Biomedical subjects

K McMillan

Publications and source records attributed to K McMillan.

At least 19 recordsLinked to original sources

PubMed2006

Using functional data analysis to summarise and interpret lactate curves.

John Tukey used the term exploratory data analysis (EDA) to describe a philosophy for analyzing data where graphical and numerical summaries are used to uncover interesting structures. The applied statistician today has a much more sophisticated set of methods to use when applying the EDA philosophy. One such collection of methods is functional data analysis (FDA), which was used to explore the structure of lactate curves. A principal components analysis and plots of the second derivatives provide new intuitive endurance markers which correlates highly with other numerical summaries of lactate curves that have been suggested in the literature.

Humans↗

PubMed2005

Lactate threshold responses to a season of professional British youth soccer.

OBJECTIVE: To examine the changes in aerobic endurance performance of professional youth soccer players throughout the soccer season. METHODS: Nine youth soccer players were tested at six different time points throughout the soccer season by sub-maximal blood lactate assessment, using an incremental treadmill protocol. Whole blood lactate concentration and heart frequency (Hf) were determined at each exercise stage. Running velocities at the first lactate inflection point (v-T(lac)) and at a blood lactate concentration of 4 mmol l(-1) (v-4mM) were determined. RESULTS: Running velocity at the two lactate thresholds increased from the start of pre-season training to the early weeks of the competitive season, from 11.67 (0.29) to 12.96 (0.28) km h(-1) for v-T(lac), and from 13.62 (0.25) to 14.67 (0.24) km h(-1) for v-4mM (p<0.001). However, v-T(lac )and v-4mM when expressed relative to maximum heart frequency (Hf(max)) remained unchanged. The Hf to blood lactate concentration relationship was unchanged after the pre-season training period. The two expressions of lactate threshold did not reveal differences between each other. CONCLUSION: Running velocity at v-T(lac )and v-4mM increased significantly over the pre-season period, but v-T(lac )and v-4mM were unchanged when expressed relative to Hf(max). This finding may indicate that increased endurance performance may be mainly attributable to alterations in Vo(2max). Although lactate assessment of soccer players is useful for determining endurance training adaptations in soccer players, additional assessment of the other two determinants of endurance performance (Vo(2max) and running economy) may provide more useful information for determining physiological adaptations resulting from soccer training and training interventions.

Adolescent↗

PubMed2005

Physiological adaptations to soccer specific endurance training in professional youth soccer players.

BACKGROUND: Improved oxygen uptake improves soccer performance as regards distance covered, involvements with the ball, and number of sprints. Large improvements in oxygen uptake have been shown using interval running. A similar physiological load arising from interval running could be obtained using the soccer ball in training. OBJECTIVES: The main aim was to study physiological adaptations to a 10 week high intensity aerobic interval training program performed by professional youth soccer players, using a soccer specific ball dribbling track. METHODS: Eleven youth soccer players with a mean (SD) age of 16.9 (0.4) years performed high intensity aerobic interval training sessions twice per week for 10 weeks in addition to normal soccer training. The specific aerobic training consisted of four sets of 4 min work periods dribbling a soccer ball around a specially designed track at 90-95% of maximal heart frequency, with a 3 min recovery jog at 70% of maximal heart frequency between intervals. RESULTS: Mean VO2max improved significantly from 63.4 (5.6) to 69.8 (6.6) ml kg(-1) min(-1), or 183.3 (13.2) to 201.5 (16.2) ml kg(-0.75) min(-1) (p<0.001). Squat jump and counter movement jump height increased significantly from 37.7 (6.2) to 40.3 (6.1) cm and 52.0 (4.0) to 53.4 (4.2) cm, respectively (p<0.05). No significant changes in body mass, running economy, rate of force development, or 10 m sprint times occurred. CONCLUSION: Performing high intensity 4 min intervals dribbling a soccer ball around a specially designed track together with regular soccer training is effective for improving the VO2max of soccer players, with no negative interference effects on strength, jumping ability, and sprinting performance.

