Comparative quality of life in patients following abdominoperineal excision and low anterior resection for low rectal cancer.

BACKGROUND: It is widely believed that quality of life is worse after abdominoperineal excision then after low anterior resection. However, this view is not supported unequivocally. OBJECTIVE: The aim of this study was to compare quality of life in patients 1 year following low anterior resection and abdominoperineal excision for low rectal cancer. DESIGN: Data were collected prospectively on 62 patients undergoing low anterior resection (32) and abdominoperineal excision (30) for low rectal adenocarcinoma within 6 cm of the anal verge. Patients with metastatic disease were excluded. Quality of life was assessed by the use of the European Organization for Research and Treatment of Cancer's QLQ-C30 and QLQ-CR38 modules and Coloplast stoma quality-of-life questionnaire. Bowel function was assessed by using the St Mark's bowel function questionnaire. Quality of life in patients who had low anterior resection was compared with those who had abdominoperineal excision both preoperatively and 1 year after surgery. SETTINGS: This study was conducted at 3 centers in the United Kingdom and 1 center in Europe. PATIENTS: Included were consecutive patients with rectal cancer within 6 cm of the anal verge, all of whom provided written consent for participation. MAIN OUTCOME MEASURES: Mann-Whitney U test comparisons of QLQ-C30 and QLQ-CR38 module scores for patients undergoing low anterior resection and abdominoperineal excision were the main outcomes measured. RESULTS: Patients undergoing low anterior resection were younger (median age, 59.5 vs 67, p = 0.03) with higher tumors (4 vs 3, p < 0.001) and less likely to receive neoadjuvant therapy (p = 0.02). At 1 year postoperatively, global quality-of-life ratings were comparable, but patients undergoing abdominoperineal excision reported better cognitive (100 vs 83, p = 0.018) and social (100 vs 67, p = 0.012) function, and less symptomatology with respect to pain (0 vs 17, p = 0.027), sleep disturbance (0 vs 33, p = 0.013), diarrhea (0 vs 33, p = 0.017), and constipation (p = 0.021). Patients undergoing low anterior resection reported better sexual function (33 vs 0, p = 0.006), but 72% experienced a degree of fecal incontinence. LIMITATIONS: This study was limited by its relatively small sample size. CONCLUSION: Abdominoperineal excision should not be regarded as an operation that is inferior to low anterior resection in the management of low rectal cancer on the basis of quality of life alone.

The unusual γ-ray burst GRB 101225A from a helium star/neutron star merger at redshift 0.33.

Long γ-ray bursts (GRBs) are the most dramatic examples of massive stellar deaths, often associated with supernovae. They release ultra-relativistic jets, which produce non-thermal emission through synchrotron radiation as they interact with the surrounding medium. Here we report observations of the unusual GRB 101225A. Its γ-ray emission was exceptionally long-lived and was followed by a bright X-ray transient with a hot thermal component and an unusual optical counterpart. During the first 10 days, the optical emission evolved as an expanding, cooling black body, after which an additional component, consistent with a faint supernova, emerged. We estimate its redshift to be z = 0.33 by fitting the spectral-energy distribution and light curve of the optical emission with a GRB-supernova template. Deep optical observations may have revealed a faint, unresolved host galaxy. Our proposed progenitor is a merger of a helium star with a neutron star that underwent a common envelope phase, expelling its hydrogen envelope. The resulting explosion created a GRB-like jet which became thermalized by interacting with the dense, previously ejected material, thus creating the observed black body, until finally the emission from the supernova dominated. An alternative explanation is a minor body falling onto a neutron star in the Galaxy.

Effect of pretransplant human leukocyte antigen antibodies detected by solid-phase assay on heart transplant outcomes.

