Antibiotic use, hospital admissions, and mortality before and after implementing guidelines for nursing home-acquired pneumonia

OBJECTIVES

To compare two strategies for implementing guidelines for nursing home-acquired pneumonia (NHAP) and to measure outcomes associated with treatment in accordance with the guidelines.

DESIGN

Randomized controlled trial.

SETTING

Ten skilled nursing facilities (SNFs) from a single metropolitan area.

PARTICIPANTS

Patients with an episode of pneumonia acquired more than 3 days after admission to SNF (N = 350): 226 preintervention episodes of pneumonia and 116 postintervention episodes.

INTERVENTIONS

Multi-faceted education intervention including small-group consensus process limited to physicians and a similar intervention that included physicians and nurses within randomly selected SNFs.

MEASUREMENTS

Antibiotic use at diagnosis compared with the guidelines, hospital admission, severity of pneumonia, and 30-day mortality.

RESULTS

Data were complete for 344 episodes of NHAP. For the preintervention group (n = 226), 62.2% (79/127) of the episodes were treated with parenteral antibiotics (PA) when PA were recommended by the guidelines and 57.6% (57/99) of episodes were treated with oral antibiotics (OA) when OA were indicated by the guidelines. Postintervention, treatment with PA and OA according to the guidelines was not significantly different between the two groups of randomized SNFs. A multivariate analysis comparing PA use pre- and postintervention for all SNFs, adjusted for variation in the frequency and severity of pneumonia, found significantly more of the postintervention episodes were treated with PA in accordance with the guidelines (P < .02). A preintervention significant difference in 30-day mortality observed between episodes with indications for PA (37.8% (48/127)) and episodes with indications for OA (6.1% (6/99)) (P < .001) was not present postintervention (11.5% (6/52); (23.8% (15/64); P = .06). There was no significant difference in 30-day mortality preintervention and postintervention for episodes with guideline indications for OA (P = .35) or for PA (P = .05) (P = .16 for multivariate analysis). The difference in PA use was not associated with significant differences in hospital admissions for episodes on NHAP.

CONCLUSION

The increase in the use of PA provides evidence that care within SNFs can be significantly changed using standard quality improvement techniques. Use of the guidelines did not significantly affect mortality. The addition of a practical severity of NHAP model or a change in reimbursement structure may enhance the guidelines' impact on hospitalization for NHAP. The financial benefits available with use of the guidelines will be limited unless the guidelines contribute to a reduction in rates of hospitalization.

Personality disorder in multiple sclerosis correlates with cognitive impairment

Previous studies of personality change in multiple sclerosis (MS) relied on brief, nonstandardized assessments or tests that are confounded with symptoms of acute psychiatric disorder. Objectives of the present study were to evaluate character change in MS by using comprehensive trait measures of personality and to determine if there is an association between personality change and cognitive dysfunction. Thirty-four MS patients and 14 healthy volunteers were studied. All underwent comprehensive neurologic and neuropsychologic evaluation. Personality assessments included both self and informant reports on the Hogan Empathy Scale and the NEO Personality Inventory. Abnormalities were found among MS patients indicating elevated neuroticism and reduction in empathy, agreeableness, and conscientiousness. Large patient/informant discrepancies were observed in the MS but not the control group. Three neuropsychological tests emphasizing executive control predicted the presence of these abnormalities; this association suggests a neurogenic, frontal lobe syndrome.

Neuropsychological effects of interferon beta-1a in relapsing multiple sclerosis. Multiple Sclerosis Collaborative Research Group

Cognitive dysfunction is common in multiple sclerosis (MS), yet few studies have examined effects of treatment on neuropsychological (NP) performance. To evaluate the effects of interferon beta-1a (IFNbeta-1a, 30 microg administered intramuscularly once weekly [Avonex]) on cognitive function, a Comprehensive NP Battery was administered at baseline and week 104 to relapsing MS patients in the phase III study, 166 of whom completed both assessments. A Brief NP Battery was also administered at 6-month intervals. The primary NP outcome measure was 2-year change on the Comprehensive NP Battery, grouped into domains of information processing and learning/memory (set A), visuospatial abilities and problem solving (set B), and verbal abilities and attention span (set C). NP effects were most pronounced in cognitive domains vulnerable to MS: IFNbeta-1a had a significant beneficial effect on the set A composite, with a favorable trend evident on set B. Secondary outcome analyses revealed significant between-group differences in slopes for Brief NP Battery performance and time to sustained deterioration in a Paced Auditory Serial Addition Test processing rate, favoring the IFNbeta-1a group. These results support and extend previous observations of significant beneficial effects of IFNbeta-1a for relapsing MS.

Capsular polysaccharide and O-specific antigen divergently modulate pulmonary neutrophil influx in an Escherichia coli model of gram-negative pneumonitis in rats

Enteric gram-negative bacilli cause a severe, often life-threatening pneumonia. An improved understanding of the pathogenesis of this infection may lead to improved treatment. Nearly all of the responsible gram-negative bacilli possess capsular polysaccharides and/or an O-specific antigen as part of their lipopolysaccharide (LPS). We hypothesized that these surface polysaccharides may modulate the pulmonary host response. To investigate this, a rat pneumonitis model was used, and pulmonary neutrophil influx, a critical aspect of host defense, was measured. To assess for the effect of the capsule and O-specific antigen on this host response, three proven, isogenic derivatives that are deficient in capsular polysaccharide alone (CP9.137), the O-specific antigen moiety of the LPS alone (CP921), and both the capsular polysaccharide and O-specific antigen (CP923), as well as their wild-type parent (CP9), were used as challenge strains at various intratracheal challenge inocula (CI). Total lung myeloperoxidase (MPO), a surrogate marker for neutrophils, was measured for 15 h post-bacterial challenge. To determine the effect of capsule and the O-specific antigen on the measured MPO levels, a mathematical model was developed and used to describe the MPO levels as a function of time for each CI of each of the four strains. The results from this analysis demonstrated that in the absence of the K54 capsule, 80.7 times the CI is necessary to achieve the same maximum MPO level relative to K54 positive strains (P < 0.0001). In contrast, a diametric effect was observed in the absence of the O-specific antigen, where 0.13 times the CI was necessary to achieve the same maximum MPO level relative to O4-positive strains (P = 0.0032). No interactive effect was observed between the capsule and the O-specific antigen. These findings demonstrate that these surface polysaccharides modulate pulmonary neutrophil influx and suggest that the K54 capsular polysaccharide is a proinflammatory mediator and that the O4-specific antigen attenuates the proinflammatory response. If these speculations are substantiated, an understanding of how the capsule and the O-specific antigen modulate host response could have significant therapeutic implications. The potential use of biologic modulators directed against the host response, as well as approaches based on inactivating bacterial components (e.g., surface polysaccharides) in attempts to modify sepsis syndromes, could be developed.

