Hypertrophy in port-wine stains: prevalence and patient characteristics in a large patient cohort.

BACKGROUND: Port-wine stains (PWS) may thicken and darken with age. Little is known about the pathogenesis and epidemiology of PWS hypertrophy because of the lack of large studies. OBJECTIVE: We sought to assess the prevalence and characteristics of patients with hypertrophic PWS. METHODS: Medical records and clinical photographs of all patients with PWS visiting our clinic between 2005 and 2009 were examined to identify hypertrophy. Patients were sent questionnaires regarding their hypertrophic PWS. RESULTS: In all, 335 patients (age 0-81 years; 69% female) with PWS were included. Hypertrophy was found in 68 patients (20%; 32 male, 36 female) and classified as thickened (5%), nodular (8%), or both (7%). Color of hypertrophic PWS was mainly red (50%) or purple (44%). Patients with hypertrophy in their PWS were mostly (68%) older than 40 years, and rarely (7%) younger than 20 years. When older than 50 years, 71% of all patients had hypertrophy in their PWS. Median age of onset of PWS hypertrophy was 31 years (12 years for thickened, 39 years for nodular). LIMITATIONS: This was a retrospective study in a selected population. CONCLUSION: Hypertrophy is an important feature in the development of PWS and affects a majority of patients older than 50 years. Depth of color of the PWS is associated with hypertrophy, whereas location and size appear not to be related. More attention should be drawn to therapy and prevention of hypertrophic PWS. Diffuse thickening and nodules should be distinguished, as a different age of onset may indicate different pathomechanisms.

Non-ablative 1550 nm fractional laser therapy not effective for erythema dyschromicum perstans and postinflammatory hyperpigmentation: a pilot study.

BACKGROUND: Erythema dyschromicum perstans and postinflammatory hyperpigmentation (PIH) are characterized by papillary dermal pigmentation or pigment incontinence. To date, no standard treatment is available. Fractional laser therapy (FLT) was recently reported to improve different pigment disorders. OBJECTIVES: To assess the efficacy and safety of non-ablative FLT in the treatment of erythema dyschromicum perstans and PIH. METHODS: Eight patients with erythema dyschromicum perstans and six patients with PIH were included. In each patient, two similar test regions were randomized to receive either five fractional laser treatments in combination with intermittent daily topical bleaching or the same intermittent regimen of topical bleaching alone. Three months after the last treatment, improvement of hyperpigmentation was assessed by melanin index, reflectance spectroscopy, physician's assessment, patient's assessment and patient's satisfaction. In addition, a biopsy of both laser treated and control site was evaluated by an independent blinded pathologist. RESULTS: No clinical improvement of hyperpigmentation was observed. Reflectance spectroscopy, melanin index, number of melanocytes and amount of dermal melanin did not significantly differ. Patients considered FLT unsatisfactory. Moreover, three patients developed laser-induced PIH. CONCLUSIONS: With these specific laser settings, non-ablative FLT was not effective for the treatment of erythema dyschromicum perstans and PIH.

Biodegradable polymer scaffold, semi-solid solder, and single-spot lasing for increasing solder-tissue bonding in suture-free laser-assisted vascular repair.

We recently showed the fortifying effect of poly-caprolactone (PCL) scaffold in liquid solder-mediated laser-assisted vascular repair (ssLAVR) of porcine carotid arteries, yielding a mean ± SD leaking point pressure of 488 ± 111 mmHg. Despite supraphysiological pressures, the frequency of adhesive failures was indicative of weak bonding at the solder-tissue interface. As a result, this study aimed to improve adhesive bonding by using a semi-solid solder and single-spot vs. scanning irradiation. In the first experiment, in vitro ssLAVR (n=30) was performed on porcine abdominal aorta strips using a PCL scaffold with a liquid or semi-solid solder and a 670-nm diode laser for dual-pass scanning. In the second experiment, the scanning method was compared to single-spot lasing. The third experiment investigated the stability of the welds following hydration under quasi-physiological conditions. The welding strength was defined by acute breaking strength (BS). Solder-tissue bonding was examined by scanning electron microscopy and histological analysis was performed for thermal damage analysis. Altering solder viscosity from liquid to semi-solid solder increased the BS from 78 ± 22 N/cm(2) to 131 ± 38 N/cm(2) . Compared to scanning ssLAVR, single-spot lasing improved adhesive bonding to a BS of 257 ± 62 N/cm(2) and showed fewer structural defects at the solder-tissue interface but more pronounced thermal damage. The improvement in adhesive bonding was associated with constantly stronger welds during two weeks of hydration. Semi-solid solder and single-spot lasing increased welding strength by reducing solder leakage and improving adhesive bonding, respectively. The improvement in adhesive bonding was associated with enhanced weld stability during hydration.

