Laser Tissue Research Articles

Monitoring the microcirculation in the critically ill patient: current methods and future approaches

To discuss the techniques currently available to evaluate the microcirculation in critically ill patients. In addition, the most clinically relevant microcirculatory alterations will be discussed. Review of the literature on methods used to evaluate the microcirculation in humans and on microcirculatory alterations in critically ill patients. In experimental conditions, shock states have been shown to be associated with a decrease in perfused capillary density and an increase in the heterogeneity of microcirculatory perfusion, with non-perfused capillaries in close vicinity to perfused capillaries. Techniques used to evaluate the microcirculation in humans should take into account the heterogeneity of microvascular perfusion. Microvideoscopic techniques, such as orthogonal polarization spectral (OPS) and sidestream dark field (SDF) imaging, directly evaluate microvascular networks covered by a thin epithelium, such as the sublingual microcirculation. Laser Doppler and tissue O(2) measurements satisfactorily detect global decreases in tissue perfusion but not heterogeneity of microvascular perfusion. These techniques, and in particular laser Doppler and near-infrared spectroscopy, may help to evaluate the dynamic response of the microcirculation to a stress test. In patients with severe sepsis and septic shock, the microcirculation is characterized by a decrease in capillary density and in the proportion of perfused capillaries, together with a blunted response to a vascular occlusion test. The microcirculation in humans can be evaluated directly by videomicroscopy (OPS/SDF) or indirectly by vascular occlusion tests. Of note, direct videomicroscopic visualization evaluates the actual state of the microcirculation, whereas the vascular occlusion test evaluates microvascular reserve.

Expression and function of heregulin-α and its receptors in the mouse mammary gland

Heregulin-alpha (HRGalpha) is a cytokine secreted by the mammary mesenchyme, adjacent to lobuloalveolar structures. To understand the role of HRGalpha and its receptors in mammary glands, and the underlying mechanisms, we performed this study to determine the expression and localization of HRGalpha and its receptors ErbB2 and ErbB3. We also determined the role of HRGalpha in the development of mammary glands, beta-casein expression and secretion, Rab3A protein expression and the phosphorylation of HRGalpha signaling molecules using confocal laser scanning microscopy, tissue culture, capillary electrophoresis, Western blotting and enzyme-linked immunosorbent assays. We found that a peak was on pregnancy day 15. Changes of ErbB2 and ErbB3 expression were positively and linearly correlated with HRGalpha, indicating that HRGalpha positively regulates ErbB2 and ErbB3 expression. During pregnancy, HRGalpha enhanced the phosphorylation of STAT5, p42/p44, p38, PKC and Rab3A protein expression, stimulated the proliferation and differentiation of the ductal epithelial cells of mammary glands, and increased and maintained the expression and secretion of beta-casein. During lactation, HRGalpha enhanced the phosphorylation of STAT5 and p38, inhibited the phosphorylation of PKC and Rab3A protein expression, maintained the morphology of the mammary glands and increased the secretion of lactoprotein to reduce the expression of beta-casein in mammary epithelial cells. During involution, HRGalpha induced the phosphorylation of STAT3 and Rab3A protein expression, and inhibited the phosphorylation of PKC to stimulate the degeneration of mammary epithelial cells. It also inhibited the secretion of beta-casein, resulting in increased levels of beta-casein in mammary epithelial cells.

Laser Tissue Welding in Lung and Tracheobronchial Repair: An Animal Model

Violation of the integrity of the airway (pulmonary parenchymal air leak or tracheobronchial injury) remains a challenging problem in chest medicine and thoracic surgery. Tissue sealants such as fibrin glue have been suggested to improve outcomes but they are still associated with significant failure rates. Laser tissue welding (LTW) is an alternative method that produces wound repairs that are significantly stronger than those of fibrin glue and may be used to repair air leaks. We used an Institutional Animal Care and Use Committees-approved New Zealand white rabbit model of lung parenchymal and tracheal injury. Lung wounds (n = 8 per condition) were created and either left open or repaired using fibrin glue or LTW. Tracheal wounds (n = 5 per condition) were created using incisions in the membranous and cartilaginous portions or by removing a tracheal ring, and were repaired using LTW. Within each tissue type, the burst strength of the wounds was measured using a digital manometer and were compared with one another using a two-tailed, paired Student t test. Among the lung injuries, the burst strength of the LTW repair (19.95 +/- 4.98 mm Hg) was significantly stronger than that of the fibrin glue repair or open wound (10.53 +/- 5.01 mm Hg, P = .001, and 7.61 +/- 2.64 mm Hg, P < .001, respectively). Among the tracheal injuries, the burst strength of the membranous incision (101.00 +/- 20.25 mm Hg) was significantly higher than that of the cartilaginous incision (75.08 +/- 10.50 mm Hg, P = .03) but not that of the cartilaginous defect (77.34 +/- 12.35 mm Hg). LTW is capable of sealing wounds in the tracheobronchial tree and can produce bonds that are twice as strong as fibrin glue in lung parenchyma. LTW may be a better alternative than fibrin glue in the repair of injuries to the airway.

