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  • 1
    ISSN: 1530-0358
    Keywords: Laparoscopic-assisted colectomy ; Port site tumors ; Aerosolization ; Laparoscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: This study was undertaken to investigate the ability of a high-pressure CO2 environment to aerosolize tumor cells in bothin vitro and in vivo models. (An aerosol is defined as a stable gaseous suspension of insoluble particles.) Also, this study was designed to determine if rapid desufflation is capable of transporting fluid laden with tumor cells. METHODS: The fourin vitro aerosol experiments were performed in an 18.9-l plastic vessel fitted with two 7-mm ports and a compliant latex balloon affixed to the top. After CO2 insufflation, the vessel was desufflated through a sterile soluset containing 25 ml of culture media that was subsequently emptied into a culture dish, incubated for two weeks, and periodicallyassessed for growth. At the bottom of the vessel, one of the following was placed: Study 1 and 2, a suspension of B16 melanoma or colon 26 tumor cells in liquid culture media; Study 3, colon 26 cells in saline solution; Study 4, several pieces of solid colon 26 tumor. In Studies 1 to 3, cell preparations were subjected to the following high-pressure CO2 conditions (pneumo): 1) static pneumo of 15 and 30 mmHg (10 minute dwell); 2) a continuous flow (CF) of CO2 (10 l) while maintaining a pressure of 15 or 30 mmHg in the vessel. In Study 4, only the 30 mmHg static and CF conditions were tested. Between 6 and 12 determinations were performed for each condition and cell preparation.In vivo aerosol experiments consisted of Spraque Dawley rats that received intraperitoneal injections of 10-5 B16 cells in 0.1 ml of liquid media.Two laparoscopic ports were placed in the abdomen, one each for insufflation and desufflation. Study groups were: 1, static CO2 pneumo of 15 mmHg; 2 and 3, continuous CO2 flow (10 l) at a stable pneumo pressure of 5 and 10 mmHg. Desufflation was performedvia the same collecting device and handled in an identical manner to thein vitro experiments described above. The in vitro balloon experiment was designed to investigate the ability of desufflation to transport fluid-containing tumor cells; latex balloon model was used. To prevent complete loss of volume on desufflation, a wire coil was placed inside the balloon. Twenty ml of media containing 20×10−6B16 cells was placed in the bottom of the balloon. The balloon was insufflated with 1 to 21 of gas. There were three study groups that differed in the degree to which the cell suspension was agitated before desufflation. Study conditions were as follows: 1) no agitation; 2) moderate agitation to coat the lower walls and coil; 3) maximum agitation to coat the entire balloon. To verify the viability of tumor cells,at the end of eachin vitro and in vivo study, a sample of tumor cells or peritoneal washing was incubated in sterile media. These samples served as positive controls. RESULTS:In vitro aerosol studies consisted of the following. At the end of two weeks of incubation, no tumor growth was noted in any of the 124 test dishes. The 14 control samples all demonstrated tumor growth.In vivo aerosol studies consisted of the following. Zero of 18 experimental dishes grew tumor. All three peritoneal washing samples demonstrated growth.In vitro balloon studies consisted of the following. Zero of 12 test dishes in Groups 1 and 2 demonstrated growth, whereas five of six dishes did so in Group 3 (maximally agitated before desufflation). Again, positive controls all grew tumor cells. SUMMARY: We were unable to demonstrate aerosol formation in any of thein vitro and in vivo studies performed. In the balloon experiment, desufflation-related transport of tumor cells was demonstrated but only when the entire balloon surface was coated with the tumor cell suspension before desufflation. CONCLUSION: Aerosols of tumor cells are not likely to form. Free intraperitoneal tumor cells are most likely found in liquid suspension. Desufflation is a potential means of transport of cell-laden fluid.
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  • 2
    ISSN: 1572-9931
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired blood disorder thought to result from a somatic mutation in a hemopoietic stem cell. PNH may evolve to aplastic anemia or to acute leukemia. PNH cells are deficient in proteins attached to the cell membrane via a glycosylphosphatidylinositol structure, called the GPI anchor, and the primary lesion in PNH is thought to be a defect in the biosynthesis of the GPI anchor. We have recently established permanent lymphoblastoid cell lines that have the PNH phenotype and we report now the isolation of human-human somatic cell hybrid clones obtained by fusing them with normal lymphoblastoid cells. In all of 21 hybrid clones, obtained from five different patients, the expression of three different GPI-linked proteins on the hybrid cells was normal. These findings indicate that the PNH mutant gene is recessive with respect to the normal allele and that a recessive mutation can cause a clonal preneoplastic disorder.
