Association of fasting glucose with subclinical cerebrovascular disease in older adults without Type 2 diabetes.

AIMS: To examine how fasting glucose and glucose tolerance are related to magnetic resonance imaging-assessed indicators of subclinical cerebrovascular disease and brain atrophy and their variation according to age, sex and education. METHODS: Participants in the present study were 172 healthy, community-dwelling older adults. An oral glucose tolerance test was administered and magnetic resonance imaging performed. Fasting, 2-h, and 2-h area-under-the-curve glucose levels, their associations with subclinical cerebrovascular disease and brain atrophy, and their respective interactions with age, sex and education were examined. RESULTS: A positive association between fasting glucose and subclinical cerebrovascular disease (but not brain atrophy) emerged; this association was more pronounced for participants with < 12 years of education; however, glucose tolerance was not related to subclinical cerebrovascular disease or brain atrophy. CONCLUSIONS: Findings revealed a potential link between fasting glucose levels and the presence of subclinical cerebrovascular disease indicators - white matter hyperintensities and silent brain infarction - in older adults without diabetes and with an education level below high school. Additional research is needed to confirm these associations and to determine the need for interventions aimed at closely monitoring and preventing elevated glucose levels in this population to reduce the prevalence of subclinical cerebrovascular disease.

Utilizing hospital discharge data (HD) to compare fatal and non-fatal work-related injuries among Hispanic workers in New Jersey.

BACKGROUND: This study explores the utilization of Hospital Discharge (HD) data to obtain estimates of work-related non-fatal injuries rates in NJ to determine if Hispanics workers have an increased risk of specific work-related injuries. In addition, HD data are used to compare the rate ratios between fatal and non-fatal injuries in this population to demonstrate the effectiveness of using HD as a surveillance tool for monitoring injury trends and performing evaluations. METHODS: Several types of fatal and non-fatal injuries were modeled using Poisson regression with the following predictor variables: gender, ethnicity, and year. The estimated number of workers by ethnicity employed in NJ each year was obtained from the U.S. Census Bureau, DataFerrett, Current Population Survey, November 2006, a data mining tool which accesses CPS data. RESULTS: These analyses, utilizing estimates of working population at-risk, indicate that Hispanic workers have an increased risk of four particular work-related injuries compared with non-Hispanics, and Hispanics were injured at a younger age than non-Hispanics. In addition the rankings of the rate ratios from the comparison between non-fatal and fatal risk estimates were similar; indicating that occupational surveillance of non-fatal injuries is a viable component to be considered. CONCLUSIONS: HD data are effective for monitoring trends over time across ethnic groups and injury types. Therefore, non-fatal injury surveillance should be considered for targeting specific worker populations for interventions to reduce exposure to workplace hazards, and can be a valuable surveillance tool in efforts to reduce occupational injuries.

Induction of tumor necrosis factor and macrophage-mediated cytotoxicity by horseradish peroxidase and other glycosylated proteins: the role of enzymatic activity and LPS.

Recent studies by these investigators have shown that horseradish peroxidase (HRP) can cause murine thioglycollate-induced peritoneal macrophages (M phi) to produce both tumor necrosis factor (TNF) and enhance macrophage-mediated cytotoxicity (MMC) to 3T12 target cells. The present study identifies the roles of both enzymatic activity and contaminating lipopolysaccharides (LPS) (less than or equal to 1 ng) on these activities. The addition of 100 ng/ml of polymyxin B (PB) to enzymatically active HRP significantly reduced TNF production but did not affect MMC. Enzymatically inactive HRP (DHRP) was more effective than HRP in both TNF production and MMC but was not affected by PB. The inability of PB to modify DHRP-induced TNF suggests that LPS was not required. The induction of TNF and MMC in the absence of LPS was also corroborated by similar studies using M phi from endotoxin-resistant C3H/HeJ mice. Glycosylated proteins such as HRP, DHRP, and mannosylated bovine serum albumin (M-BSA) are known to bind to mannose receptors (mannosyl-fucosyl receptor [MFR]) on the surface of M phi. In the present studies, M-BSA behaved similarly to DHRP in that it induced both TNF secretion and MMC. These results suggest that binding to the MFR may be sufficient to induce TNF secretion and MMC. In addition, the data suggest that neither enzymatic activity nor LPS was required for DHRP-induced TNF.

Fascioscapulohumeral muscular dystrophy: a progressive degenerative disease that responds to diltiazem.