Endovascular Laser–Tissue Interactions Redefined: Shining Light on Novel Windows of Therapeutic Opportunity Beyond Selective Photothermolysis

Photomedicine and Laser SurgeryVol. 28, No. 4 Letters to the EditorEndovascular Laser–Tissue Interactions Redefined: Shining Light on Novel Windows of Therapeutic Opportunity Beyond Selective PhotothermolysisMichal Heger, Rick Bezemer, José Fernando Huertas-Pérez, Henk Dekker, and Johan F. BeekMichal HegerDepartment of Experimental Surgery, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.Biochemistry of Membranes, Institute of Biomembranes, University of Utrecht, Utrecht, the Netherlands.Search for more papers by this author, Rick BezemerDepartment of Translational Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.Search for more papers by this author, José Fernando Huertas-PérezDepartment of Analytical Chemistry, Faculty of Sciences, Campus Fuentenueva, University of Granada, Granada, Spain.Search for more papers by this author, Henk DekkerAngiogenesis Laboratory Amsterdam, VU University Medical Center, Amsterdam, the Netherlands.Search for more papers by this author, and Johan F. BeekBiomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.Search for more papers by this authorPublished Online:12 Aug 2010https://doi.org/10.1089/pho.2009.2590AboutSectionsView articleView Full TextPDF/EPUB ToolsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail View articleFiguresReferencesRelatedDetailsCited byIn Vivo Assessment of Thermosensitive Liposomes for the Treatment of Port Wine Stains by Antifibrinolytic Site-Specific Pharmaco-Laser Therapy25 June 2020 | Pharmaceutics, Vol. 12, No. 6Thrombosis versus thermal coagulum formation as a result of endovenous laser treatment: Biochemistry versus photophysics18 September 2013 | Phlebology: The Journal of Venous Disease, Vol. 29, No. 10Endovascular laser–tissue interactions and biological responses in relation to endovenous laser therapy15 November 2013 | Lasers in Medical Science, Vol. 29, No. 2An overview of clinical and experimental treatment modalities for port wine stainsJournal of the American Academy of Dermatology, Vol. 67, No. 2An Overview of Three Promising Mechanical, Optical, and Biochemical Engineering Approaches to Improve Selective Photothermolysis of Refractory Port Wine Stains21 October 2011 | Annals of Biomedical Engineering, Vol. 40, No. 2Ablación con láser de la vesícula biliar en un modelo animalCirugía Española, Vol. 90, No. 2Laser-induced primary and secondary hemostasis dynamics and mechanisms in relation to selective photothermolysis of port wine stainsJournal of Dermatological Science, Vol. 63, No. 3 Volume 28Issue 4Aug 2010 InformationCopyright 2010, Mary Ann Liebert, Inc.To cite this article:Michal Heger, Rick Bezemer, José Fernando Huertas-Pérez, Henk Dekker, and Johan F. Beek.Endovascular Laser–Tissue Interactions Redefined: Shining Light on Novel Windows of Therapeutic Opportunity Beyond Selective Photothermolysis.Photomedicine and Laser Surgery.Aug 2010.569-572.http://doi.org/10.1089/pho.2009.2590Published in Volume: 28 Issue 4: August 12, 2010PDF download

Application of Albumin Protein and Indocyanine Green Chromophore for Tissue Soldering by Using an IR Diode Laser:Ex VivoandIn VivoStudies