INTRODUCTION: The significance of pretransplant human leukocyte antigen antibodies (HLA-Abs), especially donor-specific HLA-Abs (DSA), as detected by single antigen bead assay (SAB), is not well characterized in cardiac transplantation (CTX). We analyzed the significance of DSA detected by SAB in predicting crossmatch (XM) results and post-transplant rejection. MATERIALS AND METHODS: We performed a retrospective study of 85 CTX with negative cytotoxicity XM. We tested pretransplant sera collected within 24 hours of transplantation by flow cytometric XM (FXM) and SAB. DSA identified by SAB were utilized to perform a virtual crossmatch (VXM). Positive VXM was defined as the presence of DSA at mean fluorescence intensity (DMFI)>1500. Additionally, to analyze the significance of low-level DSA weakly positive VXM was DMFI 300 to 1500. We defined a negative VXM as MFI<300. VXM results were correlated with FXM results and with posttransplant rejection. RESULTS: Patients in the weakly positive and negative VXM had similar posttransplant rejections. DMFI>1500 correlates well with FXM results (accuracy=90%). Patients with DMFI>1500 had a higher incidence of antibody-medicated rejection (AMR; P=.0052), AMR grade I (P<.0001), cell-mediated rejection (CMR) grade>1R/1A (P=.018), and CMR grade>2R/3A (P=.057). Similarly patients with positive FXM had a higher incidence of AMR (P=.091), AMR grade 1 (P<.0001), CMR grade>1R/1A (P=.05), and CMR grade>2R/3A (P=.56). CONCLUSIONS: In conclusion, SAB defined DMFI>1500 can be used as a surrogate for FXM. Recipients with DMFI>1500 pretransplant and positive FXM have significantly higher rates of AMR and CMR compared to recipients with DMFI<1500 or negative FXM.

Transfusion service disaster planning.

The Mayo Clinic, in Rochester, Minnesota, recently set forth a directive to develop a Mayo Emergency Incident Command System (MEICS) plan to respond to major disasters. The MEICS plan that was developed interfaces with national response plans to ensure effective communication and coordination between our institution and local, state, and federal agencies to establish a common language and communication structure. The MEICS plan addresses multiple aspects of dealing with resource needs during a crisis, including the need for blood and transfusion medicine services. The MEICS plan was developed to supplement our current local emergency preparedness procedures and provide a mechanism for responding to the escalating severity of an emergency to deal with situations of a magnitude that is outside the normal experience. A plan was developed to interface the existing Transfusion Medicine disaster plan standard operating procedures (SOP) with the institutional and Department of Laboratory Medicine (DLMP) MEICS plans. The first step in developing this interface was defining MEICS. Other major steps were defining the chain of command, developing a method for visually indicating who is "in charge," planning communication, defining the actions to be taken, assessing resource needs, developing flowcharts and updating SOPs, and developing a blood rationing team to deal with anticipated blood shortages. Several key features of the interface and updated disaster plan that were developed are calling trees for response personnel, plans for relocating leadership to alternative command centers, and action sheets to assist with resource assessment. The action sheets also provide documentation of key actions by response personnel.

The dose of infused lymphocytes in the autograft directly correlates with clinical outcome after autologous peripheral blood hematopoietic stem cell transplantation in multiple myeloma.

Absolute lymphocyte count at day 15 (ALC-15) after autologous peripheral blood hematopoietic stem cell transplantation (APHSCT) is an independent prognostic factor for survival in multiple myeloma (MM); however, factors affecting ALC-15 in MM remain unknown. We hypothesized that the dose of infused peripheral blood autograft lymphocytes (autograft absolute lymphocyte count: A-ALC) impacts ALC-15 recovery. Between 1989 and 2001, 267 consecutive MM patients underwent APHSCT. We set out to determine the correlation between A-ALC and ALC-15 and the utility of A-ALC as a marker for ALC-15 recovery. A-ALC was found to be both a strong predictor for area under curve (AUC=0.93; P=0.0001) and strongly correlated with (r(s)=0.83; P=0.0001) ALC-15 recovery. Higher infused A-ALC was significantly correlated with an ALC-15>/=500/microl. In addition, median post-transplant overall survival (OS) and time to progression (TTP) were longer in patients who received an A-ALC>/=0.5 x 10(9) lymphocytes/kg versus A-ALC <0.5 x 10(9) lymphocytes/kg (58 vs 30 months, P=0.00022; 22 vs 15 months, P<0.00012, respectively). Multivariate analysis demonstrated A-ALC as an independent prognostic indicator for OS and TTP. These results indicate that an infused dose of autograft lymphocytes significantly impacts clinical outcome post-APHSCT in MM.

Infused peripheral blood autograft absolute lymphocyte count correlates with day 15 absolute lymphocyte count and clinical outcome after autologous peripheral hematopoietic stem cell transplantation in non-Hodgkin's lymphoma.

