-up was done 3 and 12 months after the final treatment to observe results and recurrences. RESULTS: The analysis shows that the only statistically significant criteria was the jagged aspects of the edges of the CALMs. Consequently, this criteria should be evaluated in further studies in relation with the laser treatment of CALMs.

Adolescent↗
PubMed1999

Redox status of cytochrome a,a3: a noninvasive indicator of dysoxia in regional hypoxic or ischemic hypoxia.

OBJECTIVE: Multiwavelength near infrared (NIR) spectrophotometry can monitor the redox state of cytochrome a,a3 (cyt a,a3) in vivo. Because cyt a,a3 is the most immediate reductant of oxygen, this technique has been proposed to evaluate tissue oxygenation. The purpose of this study was to examine the relationship between cyt a,a3 oxidation level as an indicator of dysoxia and oxygen uptake (VO2) when oxygen delivery (DO2) was progressively lowered in an in situ vascularly isolated hindlimb. DESIGN: Prospective, randomized, laboratory study. SETTING: University research laboratory. SUBJECTS: Fourteen pigs. INTERVENTIONS: Measurement of critical values for both VO2 and cyt a,a3 oxidation during ischemic and hypoxic hypoxia. MEASUREMENTS AND MAIN RESULTS: The right hindlimb of anesthetized, paralyzed, and ventilated pigs was subjected to progressive ischemic or hypoxic hypoxia for 100 mins by ten stepwise decreases in DO2. In ischemic hypoxia (n = 7), arterial inflow (Q) from a pump-membrane oxygenator system was lowered from 50 to 0 mL/min, with PaO2 maintained at 100 mm Hg. In hypoxic hypoxia (n = 6), PaO2 was lowered from 100 mm Hg to 0 mm Hg. Hindlimb DO2 was calculated as the product of Q and arterial oxygen content, and VO2 as the product of Q and arteriovenous difference. The cyt a,a3 oxidation level was measured every 10 secs with a four-wavelength spectrophotometer. These parameters were measured 9 mins after each change of DO2. Critical values for both VO2 and cyt a,a3 oxidation level as a function of DO2 were determined in each animal by dual linear regression analysis. In ischemic and hypoxic hypoxia, a strong correlation was found between cyt a,a3 oxidation level and VO2 in both ischemic and hypoxic hypoxia (r2 =.90 and .87, respectively). Hindlimb vascular resistance increased in ischemic hypoxia and decreased in hypoxic hypoxia when DO2 reached critical DO2. CONCLUSIONS: From these results, we concluded that monitoring the cyt a,a3 redox state by NIR spectrophotometry is, in this experimental setting, a sensitive indicator of dysoxia during regional hypoxic or ischemic hypoxia.

Animals↗
PubMed1999

In vivo application of intestinal pH measurement using 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF) fluorescence imaging.

Measurement of gastrointestinal intramucosal pH (pHim) has been recognized as an important factor in the detection of hypoxia-induced dysfunctions. However, current pH measurement techniques are limited in terms of time and spatial resolutions. A major advance in accurate pH measurement was the development of the ratiometric fluorescent indicator dye, 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF). This study aimed to set up and validate a fluorescence imaging technique to measure in vivo the intramucosal pH (pHim) of the intestine. The intestine was inserted into an optical chamber placed under a microscope. Animals were injected intravenously with the pH-sensitive fluorescent dye BCECF. Fluorescence was visualized by illuminating the intestine alternately at 490 and 470 nm. The emitted fluorescence was directed to an intensified camera. The ratio of emitted fluorescence at excitation wavelengths of 490 and 470 nm was measured, corrected and converted to pHim by constructing a calibration curve. The pHim controls were performed with a pH microelectrode and were correlated with venous blood gas sampling. Results show that pHim is determined with an accuracy of +/- 0.07 pH units and a response time of 1 min. In conclusion pHim mapping of rat intestine can be obtained by fluorescence imaging using BCECF. This technology could be easily adapted for endoscopic pH measurements.

Animals↗
PubMed1998

Indocyanine green: physicochemical factors affecting its fluorescence in vivo.

This study reinvestigates the spectral properties of ICG (Indocyanine green) in vivo, the role of quenching, and the possibility of an interaction of ICG with blood components and/or vessel walls. ICG quenching as a function of concentration was studied by spectrophotometry on whole blood samples from golden hamsters. Fluorescence ICG characteristics were evaluated by front-face fluorometry. In vivo, fluorescence measurements were performed on the femoral artery of golden hamsters. In vitro, on whole blood samples, fluorescence intensity is modified by ICG quenching as concentration increases above 80 microgram/ml. The maximum fluorescence peak is not affected and remains centered at 832 nm. The in vivo measurements display a similar fluorescence intensity shape, which is affected only by ICG concentrations. However, the maximum fluorescence emission peak is modified significantly with time. Between 0 and 120 min, four phases can be distinguished in which a wavelength shift from 826 to 835 nm is observed. The wavelength shift with change in fluorescence intensity observed in vivo could be due to a localization of ICG molecules in sites more hydrophobic than serum proteins. It is possible to hypothesize the presence of an endothelium-bound form with a specific fluorescence spectrum. The amphiphilic properties of ICG are consistent with fixation of some ICG molecules on sites other than plasmatic proteins after injection. The process of fixation of ICG molecules on surface components or within the vascular endothelium could be due to a change in the microenvironment of some ICG molecules.