Brain MRI lesions and atrophy are related to depression in multiple sclerosis

It is unclear whether brain MRI lesions are associated with depression in multiple sclerosis (MS). Neurological dysfunction in depressed (n= 19) and non-depressed (n = 29) MS patients was rated by expanded disability status scale (EDSS). EDSS was weakly predictive of the presence of (p = 0.03) and severity of (p = 0.01) depression. After correcting for EDSS, the presence of depression was predicted by superior frontal and superior parietal hypointense TI lesions (p<0.01); the severity of depression was predicted by superior frontal, superior parietal and temporal TI lesions, lateral and third ventricular enlargement, and frontal atrophy (p<0.01). Depression was not related to bright T2 lesions or enhancement. We conclude that atrophy and cortical-subcortical disconnection due to frontal and parietal white matter destructive lesions may contribute to depression in MS.

Comparability of nutrient estimation by three food frequency questionnaires for use in epidemiological studies

Replication of results is an important issue in studies of diet and disease, possibly dependent on data collection method. We compared assessments from the Health Habits and History Questionnaire (HHHQ), the Harvard Semiquantitative Food Frequency Questionnaire (HFFQ), and the New York State Cohort Food Frequency Questionnaire (CFFQ) for estimates of daily intakes of energy, protein, carbohydrates, total fat, dietary fiber, cholesterol, vitamins A, C, and E, and carotenoids. Fifty-nine men and 50 women aged 35-73 years completed the HHHQ and HFFQ as interviews and the 44-food CFFQ as a self-administered mailed questionnaire. Comparability was assessed with Spearman correlation coefficients. Quantitation of nutrient intake differed by nutrient, questionnaire, and nutrient calculation method. Ranking on energy and macronutrient intake for the HHHQ and HFFQ ranged from 0.62 to 0.80; ranking for micronutrient intake ranged from 0.56 to 0.80. For the CFFQ with the HHHQ or HFFQ, correlations ranged between 0.29 and 0.62. The CFFQ performs comparably to the HHHQ and HFFQ for some, but not all, nutrients; our results suggest that the HHHQ and HFFQ can be used interchangeably with reasonable confidence in studies of diet and disease.

Screening for atrial fibrillation in the community: A multicenter validation trial

BACKGROUND

Atrial fibrillation (AF) is an important public health problem. This arrhythmia is common and associated with a high risk of stroke. Further, appropriate interventions in AF can reduce the risk of stroke by approximately 68%. Population studies show that a large group of patients have intermittent or chronic AF that remains unrecognized. If a simple screening test for this arrhythmia could be developed and validated, application of the technique across populations might identify AF patients for early treatment, potentially reducing the incidence of stroke. In this study, we sought to determine whether individuals taken from the general community could be taught to find and classify the pulse of another as very irregular, implying AF, or regular, implying normal sinus rhythm (NSR). The aim was to establish that pulse examination for potential AF could be performed by individuals with sufficient sensitivity and specificity to be effectively used as a screening procedure for this medically important arrhythmia.

METHODS

We enrolled 178 subjects selected from the general community from four centers. Subjects received standardized education on the medical importance of AF and its signature, a very irregular pulse. A technique for palpating and characterizing the rhythm of the radial pulse was also taught. Without further coaching, subjects were then asked to find their pulse and then to find and classify the pulse of two models randomly presented who may or may not have had AF.

RESULTS

Of the 178 subjects tested, 92% were able to find their own pulse; 17 (9.6%) were unable to find the pulse of one or both patient models and were, therefore, excluded from the study. Of the remaining 161 subjects, 76% (122 of 161) correctly identified the pulse in an AF model, and 86% (139 of 161) correctly identified the pulse in an NSR model. Results did not statistically differ as a function of age, educational status, or location.

DISCUSSION

This multicenter trial established that given minimal standardized instructions, subjects from the general community can reliably and consistently find both their pulse as well as the pulse of another and to differentiate a regular pulse from a very irregular pulse. If similar educational programs were widely applied across large populations, periodic screening for AF might lead to earlier diagnosis and appropriate treatment for patients who have this major risk factor for stroke. These screening programs should be focused on the population over the age of 55 where the risk of stroke in AF increases with each decade.

Cerebrospinal fluid abnormalities in a phase III trial of Avonex (IFNbeta-1a) for relapsing multiple sclerosis. The Multiple Sclerosis Collaborative Research Group

BACKGROUND AND OBJECTIVE

This report provides results of CSF analyses done in a subset of relapsing remitting MS patients participating in a placebo-controlled, double-blind, phase III clinical trial of IFNbeta-Studies supported by the National Multiple Sclerosis Society (grants RG2019, RG2827),a (Avonex , Biogen). The clinical trial demonstrated that IFNbeta-1a treatment resulted in significantly reduced disability progression, annual relapse rate, and new brain lesions visualized by cranial magnetic resonance imaging. The objectives of the current study were to determine: (a) whether CSF abnormalities in MS patients correlated with disease or MRI characteristics, and (b) effects of IFNbeta-1a therapy on these CSF abnormalities.

METHODS

CSF was analyzed from 262 (87%) of the 301 study subjects at entry into the clinical trial, and a second CSF sample was analyzed from 137 of these 262 subjects after 2 years of therapy. CSF cell counts, oligoclonal bands (OCB), IgG index, and free kappa light chains were measured using standard assays. Baseline CSF results were compared with demographic, disease, and MRI parameters. Differences in on-study relapse rate, gadolinium enhancement, and EDSS change according to baseline CSF status was used to determine the predictive value of CSF for subsequent clinical and MRI disease activity. Change in CSF parameters after 104 weeks were used to determine the effects of treatment.

