Depth Of Tissue Damage Research Articles

Neuroglia - development and role in physiological and pathophysiological processes.

The dynamic development of studies on neuroglia in recent years indicates its previously underestimated role in maintaining proper brain function, both in physiological and pathological conditions. The use of modern research methods such as single-cell techniques as well as in vivo and in vitro models enriched the state of our knowledge. The most important issues regarding the maturation and development of neuroglia include cooperation between glial cell groups and with neurons in neurogenesis, neuroregeneration, (re)myelination and how the early developmental roles of glia contribute to nervous system dysfunction in neurodevelopmental and neurodegenerative disorders. There is still growing evidence emphasizing the importance of astroglia in maintaining the brain physiological homeostasis, regulation of immune response, cerebral blood flow, and involvement in the reactive neurogliosis, precisely adapted to the nature of pathological stimulus and the depth of tissue damage. The important issues related to the function of oligodendrocytes include explanation of the mechanisms of interaction between the glial cells and myelinated axons, important not only in myelination, but also in development of cognitive processes and memory. Further studies are required for understanding the mechanisms of demyelination occurring in several central nervous system (CNS) diseases. An interesting area of research is related with explanation of the NG2 glia function, characterised by significant proliferative potential and ability to differentiate in both in physiological conditions and in pathology, as well as the presence of synaptic neural-glial connections, which are especially numerous during development. The increasing knowledge of microglia comprises the presence of specialised subsets of microglia, their role the myelination process and neurovascular unit functioning. We are only beginning to understand how microglia enter the brain and develop distinct functional states during ontogeny. This review summarises the current state of knowledge on the development and role in the CNS of different, heterogeneous cell populations defined by a common term neuroglia.

К вопросу о классификации травматических отслоек покровных тканей

Introduction Detachment or sharp gross prolonged displacement of the skin, subcutaneous fatty tissue from the underlying fascia over more than 1 % of the body surface with disorders of blood supply to these and sometimes underlying tissues results from high-energy mechanical action of various moving objects and force applied at an angle. Purpose to develop a classification of integumentary tissue detachments based on the variety of clinical types, severity, extent, combination of injuries with a possible quantitative assessment of their severity and extent. Methods Analysis of the literature and our own experience of treating 40 patients with detachments of integumentary tissues enabled to identify criteria for classifying patients into groups. Results A classification and rating scales were developed that reflect the area, depth of tissue damage, localization, general condition of the patient and the stage of the pathological process. Discussion The analysis of the literature on this topic showed that, to date, none of the proposed classifications is optimal. There is no clear definition of the area of compromised integumentary tissues relative to the entire surface of the human body. The issue of pathological process staging has not been reflected; damage and crushing of bones, muscle tissue, neurovascular formations have not been reflected; there is no clearly formulated algorithm for treating a patient depending on the stage and severity of tissue damage. Conclusion Application of the classification of integumentary tissue detachments which has been proposed enables to more objectively assess the nature of local tissue damage, taking into account t he general condition of the patient.

NEED FOR TRAINING OF HEALTHCARE PROFESSIONALS FROM OUTPATIENT CARE FOR BURNS INJURIES

The severity of the burn, as a trauma is a three-dimensional magnitude determining the localization, the vastness and depth of tissue damage. It is essential that the period from the onset of the trauma to the beginning and method of treatment. Depending on timely and adequate medical care for victims with burns, possible complications can be significantly reduced and prevented. According to the normative requirements for acquiring professional competence, health care professionals must possess special training and education in the scope of the specialty "Plastic and Reconstructive Surgery" (PVEH). The purpose of this study is to study awareness of the burns and the need to train healthcare professionals from outpatient care. The study was conducted in the period March-April 2019 year among 134 health care professionals working in outpatient clinics for specialized medical care (individual or group practice), medical centers and diagnostic advisory centers on the territory of Sofia City. The study used the dokumen¬tal and sociological method through its own survey. Results. The highest relative share is the health care professionals with work experience from 21 to 30 years (38.06%) from 11 to 20 years (34.33%). The analysis of the results showed that over half (55.97%) Professionals can partly cope with a burning incident. Every fifth of respondents (20.15%) Professional preparation for medical care and 23.88% of them respond negatively. A significant share of respondents (94.77%) Want to participate in training on the topic of burns 67.16% of them giving a categorical answer "yes, completely” , 27.61% say "yes, partly". 98.05% of professionals consider it necessary to provide information to parents about the possible risk of incineration in children, with 91.79% expected to contribute to reducing incidents in their rearing. Conclusion. In recent years, health care reforms have been oriented towards improving the quality of medical care, as the main task of medical institutions to provide affordable health care. The quality of healthcare has a multi-factor modality of criteria such as safety, accessibility, adequacy, patient satisfaction, social fairness and final health care outcomes.