Formation of fibrosis after nonablative and ablative fractional laser therapy.

BACKGROUND: Fractional laser therapy (FLT) has become a widely accepted modality for skin rejuvenation and has also been used in various other skin diseases. OBJECTIVE: To observe long-term histologic effects of nonablative and ablative FLT in the treatment of pigment disorders. METHODS: A randomized controlled observer-blinded study was performed in 18 patients with pigment disorders. Two similar test regions were randomized to receive FLT with intermittent topical bleaching or topical bleaching alone. Patients with ashy dermatosis (AD) and postinflammatory hyperpigmentation (PIH) were treated using nonablative 1,550-nm FLT (15 mJ/microbeam, 14-20% coverage), whereas patients with Becker's nevus (BN) were treated with ablative 10,600-nm FLT (10 mJ/microbeam, 35-45% coverage) for three to five sessions. Biopsies were obtained 3 months after the last treatment. RESULTS: At follow-up, dermal fibrosis was observed in four of eight patients treated using ablative FLT and no patients treated using nonablative FLT (p < .05). CONCLUSIONS: Assuming that the dermal response is comparable in AD, PIH, and BN, at the given settings, ablative FLT may induce fibrosis, whereas treatment with nonablative FLT does not. Whether formation of fibrosis has to be regarded as dermal remodeling or a subtle subclinical form of scarring should be investigated in future research.

Ablative fractional laser therapy as treatment for Becker nevus: a randomized controlled pilot study.

BACKGROUND: Becker nevus (BN) is an uncommon pigment disorder characterized by hyperpigmentation and sometimes hypertrichosis. To date, no effective treatment has been available. OBJECTIVES: We sought to assess efficacy and safety of ablative 10,600-nm fractional laser therapy (FLT) in the treatment of BN. METHODS: Eleven patients with BN, older than 18 years, were included in a prospective randomized controlled, observer-blinded split-lesion trial. In each patient two similar square test regions were randomized to either ablative FLT at 10 mJ/microbeam, coverage 35% to 45%, and topical bleaching (to prevent laser-induced postinflammatory hyperpigmentation), or topical bleaching alone (to allow comparison of the regions). At 3- and 6-month follow-up, clearance of hyperpigmentation was assessed by physician global assessment, reflectance spectroscopy, melanin index, patient global assessment, patient satisfaction, and histology. RESULTS: At 6-month follow-up, physician global assessment improved in the FLT region (P < .05). Reflectance spectroscopy, melanin index, number of melanocytes, and amount of dermal melanin did not significantly differ between the regions. Patient global assessment and patient satisfaction were 5.0 and 5.9 (visual analog scale score, 0-10), respectively. Side effects were postinflammatory hyperpigmentation (n = 3), erythema (n = 3), burning sensation (n = 3), crusting (n = 3), edema (n = 2), and blistering (n = 2). LIMITATIONS: Limitations include the small number of patients, treatment in spring, possibly suboptimal laser settings, and the combined usage of FLT and a bleaching agent. CONCLUSION: Ablative FLT was moderately effective in some patients with BN. However, postinflammatory hyperpigmentation and relatively negative patient-reported outcomes still preclude ablative FLT from being a standard therapy. Larger studies with different laser settings will be required to optimize this treatment modality.

Laser-induced primary and secondary hemostasis dynamics and mechanisms in relation to selective photothermolysis of port wine stains.