We sought to examine the impact of different parameters of laser soldering on the thermophysical properties of the skin and to optimize these parameters for sealing a full-thickness incision in the rat skin under closed feedback control under in vivo conditions. Laser tissue soldering based on protein as biologic glues and other compounds can provide greater bond strength and less collateral damage. Endogenous and exogenous materials such as indocyanine green (ICG) are often added to solders to enhance light absorption. In ex vivo study, the temperature increase, number of scan (Ns), and scan velocity (Vs) were investigated. In ex vivo studies, four skin incisions were made over rat dorsa and were closed by using two different methods: (a) wound closure by suture and (b) closure by using an automated temperature-controlled system. An automated soldering system was developed based on a diode laser, IR detector, photodiode, digital thermocouple, and camera. The true temperature of heated tissue was determined by using a calibration software method. The results showed that at each laser irradiance (I), the tensile strength (σ) of incisions repaired in the static mode is higher than in the dynamic mode. It must also be noted that the tensile strength of the repaired skin wound was increased by increasing the irradiance in both static and dynamic modes. However, in parallel, an increase in the corresponding temperature was observed. The tensile strength was measured for sutured and laser-soldered tissue after 2 to 10 postoperative days. Histopathologic studies showed a better healing and less inflammatory reactions than with those caused by standard sutures after day 7. It is demonstrated that automated laser soldering technique can be practical provided the optothermal properties of tissue is carefully optimized.

O49 Autodyne and acoustic monitoring of the process of evaporating the multilayer biomaterials by CO 2 laser emission

Introduction: Laser ablation of biotissues is based on local heating results in phase transitions, intensive evaporation, substance mass emission in the form of drop-vapor mixture and tissue particles and laser-induced acoustic emission. These conditions create prerequisites for using of light scattering and optoacoustics techniques for monitoring of laser tissue ablation. Materials and Methods: Surgical CO2 laser was used to vaporize biomodels on the basis of gelatin with the different liquidwater content (60%-90%); biotissues of pig in vitro and of rat in vivo. Diagnostics of evaporating processes of the samples was accomplished by an autodyne method and by an optoacoustical method. The procedure of signal processing and extracting the informational component included fast Fourier transformation of the recorded signal and extraction the acoustic spectrum and the dependence of autodyne signal on the Doppler shift. As the quantitative characteristic of the obtained spectrum we used the spectral power of the signal and weighted mean frequency. According to the behavior of these values was made the conclusion about the approach of the moment the laser emission transmits through the boundary of the samples. Results: The autodyne signals, obtained during the cutting of biotissues by laser emission with the power density in the range from 1 to 10 kW/cm 2 were investigated. Tests on animals showed that it is possible to define the moment of the intersection the different biotissues by the laser beam. The analysis of the spectra of acoustical signals during the contact (piezoelectric ceramic) and remote (highly sensitive microphone) sounding of the laser evaporation zone of gelatin based model media and of biological tissues was made. It showed that during the laser cutting of multilayer gelatinous models a variation in the water content of layers leads to an abrupt change of the spectral power of the acoustical signal. Conclusion: It was established that interaction of CO2 laser radiation with the different biotissues possessed nonstationary nature and was manifested in a change in both the temporary form of autodyne and acoustic signals and their spectral characteristics. The developed algorithms for extracting information component of autodyne and acoustical signals allow to determine the moment of laser beam passage through the interface of biological tissues layers. The experiments have shown that the autodyne and acoustics methods can be used simultaneously to organizing the feedback in CO2 laser surgical systems. This work is performed with the support of Grant Russian Basic Research Fund No. 10 07 00605.

Temporal heating profile influence on the immediate bond strength following laser tissue soldering

Bonding of tissues by laser heating is considered as a future alternative to sutures and staples. Increasing the post-operative bond strength remains a challenging issue for laser tissue bonding, especially in organs that have to sustain considerable tension or pressure. In this study, we investigated the influence of different temporal heating profiles on the strength of soldered incisions. The thermal damage following each heating procedure was quantified, in order to assess the effect of each heating profile on the thermal damage. Incisions in porcine bowel tissue strips (1 cmx4 cm) were soldered, using a 44% liquid albumin mixed with indocyanine green and a temperature controlled laser (830 nm) tissue bonding system. Heating was done either with a linear or a step temporal heating profile. The incisions were bonded by soldering at three points, separated by 2 mm. Set-point temperatures of T(set) = 60, 70, 80, 90, 100, 110, 150 degrees C and dwell times of t(d) = 10, 20, 30, 40 seconds were investigated. The bond strength was measured immediately following each soldering by applying a gradually increased tension on the tissue edges until the bond break. Bonds formed by linear heating were stronger than the ones formed by step heating: at T(set) = 80 degrees C the bonds were 40% stronger and at T(set) = 90 degrees C the bonds strength was nearly doubled. The bond strength difference between the heating methods was larger as T(set) increased. Linear heating produced stronger bonds than step heating. The difference in the bond strength was more pronounced at high set-point temperatures and short dwell times. The bond strength could be increased with either higher set-point temperature or a longer dwell time.

