Reduction of postoperative adhesions to Marlex mesh using experimental adhesion barriers in rats.

Polypropylene mesh (Marlex) is commonly used to reinforce the abdominal wall during hernia repair. Recently, hernia repair has been performed using laparoscopic techniques. Marlex used for reinforcement is placed directly onto the peritoneum (i.e. transperitoneal) in some repairs. This practice of placing Marlex mesh directly onto the peritoneum may, however, lead to clinically significant bowel adhesions. This study tests whether three different adhesion barriers (Gore-Tex, Interceed, and poloxamer) can reduce bowel adhesion formation when placed directly over the fixed Marlex mesh in the rat. Interceed and poloxamer significantly reduced adhesion formation to Marlex mesh. Gore-Tex had the greatest amount of adhesion formation but this was not significantly different from Marlex control. Poloxamer treatment appeared to significantly reduce tensile strength and Marlex mesh incorporation. The Interceed treatment also appeared to reduce tensile strength as compared to Marlex alone, however, this difference was not significant. The use of Marlex mesh with an Interceed barrier reduces intraabdominal adhesions while not reducing the tensile strength of the Marlex mesh incorporation.

Laser education, laser usage, and surgical attitudes: a challenge for the future.

The results of a questionnaire distributed to enrollees at laser training programs at the Rochester General Hospital between 1986 and 1989 were compared with the results of a previous survey and current patterns of laser utilization and acceptance among surgical house staff. Laser utilization has improved slightly. However, both house staff and attending surgeons prefer, and are most comfortable with, nonlaser technology. Continued efforts to enhance the utilization of laser technology and the availability of laser education at teaching hospitals are key for the future.

Ergonomics of medical lasers: operator's viewpoint.

Lasers are instruments that may enhance the surgeon's ability to perform surgery. Many medical lasers sit unused. Lack of use is associated with "user unfriendliness." Nurses and surgeons often cite factors such as complexity, location, and types of controls, and content of displays. Other factors such as culture-ethnology and its relationship to command words and symbols, affect understandability of controls, displays, and user friendliness. Laser designers and engineers must analyze the interaction between laser users and products. Laser design and operation must coincide with specific needs and expectations of the nurses and physicians. Poor design and engineering compromises result in nonuse of expensive instrumentation, products which are ineffective for clinical use, and could potentially increase the risk of possible injury to patients and staff. This discussion of the design and operation of medical laser systems, presents the advantages and disadvantages of several laser systems. User interfaces for controls: color, function, touch activation, labels and size, sound cues, laser activation, type and amount of feedback information during operation; design of storage for accessories, and need for features such as pulsing, and milliwatts will be discussed. We will present what we consider to be an ideal laser system.

Augmentation of the systemic host anti-tumor response through laser excision.

This study examines whether primary laser excision results in augmentation of the systemic host anti-tumor response to tumor rechallenge. Single R3230AC mammary tumor implants, (0.5 x 0.5 x 1.0 mm), were grown in 112 female Fisher 344 rats. The animals were randomized. Group S tumors were excised by scalpel. Group E was excised with a Surgistat electrocautery (Valley Labs, Boulder, CO). Group CS was excised with a Sharplan 1100 CO2 laser (Sharplan, Allendale, NJ) at 25 watts (W) continuous wave (CW) (0.2 mm spot size) and the wound was "sterilized" with a 5-mm spot size by gently heating the tissue without blanching. Group K was excised with a KTP/532 laser (Laserscope, San Jose, CA) at 17 W CW using a 400 microns fiber. Group Y was excised with a Sharplan 2100 Nd:YAG laser set at 15W CW using a 0.2 mm clear sapphire tip. A second tumor implant, (0.5 x 0.5 x 1.0 mm), was placed at a remote site 14 days postoperatively. An unoperated control group was implanted. Secondary tumor volumes were measured for 36 days and the mean tumor volumes (MTV) were statistically compared. The MTV in groups CS, K, Y, and E was less than control (P less than 0.01). The MTV in groups CS, K, Y, and E was less than group S, although this was not statistically different. Lasers and cautery appear to increase the host response against subsequent tumor challenge. This study corroborates earlier studies of other modalities. Further studies to determine whether this host sensitization is an immune response and to elucidate the mechanisms of this effect are warranted.