BACKGROUND: Superficial vascular anomalies such as port wine stains are commonly treated by selective photothermolysis (SP). The endovascular laser-tissue interactions underlying SP are governed by a photothermal response (thermocoagulation of blood) and a hemodynamic response (thrombosis). Currently it is not known whether the hemodynamic response encompasses both primary and secondary hemostasis, which platelet receptors are involved, and what the SP-induced thrombosis kinetics are in low-flow venules. OBJECTIVES: To (1) define the role and kinetics of primary and secondary hemostasis in laser-induced thrombus formation and (2) determine which key platelet surface receptors are involved in the hemodynamic response. METHODS: 532-nm laser-irradiated hamster dorsal skin fold venules were studied by intravital fluorescence microscopy following fluorescent labeling of platelets with 5(6)-carboxyfluorescein. Heparin and fluorescently labeled anti-glycoprotein Ib-α (GPIbα) and anti-P-selectin antibodies were administered to investigate the role of coagulation and platelet receptors, respectively. Lesional sizes were quantified by software. RESULTS: Laser irradiation consistently produced sub-occlusive thermal coagula. Thrombosis was triggered in all irradiated venules in a thermal coagulum-independent manner and peaked at 6.25min post-irradiation. Heparin decreased the maximum thrombus size and caused thrombosis to reach a maximum at 1.25min. Immunoblocking of GPIbα abated the extent of thrombosis, whereas immunoblocking of P-selectin had no effect. CONCLUSIONS: The hemodynamic response ensues the photothermal response in a thermal coagulum-independent manner and involves primary and secondary hemostasis. Primary hemostasis is mediated by constitutively expressed GPIbα but not by activation-dependent P-selectin.

Nonablative 1550-nm fractional laser therapy versus triple topical therapy for the treatment of melasma: a randomized controlled pilot study.

BACKGROUND: Various treatments are currently available for melasma. However, results are often disappointing. OBJECTIVE: We sought to assess the efficacy and safety of nonablative 1550-nm fractional laser therapy and compare results with those obtained with triple topical therapy (the gold standard). METHODS: Twenty female patients with moderate to severe melasma and Fitzpatrick skin types II to V were treated either with nonablative fractional laser therapy or triple topical therapy (hydroquinone 5%, tretinoin 0.05%, and triamcinolone acetonide 0.1% cream) once daily for 8 weeks in a randomized controlled observer-blinded study. Laser treatment was performed every 2 weeks for a total of 4 times. Physician Global Assessment was assessed at 3 weeks, 3 months, and 6 months after the last treatment. RESULTS: Physician Global Assessment improved (P < .001) in both groups at 3 weeks. There was no difference in Physician Global Assessment between the two groups. Mean treatment satisfaction and recommendation were significantly higher in the laser group at 3 weeks (P < .05). However, melasma recurred in 5 patients in both groups after 6 months. Side effects in the laser group were erythema, burning sensation, facial edema, and pain; in the triple group side effects were erythema, burning, and scaling. LIMITATIONS: Limitations were: small number of patients; only one set of laser parameters; and a possible difference in motivation between groups. CONCLUSIONS: Nonablative fractional laser therapy is safe and comparable in efficacy and recurrence rate with triple topical therapy. It may be a useful alternative treatment option for melasma when topical bleaching is ineffective or not tolerated. Different laser settings and long-term maintenance treatment should be tested in future studies.

Optimization of suture-free laser-assisted vessel repair by solder-doped electrospun poly(ε-caprolactone) scaffold.

Poor welding strength constitutes an obstacle in the clinical employment of laser-assisted vascular repair (LAVR) and anastomosis. We therefore investigated the feasibility of using electrospun poly(ε-caprolactone) (PCL) scaffold as reinforcement material in LAVR of medium-sized vessels. In vitro solder-doped scaffold LAVR (ssLAVR) was performed on porcine carotid arteries or abdominal aortas using a 670-nm diode laser, a solder composed of 50% bovine serum albumin and 0.5% methylene blue, and electrospun PCL scaffolds. The correlation between leaking point pressures (LPPs) and arterial diameter, the extent of thermal damage, structural and mechanical alterations of the scaffold following ssLAVR, and the weak point were investigated. A strong negative correlation existed between LPP and vessel diameter, albeit LPP (484±111 mmHg) remained well above pathophysiological pressures. Histological analysis revealed that thermal damage extended into the medial layer with a well-preserved internal elastic lamina and endothelial cells. Laser irradiation of PCL fibers and coagulation of solder material resulted in a strong and stiff scaffold. The weak point of the ssLAVR modality was predominantly characterized by cohesive failure. In conclusion, ssLAVR produced supraphysiological LPPs and limited tissue damage. Despite heat-induced structural/mechanical alterations of the scaffold, PCL is a suitable polymer for weld reinforcement in medium-sized vessel ssLAVR.