Évaluation du flux sanguin par imagerie en résonance magnétique fonctionnelle après anastomoses artérielles assistées par laser diode 1,9 μm

The most important factor for successful free-flap transfer and replantations is a well-executed anastomosis. The aim of this study is to assess blood flow after laser assisted arterial microanastomosis (LAMA) using a 1.9 μm diode laser. LAMA was performed on a series of 10 carotidis on Wistar rats. Two 10/0 stay sutures and a standard laser tissue welding technique (λ: 1.9 μm; power: 120mW) were used. Similarly, a series of 10 conventional arterial anastomosis were performed (CSMA). For the two groups, contralateral non-operated carotidis were used as control. A positioning sequence, an anatomical sequence, an angiographic sequence and a flow sequence were performed 1 day after operation and then after 1, 4 and 8 weeks. The arterial patency rate was 100% at the time of surgery. The mean clamping time was 7.2 min in the LAMA group compared to 10.7 min in the CSMA group. In the angiographic sequence, there were no aneurysms in both groups for all observation periods. At postoperative day 1, the mean loss of blood flow at the level of anastomosis in the LAMA group was 6% compared with 14% in the CSMA group. After 1, 4 and 8 weeks, there was an unhooking of the blood flow in the CSMA group: the loss of blood flow was 23%, 27% and 31% respectively, compared with 10%, 12% and 13% in the LAMA group. Moreover, one case of thrombosis was observed in the CSMA group after 1 week. The flow-MRI emphasizes that 1.9 μm diode laser assisted microvascular anastomosis appears to be a consistent and reliable technique. These results show that 1.9 μm diode laser assisted microvascular anastomosis has potential for further development in the near future.

Therapeutic laser application and tissue interactions: Bringing light into clinical practice

Journal of BiophotonicsVolume 3, Issue 5-6 p. 259-260 EditorialFree Access Therapeutic laser application and tissue interactions: Bringing light into clinical practice Guest Editor Stefan Andersson-Engels, Guest Editor Stefan Andersson-Engels Lund University Medical Laser Centre, SwedenSearch for more papers by this authorGuest Editor Herbert Stepp, Guest Editor Herbert Stepp LIFE Center, University Clinic, Munich-Grosshadern, GermanySearch for more papers by this author Guest Editor Stefan Andersson-Engels, Guest Editor Stefan Andersson-Engels Lund University Medical Laser Centre, SwedenSearch for more papers by this authorGuest Editor Herbert Stepp, Guest Editor Herbert Stepp LIFE Center, University Clinic, Munich-Grosshadern, GermanySearch for more papers by this author First published: 18 May 2010 https://doi.org/10.1002/jbio.201000512Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume3, Issue5-6Special Issue: Therapeutic Laser Application and Tissue InteractionsJune 2010Pages 259-260 RelatedInformation

Conference Calendar: J. Biophoton. 5–6/2010

Journal of BiophotonicsVolume 3, Issue 5-6 p. 264-264 Conference Calendar Conference Calendar: J. Biophoton. 5–6/2010 First published: 18 May 2010 https://doi.org/10.1002/jbio.201090006AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume3, Issue5-6Special Issue: Therapeutic Laser Application and Tissue InteractionsJune 2010Pages 264-264 RelatedInformation

Thermal model for optimization of vascular laser tissue soldering

Laser tissue soldering (LTS) is a promising technique for tissue fusion based on a heat-denaturation process of proteins. Thermal damage of the fused tissue during the laser procedure has always been an important and challenging problem. Particularly in LTS of arterial blood vessels strong heating of the endothelium should be avoided to minimize the risk of thrombosis. A precise knowledge of the temperature distribution within the vessel wall during laser irradiation is inevitable. The authors developed a finite element model (FEM) to simulate the temperature distribution within blood vessels during LTS. Temperature measurements were used to verify and calibrate the model. Different parameters such as laser power, solder absorption coefficient, thickness of the solder layer, cooling of the vessel and continuous vs. pulsed energy deposition were tested to elucidate their impact on the temperature distribution within the soldering joint in order to reduce the amount of further animal experiments. A pulsed irradiation with high laser power and high absorbing solder yields the best results.