RESULTS

(1) At study baseline, 37% of the subjects had abnormal CSF WBC counts, 61% had abnormal levels of CSF free kappa light chains, 84% had abnormal IgG index values, and 90% were positive for OCB. (2) Baseline IgG index, kappa light chains, and OCB showed weakly positive, statistically significant correlations with Gd-enhanced lesion volume and T2 lesion volume. WBC showed a statistically significant correlation with Gd-enhancing lesion volume but was uncorrelated with T2 lesion volume. (3) There was an associated between baseline CSF WBC counts and on-study clinical and MRI disease activity in placebo recipients. (4) IFNbeta-1a treatment resulted in significantly reduced CSF WBC counts, but there was no treatment-related change in CSF IgG index, kappa light chains, or OCB, which remained relatively stable over time in both patient groups.

CONCLUSIONS

The current study documents significant reductions in CSF WBC counts in patients treated with IFNbeta-1a for 104 weeks. This finding is considered relevant to the therapeutic response, since CSF WBC counts were found to be positively correlated with subsequent clinical and MRI disease activity in placebo-treated relapsing MS patients.

Comparing the ability of various compositive outcomes to discriminate treatment effects in MS clinical trials. The Multiple Sclerosis Collaborative Research Group (MSCRG)

We compared the ability of the Kurtzke Expanded Disability Status Scale (EDSS) and a composite outcome of non-physician-based measures of time to ambulate 25 feet (TA) and manual dexterity (the Box and Block Test [BBT], and 9-Hole Peg Test [9HPT]) to discriminate treatment effects in the Phase III study of interferon beta-1a. A log-rank comparison of Kaplan-Meier curves by treatment group showed the non-physician-based composite of BBT, 9HPT, and TA was of comparable sensitivity (P = 0.013) in discriminating sustained treatment failure as the EDSS alone (P = 0.029). The composite of BBT, 9HPT, TA, and EDSS was more sensitive (P = 0.009) in discriminating sustained treatment failure than the EDSS alone. Compositive outcomes of the EDSS and non-physician-based measures of manual dexterity and timed ambulation provide an appealing strategy to reduce the number of patients required to discriminate treatment effects in MS clinical trials.

Prospective evaluation of the Ottawa Ankle Rules in a university sports medicine center. With a modification to increase specificity for identifying malleolar fractures

In a sports medicine center, we prospectively evaluated the Ottawa Ankle Rules over 1 year for their ability to identify clinically significant ankle and midfoot fractures and to reduce the need for radiography. We also developed a modification to improve specificity for malleolar fracture identification. Patients with acute ankle injuries (< or = 10 days old) had the rules applied and then had radiographs taken. Sensitivity, specificity, and the potential reduction in the use of radiography were calculated for the Ottawa Ankle Rules in 132 patients and for the new "Buffalo" rule in 78 of these patients. There were 11 clinically significant fractures (fracture rate, 8.3% per year). In these 132 patients, the Ottawa Ankle Rules would have reduced the need for radiography by 34%, without any fractures being missed (sensitivity 100%, specificity 37%). In 78 patients, the specificity for malleolar fracture for the new rule was significantly greater than that of the Ottawa Ankle Rules malleolar rule (59% versus 42%), sensitivity remained 100%, and the potential reduction in the need for radiography (54%) was significantly greater. The Ottawa Ankle Rules could significantly reduce the need for radiography in patients with acute ankle and midfoot injuries in this setting without missing clinically significant fractures. The Buffalo modification could improve specificity for malleolar fractures without sacrificing sensitivity and could significantly reduce the need for radiography.

Test-retest reliability of the cognitive lifetime drinking history

A new measure of lifetime alcohol consumption, the Cognitive Lifetime Drinking History (CLDH) uses beverage-specific questions on drink sizes and assesses drinking patterns to enhance recall. Two methods of establishing drinking intervals were examined: 1) floating--the respondent's report of when drinking changed, and 2) fixed--defined in terms of decades. Test-retest reliability for lifetime ounces of alcohol consumed and times intoxicated in lifetime estimated at visits 1 week or more apart was assessed in postmyocardial infarction patients (n = 81) and controls (n = 138) who had had at least 12 drinks in a year during their lifetimes. No significant differences in estimates of lifetime ounces of alcohol or times intoxicated were observed. Spearman's r ranged between 0.85 and 0.92 for the floating and fixed versions of the CLDH administered at a single visit and between 0.74 and 0.85 for the floating or fixed administered at both visits. Time between visits did not influence correlations. Intervals reported on the floating CLDH were comparable for postmyocardial infarction patients and controls. It took approximately 5 minutes longer to administer the floating CLDH than the fixed CLDH. Findings support use of the CLDH for case-control studies and suggest that the floating and fixed versions would yield comparable results.

Diet and alcohol consumption and lung cancer risk in the New York State Cohort (United States)

The relationship between diet and alcohol and lung cancer was evaluated among participants of the New York State Cohort (United States), comprising 27,544 men (395 cases) and 20,456 women (130 cases) who completed a brief mailed questionnaire in 1980. Participants were followed up through 1987 with the assistance of the New York State Department of Health's Vital Statistics Section and Cancer Registry. Among men, inverse relationships with vitamin C, folate, and carotenoids, and positive associations with total fat, monounsaturated and saturated fat were observed after adjusting for age, education, cigarettes/day, years smoking, and total energy intake. The relationships observed with folate and saturated fat were stronger for heavy smokers. Also, the effect of folate, total fat, and monounsaturated fat seemed to be limited to squamous cell carcinomas. We found no indication that cholesterol or polyunsaturated fat was associated with lung cancer. Diet did not appear to exert a major role on lung cancer risk among women. Although diet modification should never be considered a substitute for smoking cessation, its role as an additional strategy in lung cancer prevention deserves attention.

Impact of interferon beta-1a on neurologic disability in relapsing multiple sclerosis. The Multiple Sclerosis Collaborative Research Group (MSCRG)

BACKGROUND AND OBJECTIVE

A phase III double-blind, placebo-controlled clinical trial demonstrated that interferon beta-1a (IFN beta-1a) (Avonex, Biogen) significantly delayed progression of disability in relapsing MS patients. The primary clinical outcome was time from study entry until disability progression, defined as > or = 1.0 point worsening from baseline Kurtzke Expanded Disability Status Scale (EDSS) score persisting for at least two consecutive scheduled visits separated by 6 months. The objective of this study was to examine the magnitude of benefit on EDSS and its clinical significance.

METHODS

Post hoc analyses related to disability outcomes using data collected during the double-blind, placebo-controlled phase III clinical trial.

