Preliminary Results of Instantaneous Centre of Rotation Change after Thoracic Instrumentation in Adolescent Idiopathic Scoliosis Patients.

Introduction: The instantaneous centre of rotation (ICR) is the centre of motion with zero velocity where a rigid body moves in a particular plane. ICR, as a dynamic measurement, gives more accurate results in terms of quality and quantity of the vertebral motions compared to range of motion (ROM). We aimed to determine the effect of thoracic instrumentation on cervical movement of adolescent idiopathic scoliosis (AIS) patients who had undergone thoracic level instrumentation by measuring pre-operative and post-operative ICR change in a pilot study. Materials and methods: A total of 25 AIS patients were included in this study. C4-C5 and C6-C7 segmental ICR were determined by pre-operative and post-operative cervical flexion-extension radiographs. In addition, cervical sagittal parameters and global sagittal parameters were investigated. Results: There was no statistically significant change in ICR location post-operatively in both x and y coordinates at C4-C5 segment (p: 0.326 and p: 0.946, respectively) and C6-C7 segment (p: 0.209, p: 0.086, respectively). There was a positive correlation between LCL and C4-C5 ICR y coordinate (r: 0.481), but not with C6-C7 ICR y coordinate (r: -0.2, p: 0.398). T5-T12 kyphosis decreased (p: 0.002) and T1 pelvic angle (0.003), SVA (0.02) and sacral slope (0.049) increased significantly post-operatively. T1S was correlated with LCL (r: 0.595, p: 0.002), T5-T12 kyphosis (r: 0.423, p: 0.035), SVA (r: 0.658, p<0.001) and C2-C7 SVA (r: 0.416, p: 0.039). Conclusion: The ICR for cervical region was not changed post-operatively in AIS patients with thoracic instrumentation. There was no relationship found between the development of post-operative cervical kyphosis or lordosis and ICR, which represents the quality and quantity of intervertebral motion. The T1 vertebra plays a key role for cervical, thoracic, and global parameters interaction.

[Lumbar spine injuries in pediatric and adolescent athletes]. / Cocuk ve ergen sporcularda lomber yaralanmalar.

During the past two decades, there has been a significant increase in sports participation by pediatric athletes. Spinal injuries thus have become a great concern. The unique nature of the pediatric spine should be well-recognized and low back pain in a pediatric athlete should therefore be taken seriously and evaluated thoroughly. In this review article, sports-related lumbar spine problems will be covered including overuse injuries, spondylolysis, pars stress fractures, spondylolysthesis, and lumbar disc herniation. Early identification of these problems will eventually minimize these injuries.

Expression of membrane-type matrix metalloproteinases 4, 5, and 6 in mouse corneas infected with P. aeruginosa.

PURPOSE: To investigate the expression and regulation of membrane-type matrix metalloproteinases (MT-MMPs) 4, 5, and 6 in the mouse corneas infected with Pseudomonas aeruginosa. METHODS: C57BL/6J mice were intracorneally infected with P. aeruginosa. The expression of MT4-, MT5-, and MT6-MMP was detected at both the mRNA and protein levels by RT-PCR and immunoblot analysis. Immunohistochemical staining was performed to localize the expression of MT4- and MT5-MMP in the mouse corneas. RESULTS: Expression of MT4- and MT5-MMP was detected in the normal (uninfected) cornea by RT-PCR and immunoblot analysis. When infected with P. aeruginosa, the corneas showed significant induction of each MT-MMP. Localization of MT4- and MT5-MMP revealed that the expression of MT5-MMP was restricted to the epithelial tissue in the normal cornea, whereas the induced expression of MT4- and MT5-MMP was predominantly in the substantia propria, which contained most of the infiltrating cells. MT6-MMP expression was not detected in the uninfected cornea but was upregulated in the infected corneas. CONCLUSIONS: Expression of MT4-, MT5-, and MT6-MMP was induced in corneas infected with P. aeruginosa. Immunohistochemistry showed predominant immunoreactivity of MT4- and MT5-MMP in the substantia propria. Previous histologic studies have revealed different patterns of inflammatory cell infiltration with an increased number of polymorphonuclear neutrophils (PMNs) during the early stage of inflammation and increased macrophages during the late stage. These results indicate a good correlation between the overexpression of the MT-MMPs in the infected corneas and the inflammatory response-that is, leukocyte infiltration-indicating that inflammatory cells such as macrophages and PMNs may play a role in the upregulation of MT-MMPs during corneal infection, which in turn can cause the destruction of corneal tissue.