Effect of argon laser and Photofrin II on murine neuroblastoma cells.

Laser-induced fluorescence (LIF) of photosensitizers is used to detect cancer. The effect of argon laser light with an average irradiance of 31 mW cm-2 and Photofrin II (Dihematoporphyrin ether, DHE) at concentrations of 1.0 and 5.0 micrograms ml-1 on C1300 murine neuroblastoma cells (MNB, NB41A3) in vitro was investigated. Growth curves and cell viability (trypan blue dye exclusion) were determined at 1, 24, 96, and 144 hr post-irradiation. Light doses of 1.8 and 9.0 J cm-2 combined with 5.0 micrograms DHE ml-1 decreased both cell numbers and viability, immediately and up to 144 hr postirradiation. Argon laser light alone at a fluence of 9.0 J cm-2 caused reversible injury to the cells. This in vitro study shows that both low energy argon laser light and low dose DHE are cytocidal to C1300 MNB cells. LIF promises to aid in the detection and destruction of neuroblastoma. Surgeons should be aware that tissue irreversible damage is likely to occur when performing LIF detection of neuroblastoma. The doses of laser light and of Photofrin II found to be toxic to neuroblastoma cells in culture may provide guidelines for photodynamic therapy ablation of neuroblastoma clinically.

Methods for the endoscopic photographic and visual detection of helium cadmium laser-induced fluorescence of Photofrin II.

Endoscopic detection of small tumors is key to the early diagnosis and treatment of malignancy. This paper describes a simple, endoscopic detection system which enables tumor localization and a permanent record based on the laser-induced fluorescence of dihematoporphyrin ether (LIFD). Spectral analysis of dihematoporphyrin ether (DHE, Photofrin II) was performed with a Perkin Elmer LS-5 scanning fluorimeter. DHE at concentrations of 50 micrograms/ml and 5 micrograms/ml in 95% ethanol were tested, demonstrating fluorescence quenching at 50 micrograms/ml DHE at 406 nm excitation. This phenomenon was not observed at 442 nm excitation. Based on this data and the availability of the helium cadmium laser, a series of endoscopic detection systems was developed and tested utilizing a LiConix 4240NB helium cadmium laser (TEMoo, 442 nm, 40 mW). A fiber with a microdiverging (MDL) lens was used. Irradiance achieved at the tip of the fiber was 31.58 mW/cm2 for MDL. A Corning 34832 (550 nm) sharp cutoff barrier filter was coupled to an Olympus OES BF2T10 bronchoscope. Successful detection of LIFD was obtained. Direct observation of LIFD is possible when wearing Laserguard argon safety goggles (OD 15 at 488 nm, OD 11 at 514 nm). Photographic recording of LIFD was performed with the following cameras and parameters: Olympus OM-2S camera (OM2) with EES135 film (ISO 1600) with a 4-second exposure (method 1) and the Olympus OES SCP-10 instant camera with Polaroid 779 (ISO 640) film and a 120-second exposure (method 2). The photographic methods demonstrate the red fluorescence of DHE on filter paper disks at concentrations of 0.5 micrograms/ml (500 ng/ml). (ABSTRACT TRUNCATED AT 250 WORDS)

The lack of antigenicity of tuftsin: a naturally occurring phagocytosis stimulating tetrapeptide.

Tuftsin (Thr-Lys-Pro-Arg) is a naturally occurring tetrapeptide that stimulates all known functions of the polymorphonuclear leukocyte and macrophage cell lines. Tuftsin is located in the FC region of IgG between the 289 and 292 amino acid sequence of the CH2 domain. We describe unsuccessful attempts to generate antituftsin antibodies. In separate experiments tuftsin was chemically conjugated to methylated bovine serum albumin (CH3BSA), BSA, keyhole limpet hemocyanin (KLH) and purified protein derivative (PPD). Tuftsin was also polymerized with glutaraldehyde. Animals used for immunization were rabbits, roosters, and dogs. All experiments failed to produce antituftsin antibody. Probable reasons for the lack of antigenicity include: I) Lack of "foreignness" of tuftsin in mammal species. II) The small size of the tetrapeptide. III) Tuftsin may be exerting an adjuvant effect when coupled to foreign antigens and is therefore not recognized by the host immune system.