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  • 3
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Plasma coating (deposition of polymer under the influence of plasma) is utilized to modify the surface properties of corneal contact lens. An ultrathin layer (thickness of roughly 200 Å) of plasma polymer of acetylene/H2O/N2 is applied to poly(methyl methacrylate) (PMMA) corneal contact lenses. The surface becomes highly wettable with water compared to uncoated lens. When coated and uncoated contact lenses are placed on rabbit eyes, a remarkable difference in accumulation of mucous matter is observed. With the control lenses, the accumulation of mucous matter in a week is sufficient to affect the optical clarity of the lenses, whereas the coated lenses show no change after three months continuous wearing. The comparative degree of adhesion of the corneal epithelium cells onto glass, modified glass, PMMA, and coated PMMA surfaces is studied using tissue cultures and phase contrast microscopy. The coated PMMA surface exhibits a degree of tissue adhesion lower than that of control PMMA and higher than that of glass surface, and no sign of toxicity of the coated surface is observed by the tissue cultures.
    Additional Material: 7 Ill.
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  • 4
    ISSN: 1432-2218
    Keywords: Key words: Mouse — Murine — Model — Small animal — Laparoscopy — Laparoscopic surgery — Bowel resection cecectomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: In order to better investigate the effects of laparoscopic surgery, it is necessary to establish reliable, reproducible, and economical animal models of laparoscopic intervention. Here we describe a mouse model of laparoscopic-assisted colon resection. Methods: After successful induction of anesthesia the mouse is placed in Trendelenburg position and the peritoneal cavity is insufflated with carbon dioxide gas through an angiocatheter placed in the right upper quadrant. A 4-mm rigid scope with camera attachment is then inserted through a midline port created just caudal to the xiphoid. A second port is then created in the right lower quadrant to allow introduction of laparoscopic forceps into the peritoneal cavity. The cecum, which extends 1.5 cm beyond the ileocecal valve, is grasped with forceps and exteriorized through the operative port. Extracorporeally, the cecum is ligated and resected before the cecal stump is returned to the peritoneal cavity. The abdominal wall defects are then stapled closed. Results: This simple model can be mastered by individuals with very limited surgical experience. This laparoscopic model has been used successfully in our laboratory in a number of experiments with an intraoperative complication rate of 3.2% (3/94), which was similar to the open surgery group rate of 2.1% (2/95, p= 0.99 by chi square). We observed no postoperative leaks in either group. The only postoperative death occurred in the open resection group due to dehiscence of the laparotomy wound. Conclusions: We propose that this model may be useful for comparing the effects of open to laparoscopic surgery.
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  • 5
    ISSN: 1432-2218
    Keywords: Key words: Laparoscopy — Wound healing — Incision — Excision — Tensile strength — Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Many cellular elements responsible for wound healing are affected by laparotomy. The aim of this study was to evaluate the effects of laparotomy and CO2 pneumoperitoneum on wound healing. Methods: Male Sprague Dawley rats were randomly assigned to one of three experimental groups. Anesthesia control rats underwent no procedure. Pneumoperitoneum group rats were insufflated with CO2 gas. Laparotomy group rats underwent a 7-cm midline laparotomy incision. The interventions were 30 min long. For the incisional study (n= 30), a 4-cm dorsal full-thickness skin incision was made on each rat and then closed with staples. On postoperative days 7 and 14, an equal number of rats were sacrificed from each group, and wound tensile strength measurements were performed. For the excisional study (n= 45), each group of 15 rats underwent a 2-cm diameter circular dorsal full-thickness skin excision. Blinded measurements of wound area were performed every other day until wounds closed. Results: Wound tensile strength values were not significantly different among experimental groups at either time point. The study had a power of 80% to find a 30% difference at POD 7 and a power of 80% to find a 23% difference at POD 14 to a confidence level of p 〈 0.05. Wound contraction data from the excisional model were analyzed with the Generalized Estimation Equations statistical approach. When we modeled the treatment group as a covariate, no statistical difference was found between groups, demonstrating equal slopes across time. Conclusions: From the results of these studies, we conclude that wound healing in this model is not significantly diminished following laparotomy or peritoneal insufflation, as compared to anesthesia control.
