Characterization of intentional lurasidone ingestions using the United States National Poison Data System

Introduction: The ziprasidone analogue lurasidone is approved for the treatment of schizophrenia and bipolar disorder for adults and children older than 10 years. Small studies and case reports suggest lurasidone overdose is not generally associated with major adverse effects, but no large sample has been published.Objective: To describe intentional lurasidone overdoses reported to poison centers.Methods: Retrospective analysis of single-substance intentional lurasidone ingestions from the National Poison Data System (NPDS) from 2011 to 2018.Results: There were 1753 single-substance intentional overdoses. Average age was 28.6 years (SD = 13.3 years) and 1199 (68.4%) of patients were female. Most cases (86.6%) were coded as suspected suicide. Regarding final management site, 1143 (65.2%) were discharged or admitted to psychiatric facilities; 328 (18.8%) were admitted, half of whom were admitted to critical care units (CCUs). Major effect was coded in 12 (0.7%), moderate effect in 259 (14.8%), minor effect in 531 (30%), and no effect in 614 (35%). There were no deaths. For cases for which dose information was available, there was not a statistically significant difference between median doses when analyzed by clinical effect. Most common adverse effects were drowsiness (449, 25.6%), tachycardia (254, 14.5%), vomiting (121, 6.9%), and hypertension (115, 6.6%). Most cases had either no therapy reported, or therapy was recommended by the poison center but confirmed not to have been administered (1010, 57.6%). Of the 164 patients admitted to CCUs, 80 (48.8%) received either no therapy or intravenous fluids alone.Discussion: These data suggest major effects are uncommon from lurasidone overdose. Despite a high rate of admission to CCUs, a substantial proportion received no critical therapies.Conclusions: This report demonstrates intentional lurasidone overdoses reported to poison centers generally have a favorable clinical course.

Extracellular matrix determinants and the regulation of cancer cell invasion stratagems

During development, wound repair and disease-related processes, such as cancer, normal, or neoplastic cell types traffic through the extracellular matrix (ECM), the complex composite of collagens, elastin, glycoproteins, proteoglycans, and glycosaminoglycans that dictate tissue architecture. Current evidence suggests that tissue-invasive processes may proceed by protease-dependent or protease-independent strategies whose selection is not only governed by the characteristics of the motile cell population, but also by the structural properties of the intervening ECM. Herein, we review the mechanisms by which ECM dimensionality, elasticity, crosslinking, and pore size impact patterns of cell invasion. This summary should prove useful when designing new experimental approaches for interrogating invasion programs as well as identifying potential cellular targets for next-generation therapeutics.

Assessing natural and disturbed population structure in European grayling Thymallus thymallus: melding phylogeographic, population genetic and jurisdictional perspectives for conservation planning

Natural and human-mediated population structure of European grayling Thymallus thymallus was assessed in primarily Austrian reaches of the Danube River catchment. Data on phylogeographic structure based on mitochondrial DNA (mtDNA) were combined with variation found across 13 microsatellite loci to assess introgression stemming from stocking activities. Populations north of the Alps generally showed no signs of long-term introgression from allochthonous stocks, although one population comprised two distinct genotypic groups, one of which may stem from recently stocked material. South of the Alps, levels of introgression with stocks from the north were extensive and only one of six populations is believed to represent a reference state. Allelic diversity and expected heterozygosity were positively correlated with mtDNA admixture supporting more recent introgression and that there is little or no reproductive barrier between these two major lineages north and south of the Alps. A third unrelated mtDNA lineage is described from the Lafnitz, a tributary of the Raab drainage. The high lineage diversity in the upper Austrian Danube is not concordant with an existing model of T. thymallus evolutionarily significant units in Europe. Caveats in naming such units or following a strict hierarchical conservation unit structure for broadly distributed species with complex phylogeographic distributions stretching over various jurisdictions are discussed. The necessity of using both phylogeographic and population genetic approaches in evaluating the history and conservation value of populations in a conservation context is additionally highlighted.

Discriminated response and incentive processes in operant conditioning: a two-factor model of stimulus control

Understanding stimulus control generated in instrumental learning requires the direct investigation of discriminated response and reinforcer (incentive) processes acquired exclusively through the response-reinforcer contingencies operating on complex (multicomponent) baselines. Two series of stimulus-compounding studies accomplished this direct investigation. In one series, the independent variable was the relative reinforcement between schedule components; in the second series, it was relative response rate between components. Stimulus-compounding tests revealed that response and incentive processes enhanced each other when in agreement, counteracted each other when in opposition, and produced intermediate results when only one factor was operating. This pattern of results led to the conclusion that these factors were algebraically combining and to the development of a response/incentive matrix reflecting these dynamics. This two-factor analysis was extended to the peak-shift effect in stimulus generalization experiments and to the generation of inhibitory control. Two decades of stimulus compounding and peak-shift research were organized within this two-factor framework, extending this traditional approach to learning to active research areas heretofore not systematically considered in these terms.

The effect of reinforcement differences on choice and response distribution during stimulus compounding

In Experiments I and II, rats were trained to respond on one lever during light and another during tone. The absence of tone and light controlled response cessation. In the multiple schedule of Experiment I, all reinforcements were received for responding in tone or light; in the chain schedule of Experiment II, all reinforcements were received in no tone + no light for not responding. Experiment I subjects, for which tone and light were associated with response and reinforcement increase, responded significantly more to tone-plus-light than to tone or light alone (additive summation). Experiment II subjects, for which tone and light were associated with response increase and reinforcement decrease, responded comparably to tone, light, and tone + light. Thus, additive summation was observed when stimulus-response and stimulus-reinforcer associations in tone and light were both positive, but not when they were conflicting. All subjects in both experiments responded predominantly on the light-correlated lever during tone + light, even when light intensity was reduced in testing. Furthermore, when a light was presented to a subject engaged in tone-associated responding, all subjects immediately switched the locus of responding to the light-correlated lever. No change in locus occurred when a tone was presented to a subject engaged in light-associated responding, irrespective of the stimulus-reinforcer association conditioned to tone. The light-lever preference in tone + light indicates that the heightened responding observed in Experiment I was not the summation of tone-associated behavior with light-associated behavior. Rather, it appears to be the result of a facilitation of one operant (light-associated responding) by the reinforcement-associated cue for the other.