Beneficial effects following carbon dioxide laser excision on experimental neuroblastoma.

Treatment of neuroblastoma in children consists of primary excision with adjuvant radiation and chemotherapy. When the tumor invades surrounding structures that cannot be safely excised or when distant metastasis is present, the patient has a poor prognosis. Because the CO2 laser can be used to excise malignant tumors without seeding the surrounding tissue and because the defocused beam can vaporize malignant cells, we compared partial scalpel excision and partial laser excision of C1300 murine neuroblastoma to the growth rate of residual tumor. In 25 mice, 75% of the tumor was excised with a scalpel, and in another 25, the same percentage was excised with the CO2 laser (10 W). CO2 laser excision significantly decreases the growth of residual neuroblastoma (P less than .01). However, the effect appears to be a function of increased tumor immunogenicity after laser excision rather than the increased tumor kill. We conclude that CO2 laser excision of neuroblastoma may prove to be superior to scalpel excision for primary surgical treatment of neuroblastoma.

The first sutureless, laser-welded, end-to-end bowel anastomosis.

The use of laser energy to weld together tissue offers great promise in the expanding field of laser surgery. The published results of laser welding intestinal tissue have, to date, been limited to the successful laser closures of small enterotomies. This is the first report of using laser energy alone to create an end-to-end small bowel anastomosis. A biocompatible, water-soluble, intraluminal stent was employed during the laser welding of this sutureless, stapleless ileal anastomosis in a rabbit model. Excellent recovery and healing were observed. The rapidity, ease, and potential for full precision automation of laser welding mandates further research.

Mechanisms of reduction of tumor recurrence with carbon dioxide laser in experimental mammary tumors.

This study compares local tumor recurrence after low energy CO2 laser wound sterilization with recurrence after scalpel, laser or electrocautery excision. Wound histologic changes were studied to understand the mechanism of the interaction between the laser and wound. Single implants of R3230AC mammary tumor were grown to an average diameter of 24 millimeters in the mammary ridge of 80 female fisher 344 rats. Rats were anesthesized with pentobarbital and randomized into groups, each with similar tumor size: scalpel (S), laser (L), laser with wound sterilization (LV), scalpel with sterilization (SV) and electrocautery (E). All surgical procedures were performed by the same surgeon with the same technique, with the exception of the instruments used. Tow rats from each group were sacrificed immediately and the wounds examined histologically. The Sharplan 1100 CO2 laser was used with a 125 millimeter hand piece in focus and in continuous wave for groups L and LV. Sterilization in groups LV and SV was performed with 5 millimeter spot size by heating the site gently without causing blanching of tissue. Excision in group E was performed with coagulating current from a monopolar cautery (Valley Lab). Rats were examined periodically for 30 days and those dying during this period were excluded from analysis. The incidence of wound recurrence was eight of 12 in group S; five of eight, L; four of 13, E; three of 12, LV, and two of nine, SV (p less than 0 .05). Histologic changes in the wound demonstrated viable tumor in all groups, with fewer areas present in groups E, SV and LV. Local thermal effects and the noncontact nature of the CO2 laser make it an effective adjunct in reducing local tumor recurrence by enhancing the cytoreductive capability of surgical procedures.

Comparison of local tumor recurrence following excision with the CO2 laser, Nd:YAG laser, and Argon Beam Coagulator.