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  • 6
    ISSN: 1432-2218
    Keywords: Key words: Mouse — Immune function — Delayed-type hypersensitivity — Laparoscopy — Surgery — Phytohemagglutinin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Our laboratory has previously used pig and rat models to demonstrate that delayed-type hypersensitivity (DTH) response to an antigen challenge is suppressed following laparotomy compared to insufflation. The purpose of this study was to develop a practical and reliable mouse DTH model that could be used in future studies to test immunomodulating drugs and therapies. Methods: Female C3H/HeN mice (n= 100) were given three serial DTH challenges of 25 μl of 4 mg/ml phytohemagglutinin (PHA) 12 days before the test procedure, immediately following the test procedure, and on the 2nd postoperative day. All challenges were administered via subcutaneous injection in alternating footpads. The thickness of the footpad was determined with electronic calipers immediately prior to injection and 24 h following injection in a blinded fashion. The difference in thickness represents the response. On the day of the procedure, mice were randomized into the following three groups: (a) control (AC), (b) insufflation (INS), and (c) open (OPEN). AC mice underwent no procedure. INS mice underwent CO2 insufflation at 2–4 mmHg for 20 min. OPEN mice underwent a midline incision from xiphoid to pubis that was closed after 20 min. Data were analyzed using ANOVA and Tukey-Kramer tests to determine differences between groups. Results: Preoperatively, there were no significant differences among the three groups. On POD1, the OPEN group had significantly less response than both the AC and INS groups. On POD3, there were significant differences between the OPEN group and both the INS and AC groups. There was no significant difference between the AC and INS group at any time. Conclusions: In conclusion, a DTH mouse model has been established that allows serial assessment of cell-mediated immune function. This model can be used to study immune function after open and minimal access procedures in a simple and cost-effective manner.
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  • 7
    ISSN: 1432-2218
    Keywords: Key words: Carbon dioxide chamber — Immune — Immunosuppression — Laparoscopy — Lymphocyte proliferation — Pneumoperitoneum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Purpose: Our laboratory has demonstrated that significantly more cell-mediated immunosuppression occurs after full laparotomy than after either anesthesia control or carbon dioxide (CO2) pneumoperitoneum. We further demonstrated that the postoperative immunosuppression is related to the length of the incision. Other investigators believe that the immunosuppression observed after laparotomy is caused by peritoneal exposure to small amounts of lipopolysaccharide found in circulating air. They believe that the better-preserved immune function associated with laparoscopic surgery results from the avoidance of air contamination of the peritoneal cavity. To investigate this hypothesis, we determined and compared postoperative lymphocyte proliferation rates after (a) laparotomy in room air, (b) laparotomy in a CO2 chamber, (c) CO2 insufflation in a murine model, and (d) anesthesia alone. Methods: Female C3H/He mice (n= 21) were divided randomly into four groups: (a) anesthesia control, (b) air laparotomy, (c) CO2 laparotomy, and (d) CO2 insufflation. The control mice underwent no procedure. The group 2 animals underwent a full midline incision (xiphoid to pubis) and exposure to room air for 20 min and then were clipped closed. The group 3 mice underwent a full midline incision in a sealed CO2 chamber for 20 min, and the group 4 mice insufflation with CO2 gas at 4 to 6 mmHg for 20 min. Splenocytes were harvested from all the animals on day 2 after the interventions. Lymphocyte proliferation then was assessed using the nonradioactive colorimetric MTS/PMS system 72 h after concanavalin-A stimulation. Results: There was no significant difference in lymphocyte proliferation between the air and CO2 laparotomy groups. Lymphocyte proliferation in the anesthesia control and CO2 insufflation groups was significantly higher than in both the air laparotomy (p 〈 0.05) and CO2 laparotomy (p 〈 0.05) groups (p values by Tukey-Kramer test). There was no significant difference between the anesthesia control and CO2 pneumoperitoneum groups. Conclusions: Our results suggest that full laparotomy performed in a sealed CO2 chamber compared to room air laparotomy resulted in similar suppression of lymphocyte proliferation. Furthermore, no significant suppression of lymphocyte proliferation was observed in the CO2 pneumoperitoneum group. These results, with regard to lymphocyte proliferation rates, refute the hypothesis that postoperative immunosuppression is related to air exposure and support the alternative hypothesis that immunosuppression is related to incision length.