Generalization peak shift in rats under conditions of positive reinforcement and avoidance

Rats were trained to discriminate between two click frequencies. One frequency was associated with either variable-interval food reinforcement (Experiment 1) or free-operant avoidance (Experiment 2). The other frequency was associated with the absence of food in Experiment 1 and the absence of shock in Experiment 2. On a click frequency generalization test, the rats in both experiments showed positive peak shift with the shape of the relative gradients being very similar. This is the first reported instance of peak shift in rats when responding was maintained by an avoidance contingency. Nondifferentially trained controls showed that this shift was due exclusively to associative processes, with nonassociative stimulus factors in themselves apparently making no contribution to increased rates at particular stimulus values. These results show the comparability of appetitive and aversive control and support the position that gradient differences do not result from approach versus avoidance per se.

Discrimination training and stimulus compounding: consideration of non-reinforcement and response differentiation consequences of S

In Exp. 1, four rats were trained on a two-component multiple schedule with tone and light each associated with different variable-interval schedules. Extinction in light-out no-tone, common to previous studies reporting additive summation to compounded discriminative stimuli, was omitted from training. In testing, the simultaneous presentation of tone and light controlled a response rate intermediate between that controlled by these stimuli presented singly. In Exp. 2, animals were trained on three-ply multiple schedules. While tone and light were each associated with variable-interval schedules for both groups, light-out no-tone signalled extinction for one and differential-reinforcement-of-behavior-other-than-bar-pressing for the other. This permitted response reduction during light-out no-tone to be viewed independently of non-reinforcement. Responding of both groups showed summation to tone plus light in testing, with the effect clearly larger for extinction-trained subjects. These experiments indicate that: (1) discrimination training afforded by extinction has been integral to additive summation previously reported, (2) response differentiation and non-reinforcement consequences of extinction training contribute to the magnitude of summation, and (3) summation and peak shift might be functionally related phenomena.

Compounding discriminative stimuli controlling free-operant avoidance

The performances of three rats were stabilized on a multiple schedule that maintained responding by a free-operant avoidance schedule during independent presentations of tone and light. The simultaneous absence of these stimuli signalled shock-free periods and controlled response cessation. Subsequently, test sessions were administered consisting of independent presentations of each stimulus and these stimuli compounded (tone-plus-light). During an extinction test, additive summation was observed to the compounded stimuli, i.e., more responses were emitted to the compound than to either tone or light. During a series of 28 maintenance-test sessions in which the shock schedule remained operative, the compounded stimuli produced a generally enhanced response rate and fewer pauses terminating with shock than either single stimulus condition. These results extend the generality of free-operant additive summation to responding maintained by aversive control. In addition, a comparison of the present study with previous experiments reporting additive summation of positively reinforced responding indicates that similar variables-rate and aversive differences between training stimulus conditions-should be considered in accounting for response distributions during stimulus compounding when responding is controlled by either positive or negative contingencies.

Nanolitre liquid patterning in aqueous environments for spatially defined reagent delivery to mammalian cells

Microscale biopatterning enables regulation of cell-material interactions and cell shape, and enables multiplexed high-throughput studies in a cell- and reagent-efficient manner. The majority of available techniques rely on physical contact of a stamp, pin, or mask with mainly a dry surface. Inkjet and piezoelectric printing is carried out in a non-contact manner but still requires a substantially dry substrate to ensure fidelity of printed patterns. These existing methods, therefore, are limited for patterning onto delicate surfaces of living cells because physical contact or substantially dry conditions are damaging to them. Microfluidic patterning with laminar streams does enable non-contact patterning in fully aqueous environments but with limited throughput and reagent diffusion across interfacial flows. Here, we describe a polymeric aqueous two-phase system that enables patterning nanolitres of a reagent-containing aqueous phase, in arbitrary shapes, within a second aqueous phase covering a cell monolayer. With the appropriate medium formulation, reagents of interest remain confined to the patterned phase without significant diffusion. The fully aqueous environment ensures high reagent activity and cell viability. The utility of this strategy is demonstrated with patterned delivery of genetic materials to mammalian cells for phenotypic screening of gene expression and gene silencing.

Regulation of membrane-type matrix metalloproteinase 1 activity by dynamin-mediated endocytosis

Membrane-type matrix metalloproteinase 1 (MT1-MMP) plays a critical role in extracellular matrix remodeling under both physiological and pathological conditions. However, the mechanisms controlling its activity on the cell surface remain poorly understood. In this study, we demonstrate that MT1-MMP is regulated by endocytosis. First, we determined that Con A induces proMMP-2 activation in HT1080 cells by shifting endogenous MT1-MMP from intracellular compartments to cell surface. This phenotype was mimicked by the cytoplasmic truncation mutant MT1 Delta C with more robust pro-MMP-2 activation and cell surface expression than wild-type MT1-MMP in transfected cells. MT1 Delta C was subsequently shown to be resistant to Con A treatment whereas MT1-MMP remains competent, suggesting that Con A regulates MT1-MMP activity through cytoplasmic domain-dependent trafficking. Indeed, MT1-MMP was colocalized with clathrin on the plasma membrane and with endosomal antigen 1 in endosomes. Internalization experiments revealed that MT1-MMP is internalized rapidly in clathrin-coated vesicles whereas MT1 Delta C remains on cell surface. Coexpression of a dominant negative mutant of dynamin, K44A, resulted in elevation of MT1-MMP activity by interfering with the endocytic process. Thus, MT1-MMP is regulated by dynamin-dependent endocytosis in clathrin-coated pits through its cytoplasmic domain.

Creative arterial bypass grafting can be performed on the beating heart

BACKGROUND

To demonstrate that compromise is unnecessary in either the design or performance of beating heart surgery, we report our experience, over 1 year, of total arterial revascularization where composite or creative grafting was utilized.

METHODS

We performed 321 off-pump coronary artery bypass operations, of which, 290 (90%) were done with only arterial conduits. The mean number of distal anastomoses was 2.48, with a range of 1 to 5. There were no aortic anastomoses. One hundred eighty-nine patients (65%) were male, and 101 (35%) were female, with a mean age of 67 years. Comorbidities included chronic renal failure (CRF), 21 (7%); diabetes, 92 (32%); obesity, 68 (23%); hypertension, 212 (73%); chronic obstructive pulmonary disease, 189 (65%); cerebral vascular accident (CVA), 39 (13%); smoking, 164 (56%); and hypercholesterolemia, 151 (52%). The mean ejection fraction was 56%, with a range of 21% to 71%. All procedures were performed with external stabilizers with or without vacuum assist. The complete arterial revascularizations included a T-graft (internal thoracic [ITA]/radial arteries [RA]), 130 (45%); a sequential graft (ITA +/- RA), 118 (41%); a U-graft (coronary-coronary graft perfused by the ITA or right gastroepiploic artery), 5 (2%); an I-graft (ITA/RA), 4 (1%); an X-graft (ITA/RA), 2 (12); and a Y-graft (ITA/RA), 31 (10%).