Adaptation, Physiological↗

PubMed2002

Reproducibility of the blood lactate threshold, 4 mmol.l(-1) marker, heart rate and ratings of perceived exertion during incremental treadmill exercise in humans.

The aim of this study was to investigate the reproducibility of blood lactate measurements, heart rate (HR) and ratings of perceived exertion (RPE) during treadmill exercise at speeds corresponding to the lactate threshold ( v(Th,la)-) and a fixed blood lactate concentration of 4 mmol.l(-1)( v(la)-(,4)). Possible differences in reproducibility related to fitness levels were also investigated. A group of 20 men [mean (SD)] [age 20.5 (1.4) years] and 16 women [age 21.2 (0.9) years] took part in the study. The subjects performed two identical incremental exercise tests consisting of at least six 4 min stages. Blood lactate concentrations, HR and RPE were recorded at the end of each stage. Limits of agreement (LoA), correlation coefficients and 95% confidence intervals for the mean difference between tests were employed to investigate the level of agreement and reproducibility of blood lactate concentration, HR and RPE. For the group as a whole, the sample correlation coefficient for speed at v(Th,la)- was r=0.88, and was r=0.92 for the speed at v(la)-(,4). At v(Th,la) -, the correlation coefficients for the moderately fit and unfit were r=0.94 and r=0.36, respectively, and at v(la)-(,4) r=0.93 and r=0.68, respectively. The LoA for the moderately fit group indicated that a change of 1.62 km.h(-1) in v(Th,la)- would be necessary to be considered a change in training status. For HR and RPE, relationships between the tests were generally poor. The LoA suggested that changes in scores must be unacceptably large. These findings cast doubt on the sensitivity of testing for change of blood lactate concentration, HR and RPE in this population.

Adult↗

PubMed2001

Can voltammetry measure nitrogen monoxide (NO) and/or nitrites?

Recently, voltammetry with carbon fibre electrodes (CFE) has been implemented for real time measurement of nitrogen monoxide (NO) indicating that it is oxidised at the potential value of nitrites, approximately +700 mV. In contrast, here we show that modified CFE can monitor NO at oxidation potentials different than that of nitrites, i.e. +550 mV. Indeed, at +550 mV a significant increase of amperometric current levels was obtained when NO but not nitrites, were added to a phosphate buffer saline solution (PBS). Differential pulse voltammetry (DPV) supports these findings as two oxidation peaks were obtained when examining air preserved NO; peak 1 at +550 mV and peak 2 at +700 mV, respectively. In contrast, only peak 2 was monitored when nitrites or a solution of NO oxidised in air was added to PBS. Biological support to these in vitro data comes from the observation that the relaxation of an adrenaline-contracted aortic ring produced via addition of NO is concomitant with peak 1 at +550 mV. The relaxation is almost completed before the appearance of peak 2 at +700 mV. Furthermore, in vivo experiments performed in the striatum of rats show that the amperometric signal monitored at +550 mV is responsive to glutamatergic stimulation or inhibition of NO synthase.

2-Amino-5-phosphonovalerate↗

PubMed2001

A new laser treatment for vocal cord papilloma--585-nm pulsed dye.

OBJECTIVES: Microvascular targeting with the 585- nm pulsed dye laser (PDL) may provide a new form of therapy to control symptoms caused by recurrent respiratory papillomatosis (RRP). METHODS: Ten patients with RRP underwent 13 procedures under general anesthesia with the 585-nm PDL. A micromanipulator (11 procedures) and a flexible nasolaryngoscope (2 procedures) were used to deliver the laser pulses. Patients were followed postoperatively according to protocol. RESULTS: Clinical examination revealed regression of papillomas in all patients. Seven patients had complete regression after PDL surgery, and 2 patients had partial response to treatment. One patient was lost to follow-up. No complications were present during this prospective nonrandomized pilot study. CONCLUSION: Patients treated with PDL experienced regression of their papillomas. PDL may provide patients with RRP with an alternative treatment without the risks associated with CO(2) laser surgery. This procedure also has potential to be delivered on an outpatient basis with flexible fiberoptic laryngoscopes.