Comparative study on the effects of heated brass bar and scald methods in experimental skin burn in rat

Experimental burn can be inflicted by various means, and each method affects the healing processes. To date, several methods have been developed, but their standardization is difficult. We aimed to compare two experimental methods, heated brass bar, and scalding, to provide an in-depth understanding of their limitations and errors. Scald burn is afflicted by pouring 2.5 cc of boiling water (95 °C) into a firm rubber ring (2 cm diameter) on the dorsal surface of a rat skin for 15 s. The other experimental model is performed by bringing a brass bar (2 cm diameter) heated to 95 °C in boiling water in contact with the surface of the skin for 15 s. The clinical course of healing was evaluated macroscopically for 7 days, and then microscopically. The scald burn produced a uniform wound with the same depth of tissue damage without any marked inflammation and hemorrhage. The scab formation and the extent of granulation tissue, as well as re-epithelialization, were the same in all rats and the lesions healed uniformly. Compared with scald, burns of various depths were induced by the heated brass bar and the burn area did not heal uniformly. Widespread hemorrhage and microabscess were common in this group without any sign of scab formation or re-epithelialization. This study highlights the benefits of scald method in comparison with the heated brass bar.

Clinical and experimental studies of tissues in thermal injuries

The article is devoted to studies used in the clinic and in the experiment in the study of tissue damage caused by exposure to high temperature. Determining the area and depth of tissue damage during thermal injury is of fundamental importance not only for treatment, but also for prognosis. The use of laser Doppler flowmetry, magnetic resonance imaging, pH-metry, contactless infrared thermometry of burn wounds, the method of assessing tissue viability based on the study of dielectric parameters allows to evaluate the viability and the state of damaged tissues in dynamics. The importance of tissue research methods for establishing an accurate diagnosis, assessing the readiness of wounds for autodermoplasty and determining the extent of surgical interventions is shown. The use of morphological methods in experimental studies and in the treatment of victims with burns is substantiated. Using histological and cytological methods, the condition of the burn wound is monitored, the efficacy of surgical interventions and the use of therapeutic agents is evaluated, the wound process phase is determined, and medical tactics is planned. The histochemical method is used to study the composition and state of the tissues of a burn wound paranecrosis area, and the immunohistochemical method is used to assess the intensity of regeneration processes by determining the tissue proliferation and differentiation markers. Ultramicroscopic examination of tissues at different times after thermal injury is informative for understanding the dynamics of pathomorphological changes in burns. Review of the pathogenesis of burn disease, taking into account the data of ultramicroscopic studies, creates the prospect of developing methods for targeted correction of the condition of patients with burns at the subcellular level. The role of experimental studies in the investigation of thermal damage, preclinical trials of medicinal products used to influence the wound process, improving the existing methods and developing the new ones for treatment of burn injury has been determined.

Quantification of change in vocal fold tissue stiffness relative to depth of artificial damage

Objectives: To quantify changes in the biomechanical properties of human excised vocal folds with defined artificial damage.Methods: The linear skin rheometer (LSR) was used to obtain a series of rheological measurements of shear modulus from the surface of 30 human cadaver vocal folds. The tissue samples were initially measured in a native condition and then following varying intensities of thermal damage. Histological examination of each vocal fold was used to determine the depth of artificial alteration. The measured changes in stiffness were correlated with the depth of cell damage.Results: For vocal folds in a pre-damage state the shear modulus values ranged from 537 Pa to 1,651 Pa (female) and from 583 Pa to 1,193 Pa (male). With increasing depth of damage from the intermediate layer of the lamina propria (LP), tissue stiffness increased consistently (compared with native values) following application of thermal damage to the vocal folds. The measurement showed an increase of tissue stiffness when the depth of tissue damage was extending from the intermediate LP layer downwards.Conclusions: Changes in the elastic characteristics of human vocal fold tissue following damage at defined depths were demonstrated in an in vitro experiment. In future, reproducible in vivo measurements of elastic vocal fold tissue alterations may enable phonosurgeons to infer the extent of subepithelial damage from changes in surface elasticity.