Animals↗
PubMed1998

The origin and role of erythema after carbon dioxide laser resurfacing. A clinical and histological study.

BACKGROUND: Transient erythema, which can last up to 3 months after carbon dioxide (CO2) laser skin resurfacing, is a usual side effect with pulsed or rapidly scanned CO2 lasers. OBJECTIVE: We evaluated the cause of erythema in the clinical setting and by histology in order to determine if and how we may decrease it, or even eliminate it. METHODS: Ten patients who underwent resurfacing were recruited to this study. Skin punch biopsies were taken at 0, 7, 21, and 90 days and analyzed by light microscopy. RESULTS: Erythema was noticed from about day 8, when the crusting on the skin surface was exfoliated. It reached its maximum intensity after 14 days, and had disappeared by 60-90 days. Histology showed an early inflammatory response, with an immature neopithelium, and rich vascularization. The normal epidermis had returned by 90 days, and during this period there was reduced optical scattering and absorption in melanin. CONCLUSION: Although the erythema is an unwanted side effect in the patient's eyes, it is to be expected and thus represents the effects of a combination of epidermal immaturity, reduced melanin absorption of light, reduced dermal optical scattering, and increased blood flow secondary to the surgically induced inflammatory response.

Aged↗
PubMed1998

[Diode laser-induced retinal thermal damage control with a liposome-dye system].

PURPOSE: To evaluate the feasibility of retinal thermal damage assessment in a rabbit eye model by using laser-induced release of liposome-encapsulated dye. METHODS: After anesthesia, thermosensitive liposomes (DSPC) loaded with 5,6-Carboxyfluorescein were injected intravenously to pigmented rabbits. Retinal photocoagulations were performed with a 810 nm diode laser (p = 100 to 400 mW, phi = 500 microns, 1s) (OcuLight, IRIS Medical Instruments Inc., USA). Fluorescence measurements in the area of the laser exposures were then made with a digitized angiograph (CF-60UVi, Canon-Europe, The Netherlands; OcuLab, Life Science Resources Ltd, England). RESULTS: Fluorescent spots were observed for power ranging from 100 +/- 5 mW to 400 +/- 5 mW. The fluorescence intensity increased linearly with the power and reached a plateau at 300 +/- 5 mW. The fluorescence intensity was correlated to the maximum temperature at the center of the laser spot with a linear increase from 42 +/- 3 degrees C to 65 +/- 3 degrees C. These results are consistent with our two previous studies with DSPC liposomes for temperature measurements in a tissue model and then in a vascular model. CONCLUSION: This preliminary study demonstrates the possibility of a laser-induced release of liposome-encapsulated dye for a quantification of diode laser induced thermal damage in ophthalmology. Such a method could be useful for a real-time monitoring of laser photocoagulation for conditions such as choroidal neovascular membranes when a precise thermal damage is required near the foveolar area.

Animals↗
PubMed1997

Thermal damage assessment of blood vessels in a hamster skin flap model by fluorescence measurement of a liposome-dye system.

BACKGROUND AND OBJECTIVES: The present study was undertaken to evaluate the feasibility of thermal damage assessment of blood vessels by using laser-induced release of liposome-encapsulated dye. STUDY DESIGN/MATERIALS AND METHODS: Experiments were performed in a hamster skin flap model. Laser irradiation was achieved with a 300 microm fiber connected to a 805 nm diode laser (power = 0.8W, spot diameter = 1.3 mm and pulse exposure time lasting from 1 to 6 s) after potentiation using a specific indocyanine green (ICG) formulation (water and oil emulsion). Liposomes-encapsulated carboxyfluorescein were prepared by the sonication procedure. Carboxyfluorescein (5,6-CF) was loaded at high concentration (100 mM) in order to quench its fluorescence. The measurements were performed after i.v. injection of DSPC liposomes (1.5 ml) and lasted 40 min. Fluorescence emission was measured with an ultra high sensitivity intensified camera. RESULTS: Three different shapes of fluorescent spots were identified depending on target (blood vessel or skin) and energy deposition in tissue: (i) intravascular fluorescence, (ii) transient low fluorescence circular spot, and (iii) persistent high intense fluorescence spot. These images are correlated with histological data. CONCLUSION: Real-time fluorescence imaging seems to be a good tool to estimate in a non-invasive manner the thermal damage induced by a diode laser combined with ICG potentiation.

Animals↗