Absolute lymphocyte count at day 15 (ALC-15) after autologous peripheral blood hematopoietic stem cell transplantation (APHSCT) is an independent prognostic factor for survival in non-Hodgkin's lymphoma (NHL). Factors affecting ALC-15 remain unknown. We hypothesized that dose of infused autograft lymphocytes (A-ALC) directly impacts upon ALC-15. A total of 190 consecutive NHL patients received A-ALC between 1993 and 2001. The primary end point was correlation between A-ALC and ALC-15. A strong correlation was identified (r=0.71). A higher A-ALC was infused into patients achieving an ALC-15 > or =500/microl vs ALC-15 <500/microl (median of 0.68 x 10(9)/kg (0.04-2.21 x 10(9)/kg), vs 0.34 x 10(9)/kg (0.04-1.42 x 10(9)/kg), P<0.0001). The median follow-up for all patients was 36 months (maximum of 109 months). The A-ALC threshold was determined at 0.5 x 10(9)/kg. The median overall survival (OS) and progression-free survival (PFS) times were longer in patients who received an A-ALC >/=0.5 x 10(9)/kg vs A-ALC <0.5 x 10(9)/kg (76 vs 17 months, P<0.0001; 49 vs 10 months, P<0.0001, respectively). Multivariate analysis demonstrated A-ALC to be an independent prognostic indicator for OS and PFS. These data support our hypothesis that ALC-15 and survival are dependent upon the dose of infused A-ALC in NHL.

Effect of thalidomide on stem cell collection and engraftment in patients with multiple myeloma.

The purpose of this study was to determine the effect of thalidomide on stem cell collection and engraftment in patients with multiple myeloma. We performed a retrospective review of 67 patients newly diagnosed with multiple myeloma at Mayo Clinic and treated with a single regimen prior to stem cell transplantation between January of 2000 and September of 2001. Stem cells were collected from 24 patients who received thalidomide, 200 mg/day, with dexamethasone as initial therapy before stem cell collection. These patients were compared with 43 control patients seen during the same period who had received only one previous regimen before stem cell collection and transplantation. The cumulative thalidomide dose before stem cell collection was 17 000 mg over a median of four cycles (range, 2-7 cycles). The thalidomide and control groups were not significantly different in their baseline characteristics, number of stem cells collected, time to collection, or time to engraftment of neutrophils or platelet count of 50 000/microl. Time to platelet count of 20 000/microl was delayed by a median of 4 days (P=0.008), but platelet transfusion requirements did not differ (P=0.95). We concluded that thalidomide does not substantially affect peripheral cell mobilization or engraftment.

A mathematical algorithm to identify toxicity and prioritize pollutants in field sediments.

In order to evaluate sediment toxicity, a mathematical algorithm was developed to compute the toxicity of multiple component mixtures acting in an additive manner. A statistical approach was devised to determine the presence of potential interactive effects among mixture components. The algorithm uses three kinds of data to obtain an integrative approach to sediment toxicity assessment: Microtox toxicity data (EC50 values), sediment pollutant concentration measurements, and sequential extraction (SEQ) data to investigate metal partitioning. To simplify the analysis of complex mixtures using a prioritization scheme based on intrinsic toxicity and relative abundance, a toxicity index (TI) was employed as an indicator of adverse ecological impact. In general, the ranking of contaminants using the TI approach was found to be most efficient in reducing computational time, and concentrations using bioavailability data from SEQ was found to be the best theoretical predictor of the experimental mixture toxicity value. Only a few pollutants that were present at the greatest abundance were needed to provide a good approximation of the calculated EC50 found when all components were included. Not only does this substantially reduce the computational time needed to determine the EC50, it could in some cases dramatically reduce the pollutant monitoring effort required to track toxicity effectively. This approach would have substantial implications for both risk assessment and for remediation strategies, making them more efficient by focusing on the priority pollutants identified.

Bioaccumulation of lead in Xenopus laevis tadpoles from water and sediment.