Surgical and pathomorphological results of total mesorectumectomy by using waterjet dissection technique in patients with rectal cancer

Background. The paper presents our own experience of using a waterjet dissector ERBEJET2® in the course of surgical interventions for colorectal cancer. This experience is unique for Russia. Materials and methods. Waterjet dissection method associated with total mesorectumectomy was used by us in 20 patients suffering from rectal cancer. An average age of patients was 59.2 ± 13.9 years. In all the patients surgeries were performed for adenogenic colorectal cancer, morphologically verified at the preoperative stage. Resected preparations were studied on morphological level. For comparison, two control groups of 20 patients were selected, in which the rectum mobilization was performed by using monopolar coagulator and harmonic scalpel. The studied groups were matched by gender, age, location and the tumor extent. All the surgeries were performed by one surgical team. Results. Results of the study demonstrated advantages of waterjet dissection when performing total mesorectumectomy due to a minimum depth of tissue damage on the lateral margin of resection. Conclusion. Waterjet dissectors have taken their place in the extensive list of tools used when performing surgical interventions for colorectal cancer, that allows to expect an improvement of functional and oncological results of the surgical treatment.

Skin grafting in the treatment of open injuries of hand and fingers

The amount of open injuries of hand and fingers is equal to 55.1 % among all hand injuries and their consequences. They are often associated with tissue defect and lead to the loss of hand function. These injuries are recommended for surgical treatment with skin grafting in order to avoid amputation of injured segment. Different variants of autografting are summarized and illustrated in the article. The choice of autografting method depends upon the features of damage and clinical task — free (epidermis flaps, split-thickness and full-thickness skin grafts) and non-free (Italian, Filatov-Gillies pedicle grafting) flap coverage of wound. Their advantages and disadvantages are listed. The requirements for the performing of different types of grafting are identified. The peculiarities of prevention of cicatrical contraction development are described. Author draws attention to the special features of palm skin on hand and fingers, that limits usage of local skin flap. Methods of wound coverage on fingers and hand depend on their localization, size, and depth of tissue damage. Recommendations for coverage of donor wounds are noted. The necessity of saving of the finger terminal phalanges, especially 1st finger, is emphasized. Author showed the treatment techniques in the cases of butt defects of fingers.

Clinical effects of the use of a bipolar vessel sealing device for soft palate resection and tonsillectomy in dogs, with histological assessment of resected tonsillar tissue.

To investigate whether soft palate resection and tonsillectomy with a bipolar vessel sealing device (BVSD) improves clinical respiratory score. To document histopathological changes to tonsillar tissue following removal with a BVSD. Case series of 22 dogs with clinical signs of upper respiratory obstruction related to brachycephalic airway syndrome. Soft palate and tonsils were removed using a BVSD. Alarplasty and saccullectomy were also performed if indicated. A clinical respiratory score was assigned preoperatively, 24-h postoperatively and 5weeks postoperatively. Excised tonsillar samples were measured and then assessed histologically for depth of tissue damage deemed to be caused by the device. Depth of tissue damage was compared between two power settings of the device. Soft palate resection and tonsillectomy with a BVSD lead to a significant improvement in respiratory scores following surgery. Depth of tissue damage was significantly less for power setting 1 compared with power setting 2. Using power setting 1, median calculated depth of tonsillar tissue damage was 3.4mm (range 1.2-8.0). One dog experienced major complications. Soft palate resection and tonsillectomy with a BVSD led to significant improvement in clinical respiratory score.

Histology assessment of bipolar coagulation and argon plasma coagulation on digestive tract.