Adult↗

PubMed2001

Parental use of escape extinctionand differential reinforcement to treat food selectivity.

Escape extinction combined with differential reinforcement for acceptance has been demonstrated to be an effective treatment for food selectivity when implemented by trained professionals in clinic settings. This study evaluated the efficacy of parent-implemented escape extinction in the child's natural environment using video monitoring to train parents and assess intervention efficacy. Parents were able to use intervention to significantly increase bites accepted and decrease problem behavior.

Behavior Therapy↗

PubMed2000

Allosteric inhibitors of inducible nitric oxide synthase dimerization discovered via combinatorial chemistry.

Potent and selective inhibitors of inducible nitric oxide synthase (iNOS) (EC ) were identified in an encoded combinatorial chemical library that blocked human iNOS dimerization, and thereby NO production. In a cell-based iNOS assay (A-172 astrocytoma cells) the inhibitors had low-nanomolar IC(50) values and thus were >1,000-fold more potent than the substrate-based direct iNOS inhibitors 1400W and N-methyl-l-arginine. Biochemical studies confirmed that inhibitors caused accumulation of iNOS monomers in mouse macrophage RAW 264.7 cells. High affinity (K(d) approximately 3 nM) of inhibitors for isolated iNOS monomers was confirmed by using a radioligand binding assay. Inhibitors were >1,000-fold selective for iNOS versus endothelial NOS dimerization in a cell-based assay. The crystal structure of inhibitor bound to the monomeric iNOS oxygenase domain revealed inhibitor-heme coordination and substantial perturbation of the substrate binding site and the dimerization interface, indicating that this small molecule acts by allosterically disrupting protein-protein interactions at the dimer interface. These results provide a mechanism-based approach to highly selective iNOS inhibition. Inhibitors were active in vivo, with ED(50) values of <2 mg/kg in a rat model of endotoxin-induced systemic iNOS induction. Thus, this class of dimerization inhibitors has broad therapeutic potential in iNOS-mediated pathologies.

Allosteric Regulation↗

PubMed2000

The effect of strength training on the apparent inhibition of eccentric force production in voluntarily activated human quadriceps.

Ten male and ten female young adults trained the knee extensors of one leg eccentrically and those of the other concentrically for 6 weeks, using a gymnasium leg-extension machine. Before and after training, both legs of each subject were tested isometrically for maximum voluntary knee-extensor force, and in both eccentric and concentric isokinetic modes at 30-250 degrees x s(-1) All limbs showed improvements in mean eccentric force (ranging from 18% in the concentrically trained legs of the females to 31% in the eccentrically trained legs of the males, P < 0.01-0.001). Upward trends in isometric and concentric forces were smaller and less- or nonsignificant. In three of the four groups, mean eccentric forces after training were significantly greater than mean isometric forces, a difference that was not evident before training. Ten further subjects of each gender, not trained but tested isometrically and isokinetically three times in 2 weeks, showed no significant improvement over the series of tests. The explanation suggested is that the increased percentage activation ("decreased inhibition"), often regarded as the main mechanism of strength gain in the early weeks of training, had been displayed particularly in the subjects' eccentric performance. This implies that the activation-shortfall, which is reduced by the initial phase of strength training, is largely or completely the same as that responsible for the fact that untrained, voluntary eccentric force is less than that of isolated muscle.

Adult↗

PubMed2000

Biodistribution and dosimetry of an aqueous solution containing sodium 3-(125I)iodo-4-hydroxybenzenesulfonate (Iotrex) for brachytherapy of resected malignant brain tumors.