The authors believe that with fascioscapulohumeral muscular dystrophy (FSHD), like Duchenne muscular dystrophy, there is Ca2+ dysregulation in the muscle cells. The dysregulated Ca2+ can cause cell death in various ways. One mechanism may be Ca2+ triggering abnormal levels of tumor necrosis factor (TNF-alpha). Another mechanism may involve excessive Ca2+ levels within the mitochondria which would cause this organelle's membrane to collapse ultimately inducing apoptosis and/or necrosis. With this in mind, it has been reported that in FSHD there is over expression of adenine nucleotide translocator-1 (ANT-1). This Ca2+ dependent protein, which is a component of the mitochondrial permeability transition pore, could be an important culprit in mitochondrial membrane collapse. Therefore, dysregulated Ca2+ as well as TNF-alpha, in addition to over-expression of ANT-1, may result in cell disruption ultimately causing the characteristic dystrophic muscle wasting. The present investigators have noted that some individuals with FSHD benefit from a regimen of diltiazem, a Ca2+ channel blocker. Initial results using diltiazem may represent the first beneficial treatment for a form of muscular dystrophy. Even if there is only a slowing of progression, this would be a positive first step. A combination of several different Ca2+ regulating agents and TNF-alpha inhibitors may be necessary to truly alter and/or reverse the deleterious effects of this form of muscular dystrophy.

Treatment of lithium tremor with metoprolol.

Two patients with bipolar affective disorder and a history of bronchospastic phenomena experienced tremor during lithium carbonate therapy. In both, metoprolol produced objective and subjective improvement of the tremor without producing bronchospasm. Objective improvement of tremor after use of metoprolol was documented by accelerometry. The authors discuss the implications of these findings.

Neuromyelitis optica with unusual vascular changes.

A case of neuromyelitis optica had strikingly increased numbers of thickened, hyalinized small blood vessels, which were associated with cystic degeneration in the cervical spinal cord and the optic chiasm. These findings support the contention that neuromyelitis optica is a clinical syndrome rather than a distinct nosologic entity.

Asymptomatic carotid bruit and stenosis. A prospective follow-up study.

We observed 70 patients with asymptomatic carotid bruits with and without stenoses for cerebral and myocardial ischemic events. Four patients developed transient ischemic attacks (TIAs) without subsequent cerebral infarctions; all of the TIAs occurred distal to vessels with greater than or equal to 50% stenoses. Three cerebral infarctions occurred, but only one was distal to a vessel with stenosis greater than or equal to 50%. Six myocardial infarctions occurred, predominantly in patients with previous myocardial infarctions, congestive heart failure, and left ventricular hypertrophy. Our results confirm previous reports that an asymptomatic carotid stenosis is more often complicated by a TIA than an unheralded cerebral infarction. Cerebral infarctions that do occur are often only marginally related to the carotid bifurcation lesion. In patients with asymptomatic carotid bruit and stenosis, myocardial infarctions occur more frequently and are more commonly the cause of death than cerebral infarctions.

Relationship between balance and abnormalities in cerebral magnetic resonance imaging in older adults.

BACKGROUND: Falling is a major cause of disability and morbidity among older adults. Because poor balance is a major reason for frequent falls, assessment of balance and its risk factors are important. In this study, we postulated that cerebral changes identified on magnetic resonance (MR) imaging are related to balance, and that older adults with balance problems would have significantly greater prevalence of such brain abnormalities than older adults without balance problems. DESIGN AND MEASUREMENTS: Several measures of balance were examined in more than 700 community-dwelling older men and women, blacks and whites. Balance measures included dynamic posturography, functional reach, Romberg and 1-foot stand tests, tandem stand, and 1-foot stand. Cerebral MR imaging assessments included ventricular size, sulcal widening, white matter disease, and ischemic infarctions. Cardiovascular disease and hypertension were determined and controlled for in the analyses. RESULTS: A summary of the balance measures was significantly related to each of the 4 MR imaging measures, with those with poorer balance having more disease. The strongest associations with balance were seen for white matter disease and ventricular size. All but the ischemic infarction variable remained significantly associated with balance after adjustments for sex, race, age, cardiovascular disease, and hypertension. CONCLUSION: Cerebral changes identified by MR imaging are associated with poorer balance among older adults.

Cluster analysis and patterns of findings on cranial magnetic resonance imaging of the elderly: the Cardiovascular Health Study.