RESULTS

The postoperative incidence of atrial fibrillation was 80 of 290 (27%); CVA, 5 of 290 (2%); bleeding resulting in take-back, 5 of 290 (2%); CRF, 8 of 290 (3%); deep sternal infection, 4 of 290 (1%); and readmission (30-day) for angina, 4 of 290 (1%). The observed perioperative (30-day) mortality was 9 of 290 (3.1%), with the STS predicted rate of 3.82%.

CONCLUSIONS

Our experience indicates that once the operating surgeon has learned to safely expose the lateral and inferior walls of the heart, the type of conduit and the method of revascularization should be no different than that used with cardiopulmonary bypass. However, we still recommend conventional methods of revascularization (on-pump with saphenous vein conduits) for the ischemic patient.

Nitric oxide inhibition increases matrix metalloproteinase-9 expression by rat aortic smooth muscle cells in vitro

OBJECTIVE

The hypothesis to be tested was that diminished bioavailable nitric oxide (NO) affects matrix metalloproteinase (MMP) expression and activation in vascular smooth muscle cells (SMCs).

METHODS

Cultivated rat aortic SMCs (RA-SMCs) were exposed to increasing concentrations of L-N-monomethyl arginine (L-NMMA), a nonselective inhibitor of NO synthase, in the presence of proinflammatory cytokines (50 ng/mL interleukin [IL]-1beta, 50 ng/mL interferon-gamma, and 30 microg/mL lipopolysaccharide). Nitrite and nitrate, two of the final end products of NO metabolism, were measured in media collected at 48 hours with the use of the Saville assay (n = 4). MMP activity was measured with 1% gelatin zymography (n = 4). In separate experiments in which 2 ng/mL of IL-1beta and L-NMMA was used, MMP protein and messenger RNA (mRNA) levels were determined with Western blot analysis (n = 3) and semiquantitative reverse transcriptase-polymerase chain reaction (n = 3), respectively. Data were analyzed with nonparametric analysis of variance.

RESULTS

Increasing concentrations of the NO synthase inhibitor L-NMMA caused a dose-dependent decrease (P <.05) in nitrite and nitrate production by RA-SMCs after cytokine exposure. Zymography documented an early dosedependent increase (P <.05 compared with cytokines alone) in 92-kd MMP activity, with no significant changes in 72-kd MMP activity after treatment with L-NMMA (P >.05 compared with cytokines alone). Reverse transcriptase-polymerase chain reaction and Western blot analysis revealed that the addition of L-NMMA to IL-1beta-stimulated RA-SMCs led to significant increases in MMP-9 mRNA (n = 3, P <.01 for 1.0 mmol/L L-NMMA) and MMP-9 protein levels (n = 3, P <.05), respectively. No differences in MMP-2 mRNA or protein levels were demonstrated.

CONCLUSIONS

Inhibition of cytokine-induced NO expression in RA-SMCs is associated with a selective, dose-dependent increase in MMP-9 expression and synthesis. These findings suggest that alterations in local NO synthesis may influence MMP-9-dependent vessel wall damage.

Role of stromelysin 1 and gelatinase B in experimental acute lung injury

Matrix metalloproteinases (MMPs) are upregulated locally in sites of inflammation, including the lung. Several MMP activities are upregulated in acute lung injury models but the exact role that these MMPs play in the development of the lung injury is unclear due to the absence of specific inhibitors. To determine the involvement of individual MMPs in the development of lung injury, mice genetically deficient in gelatinase B (MMP-9) and stromelysin 1 (MMP-3) were acutely injured with immunoglobulin G immune complexes and the intensity of the lung injury was compared with genetically identical wild-type (WT) mice with normal MMP activities. In the WT mice there was upregulation of gelatinase B and stromelysin 1 in the injured lungs which, as expected, was absent in the genetically deficient gelatinase B- and stromelysin 1-deficient mice, respectively. In the deficient mice there was little in the way of compensatory upregulation of other MMPs. The gelatinase B- and the stromelysin 1-deficient mice had less severe lung injury than did the WT controls, suggesting that both MMPs are involved in the pathogenesis of the lung injury. Further, the mechanism of their involvement in the lung injury appears to be different, with the stromelysin 1-deficient mice having a reduction in the numbers of neutrophils recruited into the lung whereas the gelatinase B-deficient mice had the same numbers of lung neutrophils as did the injured WT controls. These studies indicate, first, that both gelatinase B and stromelysin 1 are involved in the development of experimental acute lung injury, and second, that the mechanisms by which these individual MMPs function appear to differ.

Predictors of cardiac patients' psychophysiological responses to caregiving

Patients who are hospitalized for treatment of cardiac problems are at risk from life-threatening cardiovascular changes related to autonomic nervous system (ANS) arousal. Physical care during hospitalization can increase ANS arousal, yet caregiving is an essential feature of patient treatment. The purpose of this study was to identify the degree to which a patient's vulnerability to sensory stimuli, perceptions of previous caregiving and stressful events during hospitalization may contribute to ANS arousal during caregiving. Fifty-nine patients, who were hospitalized for treatment of coronary artery or valvular disease, received a standardized protocol designed to simulate aspects of physical caregiving. Heart rate, incidence of arrhythmias, blood pressure and state anxiety were measured during the protocol to determine ANS arousal. Regression analyses provided evidence that sensory vulnerability was the most consistent predictor across all indices of arousal during caregiving. Previous caregiving experiences that were perceived as 'negative' by the patient also contributed to higher blood pressure and anxiety. Stressful hospital events involving the family predicted higher blood pressure during caregiving.

Use, understanding, and beliefs about complementary and alternative medicines among emergency department patients

OBJECTIVES

To describe the extent of complementary and alternative medicine (CAM) use among emergency department (ED) patients, to evaluate patients' understanding of CAMs, and to determine gender differences in beliefs about CAMs.

METHODS

This study was a convenience sampling of patients seen in an urban ED. Patient demographics were recorded. A questionnaire was administered that assessed patients' knowledge and use of CAMs. Patients were also asked about their beliefs on safety, medication interactions, and conveying information about these substances to their physicians.