RESULTS

(1) Clinical efficacy related to disability did not depend on the definition of disability progression. A significant benefit in favor of IFN beta-1a was observed when > or = 2.0 point worsening from baseline EDSS was required or when worsening was required to persist for > or = 1.0 year. (2) Placebo recipients who reached the primary clinical outcome worsened by a larger amount from baseline EDSS than did IFN beta-1a recipients who reached the primary study outcome. (3) Significantly fewer IFN beta-1a recipients progressed to EDSS milestones of 4.0 (relatively severe impairment) or 6.0 (unilateral assistance needed to walk). (4) Cox proportional hazards models demonstrated that the only baseline characteristic strongly correlated with longer time to disability progression was IFN beta-1a treatment.

CONCLUSIONS

The primary clinical outcome for the IFN beta-1a clinical trial underestimated clinical benefits of treatment. Results in this report demonstrate that IFN beta-1a treatment is associated with robust, clinically important beneficial effects on disability progression in relapsing MS patients.

Mechanism(S) of interferon inhibitory activity in blood from patients with AIDS and patients with lupus erythematosus with vasculitis

We have earlier reported that patients suffering from acquired immuno-deficiency syndrome (AIDS), systemic lupus erythematosus (SLE) with vasculitis, Wegner granulomatosis and certain types of late stage cancer have interferon inhibitory activity in their serum. The purpose of this study was to identify the factor(s) involved in this interferon inhibitory activity. Twenty patients with advanced AIDS, twenty patients with SLE and vasculitis and twenty normal healthy controls between ages 25-40 years were studied. In contrast to normal, healthy controls, significant interferon inhibitory activity was found in AIDS and SLE patients. This appears to be largely due to: (a) increased soluble circulating interferon alpha/beta receptors, (b) increased prostaglandin E2 levels which inhibits interferon and (c) a interferon inhibitory protein. Further understaging of the nature of interferon inhibitory activity in the patient's sera and development of anti-interferon inhibitory agents would greatly enhance interferons potential as a treatment modality.

Correlation of clinical, magnetic resonance imaging, and cerebrospinal fluid findings in optic neuritis

We found 42 of 74 patients (57%) with isolated monosymptomatic optic neuritis to have 1 to 20 brain lesions, by magnetic resonance imaging (MRI). All of the brain lesions were clinically silent and had characteristics consistent with multiple sclerosis (MS). None of the patients had ever experienced neurologic symptoms prior to the episode of optic neuritis. During 5.6 years of follow-up, 21 patients (28%) developed definite MS on clinical grounds. Sixteen of the 21 converting patients (76%) had abnormal MRIs; the other 5 (24%) had MRIs that were normal initially (when they had optic neuritis only) and when repeated after they had developed clinical MS in 4 of the 5. Of the 53 patients who have not developed clinically definite MS, 26 (49%) have abnormal MRIs and 27 (51%) have normal MRIs. The finding of an abnormal MRI at the time of optic neuritis was significantly related to the subsequent development of MS on clinical grounds, but interpretation of the strength of that relationship must be tempered by the fact that some of the converting patients had normal MRIs and approximately half of the patients who did not develop clinical MS had abnormal MRIs. We found that abnormal IgG levels in the cerebrospinal fluid correlated more strongly than abnormal MRIs with the subsequent development of clinically definite MS.

Thromboembolism prophylaxis in chronic atrial fibrillation. Practice patterns in community and tertiary-care hospitals

BACKGROUND AND PURPOSE

By 1992, several prospective trials established the efficacy of anticoagulation (AC) and to some extent antiplatelet (AP) agents in the prevention of stroke in the setting of atrial fibrillation (AF). The objective of this study was to determine whether practice patterns in AF stroke prophylaxis reflect the findings of clinical trials and whether stroke prophylaxis in AF differs between community hospitals and tertiary teaching hospitals.

METHODS

Retrospectively, 1250 hospital charts were reviewed. After patients who had undergone recent surgery, received treatment for malignancy, or were not in chronic AF on discharge were eliminated, 651 remaining records were analyzed for the presence of 26 clinical factors influencing the selection of thromboembolism prophylaxis. Descriptive statistics and logistic regression were used to analyze the association between clinical and demographic factors and the decision to treat with AC, AP, or no specific antiembolic therapy.

RESULTS

Of the 651 patients in AF, 273 (42%) received noemboli prophylaxis while 219 (34%) were treated with AC (warfarin), 146 (22%) were treated with AP, and 13 (2%) received both agents. Patients discharged in AF from community hospitals were significantly less likely to be treated with either AC or AP agents than patients discharged from tertiary centers. A strong bias against thromboembolism prophylaxis with either AC or AP agents in AF existed with age over 45 years. Multivariate logistic regression indicated that the decision to treat was associated only with the presence of prosthetic valve, history of prior stroke, mitral disease, and absence of a recent gastrointestinal bleed or occult blood in stool. Even after adjustment for these factors, a significant bias against treatment with either AC or AP agents with advancing age and discharge from community hospitals remained.

CONCLUSIONS

Thromboembolism prophylaxis with either AC or AP agents is underutilized in the setting of AF. Furthermore, factors known to increase the risk of embolization in AF such as age, hypertension, diabetes, and heart disease were not associated with decisions to treat with either AP or AC agents. This study suggests that the use of clinical guidelines suggested by trials of thromboembolism prophylaxis in AF could reduce the incidence of stroke.

Bombesin antagonist prevents CO2 laser-induced promotion of oral cancer

We previously reported that CO2 laser incisions in carcinogen-initiated fields promoted cancer development and caused release of growth factors. Here we examined the quantitative and additive properties of this tumor-promoting event and examined whether this promotion could be nullified by treatment with a bombesin antagonist, which down-regulates epidermal growth factor receptors. The model used for cancer promotion was the hamster buccal cheek pouch that had been treated with a carcinogen (9,10-dimethyl-1,2-benzanthracene) for 6 weeks, producing premalignant lesions. These lesions would evolve into a cancer eventually without further treatment. Promotion was measured both by increased fluorescence in response to systemically administered Photofrin, measured noninvasively using an in vivo fluorescence photometer, and by the timing of appearance of clinical tumors. Laser incisions (0-3) were made into the hamster cheek 1 week apart, or three incisions were done 1 day apart. Another group of animals received bombesin antagonist RC-3095 for 4 weeks during the time incisions were made, again measuring promotion. Laser incisions 1 week apart produced additive promotion, whereas three incisions 1 day apart were not statistically different from the group receiving only one incision. RC-3095 treatment completely eliminated the promoting effects of incision and totally stopped promotion for the 4-week period of treatment. After discontinuing treatment with RC-3095, lesion progression resumed at the untreated control rate. This work confirms that the promoting event of a laser incision follows a comparable time course to release of growth factors after such an incision and that it can be eliminated by treatment with bombesin antagonists.