OBJECTIVE: To characterize patterns of findings on cranial magnetic resonance imaging (MRI) of the elderly using a statistical technique called cluster analysis. SUBJECTS AND METHODS: The Cardiovascular Health Study is a population-based, longitudinal study of 5888 people 65 years and older. Of these, 3230 underwent cranial MRI scans, which were coded for presence of infarcts and grades for white matter, ventricles, and sulci. Cluster analysis separated participants into 5 clusters based solely on patterns of MRI findings. Participants comprising each cluster were contrasted with respect to cardiovascular risk factors and clinical manifestations. RESULTS: One cluster was low on all the MRI findings (normal) and another was high on all of them (complex infarcts). Another cluster had evidence for infarcts alone (simple infarcts), whereas the last 2 clusters lacked infarcts, one having enlarged ventricles and sulci (atrophy) and the other having prominent white matter changes and enlarged ventricles (leukoaraiosis). Factors that distinguished these clusters in a discriminant analysis were age, sex, several measures of hypertension, internal carotid artery wall thickness, smoking, and prevalent claudication before the MRI. The atrophy group had the highest percentage of men and the normal group had the lowest. Cognitive and motor performance also differed across clusters, with the atrophy cluster performing better than may have been expected. CONCLUSIONS: These MRI patterns identified participants with different vascular disease risk factors and clinical manifestations. Results of these exploratory analyses warrant consideration in other populations of elderly people. Such patterns may provide clues about the pathophysiology of structural brain changes in the elderly.

Complex partial status epilepticus in a patient with dural metastases.

We describe a 68-year-old man with invasive transitional cell carcinoma of the bladder metastatic to the dura who presented with complex partial status epilepticus (CPSE). To our knowledge, the association of CPSE and dural metastases has not been previously reported.

Validation of the ACAS TIA/stroke algorithm.

BACKGROUND AND PURPOSE: An easily administered questionnaire and algorithm classifying transient ischemic attacks (TIAs) or strokes, and also their distribution, could be invaluable for identifying endpoints in epidemiologic studies or clinical trials of prevention and therapy of cerebral ischemia. The Asymptomatic Carotid Atherosclerosis Study (ACAS) devised a symptom-based questionnaire and algorithm for detecting events in the trial. The purpose of this study was to determine sensitivity, specificity, and agreement rates of the questionnaire and algorithm against diagnoses of a panel of cerebrovascular disease authorities. METHODS: Three hundred eighty-one men and women at eight medical centers reported symptoms of stroke, TIA, or other neurologic illness. The questionnaire was administered by trained interviewers and the responses were analyzed using the algorithm. A standardized neurologic examination was performed by a neurologist. Data were submitted to two or more external reviewers. Sensitivity, specificity, and the kappa statistic (kappa) were used to evaluate the relationship between the algorithm and the external reviewers' diagnosis. RESULTS: Of the 381 reviews, 196 were diagnosed as TIA or stroke by the external panel. The algorithm's agreement with the diagnosis of TIA or stroke was 80.1%, and kappa was 0.60. Sensitivity was 87.8%, and specificity was 71.9%. CONCLUSION: While statistical agreement rates depend on the method of sample selection, the algorithm has a high agreement with an external panel of experts and is a sensitive tool for event detection. The lower specificity indicates that careful neurologic evaluation may be required to confirm or refute events identified by the screening algorithm.

Decision logic for retreatment of asymptomatic lung cancer recurrence based on positron emission tomography findings.