RESULTS

A total of 350 ED patients were included in the study; 87% had heard of at least one of the CAMs. There was no difference between genders or races concerning knowledge about CAMs. The most commonly known CAMs were ginseng (75%), ginkgo biloba (55%), eucalyptus (58%), and St. John's wort (57%). Forty-three percent of the responders had used CAMs at some time and 24% were presently using CAMs. The most commonly used CAMs were ginseng (13%), St. John's wort (6%), and ginkgo biloba (9%). All CAMs were considered to be safe by 16% of the patients. Only 67% would tell their doctors they were using CAMs. Females were more likely than males to believe that CAMs do not interact with other medications (15% vs 7%, difference 8%, 95% CI = 2% to 15%).

CONCLUSIONS

Complementary and alternative medicines are familiar to most patients and used by many of them. Despite this, a large percentage of patients would not tell their physicians about their use of alternative medications. Emergency medicine providers should be aware of the commonly used CAMs, and questions about their use should be routinely included in ED exams.

Deep hypothermic circulatory arrest: II. Changes in electroencephalogram and evoked potentials during rewarming

BACKGROUND

Electrophysiologic studies during rewarming after deep hypothermic circulatory arrest probe the state of the brain during this critical period and may provide insight into the neurological effects of circulatory arrest and the neurologic outcome.

METHODS

Electroencephalogram (EEG) and evoked potentials were monitored during rewarming in 109 patients undergoing aortic surgery with hypothermic circulatory arrest.

RESULTS

The sequence of neurophysiologic events during rewarming did not mirror the events during cooling. The evoked potentials recovered first followed by EEG burst-suppression and then continuous EEG. The time to recovery of the evoked potentials N20-P22 complex was significantly correlated with the time of circulatory arrest even in patients without postoperative neurologic deficits (r = 0.37, (p = 0.002). The nasopharyngeal temperatures at which continuous EEG activity and the N20-P22 complex returned were strongly correlated (r = 0.44, p = 0.0002; r = 0.41, p = 0.00003) with postoperative neurologic impairment. Specifically, the relative risk for postoperative neurologic impairment increased by a factor of 1.56 (95% CI 1.1 to 2.2) for every degree increase in temperature at which the EEG first became continuous.

CONCLUSIONS

No trend toward shortened recovery times or improved neurologic outcome was noted with lower temperatures at circulatory arrest, indicating that the process of cooling to electrocerebral silence produced a relatively uniform degree of cerebral protection, independent of the actual nasopharyngeal temperature.

A comparison of rural and urban ambulance crashes

Ambulance crashes are a significant safety issue both to the EMTs and to patients transported in the vehicle. Safety issues are dependent on the environment and may be different in rural and urban settings. Ambulance crashes reported to the State EMS bureau during the years of 1993 to 1997 were evaluated. Counties with >250,000 population were considered urban. State population was 2 million urban and 2.8 million rural. Two investigators determined first if the crash was urban or rural. Outcome information was extracted on the degree of injury, citations given, and information on the ambulance and other vehicle condition. In addition, independent variables of weekend versus weekday, day versus night, posted speed, weather, road condition (wet versus dry), intersections, and use of seat belts were extracted. Results were compared using a 2-tailed Chi-square or Fisher's exact with significance at P <.05. Relative risks and 95% confidence intervals were calculated for each variable. There were a total of 183 Ambulance crashes, 115 urban (19/million pop/yr), and 68 rural (8/million pop/yr). Significantly lower percentage of injury crashes occurred in the urban setting (OR = 0. 49, 95% CI = 0.24 to 0.98) with fewer of these considered "severe" (OR = 0.0, 95% CI = 0.0 to 0.73). Citations were more likely to be issued to the urban ambulance driver (OR = 4.95, 95% CI = 1.09 to 45. 70) and the other urban vehicle driver (OR = 3.65, 95% CI = 1.37 to 11.31). However, the urban ambulance was less likely to be damaged (OR = 0.24, 95% CI = 0.10 to 0.55), disabled (OR = 0.41, 95% CI = 0. 20 to 0.84), or towed (OR = 0.40, 95% CI = 0.20 to 0.83). In the urban setting fewer vehicles were traveling in areas with posted speeds >54 mph (OR = 0.24, 95% CI = 0.06 to 0.78) and nonrestrained people were less likely to be injured (OR = 0.28, 95% CI = 0.06 to 1. 25). For injured persons there was no difference in independent variables in the urban versus rural settings. Although the rate of ambulance injuries was greater in the urban environment, the severity of the injuries was worse in the rural environments where crashes occurred at higher posted speeds. In the rural setting nonrestrained passengers were more likely to be injured.

Visits to home environments by emergency medical services: a statewide study

Understanding out-of-hospital transport demographics would clarify the opportunities for injury surveillance and prevention.

OBJECTIVE

To test the hypotheses that there are demographic differences in home vs. non-home emergency medical services (EMS) scene transports and that among age groups there are differences in demographics.

METHODS

Data were extracted from the EMS State Ambulance Transport database of all reported during 1995. Transports from patient homes were compared with transports from all non-home scenes. Data extracted included age, gender, race, and type of complaint. Subgroup analysis was performed based on age groups in nonvehicular cases, safety problems, and interpersonal violence. Results were compared using a two-tailed chi-square with significance at p<0.05. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated for significant differences.

RESULTS

The study included 118,131 transported patients: 13% were children, 49% were adult between 18 and 64 years, and 38% were elder; 13% were African American, 82% were white, and 5% were other; 47% were male and 53% were female. Fifty-eight percent of the transports were for safety problems, and 17% were for interpersonal violence. Of the 118,131 transports, 56,812 (48%) were from patients' homes and 61,319 were not. Compared with EMS transports from non-home scenes, fewer home EMS transports were for injury (p<0.01, OR = 0.18, 95% CI = 0.17-0.19) and more home EMS transports were for illness (p<0.01, OR = 5.64, 95% CI = 5.49-5.79). There was no clinically significant difference in age, race, or gender. For all non-vehicular injury transports, the reason was more likely safety problems than interpersonal violence (58% vs. 17%); however, there was no difference in the percentages of type of call between the home and non-home transports. Home EMS transports were more likely interpersonal violence problems among adult patients less than 65 years old; however, among the old and young, the problems were more likely to be safety-related.

CONCLUSION

Forty-eight percent of all EMS transports are from the home. Only 18% of these EMS home transports are for injury-related problems. In general, EMS injury transports are more likely related to safety than to interpersonal violence. Among the home EMS transports, more than 50% of transports for young and old patients are safety-related. A large proportion of the home EMS transports for adults less than 65 years of age, however, are for interpersonal violence.