Intramuscular interferon beta-1a for disease progression in relapsing multiple sclerosis. The Multiple Sclerosis Collaborative Research Group (MSCRG)

The accepted standard treatment of relapsing multiple sclerosis consists of medications for disease symptoms, including treatment for acute exacerbations. However, currently there is no therapy that alters the progression of physical disability associated with this disease. The purpose of this study was to determine whether interferon beta-1a could slow the progressive, irreversible, neurological disability of relapsing multiple sclerosis. Three hundred one patients with relapsing multiple sclerosis were randomized into a double-blinded, placebo-controlled, multicenter phase III trial of interferon beta-1a. Interferon beta-1a, 6.0 million units (30 micrograms¿, was administered by intramuscular injection weekly. The primary outcome variable was time to sustained disability progression of at least 1.0 point on the Kurtzke Expanded Disability Status Scale (EDSS). Interferon beta-1a treatment produced a significant delay in time to sustained EDSS progression (p = 0.02). The Kaplan-Meier estimate of the proportion of patients progressing by the end of 104 weeks was 34.9% in the placebo group and 21.9% in the interferon beta-1a-treated group. Patients treated with interferon beta-1a also had significantly fewer exacerbations (p = 0.03) and a significantly lower number and volume of gadolinium-enhanced brain lesions on magnetic resonance images (p-values ranging between 0.02 and 0.05). Over 2 years, the annual exacerbation rate was 0.90 in placebo-treated patients versus 0.61 in interferon beta-1a-treated patients. There were no major adverse events related to treatment. Interferon beta-1a had a significant beneficial impact in relapsing multiple sclerosis patients by reducing the accumulation of permanent physical disability, exacerbation frequency, and disease activity measured by gadolinium-enhanced lesions on brain magnetic resonance images. This treatment may alter the fundamental course of relapsing multiple sclerosis.

Treatment of advanced ovarian carcinoma in the elderly

This study retrospectively analyzes the treatment of advanced ovarian cancer (Stages III and IV) in elderly patients (> or = 65) compared to that in younger patients (< 65). The purpose of this study was to identify possible treatment bias toward the elderly and to statistically analyze the nature of these differences. Seventy patients were evaluated of which 29 were identified as elderly and 41 as young. All patients were treated with platinum-based chemotherapy. Chi 2, log rank, Kaplan-Meier, and Cox model analyses were performed for multiple variables including age, grade of tumor, adequacy of surgery, and dose intensity. The elderly significantly differed from the young in the following analyses: median length of hospitalization, 20 days vs 11 days (P < 0.001); optimum surgery, 79.3% vs 97.5% (P = 0.02); initial chemotherapeutic dose reduction, 15.4% vs 0% (P = 0.02); median survival compared to age, 19.2 months vs 36.7 months (P < 0.03). When survival analysis was performed comparing 17 elderly patients and 40 younger patients who had optimum surgery and optimum initial chemotherapy, the median survival remained essentially unchanged, 22.0 months vs 36.7 months. There were differences in treatment intensity between young and old, however, the indications generally were valid and when analyzed by the Kaplan-Meier and Cox model, these differences became insignificant. It was concluded that when elderly patients can undergo aggressive surgical and chemotherapeutic management, survival remained significantly decreased for aged compared to younger patients. Physician bias was not a major factor accounting for the poorer survival observed in elderly patients. Age was the most significant variable related to survival and could not be accounted for by differences in adequacy of surgery or dose intensity.

Hormone-refractory metastatic prostatic cancer treated with methotrexate, cyclophosphamide plus adriamycin, cis-platinum plus 5-fluorouracil plus cyclophosphamide. National Prostatic Cancer Project randomized trial

From 1982 to 1985, the National Prostatic Cancer Treatment Group conducted a randomized prospective trial of single-agent or combination chemotherapy in 180 patients with metastatic prostatic disease refractory to hormonal therapy. All three of the treatment regimens, methotrexate, Adriamycin plus cyclophosphamide, cis-platinum plus 5-fluorouracil plus cyclophosphamide, showed similar survival and progression-free survival intervals. Future studies utilizing these or other agents, in similar or modified dosage schedules or delivery mechanisms, should note these results. Protocols designed to address subjective quality of life measures and other benefit ratios can be effectively employed considering this report.

Experience with the use of generalized data base management systems in cooperative group clinical trials (a project of the Gynecologic Oncology Group)

Roswell Park Management Information System (RPMIS) is a formatted video-based system of programs for file creation, data entry, editing, updating, retrieval, and report generation. It has been utilized in more than 800 intrainstitutional research studies at Roswell Park. The Gynecologic Oncology Group (GOG) is a multiinstitutional, multidisciplinary cooperative group. Its clinical trials encompass the planning, initiation, execution, analysis, and presentation of results of management and treatment of patients with gynecologic cancer. The GOG Statistical Office, located at Roswell Park Memorial Institute, is responsible for data management and analysis of all patients entered into GOG protocols. Present annual accrual is approximately 2000 patients per year; 38 protocols are actively accruing patients while follow-up continues on 14 studies that are closed to patient entry. A previous paper (J Med Syst 7:235-242, 1983) described a time study comparing use of RPMIS and a paper batch processing system in GOG data management. The time study results and potential advantages of RPMIS warranted a gradual total conversion to this system. Presently GOG maintains 43 separate, self-contained applications of RPMIS and routinely develops a new system in conjunction with each new study initiated. This paper documents GOG experience with RPMIS during the past 4 years.

Prostatic cancer. Treated at a categorical center, 1980-1983

This report covers the experience from 537 patients with prostatic cancer seen at Roswell Park Memorial Institute (RPMI) from 1980 through 1983. This is a look at experiences in the early 1980s and is a continuation of the series covering the decades of the 1950s, 1960s, and 1970s. Referrals continue to dominate the series (85% of cases) but are now only slightly younger (65 years) than in-house diagnoses (66 years), of which one third were diagnosed at autopsy. Survival rates in this series, although limited in follow-up, were similar at two years to those in the 1970s and in the extensive series collected by the survey of the American College of Surgeons. Multiple primary tumors were observed in 22 per cent of this series, most frequently involving the bladder in addition to the prostate. Treatments continue to involve chemotherapy earlier in the course of disease as part of a succession of therapeutic modalities that include transurethral resection of prostate (TURP) or prostatectomy, lymph node dissection, external irradiation, castration, and hormones.