PURPOSE: The purpose of the study was to determine if Positron emission tomography (PET) 2-[F-18] fluoro-2-deoxy-D-glucose (FDG) imaging could detect subclinical local lung cancer recurrence and whether retreatment of such recurrence was feasible and beneficial. METHODS AND MATERIALS: Twenty patients with biopsy proven lung cancer were studied with Positron emission tomography for the purpose of detecting subclinical lung cancer recurrence over a period of 4.25 years. All patients were treated with external radiation as part or all of their therapy. Twenty patients had baseline PET and computed tomography (CT) studies for comparison with later studies. Surviving patients had a total of 40 sequential PET scans and 35 CT scans. The follow-up interval ranged from 5 to 40 months posttreatment. The differential uptake ratio (DUR) was determined for regions of interest of increased FDG uptake. RESULTS: The median DUR value of the 20 baseline PET studies was 5.59. The DUR value of greater than 3 was empirically selected as being positive for tumor detection. On baseline studies, PET had a 100% correlation with the CT findings in regard to detection of the site of primary tumor involvement. Four of 20 patients showed areas of discordance in the mediastinal and hilar areas on initial PET and CT studies. Seven of 17 patients showed discordant posttreatment PET-CT findings. Two false positive PET studies were due to radiation pneumonitis and one to macrophage glycolysis in tumor necrosis. For detection of asymptomatic tumor recurrence, analysis of sequential PET and CT studies, biopsy results, and the patient's clinical course suggested that PET had a sensitivity of 100%, specificity of 89.3%, and accuracy of 92.5%. Computerized Tomography was found to have a sensitivity of 67%, specificity of 85%, and accuracy of 82% for detection of such early-stage recurrence. Five patients went on to have retreatment with external irradiation based upon the PET evidence. Four retreated patients had biopsies that corroborated the positive PET findings, and one patient was retreated on the basis of the qualitative appearance of the posttreatment PET study. Two of the five retreated patients remain alive without evidence of tumor to 34 months following initial therapy. CONCLUSION: Positron emission tomography scanning appears to be effective in detecting and following the progression of recurrent lung cancer. Retreatment of patients with asymptomatic recurrent tumor has resulted in absent or decreased FDG activity. Monitoring of patients with PET may provide prolonged survival in patients who otherwise would fail treatment because of local tumor recurrence.

Echocardiographic validation of gated SPECT ventricular function measurements.

UNLABELLED: Left ventricular (LV) volumes are valuable prognostic indicators in the management of coronary artery disease and traditionally have been obtained by x-ray contrast angiography or echocardiography. There now are several scintigraphic methods to compute volumes that are based on different LV modeling assumptions. Both the reasons that calculations from different nuclear techniques can disagree with one another and the relationship of these values to the more conventional echocardiographic measurements must be investigated thoroughly for calculations to be interpretable for individual patients. METHODS: Echocardiographic volumes were determined in 33 retrospective subjects with coronary artery disease (mean age, 61 +/- 12 y; 42% men; 70% with abnormal perfusion and 58% with abnormal segmental wall motion) using the modified Simpson's rule technique applied to digitized apical 4-chamber and apical 2-chamber views of 4 averaged heartbeats. These volumes were compared with those from 3 gated SPECT methods based on Simpson's rule LV modeling similar to standard echocardiographic algorithms (SPECT EF from St. Luke's-Roosevelt Hospital) (method 1), Gaussian myocardial count profile curve fitting (QGS from Cedars-Sinai Medical Center) (method 2), and an endocardial model based on perfusion sampling and count-based thickening (Cardiac Toolbox from Emory University) (method 3). RESULTS: By ANOVA, there were no significant differences among ejection fractions (EFs), but there were for volumes. Paired t test analysis showed volumes from methods 2 and 3 to be significantly larger than echocardiographic volumes and larger than those of method 1. Linear regression analysis comparing gated SPECT and echocardiographic volumes showed a nearly identical strong correlation (r = 0.92; P < 0.000001) for all 3 methods. Excellent correlation also was found among gated SPECT volumes from the 3 methods (r = 0.94). Bland-Altman analysis and t tests showed that method 1 volumes (70 +/- 61 mL) were the same as for echocardiography (77 +/- 55 mL), but volumes were overestimated by method 2 (105 +/- 74 mL) and method 3 (127 +/- 92 mL), particularly for larger volumes. Pearson coefficients for EFs compared with echocardiography were r = 0.82, 0.75, and 0.72 for methods 1-3, respectively. EFs correlated strongly among the 3 gated SPECT methods (r = 0.86-0.92). The Fisher z test showed no differences among these methods for any of the volume or EF linear correlation analyses. CONCLUSION: All gated SPECT parameters correlated well with echocardiographic values. However, the gated SPECT method for which underlying assumptions most closely resembled those commonly used in echocardiography produced mean volume values closest in agreement with echocardiographic measurements.

Regulation of macrophage function by human recombinant myeloperoxidase.

Myeloperoxidase is an enzyme which is found in the azurophilic granules of neutrophils and is associated with bactericidal, fungicidal, and tumoricidal activity. The present studies show that human recombinant myeloperoxidase (rec-MyPo) can regulate a number of macrophage (M phi) capacities and functions. Macrophages from mice exposed to rec-MyPo in vitro released reactive oxygen intermediates, tumor necrosis factor alpha (TNF alpha), and interferon alpha/beta (IFN alpha/beta). Enhanced target cell killing was also demonstrated with TNF alpha sensitive but not TNF alpha insensitive cells. Intravenous injection of rec-MyPo induced high titers of systemic TNF alpha and IFN alpha/beta. These results indicate that MyPo can function as an immunomodulator both in vitro and in vivo. Because of these actions, it is apparent that MyPo represents a previously unrecognized endogenous immunomodulator.