Expression of cathepsins B, D and L in mouse corneas infected with Pseudomonas aeruginosa.

C57BL/6J naïve and immunized mice were intracorneally infected with Pseudomonas aeruginosa. Semi-quantitative RT-PCR was performed to detect cathepsin gene expression and the results were further confirmed by immunoblot analysis. The enzymatic activities of cathepsins B, D and L were measured by peptidase assays. Immunohistochemical staining was carried out to localize the expression of the cathepsins. Cathepsins B, D and L were detected in the normal cornea by RT-PCR. A peptidase assay revealed activities of all three cathepsins under normal physiological conditions. In naïve mice, enzymatic activities of cathepsins B, D and L were all significantly enhanced when the corneas were infected with P. aeruginosa and the peak of the induction appeared around day 6 postinfection. Immunoblot analysis showed increased expression of cathepsins B, D and L. The infected corneal samples from immunized mice exhibited much lower induction of enzymatic activities compared to those from naïve mice. Immunohistochemistry showed that the expression of cathepsins in the normal cornea was restricted to the epithelial tissue while the induced expression of cathepsins was predominantly in the substantia propria. Our data revealed up-regulated enzymatic activities of cathepsins B, D and L in the naïve corneas infected with P. aeruginosa, which correlated well with the inflammatory response. Immunization of mice against P. aeruginosa attenuated the inducing effect on cathepsin expression caused by infection. The time sequence for induction of cathepsin proteins and enzymatic activities suggests a mechanism of host proteolytic degradation of the extracellular matrix resulting in corneal destruction after P. aeruginosa infection.

A new method for detecting pedicular wall perforation during pedicle screw insertion.

STUDY DESIGN: Sensitivity, specificity, and predictive value analyses of a method that can be used to detect pedicular wall perforation during pedicle screw insertion were assessed. OBJECTIVE: To determine the accuracy of observing the fatty material expelled during pedicle screw insertion for detecting pedicular wall perforations. SUMMARY OF BACKGROUND DATA: Although many methods for safe and accurate insertion of a pedicle screw are described, the rates of misplacement still are high, and complications may occur from improper placement of pedicle screws. Computer-assisted insertion techniques are reported to be very accurate, but these techniques are not yet commonly available. METHODS: In this study, 74 pedicle screw insertions were observed for the material expelled after drilling for the pedicle screw. The outflows of blood and fatty particles were recorded separately. The position of the pedicle screws after surgery was verified by computed tomography. The specificity, sensitivity, positive and negative predictive values, and kappa statistics were assessed. RESULTS: Visible fatty particles were observed during 51 pedicle screw insertions. The histologic analysis showed that the fatty particles were coming from the bone marrow of the corpus. For the observation of fatty particles in detecting perforations along the pedicle screw pathway, the specificity was 98%, the sensitivity 73%, the positive predictive value 84%, the negative predictive value 95%, and the kappa statistic 0.74. CONCLUSIONS: The observation of fatty particles in the blood that comes out after drilling for the pedicle screw may indicate that there is no perforation along the pedicle screw pathway. The observation is easy to perform and does not require any special instruments. Therefore, it can be used alone or in combination with other methods to improve the accuracy of pedicle screw insertion.

Handgun sales, beer sales, and youth homicide, California, 1972-1993.

Whether regulating access to firearms and alcohol will reduce violent injuries is an important policy question. Empirical answers are difficult to obtain because only observational data are available. The present study estimated the association of firearm sales and alcohol sales with subsequent homicides, after adjusting statistically for potential confounders (e.g., unemployment rates) using California data from 1972 through 1993. Handgun sales and beer sales were lagged one year and used to explain variation in the homicides of Californians (e.g., 1990 sales were used to explain 1991 homicides). Differences across population groups were investigated, with a focus on 15- to 34-year-olds, the highest risk age group. Even when taking potential confounders in the base population into account, beer sales and handgun sales generally are associated positively one year later with homicide, particularly among young men. Reducing beer sales may reduce homicides. And, although they represent a small fraction of existing firearms, regulating the number of handguns sold may reduce the number of homicides.

Plasminogen Activators and Inhibitors in the Corneas of Mice Infected with Pseudomonas aeruginosa.