Relative reliability of five serially measured markers for prognosis of progression in prostate cancer

During an 8-year period, 1,065 serum specimens were collected from 79 patients with prostate cancer of stages B2 to D1 (group I) and 51 patients with newly diagnosed stage D2 prostate cancer (group II) to evaluate statistically the relative reliability of elevated tumor-associated markers for progressive disease in prostate cancer. Forty of the group I patients and 21 of the group II patients presented a clinical progression of disease during follow-up. With the use of Gail's modification of Cox's regression model, serial acid phosphatase (AcP), total alkaline phosphatase (TAP), bone alkaline phosphatase (BAP), prostatic acid phosphatase (PAP), and prostate-specific antigen (PA) were analyzed. Results from group I patients revealed that only PA (P = .0002) and PAP (P = .0684) were prognostically important markers for detection of imminent disease progression. However, all markers were prognostically important in group II patients. Comparative studies indicated that PA (P = .0052) and PAP (P = .0359) were the more reliable markers for group I patients, whereas PA (P less than .0001), BAP (P = .0007), and PAP (P = .0206) were the more reliable markers for group II patients. Multivariate analyses revealed that, after adjustment for the effect of PA, no other marker was significantly related to the risk of progression. Elevated PA levels were predictive of increased risk 6 months before disease progression in group I patients only (P less than .0001). Overall, the apparent order of prognostic reliability for disease progression was found to be PA greater than PAP greater than BAP greater than AcP greater than TAP.

Prognostic factors in patients with advanced stage prostate cancer

The relationships of 13 potential prognostic factors to objective response to treatment and survival time were investigated, using data gathered on 1,020 patients with advanced stage prostate cancer who have participated in the clinical trials of the National Prostatic Cancer Project. Multivariate statistical analyses revealed that previous hormone response status, analgesics, pain, elevated acid phosphatase, and anemia were the important, independent prognostic factors for objective response to treatment. For survival time, the significant prognostic factors were previous hormone response status, anorexia, elevated acid phosphatase, pain, elevated alkaline phosphatase, obstructive symptoms, tumor grade, performance status, anemia, and age at diagnosis. It is recommended that future treatment protocols for advanced stage prostate cancer take into account heterogeneity of the treatment groups with respect to these factors, either through the design of the protocol, or at the time of analysis.

Postoperative respiratory complications in patients with Hodgkin's disease: relationship to the size of the mediastinal tumor

Postoperative respiratory complications were investigated in patients with Hodgkin's disease, stages I-III, presenting with a mediastinal mass. By measuring the ratio between the widest diameter of the mediastinal mass and the width of the thorax at T5-6 (mediastinal thoracic ratio, MTR) in a PA chest X-ray, patients were divided into three groups: I: MTR less than 0.35 (41 patients); II: MTR 0.35-0.49 (33 patients); and III: MTR greater than 0.50 (23 patients). Five patients of group II and eight of group III received preoperative radiation therapy (RT) to the mediastinum due to severe clinical or radiological findings associated with the mediastinal mass. No patient of group I received preoperative RT. Without preoperative RT, group III had a significantly higher incidence of respiratory complications (7/15) compared to groups I (7/41) and II (2/28). Respiratory complications were not significantly different after preoperative RT in group III (1/8) compared to that observed in groups I plus II without preoperative RT (9/69).

A comparison of estrogen and androgen receptor levels in human prostatic tissue from patients with non-metastatic and metastatic carcinoma and benign prostatic hyperplasia

Estrogen receptors (ER, N = 72) and androgen receptors (AR, N = 33) were determined by high pressure liquid chromatography (HPLC) in 72 human prostatic tissues obtained at prostatectomy, and exploratory statistical analyses of the resulting data were performed. To facilitate use of these data as well as other pertinent information from the patient charts, a program for a comparatively large data base was implemented on a Wang minicomputer. The median values of cytosolic AR in the four cancer stages examined were statistically different from each other (P = 0.01), with AR increasing from stages A through D. Even though ER differences between the four stages were not significant (P = 0.13), there was a trend, in the data examined, for median ER values to decrease with stages B through D. On the other hand, median BPH values for both ER and AR were found to lie mid-scale compared with the respective cancer stages, leading to the conclusion that receptor measurements probably cannot distinguish between CA and BPH in human prostatic tissue, at least as measured by competitive binding techniques.

Relationship between leukemic cell retention of cytosine arabinoside triphosphate and the duration of remission in patients with acute non-lymphocytic leukemia

Bone marrow cells were obtained from patients with acute non-lymphocytic leukemia immediately prior to the administration of cytosine arabinoside/anthracycline antibiotic remission induction therapy. The ability of the leukemic cells to take up and phosphorylate cytosine arabinoside (araC) and to retain cytosine arabinoside triphosphate (araCTP) was measured and compared to the outcome of remission induction therapy and the duration of remission. While the outcome of remission induction therapy was unrelated to cellular metabolism of araC, the duration of remission was highly correlated with araCTP retention. A comparison of the remission durations of patients treated on successive chemotherapeutic protocols suggests that the benefits of intensive remission consolidation therapy may be limited to patients whose leukemic cell retention of araCTP is low and that aggressive consolidation chemotherapy may reduce the prognostic significance of araCTP retention.

The clonogenic assay as a reproducible in vitro system to study predictive parameters of treatment outcome in acute nonlymphoblastic leukemia

Seven institutions studied the cloning pattern of leukemic cells from pretherapy bone marrows of 273 patients with newly presenting and relapsed acute nonlymphoblastic leukemia. The cloning assay was done in all centers using an identical double-layer agar method with a common source of colony-stimulating factor. Cells were incubated for seven days, and clones were identified visually with an inverted microscope. All centers were able to obtain clonal growth in a substantial proportion of patients. Differences in growth pattern were observed between the major contributing center and the pooled results for all other centers. However, an analysis of clinical results suggested that in vitro differences were more likely related to differences in the patient populations than to variability in laboratory technique. The proportion of marrows in which leukemic cells formed colonies (greater than 40 cells) and large clusters (20-40 cells) was greater in relapsed patients than in newly presenting patients (P less than .06). A progressive improvement in induction treatment outcome was seen with decreasing clonal growth. Patients whose marrows did not produce clones had a complete remission (CR) rate of 83% versus 50% for those patients whose marrow leukemic cells formed colonies and/or large clusters (P = .05). In vitro drug sensitivity studies with cytosine arabinoside and adriamycin were performed on bone marrow cells of patients treated with this combination clinically. The percent killing of clonogenic cells in this assay correlated with remission induction outcome. Complete remission was obtained in 73% of 15 patients whose bone marrow leukemic cells showed greater than 30% killing by in vitro drug exposure, and CR was obtained in only 30% of 23 patients whose marrows showed less than 30% killing (P less than .01). The results indicate that the clonogenic assay correlates with treatment outcome and can be used for drug sensitivity testing in patients with acute nonlymphoblastic leukemia. The limitations of the assay are discussed.