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  • 8
    ISSN: 1432-2218
    Keywords: Immune function ; Preservation ; Resection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of this preliminary study was to evaluate immunologic responses to laparoscopic vs standard open colon resection and to evaluate possible mediators of any differences found. Specifically, we compared cortisol levels and delayed-type hypersensitivity response after each method of colon resection in a group of 20 pigs. Two groups of 10 animals each were treated in identical fashion including bowel preparation, anesthesia, and postoperative management. The only difference between groups was that one underwent laparoscopic and the other an open colon resection. Blood specimens for cortisol were drawn before, during, and immediately postoperatively as well as at 11A.M. on postoperative days 1 and 2. All animals had been previously immunized as piglets with Sow Bac-E (Oxford Veterinary, Worthington, MN), an antigen preparation of common pig pathogens. At the conclusion of the operative procedure 0.5 cc of the antigen was injected intradermally on the right forelimb of the animals. At 48 and 72 h postoperatively the largest diameters of induration surrounding the injection site were measured and averaged. Cortisol levels were measured in serum samples by radioimmunoassay (Met-Path, Rockville, MD). Statistical significance was determined by t-test. Results of skin antigen testing showed that the group of pigs that underwent laparoscopic resection had a 20% greater response, 1.54 cm±0.28 cm at 48 h and 1.53 cm±0.18 cm at 72 h. For the open-surgery group results were 1.24 cm±0.26 cm at 48 h and 1.32 cm±0.21 cm at 72 h,P〈0.05 for the difference between groups at both 48 and 72 h. Cortisol levels were not significantly different between groups at any of the time points. We conclude that T-cell-related immune function in this model, as measured by delayed-type hypersensitivity, is better preserved after laparoscopic than open colon resection. We further conclude that cortisol levels are not responsible for the improved preservation of the immune response. The benefits of improved postoperative immune function may be significant for patients undergoing laparoscopic colon resection.
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  • 9
    ISSN: 1432-2218
    Keywords: Laparoscopy ; Laparoscopic-assisted ; Colon resection ; Pig ; Porcine ; Controlled ; Prospective ; Adhesion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Several series of laparoscopic colon resection have been reported in the literature with varied results; however, no controlled series of laparoscopic vs open colon resection has been reported. The purpose of this study was to determine the relative safety and adequacy of laparoscopic colon resection in a controlled trial using a porcine model. Methods: Domestic pigs (n=23) were randomly divided into two groups. Animals underwent either an open or laparoscopic-assisted segmental resection of the sigmoid colon. The open resections were performed through a 20-cm midline incision and the laparoscopic technique utilized five 12-mm ports. Laparoscopic resection took twice as long to complete as open resection (P〈0.001). Return of gastric function was significantly faster in the laparoscopic group than in the open group (P〈0.032). Results: No significant differences were found in total length of resection, proximal or distal margins, number of lymph nodes recovered, length of mesenteric vessel resected, or time to return of bowel function. At vivisection, more adhesions to the abdominal wall were noted in the open group (P〈0.002). One death occurred in the laparoscopic group 2 h postoperatively (8.3% mortality) while all open group pigs survived. However, there was no statistically significant difference in mortality rates by chi-square analysis (P〉0.5). Conclusions: Despite longer operative time, laparoscopic intervention is technically feasible, safe, and may offer significant postoperative benefits due to fewer abdominal adhesions.
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  • 10
    ISSN: 1432-2218
    Keywords: Key words: Laparoscopy — CO2 pneumoperitoneum — Pneumoperitoneum — Tumor growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Previous work has demonstrated that cell-mediated immune function is better preserved in rodents after laparoscopic than open surgery. The cause of this laparotomy-related immunosuppression is unclear. Some investigators have attributed it to the length of the incision; others, to peritoneal air exposure. It has also been shown that tumors in mice are more easily established and grow larger after sham laparotomy than after pneumoperitoneum. Lastly, the differences in tumor growth have been shown to be, at least in part, attributable to the immunosuppression that occurs after laparotomy. The purpose of this study was to determine if air pneumoperitoneum, presumably via immunosuppression related to peritoneal air exposure, is associated with increased tumor growth in the postoperative period. Methods: A total of 150 immunocompetent syngeneic mice received high-dose intradermal injections of mouse mammary carcinoma tumor cells. They were then randomized to undergo one of the following procedures: (a) anesthesia alone, (b) air insufflation (4–6 mm Hg), (c) CO2 insufflation, or (d) full laparotomy. No intraabdominal procedure was carried out. All procedures were 20 min long. After 12 days, the animals were killed and the mean tumor mass determined for each group. Results: All animals grew tumors. There was no significant difference in the mean tumor size of the anesthesia control, CO2 insufflation, and air insufflation groups (p 〉 0.85 by ANOVA). However, the laparotomy group tumors were 1.5 times as large as those of the other three groups (p 〈 0.05 by ANOVA). Conclusions: In this model, air insufflation did not significantly affect postoperative tumor growth, nor did CO2 pneumoperitoneum. However, full laparotomy was associated with increased tumor growth.
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