Deep hypothermic circulatory arrest: I. Effects of cooling on electroencephalogram and evoked potentials

BACKGROUND

Deep hypothermia is an important cerebral protectant and is critical in procedures requiring circulatory arrest. The purpose of this study was to determine the factors that influence the neurophysiologic changes during cooling before circulatory arrest, in particular the occurrence of electrocerebral silence.

METHODS

In 109 patients undergoing hypothermic circulatory arrest with neurophysiologic monitoring, five electrophysiologic events were selected for detailed study.

RESULTS

The mean nasopharyngeal temperature when periodic complexes appeared in the electroencephalogram after cooling was 29.6 degrees C +/- 3 degrees C, electroencephalogram burst-suppression appeared at 24.4 degrees C +/- 4 degrees C, and electrocerebral silence appeared at 17.8 degrees C +/- 4 degrees C. The N20-P22 complex of the somatosensory evoked response disappeared at 21.4 degrees C +/- 4 degrees C, and the somatosensory evoked response N13 wave disappeared at 17.3 degrees C +/- 4 degrees C. The temperatures of these various events were not significantly affected by any patient-specific or surgical variables, although the time to cool to electrocerebral silence was prolonged by high hemoglobin concentrations, low arterial partial pressure of carbon dioxide, and by slow cooling rates. Only 60% of patients demonstrated electrocerebral silence by either a nasopharyngeal temperature of 18 degrees C or a cooling time of 30 minutes.

CONCLUSIONS

With the high degree of interpatient variability in these neurophysiologic measures, the only absolute predictors of electrocerebral silence were nasopharyngeal temperature below 12.5 degrees C and cooling longer than 50 minutes.

Breast cancer knowledge and preventive behaviors: An urban emergency department-based survey

OBJECTIVE

To assess general knowledge and preventive behaviors regarding breast cancer among women who present to an urban emergency department.

METHODS

During a six-month study period, a convenience sampling of women aged 21 years and older who were in treatment and waiting areas was surveyed. The anonymous written survey asked about demographic variables, knowledge, and preventive behaviors regarding breast cancer. Knowledge was assessed with questions about the recommended frequency of breast self-examination and the recommended age for first mammography. Performance was assessed by questions about breast self-exam and mammography. Subgroup analysis was done by age (above and below 40 years old), race, income (above and below the median), insurance type, history of breast lump, and family history (FH) of breast cancer.

RESULTS

Four hundred women completed surveys. Two hundred twelve (53%) correctly knew the answers to the two knowledge questions. Knowledge was greater in women with private insurance. Knowledge of the frequency of breast self-exam was significantly greater among whites and Native Americans than among African Americans, Asians, or Hispanics. Stated performance of preventive behaviors was 72% (288) for breast self-exam and for mammography. Preventive behaviors were significantly more likely to be performed by higher-income and privately-insured women. Breast self-exam was more likely to be done in older women, those with a history of a breast lump, and those with a FH of breast cancer.

CONCLUSIONS

Women with lower income and without private insurance were less likely to be knowledgeable and practice preventive measures for detecting breast disease.

Effectiveness of forced air warming after pediatric cardiac surgery employing hypothermic circulatory arrest without cardiopulmonary bypass

STUDY OBJECTIVE

To evaluate the effectiveness of forced-air warming compared to radiant warming in pediatric cardiac surgical patients recovering from moderate hypothermia after perfusionless deep hypothermic circulatory arrest.

DESIGN

Prospective unblinded study. SETIING: Teaching hospitals.

PATIENTS

24 pediatric cardiac surgical patients.

INTERVENTION

Noncyanotic patients undergoing repair of atrial or ventricular septal defects were cooled by topical application of ice and rewarmed initially in the operating room by warm saline lavage of the pleural cavities. On arrival at the intensive care unit (ICU), patients were warmed by forced air (n = 13) or radiant heat (n = 11). The time, heart rate, and blood pressure at each 0.5 degrees C increase in rectal temperature were measured until normothermia (36.5 degrees C) to determine the instantaneous rewarming rate.

MEASUREMENTS AND MAIN RESULTS

Baseline characteristics were not different in the two groups. The mean (+/- SD) age was 5.6 +/- 3.4 years, weight was 20 +/- 8 kg, esophageal temperature for circulatory arrest was 25.7 +/- 1.3 degrees C, and duration of circulatory arrest was 25 +/- 11 minutes. The mean core temperature on arrival at the ICU was 29.9 +/- 1.3 degrees C and ranged from 26.1 to 31.5 degrees C. The mean rewarming rate for each 0.5 degrees C was greater (p < 0.05) for forced-air (2.43 +/- 1.14 degrees C/hr) than radiant heat (2.16 +/- 1.02 degrees C/hr). At core temperatures <33 degrees C, the rewarming rate for forced-air was 2.04 +/- 0.84 degrees C/hr and radiant heat was 1.68 +/- 0.84 degrees C/hr (p < 0.05). At core temperatures > or = 33 degrees C, the rewarming rate for forced air was 2.76 +/- 1.20 degrees C/hr and radiant heat was 2.46 +/- 1.08 degrees C/min (p = 0.07). Significant determinants of the rewarming rate in a multivariate regression model were age (p < 0.001), temperature (p < 0.05), time after arrival to the intensive care unit (p < 0.05), pulse pressure (p < 0. 05) and warming device (p < 0.001). The duration of ventilatory support and ICU length of stay was not different in the two groups.

CONCLUSIONS

Both forced-air and radiant heat were effective for rewarming moderately hypothermic pediatric patients. When core temperature was less than 33 degrees C, the instantaneous rewarming rate by forced air was 21% faster than by radiant heat.

The utility of anoscopy and colposcopy in the evaluation of male sexual assault victims

STUDY OBJECTIVE

We sought to compare the use of anoscopy and colposcopy in examinations of male sexual assault victims and to characterize the demographics of male sexual assault victims.