The overall objective of this research was to monitor the uptake kinetics of lead in an amphibian model and correlate metal content with embryo development. Based upon the concentration of lead found in the water and sediment of a Louisiana swamp adjacent to a Superfund site, a controlled laboratory experiment exploring lead uptake from water and sediment by Xenopus laevis tadpoles was conducted. For 5 weeks, tadpoles were exposed to water and a simulated sediment, kaolin, spiked with 1, 5, or 10 times the concentration of lead found in field water and sediment samples. Additionally, organisms were exposed to the 5 x condition for 3 and 6 weeks. The experimental controls consisted of unexposed tadpoles and ones exposed to lead originating from water or sediment exclusively. At the end of the exposure periods, developmental data, i.e., body weight and developmental stage, were recorded, and the tadpoles were analyzed for whole body lead concentration. Lead extraction was accomplished by dry ashing, and its amount was quantified polarographically. Results showed that lead inhibited the normal development of these amphibians, in a manner that generally was more severe as exposure level increased. The hindrance of tadpole development also coincided with an increase in whole body lead concentration at higher exposures. Temporally, at the 5 x exposure concentration, the mean lead level increased with time, but this difference was not statistically significant (P<.05). Additionally, control animals exposed to lead (either in water or in sediment) showed no statistical difference with regard to weight and lead uptake, indicating that lead originating from both water and sediment is incorporated into the tadpole. The controlled laboratory experimental protocol used here is thus capable of investigating the uptake of a single metal (Pb in this case) and determining its effect on the development of tadpoles while differentiating the significance of multiple sources of exposure.

Examination of in vivo influences on bioluminescent microbial assessment of corrosion product toxicity.

The composition of ionically dissolved and precipitated corrosion products from both free corrosion of ASTM F75 Co-Cr-Mo and galvanostatic polarization of Co-Cr-Mo and F138 316L stainless steel was determined using differential pulse polarography and inductively coupled plasma atomic emission spectroscopy. A bacterial bioluminescence assay, Microtox, was used to assess the toxicity of the solid and dissolved corrosion products produced by galvanostatic polarization and the individual ions within them. The role of in vivo salinity, temperature, and protein content as modulators of corrosion product toxicity assessment was investigated empirically and mechanistically. Co-Cr-Mo products were found to be more toxic than those of 316L, and the most toxic ions were Cr6+, Ni2+, and Co2+. Ringer's solution potentiated the toxicity of the more toxic metal ions and reduced the toxicity of the less toxic ions. Using theoretical analysis in conjunction with experimental measurements, the ions in both alloys were found to interact in an antagonistic fashion. The presence of albumin was found to decrease metal toxicity, presumably by chelation.

Measurement of fibroblast and bacterial detachment from biomaterials using jet impingement.

Fibroblast and Staphylococcus aureus detachment strength from orthopaedic alloys and a tissue culture plastic (Thermanox) have been investigated with jet impingement. For S. aureus, unlike fibroblasts, detachment is caused more by pressure than shear. For these biomaterials, detachment strength is much higher for S. aureus than fibroblasts. Comparing materials under equivalent flow conditions, S. aureus attach to stainless steel and titanium with equal strength and more strongly than to Thermanox. For fibroblasts, detachment strength from all materials was similar. Fibroblast detachment strength from these biomaterials substantially decreases with time at equal flow rates and increases with flow rate at equal exposure times. Detachment strength is very similar for 3T3 and L929 fibroblasts on Thermanox for equivalent flow rate/time combinations, though enhanced adhesion of 3T3 cells was often noted for metals. Time effects are less evident for S. aureus. S. aureus adhesion to metals is more affected by flow rate than fibroblast adhesion.

Evaluation of metallic and polymeric biomaterial surface energy and surface roughness characteristics for directed cell adhesion.

Directed cell adhesion remains an important goal of implant and tissue engineering technology. In this study, surface energy and surface roughness were investigated to ascertain which of these properties show more overall influence on biomaterial-cell adhesion and colonization. Jet impingement was used to quantify cellular adhesion strength. Cellular proliferation and extracellular matrix secretion were used to characterize colonization of 3T3MC fibroblasts on: HS25 (a cobalt based implant alloy, ASTM F75), 316L stainless steel, Ti-6Al4V (a titanium implant alloy), commercially pure tantalum (Ta), polytetrafluoroethylene (PTFE), silicone rubber (SR), and high-density polyethylene (HDPE). The metals exhibited a nearly five-fold greater adhesion strength than the polymeric materials tested. Generally, surface energy was proportional to cellular adhesion strength. Only polymeric materials demonstrated significant increased adhesion strength associated with increased surface roughness. Cellular adhesion on metals demonstrated a linear correlation with surface energy. Less than half as much cellular proliferation was detected on polymeric materials compared to the metals. However the polymers tested demonstrated greater than twice the amount of secreted extracellular matrix (ECM) proteins on a per cell basis than the metallic materials. Thus, surface energy may be a more important determinant of cell adhesion and proliferation, and may be more useful than surface roughness for directing cell adhesion and cell colonization onto engineered tissue scaffoldings.

Correlation of field-measured toxicity with chemical concentration and pollutant availability.