UNLABELLED: Iotrex is an aqueous radiotherapy solution containing sodium 3-(125I)iodo-4-hydroxybenzenesulfonate (125I-HBS), which is used as the radiation source for the brachytherapy of resected of brain tumor cavity margins with the GliaSite catheter. During routine clinical use of this brachytherapy applicator and radiation source, approximately 0.1% of the afterloaded Iotrex will diffuse through the GliaSite balloon. Our purpose was to assess the radiation doses to normal organs under routine clinical use of the GliaSite. METHODS: Five groups of rats received intracerebral injections of an 131I-HBS solution (131I used as a surrogate for 125I in the synthesis of 125I-HBS) with one group sacrificed at 15 minutes, 30 minutes, 1 hour, 2 hours and 4 hours post-administration. Urine was collected and activity retention in numerous organs was measured. The biodistribution data were used to estimate radiation doses to normal organs of the Reference Adult Male and Female phantoms. RESULTS: Radioactivity was rapidly and completely cleared from the brain (98% cleared by 2 hours) and total body (urinary clearance; 93%@2 hours). No organ retained > 0.7% of the radioactivity at 4 hours. For 100% loss of the radiotherapy solution from the balloon catheter (device failure), all organs would receive less than 100 mGy (10 rad), except the bladder wall (2800 mGy, 280 rad), uterus (130 mGy, 13 rad) and distal colon (270 mGy, 27 rad). Under normal conditions, all organ doses are 1000-fold lower (< 3 mGy or 0.3 rad). CONCLUSIONS: Under routine clinical conditions, the radiation doses to normal organs are inconsequential. Should the maximum clinical load of Iotrex (16.7 GBq of 125I) be released intracerebrally, the radiation doses to all organs would be below the thresholds for deterministic effects.

Animals↗

PubMed1999

Essential thiol requirement to restore pterin- or substrate-binding capability and to regenerate native enzyme-type high-spin heme spectra in the Escherichia coli-expressed tetrahydrobiopterin-free oxygenase domain of neuronal nitric oxide synthase.

Nitric oxide (NO) synthases (NOS) are thiolate-ligated heme-, tetrahydrobiopterin (BH(4))-, and flavin-containing monooxygenases which catalyze the NADPH-dependent conversion of L-arginine (L-Arg) to NO AND citrulline. NOS consists of two domains: an N-terminal oxygenase (heme- and BH(4)-bound) domain and a C-terminal reductase (FMN- and FAD-bound) domain. In this study, we have spectroscopically examined the binding of L-Agr and BH(4) to the dimeric, BH(4)-free ferric neuronal NOS (NNOS) oxygenase domain expressed in Escherichia coli separately from the reductase domain. Addition of L-Arg or its analogue inhibitors (N(G)()-methyl-L-Arg, N(G)()-nitro-L-Arg) and BH(4), together with dithiothreitol (DTT), to the pterin-free ferric low-spin oxygenase domain (gamma(MAX): 419, 538, 568 NM) and incubation for 2-3 days at 4 degrees C converted the domain to a native enzyme-type, predominantly high-spin state (gamma(MAX): approximately 395, approximately 512, approximately 650 NM). 7,8-Dihydrobiopterin and other thiols (E.G., beta-mercaptoethanol, cysteine, and glutathione, with less effectiveness) can replace BH(4) and DTT, respectively. the UV-visible absorption spectrum of L-Arg-bound ferric full length NNOS, which exhibits a relatively intense band at approximately 650 NM (epsilon equals 7.5-8 MM(-)(1) CM(-)(1)) due to the presence of a neutral flavin semiquinone, can then be quantitatively reconstructed by combining the spectra of equimolar amounts of the oxygenase and reductase domains. Of particular note, the heme spin-state conversion does not occur in the absence of a thiol even after prolonged (35-48 H) incubation of the oxygenase domain with BH(4) and/or L-Arg under anaerobic conditions. Thus, DTT (or other thiols) plays a significant role(s) beyond keeping BH(4) in its reduced form, In restoring the pterin- and/or substrate-binding capability of the E. coli-expressed, BH(4) free, dimeric NNOS oxygenase domain. Our results in combination with recently available X-ray crystallography and site-directed mutagenesis data suggest that the observed DTT effects arise from the involvement of an intersubunit disulfide bond or its rearrangement in the NOS dimer.