To analyze the effect of bipolar electrocoagulation and argon plasma coagulation on fresh specimens of gastrointestinal tract. An experimental evaluation was performed at Hospital das Clinicas of the University of São Paulo, on 31 fresh surgical specimens using argon plasma coagulation and bipolar electrocoagulation at different time intervals. The depth of tissue damage was histopathologically analyzed by single senior pathologist unaware of the coagulation method and power setting applied. To analyze the results, the mucosa was divided in superficial mucosa (epithelial layer of the esophagus and superficial portion of the glandular layer of the stomach and colon) intermediate mucosa (until the lamina propria of the esophagus and until the bottom of the glandular layer of the stomach and colon) and muscularis mucosa. Necrosis involvement of the layers was compared in several combinations of power and time interval. Involvement of the intermediate mucosa of the stomach and of the muscularis mucosa of the three organs was more frequent when higher amounts of energy were used with argon plasma. In the esophagus and in the colon, injury of the intermediate mucosa was frequent, even when small amounts of energy were used. The use of bipolar electrocoagulation resulted in more frequent involvement of the intermediate mucosa and of the muscularis mucosa of the esophagus and of the colon when higher amounts of energy were used. In the stomach, these involvements were rare. The risk of injury of the muscularis propria was significant only in the colon when argon plasma coagulation was employed. Tissue damage after argon plasma coagulation is deeper than bipolar electrocoagulation. Both of them depend on the amount of energy used.

In vitro comparison of the vaporesection of human benign prostatic hyperplasia using 70- and 120-W 2-µm lasers

The purpose of the current ex vivo study was to compare the speed of vaporesection of human prostatic tissue with benign prostatic hyperplasia (BPH) and the depth of tissue damage using 70- and 120-W 2-µm laser devices. Fresh prostatic tissue specimens were obtained from five patients by open prostatectomy, and were divided into separate groups (70 and 120 W) based on the energy of the laser output (70 and 120 W, respectively). The vaporesection speed, coagulation zone depth and the necrotic tissue layer in the prostatic tissue were evaluated. The current result showed that the speeds (mean±s.d.) of vaporesection were 5.21 ± 0.66 and 10.39 ± 1.15 g/5 min for the 70 and 120 W groups, respectively (P=0.000). There was no difference in the depth of necrosis/coagulation (0.98 ± 0.13/0.30 ± 0.09 and 0.99 ± 0.12/0.31 ± 0.08 mm) for the 70 and 120 W groups, respectively. In conclusion, both 70- and 120-W 2-µm laser devices had superficial tissue damage during the vaporesection of human prostate tissue; moreover, the 120-W laser offers a higher vaporesection speed than the 70-W laser.

Clinicopathologic Comparison of Radiofrequency Versus Scalpel Incision for Upper Blepharoplasty

To compare the sensation recovery, scar formation, and histopathologic aspects of upper blepharoplasty eyelid incision performed with radiofrequency or scalpel. In a prospective, randomized, blind, comparative, interventional study, 46 eyelids from 23 subjects underwent upper blepharoplasty using radiofrequency incision on one side and a scalpel on the other side. Exclusion criteria were diseases resulting in peripheral neuropathy such as diabetes mellitus, previous upper eyelid surgery or trauma, and history of skin disease. Eyelid sensation was measured preoperatively and 1 week, 1 month, and 6 to 7 months after surgery by a masked observer. Eyelid scar was evaluated by 2 masked observers at final follow-up. Histologic examination for zone and depth of tissue damage, hemorrhage, and inflammatory cell reaction was performed in a masked fashion on 16 eyelids. The mean patient age was 52 years (SD, 5.48 years). Mean aesthesiometry reading significantly decreased in both groups at all follow-up visits in comparison with preoperative measurement (p = 0.000). Mean sensation recovery was insignificantly (0.2 < p < 0.6) higher in the radiosurgery group at all follow-up visits. Mean scar score was insignificantly (p = 0.055 for observer 1, and 0.241 for observer 2) less in the radiosurgery group. The scar score was not significantly different between Fitzpatrick skin types 3 and 4, scored by either observer. The zone and depth of tissue damage on histopathologic examination was greater in the radiofrequency group. However, the hemorrhage and infiltration of inflammatory cells were the same. There was no significant difference between radiofrequency and scalpel incision in upper blepharoplasty with regard to sensation recovery and scar formation. Histologic zone and depth of tissue damage were greater in the radiofrequency group.