PURPOSE: To characterize the presence of plasminogen activators and their inhibitors in the corneas during the inflammatory response in naïve and immunized mice intracorneally infected with Pseudomonas aeruginosa. METHODS: RT-PCR was used to detect gene expression for plasminogen activators and their inhibitors in naïve and immunized mice. Immunoblot analysis, zymography, and ELISA were used to demonstrate the syntheses of these proteins. RESULTS: Naïve mice intracorneally infected with P. aeruginosa showed a temporally enhanced expression of tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA), its receptor (uPAR), and plasminogen activator inhibitors 1 and 2 (PAI-1 and PAI-2), over a several-day holding period. Immunized mice demonstrated a lower and shorter expression of these factors over the same period. Expression of these factors at the mRNA and protein levels may have been due to enzymes and inhibitors present in inflammatory cells and in resident corneal cells. CONCLUSIONS: These results show a correlation between the overexpression of the PA system in infected naïve mice as part of the inflammatory response, with eventual ocular destruction. Immunized mice exhibit a more balanced and shorter expression of the PA system, which may contribute to the restoration of corneal clarity.

Using a faculty evaluation triad to achieve evidence-based teaching.

Aneffective and comprehensive faculty evaluation system provides both formative and summative data for ongoing faculty development. It also provides data for annual faculty evaluation and tenure and promotion decision making. To achieve an effective system, a triad of faculty evaluation data sources--student ratings, teaching portfolio, and peer evaluation--were developed. Concurrently, a system of faculty mentorship was implemented, as well as an administrative structure to effectively use data to assist in merit pay and promotion decisions. Using a comprehensive, evidenced-based system to document, analyze, and improve teaching effectiveness is essential to assuring excellence in teaching and learning.

Membrane-type matrix metalloproteinases in mice intracorneally infected with Pseudomonas aeruginosa.

PURPOSE: To establish the presence of membrane-type matrix metalloproteinases (MT-MMPs) in the cornea and their expression in naive and immunized mice intracorneally infected with Pseudomonas aeruginosa. METHODS: Naive (unimmunized) and immunized C57BL/6J mice were infected with P. aeruginosa, and gene expression of MT-MMPs were detected by RT-PCR. Immunoblot analysis and immunostaining were also used to characterize the MT-MMP response in both sets of animals. RESULTS: Expression of MT1-MMP, MT2-MMP, and MT3-MMP (MMP 14, 15, and 16) was detected by RT-PCR and immunoblot analysis. Of the three MT-MMPs detected, MT1-MMP exhibited the greatest expression at protein levels. In general, a bell-shaped curve was obtained for each of the MT-MMPs in naive mice, but all of them showed much less expression in the immunized mice. MT1-MMP was localized in the epithelial tissue of the cornea, whereas MT2-MMP and MT3-MMP were mainly found in the interface between the epithelium and substantia propria. CONCLUSIONS: MT1-MMP was detected and expressed to a greater extent in naive mice than MT2-MMP and MT3-MMP. Peak expression of all three MT-MMPs showed a good correlation with the overall inflammatory response.

Measuring consumer experiences with primary care.

OBJECTIVE: To assess the adequacy of the Primary Care Assessment Tool-Child Edition (PCAT-CE) for evaluating the attainment of the key characteristics of primary care services for children and youth. DESIGN: Community-based telephone survey. SETTING: Specific political subdivision in Washington, DC. PARTICIPANTS: Four hundred fifty parents/guardians of offspring 18 years of age or less. MEASURES: Reliability, validity and principal component analysis of 5 scales representing key aspects of the 4 cardinal domains of primary care included in the PCAT-CE. In addition, 2 subdomains (first contact use and extent of affiliation with a primary care source) were included as indices to describe overall patterns of use and affiliation with the particular source of care. RESULTS: Most scales had adequate internal consistency, test-retest reliability, and construct validity. The principal components factor analysis yielded 5 separate factors. These corresponded to the subdomains of first contact accessibility; coordination of care; characteristics of the professional-patient relationship over-time; and comprehensiveness (both services available and indicated services received). CONCLUSIONS: Psychometric assessment supported the integrity and general adequacy of the PCAT-CE for assessing the characteristics and quality of primary care for children and youth. Testing of revised versions in a variety of different settings is underway. A major component of this testing is to explore the possibility of reducing the number of items while retaining sufficient detail about each component of primary care to make judgements about people's experiences with that care.