Binding Sites↗

PubMed1999

Low-temperature stabilization and spectroscopic characterization of the dioxygen complex of the ferrous neuronal nitric oxide synthase oxygenase domain.

Nitric oxide (NO), an intercellular messenger and an immuno-cytotoxic agent, is synthesized by the family of nitric oxide synthases (NOS), which are thiolate-ligated, heme-containing monooxygenases that convert L-Arg to L-citrulline and NO in a tetrahydrobiopterin (BH4)-dependent manner, using NADPH as the electron donor. The dioxygen complex of the ferrous enzyme has been proposed to be a key intermediate in the NOS catalytic cycle. In this study, we have generated a stable ferrous-O2 complex of the oxygenase domain of rat neuronal NOS (nNOS) by bubbling O2 through a solution of the dithionite-reduced enzyme at -30 degrees C in a cryogenic solvent containing 50% ethylene glycol. The most stable dioxygen complex is obtained using the oxygenase domain which has been preincubated for an extended length of time at 4 degrees C with BH4/dithiothreitol and NG-methyl-L-arginine, a substrate analogue inhibitor. The O2 complex of the nNOS oxygenase domain thus prepared exhibits UV-visible absorption (maxima at 419 and 553 nm, shoulder at approximately 585 nm) and magnetic circular dichroism spectra that are nearly identical to those of ferrous-O2 cytochrome P450-CAM. Our spectral data are noticeably blue-shifted from those seen at 10 degrees C for a short-lived transient species (lambdamax = 427 nm) for the nNOS oxygenase domain using stopped-flow rapid-scanning spectroscopy [Abu-Soud, H. M., Gachhui, R., Raushel, F. M., and Stuehr, D. J. (1997) J. Biol. Chem. 272, 17349], but somewhat similar to those of a relatively stable O2 adduct of L-Arg-free full-length nNOS (lambdamax = 415-416.5 nm) generated at -30 degrees C [Bec, N., Gorren, A. C. F., Voelder, C., Mayer, B., and Lange, R. (1998) J. Biol. Chem. 273, 13502]. Compared with ferrous-O2 P450-CAM, however, the ferrous-O2 adduct of the nNOS oxygenase domain is considerably more autoxidizable and the O2-CO exchange reaction is noticeably slower. The generation of a stable ferrous-O2 adduct of the nNOS oxygenase domain, as described herein, will facilitate further mechanistic and spectroscopic investigations of this important intermediate.

Camphor 5-Monooxygenase↗

PubMed1999

Tumor growth inhibition and regression induced by photothermal vascular targeting and angiogenesis inhibitor retinoic acid.

The effect of photothermal vascular targeting, alone and in combination with antiangiogenic therapy, was evaluated using tumors produced in mice by transplantation of KB cells. Tumor growth inhibition and regression followed vascular damage produced by pulsed dye laser (PDL) radiation. Administration of the antiangiogenic agent all-trans-retinoic acid (RA) was associated with smaller average tumor volumes in the presence and absence of PDL irradiation, but this effect was not statistically significant. The ability of PDL photothermal vascular targeting to cause regression of tumors without harming normal tissue may be a consequence of preferential damage to supplying vessels at the tumor periphery.

Animals↗

PubMed1998

Diagnosis of head and neck precancerous lesions in an animal model using fluorescence spectroscopy.