This study compares the incidence of local tumor recurrence following primary excision with the CO2 laser, Nd:YAG laser (contact), Argon Beam Coagulator, or electrocautery. One hundred eight Fisher 344 rats with R3230AC mammary tumors (1.6 +/- 0.04 [SD] cm diameter) were used. All animals were randomized into groups of similar tumor size. In groups C and CS, excision was performed with a Sharplan 1060 CO2 laser (TEMoo, 25 W, continuous wave [CW], 0.2-mm spot size). Wounds in group CS were "sterilized" (0.5-mm spot size, 25 W, CW) by gently heating the wound without causing blanching or charring. In group N, a 0.4-mm contact Laser Blade and a Cooper 8000 Nd:YAG laser at 20 W CW was used. In groups SA1 and SA2, tumors were excised with the scalpel, and hemostasis and wound "sterilization" were accomplished with the Bard System 6000 Argon Beam Coagulator (ABC) at 40 W and 4 liters/min argon gas flow in SA1 and 12 liters/min in SA2. In group E, excision was accomplished at 40 W blend mode, 10 W spray mode. In group EA, excision was accomplished at 60 W cutting current, and hemostasis was achieved with the ABC. The animals were examined for evidence of recurrence for 34 days postoperatively. Mortalities were excluded from analysis. The incidence of recurrence was 11/14 (79%) in C, 6/16 (38%) in CS, 10/14 (71%) in SA1, 6/13 (46%) in SA2, 6/15 (40%) in N, 7/10 (70%) in EA, and 3/15 (20%) in E. Group E is statistically different (P less than .01) from groups EA, C, and SA1. Group C was different (P less than .01) from groups E, CS, and N. These results demonstrate an inverse relationship between tumor recurrence and local thermal effects at the surgical site. The ABC did not increase tumor recurrence. Contact YAG surgery was similar to CO2 laser excision and "sterilization." An attempt to study the influence of gas flow and pressure on local tumor recurrence and metastases should be made.

Comparison of continuous-wave, chop-wave, and super pulse laser wounds.

Some of the latest generation of CO2 lasers incorporate features that alter the wave form. The present study was undertaken to evaluate the relative zone of coagulation in acute laser wounds created in continuous-wave (CW), chop-wave (CPW), and super pulse wave (SPW) modes. The damage from single-point impact sites and incisions was compared in a guinea pig model. Animals were anesthetized with pentobarbital, and wounds were created with a 125-mm handpiece in focus (0.2-mm spot size) on dorsal and flank skin sites with the Sharplan 743 and 1100 CO2 lasers (Sharplan, Ltd., Allendale, NJ). Point impacts of CW and CPW were compared at power levels of 5, 10, 25, 40, 60, and 80 W at time durations of 0.05, 0.1, 0.2, and 0.5 seconds. Incisions of 3.0 cm were created at 25 W in CW, CPW, and SPW modes. Histologic sections stained with hematoxylin and eosin and Van Giesen elastin stains were evaluated by a single observer (R.J.L.). Zones of coagulation for the point-impact study varied from 79 to 257 +/- 66 (SD) micron in width with no significant differences between any of the wounds. Greater thermal damage (coagulation) occurred as the time interval increased. The zones of coagulation in the incision study were 309 +/- 83 (SD) micron for CW, 238 +/- 51 (SD) micron for SPW1 (743), 260 +/- 79 (SD) micron for CPW, and 194 +/- 56 (SD) micron for SPW2 (1100). These results are significant to the P less than 0.01 level.(ABSTRACT TRUNCATED AT 250 WORDS)

The identification of serum tuftsin by reverse-phase high-performance liquid chromatography and mass spectrometry.

We describe for the first time a method for unambiguously identifying the phagocytic stimulating tetrapeptide tuftsin from trypsinized human serum. The method consists of separating serum tuftsin by reverse-phase (RP)-HPLC, collecting HPLC fractions corresponding to the synthetic tuftsin retention time, and then subjecting those fractions to mass spectrometry/mass spectrometry (MS/MS) analysis, which provides optimal molecular specificity to the measurement. Although quantification was not the goal, it was estimated that the amount of tuftsin found by RP-HPLC and MS/MS was in the hundreds of nanograms per milliliter.

The use of the carbon dioxide laser permits primary closure of contaminated and purulent lesions and wounds.

Excision of contaminated and purulent wounds with the carbon dioxide laser makes it safe to close the wounds primarily when certain steps are observed during the operation. The contaminated surface is sterilized with the defocused beam. The surgeons' and assistants' hands should not touch the contaminated areas, and both should wear two pairs of rubber gloves to protect against accidental contamination. All infected tissue is excised completely, and the wound cleansed by copious irrigation and the defocused laser. The wound may then be safely closed by simple sutures, skin graft, or by the rotation of a vascularized musculocutaneous flap. A series of cases are presented in order to illustrate these points.