Cause specific mortality following cerebral infarction.

Mortality from four causes (index stroke, subsequent stroke, cardiac disease and non-cardiovascular causes) was examined during a 5 year follow-up of 1694 cerebral infarction patients admitted to 25 community hospitals between 1969 and 1973. The hazard for mortality from the index stroke was high initially, but declined to a negligible level by 6 months post-stroke. In contrast, hazards for mortality from subsequent strokes, cardiac diseases and non-cardiovascular causes each peaked midway through the first year, declined during the remainder of that year, and then increased in the latter part of the follow-up. Proportional hazards analysis indicated that advanced age and increased stroke severity were the only factors significantly related to increased risk from each of the four causes of death. Other risk factors were significant only for one or two select causes of death. White patients were less likely to die from subsequent strokes, but more likely to die from cardiac diseases, than were non-white patients (primarily blacks). Males were more likely to die from both the index stroke and non-cardiovascular causes than females. A history of cardiac disease increased the risk of death from both the index stroke and from future cardiac events, while a history of hypertension or diabetes increased the risk of death from non-cardiovascular causes, and a history of previous stroke increased the risk of death from subsequent stroke.

Comparison of centralized versus "site-based" measurement of angiographic stenosis for eligibility in the asymptomatic carotid atherosclerosis study.

RATIONALE AND OBJECTIVES: The authors determine the reliability of centralized versus noncentralized (site-based) measurement of angiographic stenosis of patients enrolled into the multicenter, prospective, Asymptomatic Carotid Atherosclerosis Study by angiographic studies. METHODS: Percent agreements and correlations of 244 masked and prospectively interpreted angiograms were calculated for comparison of centralized and noncentralized readers measuring the percent carotid stenosis from the same angiographic studies. Univariate summary statistics for differences in percent stenoses were calculated for these readings. RESULTS: Agreement between readings were 88.5% and 91.8% with kappa statistics of 0.77 and 0.73 for > or = 60% and > or = 80% stenosis, respectively, for comparison of 33 centers to the designated central reader. Comparison between the designated central reader and a second central reader derived percent agreements of 85.0% and 86.5% with kappa statistics of 0.69 and 0.41 for > or = 60% and > or = 80% stenoses, respectively, for arteries selected from the original group. Hence, agreement was slightly better between the enrolling centers and the designated central reader than between the two central readers. CONCLUSIONS: Both centralized and noncentralized (site-based) methods of angiographic measurement of stenosis are equally reliable for large, prospective, masked, multicenter trials when quality control measures are instituted to ensure uniform application of eligibility criteria.

Daytime sleepiness predicts mortality and cardiovascular disease in older adults. The Cardiovascular Health Study Research Group.