Endonasal Laser Tissue Welding: First Human Experience

Adequate repair of cerebrospinal fluid leak remains a significant challenge in endoscopic skull base surgery. Laser tissue welding (LTW) is a method of creating an instant watertight wound closure using a chromophore doped biological solder, which may be used for cranial base reconstruction. The objective of this study is to assess the safety and technical feasibility of endoscopic LTW in human sinonasal mucosa. A prospective, Institutional Review Board-approved study was performed of 10 patients undergoing endoscopic LTW using an albumin and hyaluronic acid-based solder for repair of mucosal injuries. Data were collected on patient demographics, total lasing time, and volume of solder used. Wounds were prospectively followed by endoscopic exam and scored on a scale of zero to two by three blinded observers (B.S.B., J.N.P., and A.G.C.) for inflammation, thermal injury, and edema. Results were compared with control wounds using the Mann-Whitney U test. Ten patients (seven men and three women; average age 50 years; range, 33-71 years) underwent endoscopic LTW. Total lasing time was 11 +/- 11 minutes requiring 0.96 +/- 0.83 mL of solder per patient. Patients were followed for an average of 72 days (range, 12-138 days) and no complications were noted. Solder persisted for up to 26 days and there was no significant difference between the lased and control wounds with regard to inflammation (0.87 +/- 0.72 versus 1.31 +/- 0.87), thermal injury (0.06 +/- 0.25 versus 0.12 +/- 0.34), or edema scores (1.13 +/- 0.81 versus 1.44 +/- 0.73). Endoscopic LTW is a technically feasible and rapid method of wound closure in sinonasal mucosa that does not result in any significant thermal or inflammatory sequelae.

Modulated and continuous-wave operations of low-power thulium (Tm:YAP) laser in tissue welding

Our aim is to explore the welding capabilities of a thulium (Tm:YAP) laser in modulated and continuous-wave (CW) modes of operation. The Tm:YAP laser system developed for this study includes a Tm:YAP laser resonator, diode laser driver, water chiller, modulation controller unit, and acquisition/control software. Full-thickness incisions on Wistar rat skin were welded by the Tm:YAP laser system at 100 mW and 5 s in both modulated and CW modes of operation (34.66 Wcm(2)). The skin samples were examined during a 21-day healing period by histology and tensile tests. The results were compared with the samples closed by conventional suture technique. For the laser groups, immediate closure at the surface layers of the incisions was observed. Full closures were observed for both modulated and CW modes of operation at day 4. The tensile forces for both modulated and CW modes of operation were found to be significantly higher than the values found by conventional suture technique. The 1980-nm Tm:YAP laser system operating in both modulated and CW modes maximizes the therapeutic effect while minimizing undesired side effects of laser tissue welding. Hence, it is a potentially important alternative tool to the conventional suturing technique.

Blood flow assessment with magnetic resonance imaging after 1.9 µm diode laser‐assisted microvascular anastomosis

Microvascular surgery associates intricate surgical techniques to join tiny blood vessels and help transfer large amount of tissues. Successful venous anastomosis remains the main challenge because inadequate blood flow correlates with a major risk of free flaps venous congestion and thrombosis. The aim of this study is to assess blood flow after laser-assisted microvascular anastomosis (LAMA) using a 1.9-microm diode laser. LAMA was performed on a series of 10 external jugular veins of Wistar rats. Two stay sutures and a standard laser tissue welding technique (lambda: 1.9 microm; power: 110 mW) were used. Similarly, a series of 10 conventional venous anastomosis were performed (CSMA). In both groups, contralateral non-operated jugular veins were used as control. MRI was used to perform positioning, anatomical, angiographic blood flow sequences, 1 day post-procedure and at 1, 4 and 8 weeks. Venous patency rate was 100% at the time of surgery. Mean clamping time was 7.9 minutes in the LAMA group compared to 11.4 minutes in the CSMA group. In the angiographic sequence, there were no aneurysms in both groups for all observation periods. At post-operative day 1, mean loss of blood flow at the level of anastomosis in the LAMA group was 7% compared with 22% in the CSMA group. At 1, 4 and 8 weeks, blood flow reduction was greater in the CSMA group: 34%, 38% and 41%, respectively, compared to 12%, 15% and 16% in the LAMA group. Moreover, three cases of thrombosis were observed in the venous anastomosis performed with the conventional technique at 1 (n = 2) and 3 months (n = 1). The flow-MRI further demonstrates that 1.9 microm diode LAMA is a consistent, reliable and reproducible technique, capable of improving blood flow in veins when compared to conventional surgery.