Electrospun poly(ɛ-caprolactone) scaffold for suture-free solder-mediated laser-assisted vessel repair.

BACKGROUND AND OBJECTIVE: The addition of poly(lactic-co-glycolic) acid (PLGA) scaffolds to liquid solder-mediated laser-assisted vascular repair (sLAVR) has been shown to increase soldering strength significantly. Unfortunately, the fast degradation of PLGA is associated with adverse effects such as acidity of the degradation products. This study investigated the possibility of using electrospun poly(ɛ-caprolactone) (PCL) as reinforcement material in scaffold and solder-mediated LAVR (ssLAVR). MATERIALS AND METHODS: In vitro sLAVR of 10-mm arteriotomies (n = 62) was performed on 0.3- to 0.6-cm diameter porcine carotid arteries with a 670-nm diode laser. The solder contained 50% bovine serum albumin (BSA) and 0.1-0.7% methylene blue (MB) as a chromophore. The soldering strength was studied as a function of PCL-scaffold thickness, scaffold-fiber diameter, MB concentration, number of laser passes, and different sLAVR techniques. Leaking-point pressures (LPPs) were measured with a fluid-infusion technique. RESULTS: The highest mean ± SD LPP (749 ± 171 mm Hg) was produced by the ssLAVR modality that included the sheathing of the arteriotomy with 30 µL solder containing 50% BSA and 0.5% MB, followed by application of the PCL scaffold (mean ± SD thickness of 187 ± 9 µm and 14-µm fiber diameter) and irradiation with two consecutive continuous-wave laser passes. CONCLUSIONS: The study demonstrated the potential applicability of an electrospun PCL scaffold as reinforcement material in ssLAVR. Soldering strength was dependent on the scaffold physical properties, chromophore concentration, the number of laser passes, and the ssLAVR technique.

Non-ablative 1,550 nm fractional laser therapy versus triple topical therapy for the treatment of melasma: a randomized controlled split-face study.

BACKGROUND: Melasma is a uichronic, often relapsing skin disorder, with poor long-term results from all current therapies. OBJECTIVE: To assess efficacy and safety of non-ablative 1,550 nm fractional laser therapy (FLT) as compared to the gold standard, triple topical therapy (TTT). STUDY DESIGN: Twenty-nine patients with melasma were included in a randomized controlled observer-blinded study with split-face design. Each side of the face was randomly allocated to either 4-5 non-ablative FLT sessions (15 mJ/microbeam, 14-20% coverage) or TTT (hydroquinone 5%, tretinoin 0.05%, triamcinolone acetonide 0.1% cream). TTT was applied once daily for 15 weeks until the last FLT session. After this last treatment, patients were asked to apply TTT twice weekly on both sides of the face during follow-up. Improvement of melasma was assessed by patient's global assessment (PGA), patient's satisfaction, physician's global assessment (PhGA), melanin index, and lightness (L-value) at 3 weeks, and at 3 and 6 months after the last treatment. RESULTS: Mean PGA and satisfaction were significantly lower at the FLT side (P<0.001). PhGA, melanin index, and L-value showed a significant worsening of hyperpigmentation at the FLT side. At the TTT side, no significant change was observed. At 6 months follow-up, most patients preferred TTT. Side effects of FLT were erythema, burning sensation, edema, and pain. Nine patients (31%) developed PIH after two or more laser sessions. Side effects of TTT were erythema, burning sensation, and scaling. CONCLUSIONS: Given the high rate of postinflammatory hyperpigmentation, non-ablative 1,550 nm fractional laser at 15 mJ/microbeam is not recommendable in the treatment of melasma. TTT remains the gold standard treatment.

Cryoablation induces greater inflammatory and coagulative responses than radiofrequency ablation or laser induced thermotherapy in a rat liver model.