METHODS

This is a case series of 67 male sexual assault victims evaluated over an 8-year period by the Sexual Assault Forensic Examination team. The setting is a university-based emergency department serving as the primary site for examination of sexual assault victims by trained nurse practitioners and physician's assistants. Police and victims' advocates are available at the time of the examination. Anoscopy was done routinely over the entire study period in all patients with any anal penetration or involvement. Colposcopy use started in 1994 to magnify and take pictures. Patients were categorized into 2 groups. Group 1 consisted of subjects receiving only anoscopy, and group 2 consisted of subjects receiving initial colposcopy. Anoscopy in group 1 and colposcopy in group 2 were compared for positive results. A positive result was defined as an additional finding to those obtained by means of gross examination by using the test being evaluated (anoscopy versus colposcopy). Colposcopy and anoscopy were also compared among the subjects receiving both tests. Groups were compared by using a Pearson chi(2) test.

RESULTS

Sixty-seven male sexual assault victims were evaluated between 1991 and 1998. The average age was 26+/-8 years, and the distribution of races was 30% black, 62% white, and 8% Hispanic. Results of gross examination were positive in 42 (63%) subjects. Four patients did not receive either anoscopy or colposcopy. Of the remaining 63, 25 patients had anoscopy only (group 1), and 38 patients had initial colposcopy (group 2). There were no significant differences in age, race, or rate of positive gross examination results between groups. Findings in addition to those obtained by means of gross examination were revealed by means of anoscopy in 8 (32%) of 25 subjects in group 1 and colposcopy in 3 (8%) of 38 subjects in group 2 (P =.03, difference 24%, 95% confidence interval 4% to 44%). In the 36 subjects who had both examinations, the gross examination revealed at least one finding in 22 (61%). The combination of anoscopy and colposcopy yielded positive findings in 17 subjects, including 4 subjects who had no findings on gross examination (increasing the positive rate to 26/36 [72%]).

CONCLUSION

In male sexual assault victims with anal penetration, anoscopy is significantly better for gathering evidence than is colposcopy. The addition of colposcopy and anoscopy increased the rate of cases with positive findings from 61% to 72%. These 2 methods together may be a valuable adjunct in gathering evidence of damage.

Hemodynamic monitoring of the postoperative adult cardiac surgical patient

Surgery on the central blood pump, the heart, is performed either to prevent homeostatic compromise (ie, coronary artery disease potentially causing myocardial infarction and heart failure) or to treat actual homeostatic imbalance (ie, valvular disease causing heart failure). The cardiovascular homeostatic state is what we generally define as hemodynamics. The heart must deliver adequate oxygen and nutrients to all organs at appropriate pressures to allow optimal organ function. We monitor hemodynamic variables to assess the adequacy of a given cardiac repair and to detect any organ dysfunction that may independently coexist or be intimately related with the cardiac disease or its surgical repair. Hemodynamic monitoring initially relied on vital signs and periodic physical examination. The current monitoring capabilities have field expanded to include systemic and pulmonary arterial pressures, central venous pressures, cardiac output, systemic and pulmonary vascular resistance, and systemic and mixed venous oxygen saturation. These variables reflect a synthesis of global cardiac function and the peripheral or pulmonary vascular state. Arterial blood gas analysis further assesses the adequacy of overall oxygen delivery, carbon dioxide removal and acid-base balance. Echocardiography allows a qualitative and quantitative description of both global and regional cardiac function to better define the cardiac components of any hemodynamic state.

Gender differences in state-wide EMS transports

There are gender differences in emergency medical services (EMS) transports and management based on diagnosis. Data were extracted from the EMS State Ambulance Transport database. This database exists because of a legal requirement that all EMS transports generated by 911 calls and all interhospital transports be reported to the State EMS Bureau. All ambulance transports reported to the State EMS Division during 1995 were evaluated. Cases were excluded if they were aborted, admission or discharge transports, outpatient transports, or cases listed as "other" without a diagnosis. Gender-related treatment differences were determined for problems for which EMTs have specific treatment options. These were cardiac arrest, chest pain, allergic reactions, and extremity fractures. Results were compared using a two-tailed Chi squared or Fischer's Exact with significance at P < .05. Odds Ratios (OR) and 95% confidence intervals (CIs) were calculated. There were a total of 164,595 ambulance transports reported to the State EMS Division. Of these 76,074 (46%) were men and 88,521 (54%) were women. Of these, 50,211 were excluded. This left 52,607 injury transport and 61,777 illnesses transport. Men were significantly more likely than women to have injuries related to all-terrain vehicle accidents, motorcycle accidents, RV accidents, burns, gunshot wounds, and stab wounds. Men were significantly more likely than women to have illnesses related to cardiac arrest, dead on arrivals (DOAs), drowning, and smoke inhalation. For cardiac arrest transports, significantly more male patients presented ventricular fibrillation, more males received defibrillation, lidocaine, and bicarbonate, but more women received atropine. Male chest pain patients were more likely to receive oxygen and morphine and less likely to receive nitroglycerin. Male allergic reaction patients were more likely to receive an i.v. and subcutaneous epinephrine. Male extremity fracture patients were more likely to get an i.v. line, but there was no difference in morphine use or splinting. There are numerous disease-specific gender differences in the demographics of illness and injury transported by EMS. The use of various medications and procedures may also be related to gender. Understanding these differences may help in preparing EMS professionals for patient management.

Domestic violence awareness in a medical school class: 2-year follow-up

BACKGROUND

[corrected] Previous studies have examined short-term effectiveness of domestic violence instruction. We studied the long-term effectiveness (LTE) and long-term retention (LTR) of formal instruction about domestic violence.

METHODS

A general knowledge survey on domestic violence was given before, 1 month after, and 2 years after 3 hours of instruction to medical students. Good LTE was defined as significant improvement in responses between the first and third surveys. Good LTR was defined as lack of a significant decrease in results between the second and third surveys.

RESULTS

Two years after the instruction, 104 of 148 (70%) participated. Knowledge of rates of domestic violence against women showed neither good LTE nor good LTR. Responses showed good LTE and LTR concerning domestic violence incidence among men, ethnic and socioeconomic groups being equally represented, victims not being personally responsible for the abuse, and physicians not being required to report domestic violence in the survey state. Responses showed poor LTR and LTE regarding rates of domestic violence in women and abused persons being unable to simply leave their situation.

CONCLUSIONS

Some improvement in domestic violence awareness was seen 2 years after instruction. However, some information was not retained. Domestic violence instruction should be reemphasized throughout medical school.

The effect of prior hypothermia on the physiological response to norepinephrine

OBJECTIVE

this study determines the effect of prior hypothermia on the cardiovascular responses to norepinephrine (NE) after rewarming.