Lasers in prosthodontics — An overview part 1: Fundamentals of dental lasers

The introduction of lasers in the field of prosthodontics has replaced many conventional surgical and technical procedures and is beginning to replace the dental handpiece. Although lasers were introduced in dentistry as early as the 1960s it has gained widespread popularity mainly in the developed countries only from the early 90s. Today, prosthodontists can select from a variety of laser wavelengths available in dentistry. This has led to great confusion regarding laser operation and selection of the most appropriate laser wavelength for a given procedure. This article reviews literature on lasers with the aim of providing a complete understanding of the fundamentals of lasers and their applications in the various disciplines of prosthodontics. Peer reviewed literature published in English language between 1991 and 2007 obtained using Medline, and hand searches is reviewed in a series of three articles: Part 1 will describe the fundamentals of laser science, laser tissue interaction, laser wavelengths available in dentistry, laser parameters and safety measures in brief to enable the clinician to select the best laser for a certain procedure and also understand the biologic rationale for its use. Part 2 will deal in brief with the applications of lasers in the various branches of prosthodontics and their advantages over conventional techniques. Part 3 will deal with lasers in prosthodontics from an Indian perspective.

Laser Therapy in the Tissue Repair Process: A Literature Review

Carry out a literature review on the use of laser therapy in the tissue repair process and address the different lasers and parameters used by the authors. A review was carried out of the literature from 1960 to 2008 in the Lilacs, Medline, and PubMed databases using the following key words: Laser Therapy, Wound Healing, and Tissue repair. The most frequently used types of laser are helium neon (HeNe) lasers and diode lasers, including gallium-aluminum-arsenium (GaAlAs), arsenium-gallium (AsGa), and indium-gallium-aluminum-phosphide (InGaAlP) lasers. However, implementation of different protocols was found, with different materials and different activating wavelengths, thus making it difficult to compare results and choose the parameters of treatment. The majority of authors report that laser therapy speeds up the process of tissue repair, but further studies are suggested to determine the best parameters to be used.

Laser‐mediated fixation of collagen‐based scaffolds to dermal wounds

Collagen scaffolds are popular for the reconstitution of dermal equivalents. Usually, these scaffolds are fixed with sutures or staples and in many cases these devices have to be removed in a second procedure. Laser-mediated tissue welding in a wet environment is a potential alternative for collagen scaffold fixation and may be advantageous to suture, staple, and tissue glue fixation. Welding was performed with a continuous-wave diode laser system emitting radiation at a wavelength of 968 nm. Tensile strength after fixation to porcine skin and laser parameters were determined in vitro. In vivo, 24 excisional deep partial thickness wounds were created on flanks of two Goettingen mini pigs and covered with collagen scaffolds. These were randomized and fixated with either (1) staples, (2) fibrin glue, or (3) laser-mediated welding. Tissue biopsies for histological analysis were periodically performed and analyzed for wound healing progression, epidermal thickness, and extracellular matrix formation. Biomechanical stability after laser welding was time dependent. A dwell time of up to 10 seconds led to a strong bonding with a tensile strength of more than 30 g. In vivo, the wound healing process was macroscopically comparable in all groups and showed no significant differences. Microscopic analysis determined a more progressed and quicker wound closure in both the laser and staples group compared to the fibrin glue fixated scaffold. Laser-mediated fixation led to a significantly reduced epidermal thickness when compared with stapling or fibrin glue (P < 0.05). Laser tissue welding is a feasible approach for temporary fixation of collagen scaffolds to the wound bed. It improves wound healing properties and may lead to faster wound healing and cosmetically better scarring. Laser tissue welding is thus a very interesting and promising alternative to currently established fixation methods in a single step, no touch procedure.