Skin pressure measurements on various mattress surfaces in cancer patients

Twenty-eight patients with histologically proven carcinoma were studied on two dynamic and six static mattress surfaces to determine which mattress surface would provide the least skin surface pressure at the sacrum, dorsal spine, trochanter and heels. Measurements were taken with an especially designed inflatable bladder, and the mean of the maximum skin surface pressures was determined for the static and dynamic surfaces in the inflated and deflated state. Using less than or equal to 32 mm Hg as the skin surface pressure at which the arteriolarcapillary blood flow is interrupted, we concluded that the mud gel bed generally tended to record the lowest skin surface pressure for all of the sites. Although some of the static surfaces recorded pressures less than or equal to 32 mm Hg at the sacrum and dorsal spine, the deflated dynamic surfaces were superior to the remaining static surfaces in reducing the skin surface pressures.

Recognition of drug resistance during remission induction therapy for acute non-lymphocytic leukemia: utility of day 6 bone marrow biopsy

While the majority of patients under 70 years of age with acute non-lymphocytic leukemia enter remission when treated with a combination of cytosine arabinoside and an anthracycline antibiotic, 20-45% of patients do not. The reasons for treatment failure in these patients vary from drug resistant disease to death from infection or bleeding shortly after remission induction therapy is initiated. Clearly, more intensive remission induction therapy should be administered only to those patients for whom the therapy being employed is of insufficient intensity. Bone marrow biopsies after six days of therapy have been performed on 53 patients who received 65 courses of remission induction therapy. Eighty-eight per cent of the remissions occurred in patients whose marrow cellularity was less than 62.5% on day 6 while 78% of patients who had drug resistant disease had day 6 marrow cellularities which exceeded 62.5%. Hence, a bone marrow biopsy performed after six days of therapy permits the recognition of the majority of patients who will enter complete remission or alternatively who need more aggressive therapy.

Phase I trial and pharmacokinetics of a daily x 5 schedule of 3-deazauridine

The uridine analog 3-deazauridine has been given to 19 patients in a phase I and pharmacokinetic study. Only mild toxicity was seen at doses less than 1200 mg/m2/day for 5 days. At a dose of 1200 mg/m2/day x 5, leukopenia (mean wbc count nadir of 2650/mm3) was seen in nine of 12 patients and thrombocytopenia (mean platelet count nadir of 47,000/mm3) in five of 12 patients. Nausea and vomiting and oral toxicity were each seen in two patients, and diarrhea and skin toxicity occurred in one patient each. Pharmacokinetic studies indicate a biphasic plasma decay with a beta-half-life of 6.9 hours and urinary excretion, mostly of unchanged drug, as the most important route for drug elimination. A dose of 1200 mg/m2/day x 5 is recommended for phase II studies and great caution is advised in administering the drug in the presence of renal impairment.

U.S. centralized cancer patient data system for uniform communication among cancer centers

The evolution of the Centralized Cancer Patient Data System, a cooperative venture of the 21 comprehensive cancer centers in the United States, and its structure at the end of 3 years of data collection are described. Functions of the data system are detailed in terms of input and output. It is concluded that the short-run objective of establishing a data system to provide high-quality patient data that ae 21 comprehensive cancer centers in the United States, and its structure at the end of 3 years of data collection are described. Functions of the data system are detailed in terms of input and output. It is concluded that the short-run objective of establishing a data system to provide high-quality patient data that ae 21 comprehensive cancer centers in the United States, and its structure at the end of 3 years of data collection are described. Functions of the data system are detailed in terms of input and output. It is concluded that the short-run objective of establishing a data system to provide high-quality patient data that are comparable among cancer centers has been largely accomplished. Moreover, the very process of setting up the national data system has benefited the participating centers by upgrading their individual cancer registries. For the future, the goal is to realize the research potential of this new cooperative data collection mechanism, as well as the accumulating data themselves. Progress toward the long-term goal is just beginning.

A genetic analysis of melanoma--polygenic inheritance as a threshold trait

A total of 214 melanoma patients and 193 age- and sex-matched controls, interviewed at the Roswell Park Memorial Institute during the years 1974--1978, provided information regarding 1134 and 1043 New York State first order relatives (parents, offspring and siblings). The vital information provided was checked against the records of the New York State Tumor Registry to find cases of melanoma among relatives. Five cases of melanoma were found among the 1027 New York State relatives of melanoma index cases alive during the period 1949--1978, inclusive. No cases of melanoma were found among New York State relatives of controls. The expected number of melanomas among a cohort of relatives of identical sex and age composition for the interval was 0.625 cases, giving a ratio of observed to expected of 8.0. A similar analysis, restricted to parent-offspring pairs, yielded a ratio of observed to expected of 12.7. A search for additional melanoma cases among second degree relatives of familial index cases yielded no further affected relatives. The incidence of melanoma among relatives of melanoma cases and in a comparable general population were used to estimate the heritability of liability to melanoma as a polygenic trait. A heritability estimate of 0.49 was obtained, using parent-offspring data, indicating that nearly half of the variability in liability to melanoma in this population may be attributed to the additive action of many genes, each with small effect. Pending the replication of these findings, the 12-fold increase in incidence of melanoma among parents and offspring of melanoma cases suggests the importance of counseling and surveillance of relatives of affected individuals by the clinician.

Prostate cancer mortality among Catholic priests

To investigate the possible role of celibate lifestyles in the etiology of prostate cancer, analyses of mortality from cancers of the prostate and other sites among an average annual cohort of 6,226 Roman Catholic clergymen in New York State from 1965 through 1977 were conducted. The death certificates of 1006 (95%) priests were reviewed. Of these 156 deaths were attributable to malignant neoplasms. Clerics experienced mortality ratios of 15% less for all causes of death and 30% less for cancer mortality, given mortality patterns among New York State white males of comparable ages. Twelve deaths from prostatic cancer were observed while 19.8 were expected. This represents a mortality experience significantly less than that of the general noncelibate population. Lower mortality ratios were found also for cancers of the lung, colo-rectum, and stomach. Higher mortality ratios were found for malignant melanoma and unspecified respiratory organs.