METHODS

the experiment was a 2x2 controlled design with four groups of feline animals. The two variables were the presence or absence of previous cooling, and the use or non-use of NE after rewarming. During the 'cooling' phase, animals were either cooled using an external arterial-venous femoral shunt to 30 degrees C or maintained at 37 degrees C. After 'rewarming' animals were stratified to receive either NE at rates to deliver 0.2, 1.0 or 5 microg/kg per h or normal saline infusions. Animals were instrumented to measure mean arterial pressure (MAP) and cardiac output (CO) and systemic vascular resistance (SVR) was calculated.

RESULTS

there were no differences between groups at baseline and low dose NE (0.2 microg/kg per min). At 1.0 microg/kg per min, NE caused a significant increase in CO (P<0.01) and no effect of MAP or SVR in the rewarmed animals when compared with normothermic controls. In rewarmed animals 5.0 microg/kg per min NE caused a significant increase in CO (P<0.01) and no effect on MAP or SVR. In normothermic controls there was a significant increase in SVR (P=0.02) and MAP (P=0.05) and no effect on CO.

CONCLUSION

this study shows that the effect of prior hypothermia on cardiovascular responses to moderate and high doses of NE is an improved CO with no affect on SVR and MAP. This could alter the clinical utility of NE in this situation.

Regulation of membrane type-1 matrix metalloproteinase activation by proprotein convertases

Membrane type-1 matrix metalloproteinase (MT1-MMP) is the prototypical member of a subgroup of membrane-anchored proteinases that belong to the matrix metalloproteinase family. Although synthesized as a zymogen, MT1-MMP plays an essential role in extracellular matrix remodeling after an undefined process that unmasks its catalytic domain. We now report the existence of a proprotein convertase-MT1-MMP axis that regulates the processing and functional activity of the metalloproteinase. Two sets of basic motifs in the propeptide region of MT1-MMP are identified that potentially can be recognized by the proprotein convertase family of subtilisin-like proteases. Processing of proMT1-MMP as well as the expression of its proteolytic activity were blocked by mutating these recognition motifs or by inhibiting the proprotein convertases furin and PC6 with the serpin-based inhibitor alpha(1) antitrypsin Portland. Furthermore, both furin-dependent and furin-independent MT1-MMP processing pathways are identified that require tethering of the metalloproteinase to the cell surface. These findings demonstrate the existence of a proprotein convertase-MT1-MMP axis that can regulate extracellular matrix remodeling.

Stimulus compounding enhances conditioned suppression produced by cocaine-paired stimuli

When 2 stimuli that occasion cocaine self-administration are presented in compound, their ability to increase cocaine-reinforced operant responding is substantially enhanced. The goal of the present experiment was to determine whether stimulus compounding could produce analogous enhancements of a classically conditioned drug effect. Food-maintained responding in rats was suppressed by a tone and a light that were individually paired with response-independent cocaine (3 mg/kg iv). This conditioned suppression was significantly enhanced when the stimuli were presented together in a stimulus-compounding test. The magnitude of this enhancement was similar to that in previous studies in which responding was suppressed by shock-paired stimuli. These results demonstrate that multiple drug-related cues interact in a predictable manner to influence both operant and classically conditioned behavior.

Blood pressure in acute vaso-occlusive crises of sickle cell disease

OBJECTIVE

We compared blood pressure (BP) in patients with sickle cell disease (SCD)-related crises and black patients without SCD.

METHODS

We retrospectively reviewed charts of emergency department (ED) patients with SCD crises in a 2-year period, recording BPs and demographic and SCD data. A cohort of consecutive black patients without SCD was compared.

RESULTS

Included were 459 SCD-related visits, 187 by men and 272 by women, representing 106 patients. Women had significantly lower BP than men, diastolic BP was significantly lower in patients with hemoglobin SS disease than in those with hemoglobin SC disease, and systolic BP was significantly lower in patients with bilateral versus unilateral pain. One SCD patient had a history of hypertension. The 125 non-SCD patients, excluding 25 with a history of hypertension, had significantly higher systolic and diastolic BP than patients in SCD crisis.

CONCLUSION

No patients seen in SCD crisis were hypertensive. Patients who were female, had SS disease, or had bilateral pain had lower BP. Significantly higher BP and more hypertension occurred in black patients without SCD.

Spontaneous splenic rupture due to subcutaneous heparin therapy

We report a case of spontaneous splenic rupture in a 59-year-old woman who was receiving 15,000 units of heparin subcutaneously (s.c. ) twice a day for deep venous thrombosis (DVT) prophylaxis. Her past medical history included multiple DVT, pulmonary emboli, and ovarian cancer stage III-C with known ascites. The diagnosis of splenic rupture was initially missed because of the ascites. This case illustrates both a previously undescribed complication of s.c. heparin therapy and a failure of ultrasound diagnosis. We emphasize the unique presentation, difficulty in diagnosis, and need for early surgical involvement to ensure the most favorable outcome.

EMT domestic violence knowledge and the results of an educational intervention

The objective of this study was to determine levels of knowledge regarding domestic violence (DV), and the effectiveness of formal instruction about DV. A general knowledge survey of DV was given before and approximately 4 to 6 months after 3 hours of instruction given by Emergency Medicine and Law Enforcement faculty. A Emergency medical service (EMS) consisting of 73% paramedic-level providers in a metropolitan urban/suburban area. Differences in DV knowledge before and after the instruction were the main outcome measures. In the preinstruction series, 46 emergency medical technicians (EMTs) participated. After the instruction 19 EMTs participated (42%). Thirty-five percent of EMTs before instruction and 37% after instruction correctly identified the prevalence of DV against women as 15% to 30%. Thirty-five percent of EMTs before instruction and 63% after instruction (P < .05) correctly identified the prevalence of DV against men as 0% to 15%. Before instruction 54% knew that DV is equal among races, and 79% after instruction (P < .05). Before instruction 37% of EMTs knew that DV is equal in different socioeconomic groups and 68% after instruction (P < .05). The percent of EMTs who knew that the victim is not responsible for the abuse was 50% before instruction and 89% after instruction (P < .05). Before instruction, the results on a knowledge questionnaire were 54% correct, after instruction, results improved to 71% correct. Improvement in understanding of DV was shown for 4 of 11 questions after 3 hours of instruction. These results indicate the need for more instruction on DV for EMTs.