Measuring consensus about scientific research norms.

In this paper, we empirically explore some manifestations of norms for the conduct of science. We focus on scientific research ethics and report survey results from 606 scientists who received funding in 1993 and 1994 from the Division of Molecular and Cellular Biology of the Biology Directorate of the National Science Foundation. We also report results for 91 administrators charged with overseeing research integrity at the scientists' research institutions. Both groups of respondents were presented with a set of scenarios, designed by fractional factorial methods, describing different kinds of scientific conduct that in the eyes of some would likely be unethical. Respondents then were asked to evaluate each of these scenarios for how unethical the behavior might be and what kinds of sanctions might be appropriate. We use the responses to consider the nature of consensus around norms related to the practice of science and in particular, similarities and differences between scientists and science administrators. Implications for policy are also discussed.

Chondrosarcoma of the spine: 1954 to 1997.

OBJECT: Primary chondrosarcoma of the spine is extremely rare. During the last 43 years only 21 patients with this disease were registered at The University of Texas M. D. Anderson Cancer Center. The purpose of this study was to examine the demographic characteristics, treatments, and outcomes of this set of patients. METHODS: Medical records for 21 patients were reviewed. Age, sex, race, clinical presentation, tumor histology, tumor location in the spinal column, treatments, surgical details, and response to treatment were recorded. Surgical procedures were categorized as either gross-total resection or subtotal excision of tumor. Neurological function was assessed using Frankel's functional classification. Time to recurrence and survival analyses were performed using the Kaplan-Meier method. The median age of patients was 51 years, with fairly equal gender representation. Eighteen patients underwent at least one surgical procedure for a total of 28 surgical procedures: seven radical resections and 21 subtotal excisions. Radiation therapy was used in conjunction with 10 of the 28 surgical procedures. The median Kaplan-Meier estimate of overall survival for the entire group was 6 years (range 6 months-17 years). Tumors recurred after 18 of the 28 procedures. Kaplan-Meier analysis revealed a statistically significant difference in the per-procedure disease-free interval after gross-total resection relative to subtotal excision (exact log rank 3.39; p = 0.04). The addition of radiation therapy prolonged the median disease-free interval from 16 to 44 months, although this was not statistically significant (exact log rank 2.63; p = 0.16). CONCLUSIONS: Our results suggest that gross-total resection of the chondrosarcoma provides the best chance for prolonging the disease-free interval in patients. Subtotal excision should be avoided whenever possible. Addition of radiation therapy does not appear to lengthen significantly the disease-free interval in this patient population.

Reporting unethical research behavior.

Scientists, as professionals, have a responsibility to self-regulate. However, whistleblowing is rare. We investigated scientists' infrequent disclosure of unethical behavior by studying their responses to scenarios describing unethical research acts and compared their responses to those of research administrators. A cross-sectional survey was administered to National Science Foundation-funded principal investigators and their institutions' representatives (IRs) to the Office of Research Integrity. Both scientists and IRs proposed to respond to nearly all research behaviors that they rated as unethical. Scientists more often proposed responses limited to the research team (58% vs. 25% of cases, p < .001) whereas IRs more often proposed to inform an administrator or dean, journal editor, funding agency, professional society, or reporter. The prior behavior and academic rank of the scenario protagonist were associated with responses, but consequences of the unethical behavior were not. Scientists appear to perceive that they uphold their responsibility to respond to unethical behavior by disclosures within the research team, whereas administrators propose to report to externally accountable individuals, raising the question of whether scientists' behavior constitutes professional self-regulation or cover up.

Young guns: an empirical study of persons who use a firearm in a suicide or a homicide.

OBJECTIVES: The purpose of this investigation was to identify population groups at highest risk of using a firearm in a fatal incident. SETTING: Los Angeles County (California, USA). METHODS: Data were gathered from vital statistics reports and law enforcement records on the characteristics of suicide victims (n = 4799) and homicide suspects (n = 5369) from 1990 through 1994. Logistic regression was used to identify characteristics of the actor/perpetrator that were associated with firearm use. RESULTS: Persons less than 21 years old and males were more likely to use a firearm to kill themselves or someone else. Even when their other demographic attributes and characteristics of the incident itself were taken into consideration, persons under the age of 18 were substantially more likely than those 21 or more years old to use a firearm in the commission of a homicide (adjusted odds ratio = 2.59). Asians were less likely than white people to use a firearm in the commission of a suicide, whereas black people, Hispanics, and Asians were more likely than whites to use a firearm in the commission of a homicide. CONCLUSIONS: The US enacts and enforces some policies differentially by age. These data support the idea that such an approach may be warranted when addressing fatalities associated with the use of a firearm. Of particular interest, given minimum age requirements for firearm purchases, is the source of the weapons themselves.