Antitumor activity of Corynebacterium parvum and retinyl palmitate used in combination on the Lewis lung carcinoma

The effects of Corynebacterium parvum and retinyl palmitate given at various levels, schedules, and routes of administration on primary Lewis lung carcinoma and its metastases have been evaluated in C57BL/6J mice given s.c. inoculations of 5 X 10(5) tumor cells. Single i.v., but not i.p., s.c., or i.m., administration of C. parvum (0.35 mg/mouse given on Days 0, 1, or 3) reduced growth of tumor and prolonged survival time. Retinyl palmitate (3000 IU/mouse/day) given alone i.p. either before, after, or both before and after tumor inoculation showed no effect on tumor growth, survival of mice, or lung metastases. The combination of retinyl palmitate i.p. (6 daily injections of 1500 IU/mouse after tumor implantation) and C. parvum (0.175 mg/mouse) given i.v. resulted in an increase in life span over control of 146% and appeared to be therapeutically synergistic. This combination produced 90-day cures in about 20% of the treated animals, all of which were found to be tumor free. Two nonparametric statistical procedures, the Kruskal-Wallis and the Dunn test, were used to assess the effects of treatments on survival time and tumor growth and may be generally applicable to animal tumor studies. They provide multiple comparisons of different treatments and allow the inclusion of long-term survivors into the analysis.

Cellular differentiation of the immune system of mice. V. Class differentiation in marrow precursors of plaque-forming cells

Marrow cells and thymocytes of unprimed donor mice were mixed in vitro and transplanted into X-irradiated syngeneic hosts. 18 hr later sheep erythrocytes were injected to induce immune responses. Splenic plaque-forming cells (PFC) secreting IgM (direct PFC) or IgG (indirect PFC) hemolytic antibody were enumerated at the time of peak responses. By transplanting graded and limiting numbers of marrow cells with 5 x 10(7) thymocytes, inocula were found that contained few precursors of PFC (P-PFC) reaching the recipient spleens, interacting with thymocytes, and generating PFC. However, the frequency of responses in relation to the number of grafted marrow cells did not follow Poisson statistics, presumably because the interaction of marrow cells with thymocytes was more complex than a single or a one-to-one cell event. The frequency of direct PFC responses was greater than that of indirect PFC responses in 13 of 15 groups of mice tested. This was interpreted as evidence for the existence of two classes of P-PFC, each of which was restricted to generate either direct or indirect PFC. The precursors of direct PFC were approximately 15 times more frequent than those of indirect PFC. Since thymic antigen-reactive cells were not differentiated for antibody class, it follows that antigen-sensitive units reactive to sheep erythrocytes owe their class restriction to specialized marrow cells. Specialization of P-PFC may have arisen within marrow cell lines by differentiation, or may have been conferred upon P-PFC by interaction with other cells, including those of the irradiated host.

Cellular differentiation of the immune system of mice. IV. Lack of class differentiation in thymic antigen-reactive cells

Thymocytes and marrow cells of unprimed donor mice were mixed in vitro and transplanted into X-irradiated syngeneic mice. 18 hr later, sheep erythrocytes were injected to induce immune responses. Splenic plaque-forming cells (PFC) secreting IgM (direct PFC) or IgG (indirect PFC) hemolytic antibody were enumerated at the time of peak responses. By transplanting graded and limiting numbers of thymocytes with 4 x 10(7) marrow cells, inocula were found which contained one or a few thymic antigen-reactive cells (ARC) reaching the recipient spleens, interacting with marrow cells, and inducing PFC formation. The frequency values of ARC inferred from direct and indirect plaque assays were very similar, 1 in approximately 10(7) thymocytes. Furthermore, statistical analysis indicated that the formation of direct PFC was not independent of the formation of indirect PFC. This was interpreted to mean that ARC were not specialized themselves and did not determine the molecular class of antibody to be secreted after interaction with marrow cells. Spleens of thymus-marrow grafted mice containing one or two ARC and non-limiting numbers of marrow precursors of PFC (P-PFC), had direct and indirect PFC clustered in several focal areas. Assuming that each focal area represented the progeny of one P-PFC that had interacted with ARC, these results confirmed the statistical evidence for lack of class differentiation in thymic ARC, and also indicated that each ARC or its progeny cells interacted with more than one P-PFC of either class.

Cellular differentiation of the immune system of mice. II. Frequency of unipotent splenic antigen-sensitive units after immunization with sheep erythrocytes

Spleen cell suspensions of primed donor mice containing precursors of immunocytes have been transplanted into X-irradiated recipient mice 122-138 days after immunization. Following secondary stimulation with antigen (sheep erythrocytes), these precursors, called antigen-sensitive units (ASU), gave rise to progeny cells secreting specific antibody in the spleens of recipients. Single cells releasing IgM hemolysins (direct plaque-forming cells or PFC), IgG hemolysins (indirect PFC), and hemagglutinins (cluster-forming cells or CFC) were enumerated. By transplanting graded and limiting numbers of primed spleen cells, inocula were found which contained one or a few ASU reaching the recipient spleens. We estimated, thereby, the frequency of ASU detectable by our procedures in donor cell suspensions. The values obtained from direct and in-indirect plaque assays, and from cluster assays were 1 in approximately 8.0 x 10(5), 1 in approximately 4.4 x 10(5), and 1 in approximately 5.9 x 10(5) nucleated spleen cells, respectively. The number of splenic ASU for direct PFC was not greater than that of unimmunized mice; however, immunization greatly increased the number of splenic ASU for indirect PFC and for CFC. By applying to each recipient spleen direct and indirect plaque tests and cluster tests, we found that positivity for each type of immunocyte was independent from that of the other two types. These results confirm the unipotent nature of splenic ASU in general, and document the commitment of ASU primed with SRBC to generate progeny cells secreting antibody of a single molecular (IgM or IgG) or functional (lysin or agglutinin) class. We concluded that splenic ASU are composed of relatively differentiated cells of the immune system of mice. With respect to specificity and class differentiation, ASU appear to be as specialized as antibody-producing cells themselves. Our results did not support the view that ASU-derived clonal populations shift from IgM to IgG antibody production.