BACKGROUND: Cryoablation (CA), radiofrequency ablation (RFA), and laser induced thermotherapy (LITT) are alternative therapies for patients with unresectable liver tumors. We investigated whether there are different inflammatory and coagulative responses between these techniques. METHODS: Livers of 48 rats were subjected to either CA, RFA, LITT, or sham operation (n = 12 in each group). Blood was withdrawn before, and 1, 3, 6, and 24 h after ablation. Liver enzymes as well as inflammatory and coagulation parameters were determined. Whole liver sections from the coagulated liver lobe were stained for quantification of necrosis and morphologic examination. RESULTS: Histologic examination showed similar volume of complete destruction of liver parenchyma after CA, RFA, or LITT. Transaminase levels as well as the inflammatory response upon CA, as reflected by white blood cell count and cytokine levels, were significantly higher than following RFA or LITT. The systemic intravascular procoagulative state in rats that underwent CA, as reflected by platelets, and levels of sensitive markers for activation of coagulation and fibrinolyis, was also significantly higher. CONCLUSION: CA of liver in rats induces greater inflammatory and coagulative responses than RFA or LITT. The combined activation of inflammation and coagulation may importantly contribute to the higher morbidity after CA.

Fluorescent labeling of platelets with polyanionic fluorescein derivatives.

OBJECTIVE: To investigate whether polyanionic fluorescein derivatives are capable of labeling resting and activated hamster and human platelets. STUDY DESIGN: 5,6-Carboxyfluorescein and calcein were incubated with resting and convulxin-activated hamster and human platelets in the 0-3.4 microM and 0-2.5 microM final concentration range, respectively, and assayed by flow cytometry and confocal microscopy. RESULTS: Resting and activated platelets of both species could be labeled by both fluorophores and quantified by flow cytometry. The fluorescence emission intensity and the fraction of labeled platelets increased linearly with final fluorophore concentration. Examination of labeled platelets by confocal microscopy revealed that 5,6-carboxyfluorescein and calcein colocalized with the platelet glycocalyx and that the fluorophores were often sequestered by the cells. The latter manifested itself by compartmentalization or relatively homogenous fluorophore distribution in the cytosol. CONCLUSION: Hamster and human resting and activated platelets can be fluorescently labeled by the lipophobicfluorescein derivatives 5,6-carboxyfluorescein and calcein as a result of fluorophore avidity to the platelet glycocalyx and sequestration by the cells. Consequently, platelets could be quantified by flow cytometry and visualized by confocal microscopy.

On the interaction of fluorophore-encapsulating PEGylated lecithin liposomes with hamster and human platelets.

Polyethylene glycol (PEG)-grafted phosphatidylcholine liposomes are used as drug carriers due to their low immunogenicity and prolonged circulation time. The interaction between sterically stabilized lecithin liposomes and platelets has not been investigated before, and deserves to be subjected to scrutiny inasmuch as the uptake of liposomes by platelets could be detrimental for drug delivery and primary hemostasis. Consequently, the interaction between resting and convulxin-activated hamster and human platelets and calcein- or 5,6-carboxyfluorescein-encapsulating PEGylated liposomes composed of distearoyl- and dipalmitoyl phosphatidylcholine and PEG-derivatized distearoyl phosphatidylethanolamine was investigated by flow cytometry, confocal microscopy, and a glass capillary thrombosis model. Fluorescently labeled liposomes of the same composition were subsequently assayed in vivo after 15 and 45 min of systemic circulation. Neither resting nor activated hamster and human platelets interacted with liposomes at 0.70 mM lipid concentration. An absence of any interaction was corroborated in the in vivo experiments. Alternatively, flow cytometry assays evinced that human platelets interact with liposomes at lipid concentrations of >or=1.35 mM. These interactions were more profound for activated platelets than resting platelets. We conclude that the use of PEGylated lecithin liposomes at lipid concentrations of <1.35 mM has no detrimental impact on liposomal drug delivery based on PEGylated lecithin liposomes, but that these drug carriers may be associated with a reduced targeting efficacy or compromised primary hemostatic system when used at concentrations of >or=1.35 mM. In contrast, these drug carriers may become valuable in thrombosis- and drug delivery-related research and applications at concentrations of >or=1.35 mM.

Mitochondrial oxygen tension within the heart.