Punishment for unethical behavior in the conduct of research.

PURPOSE: To investigate the perceptions of scientists and institutional representatives (IRs) to the National Institutes of Health's Office of Research Integrity concerning appropriate punishment for unethical research behavior. METHOD: In 1994-95, 606 scientists and 91 IRs rated the ethical behaviors of and suggested appropriate punishments for protagonists in randomly generated scenarios describing scientific research behaviors. The authors evaluated the relationships of the suggested punishments to the protagonists' behaviors and characteristics, and compared recommendations of the scientists and IRs. RESULTS: The respondents suggested punishments for 80% of the scenarios that were rated unethical. Punishments were more often prescribed for behaviors rated more unethical and for repeat offenders. The type of punishment was related to the protagonist's academic status and the nature of the unethical behavior. IRs proposed more and different punishments than did scientists. CONCLUSION: Scientists and IRs proposed that most unethical research behaviors be punished. The decision to punish depended on the unethical level of the behavior. The type of punishment depended on the aims: correcting the wrong, rehabilitation, or sanction. Variation in the respondents' selections of punishments and the IRs' greater propensity to punish suggest that scientists committing similar ethical violations may receive different punishments. Explicit consideration of which punishment is merited under what circumstances should be undertaken by the scientific community.

News media coverage and the epidemiology of homicide.

OBJECTIVES: This study assessed how newspaper coverage of homicides corresponds to the epidemiology of homicide. METHODS: Stories in the Los Angeles Times about homicide (n = 2782) were compared with the homicides that occurred in Los Angeles County from 1990 through 1994 (n = 9442). The generalized linear model assessed how victim, incident, and suspect characteristics related to coverage. RESULTS: Even when multiple variables were taken into account, some homicides (those with female, child, or elderly victims; those in which the suspect was a stranger to the victim; those in wealthier neighborhoods) received more coverage and others (those with Black or Hispanic victims or victims with less than a high school education; those committed with nonfirearm weapons; those in which the suspect was an intimate of the victim) received less coverage than expected. CONCLUSIONS: Some homicides are more newsworthy than others. Potential implications of not providing the public with representative data are discussed.

Consumer experiences and provider perceptions of the quality of primary care: implications for managed care.

BACKGROUND: The purpose of this study was to determine the extent to which consumer and provider reports of primary care differ according to particular characteristics of the primary care setting. METHODS: A random sample of consumers was surveyed by telephone in a defined geographic area of Washington, DC, to determine their experiences with care provided to a randomly chosen child. The primary care provider of each respondent was sent a parallel survey. Scores were obtained for each of two subdomains in the four cardinal primary care domains (first contact, longitudinality, comprehensiveness, and coordination) and for three related domains (family centeredness, community orientation, and cultural competence). Differences between settings that did or did not impose limitations on autonomy for referrals and between fee-for-service and capitated settings were ascertained. RESULTS: Both consumers and their providers in settings characterized by high degrees of limitation on physician autonomy or by capitation reported better first-contact accessibility and a greater range of services available than did consumers in settings with low degrees of limitation, or by fee-for-service reimbursements to physicians. Consumers but not providers reported better family centeredness in these settings. Most other differences favored these settings as well, but these were not consistently statistically significant for both providers and consumers in both types of settings. CONCLUSIONS: The quality of primary care services in different settings can be ascertained by using an instrument with demonstrated reliability and convergent validity. Although certain types of settings, in the particular geographic area studied, appear to perform better in several key aspects of the primary care, replication of the study in other areas would be useful judging the performance of the newer types of settings to be superior to more conventional care for general populations.

Evaluation of the research norms of scientists and administrators responsible for academic research integrity.