Laser-induced fluorescence (LIF) of tissues depends on their biochemical and histomorphologic characteristics. LIF spectroscopic properties of 9,10-dimethyl-1,2-benzanthracene (DMBA)-induced precancerous and early cancerous lesions in a hamster buccal pouch mucosa model were studied. Fluorescence spectra from neoplastic lesions showed a characteristic fluorescence peak in the red region of the visible spectrum centered between 630 and 640 nm when excited with 410-nm light. Using this as a diagnostic criterion, 45 of 49 lesions studied were correctly diagnosed, including early dysplastic lesions. Follow-up study of four dysplastic lesions over 2 weeks revealed an increase in red fluorescence intensity. The findings of these experiments suggest that LIF spectroscopy may be a valuable noninvasive technique not only for early diagnosis of head and neck cancer, but also to probe a possible biochemical surrogate biomarker in the follow-up of suspected lesions.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1998

A 585-nanometer pulsed dye laser treatment of laryngeal papillomas: preliminary report.

OBJECTIVES/HYPOTHESIS: Standard management of recurrent respiratory papillomatosis (RRP) currently consists of CO2 laser microsurgical ablation of papillomas. Because of the recurrent nature of this viral disease, patients are often faced with significant cumulative risk of soft tissue complications. As a minimally traumatic alternative to management of RRP, we have investigated the use of the 585-nm pulsed dye laser (PDL) to cause regression of papillomas by selective eradication of the tumor microvasculature. STUDY DESIGN: Nonrandomized prospective pilot study. METHODS: Patients with laryngeal papillomas were treated with the PDL at fluences of 6 J/cm2 (double pulses per irradiated site), 8 J/cm2 (single pulses), and 10 J/cm2 (single pulses), at noncritical areas within the larynx, using a specially designed micromanipulator. Lesions on the true cords were treated with the CO2 laser, using standard methodology. RESULTS: Clinical examination of three patients treated to date showed that PDL treatment appeared to produce complete regression of papillomas. Unlike the sites of lesions treated by the CO2 laser, the epithelial surface at the PDL treatment sites was preserved intact. CONCLUSIONS: These preliminary results suggest the PDL may eradicate respiratory papillomas with minimal damage to normal laryngeal tissue. Further analysis of the ongoing study is required to demonstrate potential benefits of the technique.

Adult↗

PubMed1997

Substrate binding-induced changes in the EPR spectra of the ferrous nitric oxide complexes of neuronal nitric oxide synthase.

A versatile diatomic physiological messenger, nitric oxide (NO), is biosynthesized by a group of flavo-heme enzymes, the nitric oxide synthases. We have examined the active site of the neuronal isoform by EPR spectroscopy of the ferrous nitric oxide complex. The nitric oxide complex of the substrate-free enzyme exhibits a cytochrome P450-type EPR spectrum typical of a hexacoordinate NO-heme complex with a non-nitrogenous proximal axial heme ligand. The NO complex of the substrate-free enzyme is rather unstable and spontaneously converts to a cytochrome P420 type pentacoordinate denatured form. Binding of L-arginine (l-Arg) enhances the stability of the hexacoordinate NO form. The EPR spectrum of the NO adduct of the enzyme-substrate complex has an increased g-anisotropy and well-resolved hyperfine couplings due to the 14N of nitric oxide. Significant perturbations in the NO EPR spectrum were observed upon Nomega-monomethyl-L-Arg and Nomega-hydroxy-L-Arg binding. The perturbations in the EPR spectrum indicate that L-Arg and its derivatives bind on the distal site of the heme in very close proximity to the bound NO to cause alterations in the heme-NO coordination structure. Interactions between the bound NO and the substrate or its analogues appear to affect the Fe-NO geometry, resulting in the observed spectral changes. We infer that analogous interactions with oxygen might be involved in the hydroxylation events during enzyme catalysis of nitric oxide synthase.