The effect of sunburn damage on the fruit quality parameters of apple (Malus domestica cv. Idared)

In the present study the authors investigated the effect of sunburn injury on fruit quality parameters (cover colour, depth of tissue damage, fruit flesh firmness, dry matter content) of apple.The symptoms of sunburn injury appeared as concentric rings, differing in colour from each other and the cover colour. This can be connected with the ratio of the injury. The authors observed the following colours on the fruit surface (from the epicentre of spots on the surface of the fruit) dark brown (strongly damaged), light brown (moderately damaged), pale red transition (weakly damaged), red surface cover colour (not damaged).Sunburn of apple fruits is a surface injury caused by solar radiation, heat and low relative humidity. In the initial phase, a light corky layer, golden or bronze discolouration and injuries of the epidermal tissue appear on the surface exposed to radiation. Thus, it detracts from the fruit’s appearance, but in most of the cases it would not cause serious damages in the epidermal tissue. The depth of tissue damage is not considerable, its values are between 1.5-2.0 mm in general. It is commonly known, that tissue structure of the apple fruit is not homogeneous. Accordingly, the degree of injury shows some differences under the different parts of the fruit surface.On the basis of the flesh firmness studies, it can be stated that the flesh firmness of the damaged parts increases due to the sunburn effect. This is due to the fact that the damaged plant cells die, the water content of the tissue decreases and it hardens. However, due to this reduction in the water content the dry matter content will increase.

Shaver, Bipolar Radiofrequency, and Saline Jet Instruments for Cutting Meniscal Tissue: A Comparative Experimental Study on Sheep Menisci

The purpose of this study was to compare the quality of meniscal tissue cut with 3 different surgical instruments (traditional shavers, bipolar radiofrequency (RF) wands, and a high-pressure saline jet) and that of control menisci. Experimental design, biochemical and histologic study. Sixty samples of sheep menisci were separated into 4 groups. Three groups were shaved on the apical surface with the different instruments. The smoothness of the cut surfaces was evaluated visually by an orthopaedic surgeon and then scored by laser scanning cytometry and by line measurement analysis. The depth of tissue damage was measured by fluorescent cytochemistry. Means and standard deviations were calculated and comparative statistics used (P < .05). The edges cut by the saline jet and bipolar RF were significantly smoother when judged by the surgeon than those cut by traditional shaver. There was no significant difference between the saline jet and bipolar RF. There were no significant differences in smoothness when measured by laser scanning cytometry or by line measurement techniques. The control menisci had less depth of damage along the edge as measured by fluorescent cytochemistry than did any of the menisci cut with the instrument. The saline jet had significantly less depth of damage than did the shaver. No other significant differences existed between the instruments for depth of damage. The results of our investigation conclude that high-pressure saline instruments may cause less damage to residual meniscal tissue when compared with bipolar RF and shavers. Saline jets and bipolar RF also produce a smoother cut than shavers. Surgeons may want to consider the degree of residual damage to meniscal tissue from the application of various surgical instruments. Saline jets may be a superior cutting instrument than RF or shavers when considering depth of residual damage and smoothness of residual meniscal edges.

ARGON PLASMA COAGULATION: IN VIVO TISSUE DAMAGE TO THE ESOPHAGUS AND STOMACH AND CLINICAL EFFICACY FOR EARLY ESOPHAGEAL AND GASTRIC CANCER

Background: Argon plasma coagulation (APC) has been proven to be safe in vitro, and has been widely introduced to therapeutic endoscopy. We evaluated the thermal effects on esophageal or gastric wall in vivo, and its effectiveness as an adjunct to incomplete resection of early esophageal and gastric cancer after endoscopic mucosal resection (EMR).Methods: Thermal injuries were made using endoscopic APC irradiation in porcine esophagus and stomach under various conditions during general anesthesia, and depth of tissue damage was determined histopathologically. Patients with early gastric cancer (n = 24) and early esophageal cancer (n = 5) were treated with additional APC following microscopically incomplete EMR. APC was applied to coagulate the entire edge of EMR‐induced ulcer 1 week after resection at power/gas settings of 50 W and 1.5 L/min in the stomach, and 40 W and 1.5 L/min in the esophagus for less than 5 s at each point.Results: Depth of tissue damage was related to pulse duration and power output. At power/gas settings of 60 W and 2.0 L/min, thermal damage extended across the submucosal layer with 5‐s pulse duration in the stomach. Thermal damage with 5‐s pulse duration at power/gas settings of 40 W and 2.0 L/min extended to the muscularis propria in the esophagus. In the clinical study of additional APC therapy, the recurrence rate was 6.9% (two of 29 cases).Conclusion: To avoid perforation, we recommend an APC power setting of 40–60 W for less than 5 s in the stomach and a lower power setting with shorter duration in the esophagus. APC seems to reduce recurrence of esophageal or gastric cancer after incomplete EMR.