CONTEXT: The professional integrity of scientists is important to society as a whole and particularly to disciplines such as medicine that depend heavily on scientific advances for their progress. OBJECTIVE: To characterize the professional norms of active scientists and compare them with those of individuals with institutional responsibility for the conduct of research. DESIGN: A mailed survey consisting of 12 scenarios in 4 domains of research ethics. Respondents were asked whether an act was unethical and, if so, the degree to which they considered it unethical and to select responses and punishments for the act. PARTICIPANTS: A total of 924 National Science Foundation research grantees in 1993 or 1994 in molecular or cellular biology and 140 representatives from the researchers' institutions to the US Department of Health and Human Services Office of Research Integrity. MAIN OUTCOME MEASURES: Percentage of respondents considering an act unethical and the mean malfeasance rating on a scale of 1 to 10. RESULTS: A total of 606 research grantees and 91 institutional representatives responded to the survey (response rate of 69% of those who could be contacted). Respondents reported a hierarchy of unethical research behaviors. The mean malfeasance rating was unrelated to the characteristics of the investigator performing the hypothetical act or to its consequences. Fabrication, falsification, and plagiarism received malfeasance ratings higher than 8.6, and virtually all thought they were unethical. Deliberately misleading statements about a paper or failure to give proper attribution received ratings between 7 and 8. Sloppiness, oversights, conflicts of interest, and failure to share were less serious still, receiving malfeasance ratings between 5 and 6. Institutional representatives proposed more and different interventions and punishments than the scientists. CONCLUSIONS: Surveyed scientists and institutional representatives had strong and similar norms of professional behavior, but differed in their approaches to an unethical act.

The ethics of scientific research: an analysis of focus groups of scientists and institutional representatives.

BACKGROUND: Little is known about scientists' views on normative research ethics and how these compare with the views of the institutional representatives (IRs) involved in matters of scientific conduct. We qualitatively evaluated scientist and IR perceptions of the norms of science, ethical violations and their harms, factors contributing to violations, and approaches to improve scientific conduct. METHODS: Focus groups were conducted with National Science Foundation investigators and with IRs. Themes were extracted from observation, notes, and transcripts. Consensus and contrasts within and between groups were described. RESULTS: Scientists described a rich set of norms including honesty, integrity, service, sharing, openness, mentoring, and meticulous work habits. Institutional representatives focused on good citizenship and abiding by administrative rules. Both groups listed similar ethical violations, though scientists felt that severe violations were rare, that science was self-correcting, and that the greatest harm from misconduct disclosure was the loss of public trust and funding. Institutional representatives called for increased and less confidential misconduct investigations. Reporting misconduct was strongly supported by IRs but rejected by scientists. Both scientists and IRs believed that formal research ethics education was needed for trainees. CONCLUSIONS: Scientists in these focus groups upheld a complex set of norms that mirror prior codes of science and exceed national misconduct rules. The sharply contrasting views of scientists and IRs concerning responsibility to report misconduct, the utility of misconduct investigation, and penalties for misconduct highlight areas where open discussion and constructive resolution are needed to formulate a functional mechanism to enhance the ethical conduct of science.

In vivo characterization of host and bacterial protease expression during Pseudomonas aeruginosa corneal infections in naive and immunized mice.

PURPOSE: The corneal destruction resulting from P. aeruginosa keratitis is thought to be due, in part, to the actions of host and bacterial proteases on corneal tissue. The intent of the current study was to compare host and bacterial protease expression in the ocular tissues of mice that have been shown to be susceptible to corneal infection with mice that have been protected from such infection as a result of prior immunization. METHODS: Supernatants of infected corneal homogenates from naive mice or from mice immunized as a result of prior corneal infection or that had been immunized against bacterial protease were analyzed by gelatin zymography for the presence of host gelatinases and bacterial proteases at various times after infection. In addition, studies were carried out to examine the effect of immunization with bacterial protease on numbers of ocular bacteria. RESULTS: Mice that were protected against the tissue destruction during infection were found to have reduced proteolytic activity in corneal tissues when compared with susceptible mice. More specifically, the resistant mice displayed lower levels of bacterial alkaline protease, latent MMP-2, and both the active and latent forms of MMP-9. In addition, immunization against either bacterial alkaline protease or elastase failed to reduce bacterial numbers in ocular tissues from 6 to 72 hours after infection. CONCLUSIONS: These results suggest that increased proteolytic activity in ocular tissues during P. aeruginosa infection may contribute to the irreversible corneal damage observed during the infection.