By using a newly developed optical technique which enables non-invasive measurement of mitochondrial oxygenation (mitoPO(2)) in the intact heart, we addressed three long-standing oxygenation questions in cardiac physiology: 1) what is mitoPO(2) within the in vivo heart?, 2) is mitoPO(2) heterogeneously distributed?, and 3) how does mitoPO(2) of the isolated Langendorff-perfused heart compare with that in the in vivo working heart? Following calibration and validation studies of the optical technique in isolated cardiomyocytes, mitochondria and intact hearts, we show that in the in vivo condition mean mitoPO(2) was 35+/-5 mm Hg. The mitoPO(2) was highly heterogeneous, with the largest fraction (26%) of mitochondria having a mitoPO(2) between 10 and 20 mm Hg, and 10% between 0 and 10 mm Hg. Hypoxic ventilation (10% oxygen) increased the fraction of mitochondria in the 0-10 mm Hg range to 45%, whereas hyperoxic ventilation (100% oxygen) had no major effect on mitoPO(2). For Langendorff-perfused rat hearts, mean mitoPO(2) was 29+/-5 mm Hg with the largest fraction of mitochondria (30%) having a mitoPO(2) between 0 and 10 mm Hg. Only in the maximally vasodilated condition, did the isolated heart compare with the in vivo heart (11% of mitochondria between 0 and 10 mm Hg). These data indicate 1) that the mean oxygen tension at the level of the mitochondria within the heart in vivo is higher than generally considered, 2) that mitoPO(2) is considerably heterogeneous, and 3) that mitoPO(2) of the classic buffer-perfused Langendorff heart is shifted to lower values as compared to the in vivo heart.

Suture-free laser-assisted vessel repair using CO2 laser and liquid albumin solder.

Numerous studies have shown that the use of proteinic solders during laser-assisted vascular anastomosis (LAVA) and repair (LAVR) can significantly increase welding strength, but these studies combined solder-mediated LAVA/R with the use of stay sutures, thereby defeating its purpose. In an in vitro study, we examined the leaking point pressures (LPPs) and histological damage profile of porcine carotid arteries following albumin solder-mediated CO(2) LAVR without the use of sutures. Longitudinal arteriotomies (9.1+/-0.8 mm in length) were sheathed with 25% liquid bovine serum albumin solder, and LAVR was performed using a micromanipulator-controlled CO(2) laser operating at 170-mW power and 1.25-mm spot size in continuous wave mode. The welding regime consisted of a transversal zigzag pass followed by one or two longitudinal zigzag passes, producing an irradiance of 13.9 W/cm(2) and energies of 10.5 J and 11.3 J per mm weld, respectively. LPPs were measured by the fluid infusion technique, and histological analysis was performed with light, fluorescence, and polarization microscopy. The LPP of the two-pass welds was 351+/-158 mmHg versus 538+/-155 mmHg for the three-pass welds. Thermal damage was confined primarily to the adventitial layers, with limited heat diffusion into the media below the solder around the coaptation interface.

In vivo mitochondrial oxygen tension measured by a delayed fluorescence lifetime technique.

Mitochondrial oxygen tension (mitoPO(2)) is a key parameter for cellular function, which is considered to be affected under various pathophysiological circumstances. Although many techniques for assessing in vivo oxygenation are available, no technique for measuring mitoPO(2) in vivo exists. Here we report in vivo measurement of mitoPO(2) and the recovery of mitoPO(2) histograms in rat liver by a novel optical technique under normal and pathological circumstances. The technique is based on oxygen-dependent quenching of the delayed fluorescence lifetime of protoporphyrin IX. Application of 5-aminolevulinic acid enhanced mitochondrial protoporphyrin IX levels and induced oxygen-dependent delayed fluorescence in various tissues, without affecting mitochondrial respiration. Using fluorescence microscopy, we demonstrate in isolated hepatocytes that the signal is of mitochondrial origin. The delayed fluorescence lifetime was calibrated in isolated hepatocytes and isolated perfused livers. Ultimately, the technique was applied to measure mitoPO(2) in rat liver in vivo. The results demonstrate mitoPO(2) values of approximately 30-40 mmHg. mitoPO(2) was highly sensitive to small changes in inspired oxygen concentration around atmospheric oxygen level. Ischemia-reperfusion interventions showed altered mitoPO(2) distribution, which flattened overall compared to baseline conditions. The reported technology is scalable from microscopic to macroscopic applications, and its reliance on an endogenous compound greatly enhances its potential field of applications.