Animals↗

PubMed1997

The influence of chaotropic reagents on neuronal nitric oxide synthase and its flavoprotein module. Urea and guanidine hydrochloride stimulate NADPH-cytochrome c reductase activity of both proteins.

Changes in flavin and protein fluorescence of neuronal nitric oxide synthase (nNOS) and its flavoprotein module were studied in the presence of urea and compared with those previously reported for cytochrome P450 reductase (CPR) [R. Narayanasami, P. M. Horowitz, and B. S. S. Masters (1995) Arch. Biochem. Biophys. 316, 267-274]. As in the case of CPR, FMN was relatively loosely bound to nNOS and the flavoprotein module, but FAD remained bound at concentrations of up to 2 M urea Protein fluorescence increased progressively with increasing urea concentration, but could not be correlated with changes in flavin binding. NADPH-cytochrome c reductase activity of both nNOS and the flavoprotein module, but not that of CPR, was stimulated at early time points by both urea and guanidine hydrochloride (GnHCl), with levels of initial activity returning to baseline values within 60 min after addition of the chaotropic agent. Thus, at 3-4 M urea, enhancements of reductase activities of 20- and 5-fold with nNOS and the flavoprotein module, respectively, were obtained. Comparable enhancements of 12- and 6- to 7-fold, respectively, were obtained with calmodulin (CaM)/ CaCl2 and 0.5 M GnHCl. Thus, the effects of urea and GnHCl mimicked the stimulating effects of CaM. Separate preincubations of nNOS and cytochrome c with urea or GnHCl prior to initiation of the reductase assay showed that sensitivity to chaotropic agent under these conditions was a property of nNOS and not of cytochrome c. Moreover, when the nonprotein electron acceptor 2,6-dichlorophenolindophenol was employed in place of cytochrome c, comparable stimulation of reductase activity was observed in the presence of either urea or GnHCl. Fluorescence of 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfate in the presence of either nNOS or the flavoprotein module was increased optimally between 3 and 4 M urea, consistent with simultaneous exposure of hydrophobic regions of both proteins to solvent and optimization of reductase activity. FMN release from nNOS, but not from the flavoprotein module, was enhanced by CaM. Addition of FMN or FMN + FAD to nNOS, in the presence or absence of urea, brought about a doubling of initial cytochrome c reductase activity, but did not prevent the eventual decline in activity to basal levels. These data are consistent with conformational changes which favor increased electron transfer similar to that achieved with nNOS in the presence of CaM.

Base Sequence↗

PubMed1997

Effect of dynamic cooling on 585-nm pulsed dye laser treatment of port-wine stain birthmarks.

BACKGROUND AND OBJECTIVE: The objective of this study was to determine the effectiveness of a dynamic cooling device (DCD), spraying the skin with a brief spurt of cryogen prior to the laser pulse, in reducing transient pain associated with 585-nm pulsed dye laser (PDL) treatment of port-wine stains (PWS), and reducing epidermal damage (hypo/hyperpigmentation) caused by this laser during PWS treatment. MATERIALS AND METHODS: Matched treatment sites were compared with and without the use of the cryogen spray in 47 patients at two investigational sites. Pain ratings, clearance of the PWS, and pigmentation changes were assessed. The results were analyzed by skin type and patient age. RESULTS: A statistically significant reduction in pain ratings was found in all patient groups using the DCD without changing the efficacy of PWS clearance. Pain reduction was most remarkable in patients with darker skin types. Dynamic cooling prevented the occurrence of epidermal damage or pigmentation change in most cases. CONCLUSIONS: This study suggests that dynamic cooling can dramatically diminish pain during PWS treatment with the 585-nm PDL without reducing treatment efficacy. The absence of epidermal damage in most patients suggests that precooling with the DCD may allow the use of higher laser fluences to expedite clearance without inducing epidermal change. Dynamic cooling has potential use with other lasers and different lesions where discomfort and epidermal effects limit therapy.

Adolescent↗