Effect of repetitive impacts on subcutaneous tissue discolouration in potato tubers

The relation between one or more impacts at one tuber site and the resulting volume and depth of discoloured tissue were investigated. Tubers were impacted at the desired rate by a computer-controlled pendulum. The tubers were from plants grown at 2 potassium levels (i.e. susceptibilities to tissue discoloration - high and low) and stored for 3, 5 or 7 months. Splitting of the impact energy into various (up to 9) doses reduced the volume of discoloured tissue by up to 64%. The depth of tissue damage was less affected (33% reduction) by splitting the impact energy than was the volume. The volume and depth of discoloured tissue increased with the number of 0.3 J impacts. A decreasing and an increasing order of impact energy caused the same tissue damage. Despite experimental simplification and standardization, the observed effects of the energy and frequency of impacts on the degree of subcutaneous tissue discoloration yielded relevant suggestions for practical potato handling.

Interaction of holmium laser radiation and cortical bone: ablation and thermal damage in a turbid medium

The ablation of cortical bone by holmium laser radiation is described by experimental values of the ablation rate, the depth of tissue damage, and the tissue temperature. An ablation model is presented on the basis of photon diffusion in a turbid medium. When this model is compared with experimental results for the ablation rate, the penetration depth is determined. The expansion of the laser-induced heat can be explained by a point heat source located in a distance beneath the surface equal to the ablation depth. The accumulation of heat as a function of the repetition rate of the laser leads to a limitation of the repetition rate. In order to avoid traumatic heat accumulation, a maximum repetition rate should not be exceeded.

Immediate Histological Changes in Soft Palate after Uvulopalatopharyngoplasty with CO2, Contact Nd : YAG or Combined CO2 and Nd : YAG Laser Beams

CO2, contact Nd : YAG and Combolaser (combined, simultaneous and coaxial CO2 + Nd : YAG laser beam) were used for uvulopalatopharyngoplasty (UPPP). It has been proposed that the combined beam geometry diminishes thermal damage to surrounding tissues when compared with single laser radiation. To study the extent of thermal tissue damage produced by the lasers, tissue samples for light (LM) and transmission electron microscopy (TEM) were taken from the surface of the resected area and 2 and 4 mm below the resection plane. The depth of tissue damage and coagulation was measured. The results showed no consistent differences in the inflammatory reactions or the amount and depth of tissue coagulation observed in samples taken immediately after the operation. The CO2 laser typically produced a carbonized and coagulated wound edge. Combolaser and contact Nd : YAG lasers generated slightly less charring but otherwise resembled each other with coagulated and vacuolized resecate margins. These results indicate that the beam geometry in Combolaser does not diminish thermal damage to surrounding tissues.

A new addition to face lift surgery: the argon gas surgical unit.

In the quest to improve the technique of performing face lift surgery, we have encountered a device, the argon gas surgical unit, that offers a number of advantages over current techniques. These advantages include significant reductions in the amount of both intraoperative and postoperative blood loss, depth of tissue damage, amount of postoperative swelling, and amount of postoperative pain. This paper describes our experience with the use of the argon gas surgical unit compared with conventional electrocautery in 30 patients undergoing face lift. On histologic examination of the skin specimens, there was a consistent decrease in the depth of tissue damage with the argon gas surgical unit. With regard to blood loss, as a whole there was a marked decrease in the argon gas surgical unit group. Additionally, there is a clinically significant decrease in postoperative swelling in the patients in whom the argon gas surgical unit was employed that contributes to improved wound healing and an overall improved postoperative course.

Liver tissue damage by ultrasound in combination with the photosensitizing drug, Photofrin II

We have investigated whether ablation of normal rat liver by ultrasound can be enhanced after administration of a photosensitizing agent (Photofrin II). After laparotomy and administration of Photofrin II (30 mg/kg), ultrasound (210 kHz, 1.3 W/cm 2) was directed directly to the surface of the liver for a total duration of 3 min by a plane type unfocused transducer (6 mm × 6 mm). The depth of tissue damage was histologically compared to rats exposed to ultrasound alone. The mean maximum lesion depth on rats applied with ultrasound and Photofrin II was 5.7 ± 0.9 mm (mean ± SD) whereas in rats treated with ultrasound alone this was 3.0 ± 0.4 mm. There was a significant difference between the two groups ( P < 0.05). The present study suggests the possible use of a photosensitizing agent as an enhancer for the treatment of liver tumors by ultrasound.