Intra-aortic balloon pump associated with dynamic left ventricular outflow tract obstruction after valve replacement for aortic stenosis

An unstable patient with critical aortic stenosis had an intra-aortic balloon pump placed preoperatively for hemodynamic support and alleviation of symptoms. After separation from cardiopulmonary bypass following aortic valve replacement, the patient was hypotensive with increased pulmonary artery pressures. Transesophageal echocardiography revealed left ventricular outflow tract obstruction associated with systolic anterior motion of the mitral valve and severe mitral regurgitation. This pathophysiology was present when ventricular systole was preceded by balloon counterpulsation, but was absent during unassisted systole. This case report demonstrates a potentially significant untoward effect of intra-aortic balloon pump augmentation after aortic valve replacement for aortic stenosis. The timely diagnosis of this iatrogenic condition in the operating room permitted the prompt implementation of appropriate management strategies and avoided unnecessary surgical intervention.

Effects of compounding drug-related stimuli: escalation of heroin self-administration

Previous experiments have demonstrated that presenting independently established discriminative stimuli in compound can substantially increase operant responding maintained by food reinforcement or shock avoidance. Recently, this phenomenon was also shown to occur with cocaine self-administration. The present study further assessed the generality of these stimulus-compounding effects by systematically replicating them with heroin self-administration. Rats' nose-poke responses produced intravenous heroin (0.025 mg/kg per infusion) on a variable-ratio schedule when either a tone or a light was present. In the absence of these stimuli, responding was not reinforced. Once discriminative control by the tone and light had been established, the stimuli were presented in compound under extinction (with heroin discontinued) or maintenance conditions (with heroin available during test-stimulus presentations). In extinction, the tone-light compound increased responding approximately threefold compared to tone or light alone. Under maintenance conditions, compounding increased heroin intake approximately twofold. These effects closely matched those obtained earlier with cocaine. This consistency across pharmacological classes and across drug and nondrug reinforcers further confirms that (a) self-administered drugs support conditioning and learning in a manner similar to that supported by other reinforcers; and (b) multiple drug-related cues interact in lawful and predictable ways to affect drug seeking and consumption.

Domestic violence in a university emergency department

BACKGROUND

We attempted to determine the prevalence and demographics of domestic violence (DV) among male and female patients in a university emergency department (ED).

METHODS

The validated Index of Spouse Abuse (ISA) was used. Patients aged 18 years or older seen during 28 randomly selected 4-hour shifts were eligible.

RESULTS

Of the 97 participants in the study, 57 were female. One man and 3 women were victims of present physical DV, with 1 male and 2 female victims of present nonphysical abuse. Three of the 40 men and 22 of the 57 women had been victims of past physical violence. One man and 15 women had been victims of past nonphysical abuse. Alcohol use, suicidal ideation, family history, and psychiatric history were all strongly correlated with DV.

CONCLUSIONS

The prevalence of DV past was significantly higher in the females. Present violence was more rare and less than that reported in other ED studies.

Nicardipine intravenous bolus dosing for acutely decreasing arterial blood pressure during general anesthesia for cardiac operations: pharmacokinetics, pharmacodynamics, and associated effects on left ventricular function

The objective of this study was to evaluate the efficacy of nicardipine, a dihydropyridine calcium channel antagonist, administered as an IV bolus dose to acutely decrease arterial pressure in anesthetized cardiac surgical patients. We performed a double-blind, randomized, self-controlled, dose-ranging study in 40 adult cardiac surgical patients to determine the pharmacokinetics and pharmacodynamics of nicardipine 0.25 mg, 0.50 mg, 1.00 mg, and 2.00 mg administered as an IV bolus. Transesophageal echocardiography was used to assess left ventricular preload, afterload, and global systolic function. Plasma nicardipine concentration was measured using high-performance liquid chromatography. Nicardipine selectively decreased arterial pressure in a dose-dependent manner with a maximum response within 100 s and recovery to half the maximum response within 3-7 min without associated changes in heart rate. The decreases in arterial pressure were associated with only small decreases in left ventricular end-systolic wall stress and small increases in global left ventricular systolic function without changes in left ventricular end-diastolic cavity area or cardiac output. The time course for nicardipine bolus was consistent with a two-compartment pharmacokinetic model with rapid redistribution from a small central compartment.

IMPLICATIONS

Nicardipine was effective for selectively decreasing arterial blood pressure acutely, but had no effects on ventricular preload or cardiac output. The absence of dose-dependent changes in cardiac output, left ventricular systolic performance, and left ventricular afterload despite significant decreases in arterial pressure suggested that nicardipine had a small negative inotropic action.

Prehospital ECG monitoring of chest pain patients

Prehospital electrocardiograms (ECGs) have been shown to decrease the time from onset of pain to onset of treatment. They are obtained prior to treatment while the patient is likely to have his/her most intense pain. With paramedics initiating care in the field, patient assessments may be clinically different by the time the patient reaches the hospital. Thus, obtaining an ECG as early as possible during treatment could aid in the access to treatment for the few patients whose ECGs improve with prehospital care. We present a case in which the prehospital presentation was indicative of an acute myocardial infarction (MI), whereas the presentation to the hospital was not as clear-cut. The patient was taken immediately to the catheterization laboratory based on the prehospital findings and was found to have an acute MI that was treated. Laboratory findings indicated that there was a significant improvement in patient outcome based on this early treatment. This case further illustrates the role of a prehospital ECG.

Role of membrane type 1-matrix metalloproteinase and gelatinase A in head and neck squamous cell carcinoma invasion in vitro

The proteolytic activity of gelatinase A, a member of the matrix metalloproteinase (MMP) family, is considered to be a critical factor in tumor cell penetration of the extracellular matrix. To express catalytic activity, however, gelatinase A requires activation by another MMP, membrane type 1-matrix metalloproteinase (MT1-MMP). The head and neck squamous cell carcinoma cell line, UM-SCC-1, forms a quiescent monolayer atop collagen unless stimulated with epidermal growth factor (EGF; 3.5 nmol/L), which induces single cell invasion within 48 hours. To determine the role of the MT1-MMP/gelatinase A protease system in an in vitro stromal invasion model, expression vectors for MT1-MMP and gelatinase A were transfected into UM-SCC-1 (SCC-1/MT and SCC-1/gelA, respectively). SCC-1/MT tumor cells were found to invade in the absence of growth factor stimulation. Additionally, these cells displayed shorter onset to invasion and penetrated deeper into the collagen gel with EGF stimulation than did control vector transfectants. SCC-1/gelA cells similarly demonstrated invasion in the absence of EGF and a heightened invasive potential under EGF-stimulated conditions. These results suggest that the MT1-MMP/gelatinase A protease system participates in squamous cell carcinoma invasion of collagenous matrices.