Direct field toxicity tests were performed in two Louisiana waterways, Bayous Trepagnier and St. John, on sediments containing organic/heavy metal mixtures. Our approach involved bioluminescent bacterial toxicity assays (using DeltaTox, which qualitatively identifies polluted areas, and Microtox, which quantifies toxicity). Samples were more completely analyzed in our laboratory using inductively coupled plasma atomic emission spectroscopy (ICP-AES) and gas chromatography/mass spectrometry (GC/MS). Results indicate that lead is the primary toxic metal at the sites examined, though concentrations of metals fluctuate due to spatial variation and the dynamic nature of the waterways. Polycyclic aromatic hydrocarbons (PAHs) are the most abundant group of organics measured and appear to contribute to the overall toxic response. DeltaTox located toxic hotspots where there was an average light loss of 53-100%. Toxicity results from both assays agree but are well correlated with concentration measurements only for certain sediment fractions. Overall, the DeltaTox/Microtox approach appears to be rapid and cost effective for on-site hotspot identification, and may increase understanding of hazards associated with heavy metal and organic contaminants in these waterways.

An improved peel test method for measurement of adhesion to biomaterials.

Adhesion of tissues to biomaterials is desirable to prevent bacterial proliferation and for epithelial/transmucosal sealing of transcutaneous appliances, but can be counter-productive elsewhere, e.g. implants contacting tendons or maxillofacial subcutaneous tissue. It is therefore important to gauge adhesion strength of tissues to biomaterials before clinical use. Peel-testing is widely used for industrial product adhesion monitoring, but has rarely been applied biomedically. Here we describe peel-testing instrumentation designed for testing adherence of soft tissues to biomaterials. It offers the advantage that a 90 degrees angle between peel and substrate is maintained, simplifying determination of applied normal forces separating tissue layers from material surfaces. The device is portable and can be brought directly to the specimen removal site. This minimizes time delays between explantation and testing, maintaining the tissue/biomaterial interface in the freshest possible state closely approximating in vivo conditions, and so avoids measurement artifacts. So far, the instrument has been used to test adhesion of tape to a biomaterial surface (for determining the device's technical performance), assess strength of tissue adhesives, and measure adhesion of subcutaneous tissue to orthopaedic biomaterials. However, its versatility suggests additional applications for the peel-tester where adhesion of soft tissue to biomaterials is of interest.

Toxicity measurement of orthopedic implant alloy degradation products using a bioluminescent bacterial assay.

The toxicity of aqueous metal solutions representative of ionic degradation products from orthopedic implant alloys was determined using a bacterial bioluminescence assay, Microtox. The toxicity of forms of the individual elements released from ASTM F75 Co-Cr-Mo (Co-Cr-Mo), F138 316L stainless steel (316L), and F136 Ti-6Al-4V (Ti-6Al-4V) was first determined, and a mathematical model was developed to predict the toxicity of mixtures of these ions. Aqueous metal solutions were then mixed according to the proportions of the ions found in these alloys, and their toxicity was measured with Microtox. Mixture behavior was classified as synergistic, antagonistic, or additive by comparing measured toxicity to predicted toxicity. Since relating these tests to actual implant corrosion processes can be confounded by selective leaching, the predicted and measured toxicity of aqueous metal solutions mixed according to proportions representative of selective leaching were next determined, and the mixture behaviors were classified as before. The most toxic individual alloying elements were found to be hexavalent Cr, Ni, and Co, in that order: a finding in accord with prior biocompatibility research. Co-Cr-Mo was found to be the most toxic alloy mixture of both those combined according to alloy composition and those combined to reflect selective leaching. The Ti-6Al-4V mixtures were found to behave synergistically, while the Co-Cr-Mo and 316L mixtures behaved antagonistically. By providing insight into degradation product toxicity and elemental interaction, these experiments demonstrate the utility of employing bioluminescent bacterial assays to investigate biocompatibility of implant materials. Further studies to more closely simulate in vivo conditions, though, are required to fully gauge their potential in this regard.

Do cold agglutinins have any impact on the outcome of liver transplantation?