INTRODUCTION: As part of the baseline examination in the Cardiovascular Health Study, sleep disturbance symptoms including snoring and daytime sleepiness, were assessed as potential risk factors or precipitants of cardiovascular disease (CVD). Because of the association of sleep disturbance with poorer health and the possible associations of sleep apnea with CVD, we hypothesized that those with poorer sleep or daytime sleepiness may be at increased risk of mortality or incident CVD. SETTING: Participants (n = 5888) were recruited in 1989, with an additional minority cohort recruited in 1993, in four US communities for a cohort study designed to evaluate risk factors for cardiovascular disease. METHODS: An interview-administered questionnaire regarding health and sleep habits with ongoing ascertainment of total mortality and cardiovascular disease morbidity and mortality, including total CVD morbidity and mortality, incident myocardial infarction, and congestive heart failure. RESULTS: Daytime sleepiness was the only sleep symptom that was significantly associated with mortality in both men and women. The unadjusted hazard ratio was 2.12 (1.66, 2.72) in women and 1.40 (1.12, 1.73) in men. Men who reported difficulty falling asleep also had an increased mortality rate (HR = 1.43 (1.14, 1.80)) which was not seen in women. The risks were attenuated with adjustment for age but remained significant for daytime sleepiness in women (HR = 1.82 (1.42, 2.34)) and for difficulty falling asleep in men. (HR = 1.29 (1.03, 1.63)). Frequent awakenings, early morning awakening, and snoring were not associated with a significantly increased risk of mortality in these older men and women. Crude event rates were evaluated for total incident cardiovascular morbidity and mortality, incident myocardial infarction, and incident congestive heart failure (CHF). Incident CVD rates were higher in both men and women with daytime sleepiness. The aged adjusted HR was 1.35 (95% CI = 1.03, 1.76) in men and was 1.66 (95% CI = 1.28, 2.16) in women. Incident CVD was not higher in those with any other sleep disturbance including snoring. The risk of CVD events associated with daytime sleepiness was attenuated but remained significant in women after adjustment for age. Incident myocardial infarction (MI) rates were also higher in women with daytime sleepiness but were not significantly higher in men. Incident CHF rates were increased in both men and women with daytime sleepiness. In men, the age adjusted HR was 1.49 (95% CI, 1.12- 1.98) and in women, was 2.21 (95% CI, 1.64-2.98). Women reporting both daytime sleepiness and frequent awakening had a hazard ratio of 2.34 (95% CI, 1.66-3.29) for incident CHF compared with those with daytime sleepiness but without frequent awakening. This interaction was not found in men. CONCLUSIONS: In this study, daytime sleepiness was the only sleep disturbance symptom that was associated with mortality, incident CVD morbidity and mortality, MI, and CHF. These findings were stronger in women than men, i.e., the associations persisted for mortality, CVD, and CHF in women after adjustment for age and other factors. Thus, a report of daytime sleepiness identifies older adults at increased risk for total and cardiovascular mortality, and is an independent risk factor in women.

Hyperacute ischemic stroke missed by diffusion-weighted imaging.

We present two cases of hyperacute ischemic stroke that were initially missed by diffusion-weighted imaging; abnormalities in locations corresponding to focal neurologic deficits were discovered by MR angiography and perfusion-weighted imaging. Within hours, follow-up diffusion-weighted scans revealed partial conversion of the hypoperfused regions to complete stroke. These cases illustrate the potential for a nonresolving stroke-in-evolution to go undetected by diffusion-weighted imaging at hyperacute timepoints.

The effects of alcohol on murine macrophage function.

Animal models used to measure the effects of alcohol on lymphoid cells and their functions provide useful ways to evaluate the multisystem effects of this substance. The effects of ethanol ingestion on the function of murine peritoneal macrophages (M phi) was evaluated. Both the production of reactive oxygen intermediates (ROI) and the ingestion of foreign particles (phagocytosis) were studied. Mice were pair fed ad libitum a nutritionally complete liquid diet containing 7% v/v ethanol or a calorically balanced control diet. Two regimens were employed for the administration of the diets. One regimen represented "binge" drinking (short term-4 days) while the other represented "chronic" consumption (long term-14 days). Following the short term administration of the diets, an increase in the respiratory burst (RB), as well as a decrease in phagocytosis, were observed with M phi from the ethanol fed mice. The decrease in phagocytosis, was noted using either in vitro or in vivo methods. Results observed after long term administration indicated no significant change in the RB or in in vitro phagocytosis between the ethanol and control groups. Phagocytosis measured in vivo, however, was decreased in M phi from ethanol fed mice following long term administration. These results indicate an alteration in murine peritoneal M phi function following short term an long term administration of alcohol.

Peroxidase-induced enhancement of chemiluminescence by murine peritoneal macrophages.

A number of substances have been shown to enhance the respiratory burst (RB) of macrophages. Many of these substances are not normally found in vivo. The present study suggests that a group of enzymes characterized as peroxidases have the ability to significantly enhance the RB and concomitant phagocytosis by murine peritoneal macrophages. Horseradish peroxidase (HRP), lactoperoxidase (LPO), and microperoxidase (MPO) can significantly augment these functions. Both resident and thioglycollate-induced macrophages exhibited enhanced chemiluminescence (CL) upon exposure to HRP, however, the effect was more pronounced with the latter. The increase in CL was correlated with an increase in production of superoxide, which was measured by reduction of cytochrome c. Horseradish peroxidase immobilized on an inert carrier, was capable of enhancing the RB suggesting that it does not have to enter the cell in order to function. Hemin, hematoheme and hematoporphyrin had little effect on macrophage stimulated CL. All of the peroxidases tested caused increased phagocytosis of opsonized zymosan. These studies indicate that peroxidases are capable of stimulating the RB, phagocytosis and possibly other macrophage functions.