Modeling acardiac twin pregnancies.

Acardiac twin pregnancies are a rare but severe complication of monochorionic twinning, where the acardiac twin lacks cardiac function but nevertheless grows during pregnancy because it is perfused by the pump twin through a set of placental arterioarterial and venovenous anastomoses. Because the acardiac twin's body is only perfused by the pump twin's arterial blood, acardiac twins have reduced blood oxygen saturation (SO(2)) levels. Furthermore, the pump twin has reduced blood oxygen saturation because the anastomoses merge the blood of the two twins. We suggested that angiogenesis from hypoxia mediated neovascularization increases the capillary density in the acardiac twin and causes a continuously decreasing vascular resistance of the acardiac body. The pump twin therefore has a continuously increasing cardiac output and decreasing oxygen saturation, which may cause a vicious circle of increasing levels of pump twin complications, often leading to intrauterine fetal death. Our aim in this article was twofold. First, to summarize our previous modeling work of acardiac twin pregnancies, and add an estimate of the capillary density in mammals at different levels of SO(2) from a literature search on angiogenesis related to SO(2), Hypoxia Inducible Factor, and Vascular Endothelial Growth Factor. Second, to speculate that combination of these efforts and our most recent model of monochorionic twin pregnancies and twin-twin transfusion syndrome may result in an improved computational model for acardiac twin pregnancies, aimed at identifying early clinical prognostic markers for pump twin complications.

Redarkening of port-wine stains 10 years after pulsed-dye-laser treatment.

BACKGROUND: Although pulsed-dye-laser therapy is currently the gold standard for the treatment of port-wine stains, few objective data are available on its long-term efficacy. Using objective color measurements, we performed a 10-year follow-up of a previously conducted prospective clinical study of the treatment of port-wine stains with a pulsed-dye laser. METHODS: We invited the patients to undergo repeated color measurements performed by the same procedures as in the previous study. The results at long-term follow-up were compared with color measurements obtained before treatment and after completion of an average of five laser treatments of the complete port-wine stain. A questionnaire was used to investigate patients' satisfaction with the treatment and their perception of long-term changes in the stain. RESULTS: Of the 89 patients from whom color measurements were obtained in the previous study, 51 were included in this study. The patients had received a median of seven additional treatment sessions since the last color measurement, which had been made after an average of five treatments. The median length of follow-up was 9.5 years. On average, the stain when measured at follow-up was significantly darker than it was when measured after the last of the initial five laser treatments (P=0.001), but it was still significantly lighter than it was when measured before treatment (P<0.001). Fifty-nine percent of patients were satisfied with the overall treatment result. Six percent of patients reported that the stain had become lighter since their last treatment, 59% that it was unchanged, and 35% that it had become darker. CONCLUSIONS: Using objective color measurements, we observed significant redarkening of port-wine stains at long-term follow-up after pulsed-dye-laser therapy. Patients should be informed about the possibility of redarkening before beginning treatment.

Mitochondrial PO2 measured by delayed fluorescence of endogenous protoporphyrin IX.

Molecular oxygen is the primary oxidant in biological systems. The ultimate destination of oxygen in vivo is the mitochondria where it is used in oxidative phosphorylation. The ability of this process to produce an amount of high-energy phosphates adequate to sustain life highly depends on the available amount of oxygen. Despite a vast array of techniques to measure oxygen, major (patho)physiological questions remain unanswered because of the unavailability of quantitative techniques to measure mitochondrial oxygen in situ. Here we demonstrate that mitochondrial PO(2) can be directly measured in living cells by harnessing the delayed fluorescence of endogenous protoporphyrin IX (PpIX), thereby providing a technique with the potential for a wide variety of applications. We applied this technique to different cell lines (V-79 Chinese hamster lung fibroblasts, HeLa cells and IMR 32-K1 neuroblastoma cells) and present the first direct measurements of the oxygen gradient between the mitochondria and the extracellular volume.