Cold agglutinins, IgM red blood cell autoantibodies, cause cold agglutinin disease with hemolysis and microvascular occlusion. Cold preservation of kidneys during renal transplantation in the presence of cold agglutinins can cause graft malfunction. However, the impact of cold agglutinins on the outcome of liver transplantation is unknown. We measured the pretransplant presence and titer of cold agglutinins in 327 primary liver allograft recipients and analyzed their relationship to outcome after transplant. Thirty-three percent of pretransplant patients had cold agglutinins. Cold agglutinins were more common in patients with viral-related liver diseases (49%) compared with those with nonviral-related liver disease (32%). There was no difference between recipients with and without cold agglutinins in usage of blood products, postoperative day 2 aminotransferase levels, acute rejection at day 7, the development of hepatic artery thrombosis, nonanastomotic biliary strictures, or 4-month allograft survival. In conclusion, cold agglutinins are common in liver transplant patients before surgery, especially those with viral-related liver diseases. However, the presence of cold agglutinins does not impact on outcome after liver transplantation.

Comparison of the polyethylene glycol antiglobulin test and the use of enzymes in antibody detection and identification.

BACKGROUND: The polyethylene glycol indirect antiglobulin test for detection of red cell antibodies was compared with a proven, highly sensitive test system using papain. STUDY DESIGN AND METHODS: Parallel, prospective testing of 1508 samples with polyethylene glycol and with albumin and papain evaluated the sensitivity and specificity of polyethylene glycol. Retrospective analysis of antibody specificities was performed for the 2 years before and the 2 years after the institution of polyethylene glycol testing. RESULTS: Of 1508 prospective screens, 53 (3.5%) had discordant results: 5 were positive only in polyethylene glycol and 48 were positive only in albumin and papain. Upon antibody identification, the 5 samples that were positive only in polyethylene glycol showed 1 anti-D, 2 warm autoantibodies, and 2 false-positive results. The 48 samples that were positive only in albumin and papain showed 1 each of the following: anti-Le(b); anti-P1; anti-S; high-titer, low-avidity antibody; and cold autoantibody; there were 43 false-positive results. False-positive results totaled 12 (0.8%) with polyethylene glycol and 53 (3.5%) with albumin and papain. The retrospective analysis of antibody specificity with polyethylene glycol showed a significant increase in the detection of Fy(a) and/or Fy(b) (p < 0.0002) and Jk(b) (p < 0.0002) antibodies and a decrease in the detection of Le(a) and/or Le(b) antibodies (p < 0.0002). CONCLUSION: Polyethylene glycol retained the high sensitivity of the albumin and papain, while significantly lowering the number of false-positive results and decreasing the detection of antibodies of doubtful clinical significance.

Social skills training for young adolescents: cognitive and performance components.

An assertiveness training curriculum that was an expansion of two previous programs with young adolescents (Thompson, Bundy, & Broncheau, 1995; Wise, Bundy, Bundy, & Wise, 1991) was presented to 22 fifth graders. Cognitive acquisition and retention of the symbolic assertiveness information were measured with multiple-choice pre- and posttests used in the two prior programs. The performance components, including verbal (word choice) and non-verbal (body orientation, posture, and gestures) aspects of assertive behavior were measured in pretest and posttest role-play situations, with the posttest administered at two levels of motivation. When trained students were compared to control groups on the cognitive measures, a significant effect for treatment (p < or = .000); a significant effect for measures (p < or = .000); and a significant Treatment x Measures interaction (p < or = .000) were found. However, the results did not show that training facilitated assertiveness on the performance components. When trained and control subjects' performance scores were combined, a significant effect for measures was found across role-play tests on some of the performance measures. Discussion focuses on factors that facilitate adolescents' appropriate application of stored symbolic information regarding assertiveness. Suggestions are offered for designing programs aimed at developing adolescents' assertive behavior in ways that will generalize to their lives beyond the training context.

Microjet impingement followed by scanning electron microscopy as a qualitative technique to compare cellular adhesion to various biomaterials.

Adhesion of cells to biomaterial surfaces is one of the major factors which mediates their biocompatibility. Quantitative or qualitative cell adhesion measurements would be useful for screening new implant materials. Microjet impingement has been evaluated by scanning electron microscopy, to determine to what extent it measures cell adhesion. The shear forces of the impingement, on the materials tested here, are seen to be greater than the cohesive strength of the cells in the impinged area, causing their rupture. The cell bodies are removed during impingement, leaving the sites of adhesion and other cellular material behind. Thus the method is shown not to provide quantification of cell adhesion forces for the metals and culture plastic tested. It is suggested that with highly adherent biomaterials, the distribution and patterns of these adhesion sites could be used for qualitative comparisons for screening of implant surfaces.