Evolution and success of holmium laser enucleation of the prostate

Aims:The purpose of this article is to review the development of instruments, current technique, and expected outcomes for holmium laser enucleation of the prostate (HoLEP).Materials and Methods:A review of published, peer-reviewed articles focusing on HoLEP was performed using the MEDLINE database.Results:Historically, the gold-standard management for symptomatic obstructing benign prostatic hyperplasia (BPH) has been transurethral resection of the prostate (TURP). With the development of new laser technology minimally invasive surgical procedures have been introduced in an attempt to decrease the morbidity experienced with standard TURP. Laser treatment of BPH has evolved from coagulation to complete adenoma enucleation. The holmium laser was initially utilized for prostate ablation and soon evolved into holmium laser tissue resection, but was limited by difficulties with extracting the prostate tissue from the bladder. With the development of a compatible tissue morcellator whole prostate lobes could be enucleated similar to an open prostate enucleation and the HoLEP procedure was developed. Currently HoLEP is the only procedure to demonstrate superior outcomes to TURP on urodynamic studies and long-term studies demonstrate its durability up to 7 years post procedure. Changes in enucleation technique have also increased the efficiency of the HoLEP procedure, such that any sized prostate can be treated.Conclusions:HoLEP is a safe and effective surgical treatment for symptomatic BPH, dependent on a high powered laser and morcellation system. The procedure continues to gain acceptance due to excellent short and long-term results, its wide application, and further simplification of technique.

Ambulante Holmiumlaserenukleation und mechanische Morcellierung der Prostata

Holmium laser enucleation of the prostate (HoLEP) is increasingly being used as an alternative to transurethral resection of the prostate (TURP) and transurethral electrovaporisation of the prostate (TVP), the"gold standard" procedures for treating symptomatic benign prostatic hyperplasia. Mechanical tissue morcellation was introduced in 1998, and its efficiency could be improved. We investigated the efficiency and complication rate of a morcellator in a day-case setting. From 2004 to 2008, 137 men were treated with an 80W holmium:YAG laser and subsequent tissue morcellation. The average patient age was 68.0+/-7.1 (51-86) years. Morcellation time was 8.6+/-6.8 (1-35) min. The weight of the resected tissue was 36.6+/-30.0 (2-175) g. The total time for the procedure was 69.6+/-28.7 (29-150) min, and the efficiency of morcellation was 5.0+/-2.6 (0.2-11.5) g/min. The complication rate due to morcellation was 4.3%. HoLEP with mechanical morcellation is safe even in a day-case setting. The total procedure time approximates that for TURP, so a longer theatre time loses significance as an argument against the method. Complications are rare and not severe. Further technical improvement is desirable.

Tissue-based Quantification of 8-Hydroxy-2′-Deoxyguanosine in Human Prostate Biopsies Using Quantitative Fluorescence Imaging Analysis

To quantify 8-hydroxy-2'-deoxyguanosine (8-OHdG) in prostate stromal and acini tissue compartments from benign and cancer-containing prostate specimens using a new quantitative fluorescence imaging analysis protocol. Prostate biopsy specimens from 20 age-matched benign (control) and cancer-containing tissue sections were used to quantify 8-OHdG. 8-OHdG was quantified within individual acini nuclei and the surrounding stroma nuclei. Paraffin sections were treated with RNAse and protease to expose the nuclear chromatin, reacted with anti-8-OHdG mouse monoclonal antibody bound to saturation and detected with secondary goat anti-mouse IgG labeled with Alex Fluor 488, and quantified with a calibrated quantitative fluorescence imaging analysis system. The results were analyzed using a paired Student's t test. 8-OHdG was successfully quantified within individual cellular compartments without the need for laser tissue dissection, using the mean pixel intensity of fluorescent-labeled 8-OHdG. Matched-pair analysis of the global expression of 8-OHdG, as well as the acini and stroma individually, revealed no difference between the cancerous and control prostatic tissue. All patients with prostate cancer and those with benign findings had significantly greater 8-OHdG within the acini compared with the surrounding stoma (P < .05). A protocol to quantify 8-OHdG in paraffin-embedded human prostatic tissue was successfully developed. 8-OHdG was not significantly elevated in the acini or stroma of cancer-containing prostatic tissue compared with age-matched benign prostatic tissue. Although 8-OHdG was significantly elevated in the acini nuclei compared with the surrounding stroma nuclei in both cancer-containing and benign prostatic tissue, it, by itself, was not a strong biomarker for prostate cancer risk assessment.