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Culturally competent diabetes education for Mexican Americans: the Starr County Study.

PURPOSE: Few culturally competent health programs have been designed for Mexican Americans, a group that bears a disproportionate burden of Type 2 diabetes. In Starr County, a Texas-Mexico border community, investigators designed and tested a culturally competent intervention aimed at improving the health of this target population. The purpose of this article is to describe the development process of this diabetes education and support group intervention. METHODS: The development stages were (1) community assessment, (2) intervention design, (3) selection or development of outcomes, (4) pilot testing, and (5) a randomized clinical investigation. RESULTS: Focus group participants identified knowledge deficits regarding diabetes and self-management strategies, and suggested characteristics of an effective intervention for Mexican Americans. Outcome measures included metabolic control indicators, a newly developed knowledge instrument, and an existing health belief instrument. Preliminary analyses indicated that the intervention was successful in significantly improving metabolic control in the target population. CONCLUSIONS: Developing successful diabetes interventions for minority groups requires a number of stages, careful planning, assessment of cultural characteristics of the target population, and a systematic approach to implementation.

Clinical Competence↗

Radioprotection of bone marrow stem cell subsets by interleukin-1 and kit-ligand: implications for CFU-S as the responsible target cell population.

Various cytokines have been reported to have radioprotective effects on the bone marrow. Of these, c-kit-ligand (KL) and interleukin-1 (IL-1) have the most dramatic effect when given prior to total body irradiation (TBI). Given simultaneously, KL and IL-1 demonstrated a strong effect on increasing the LD50/30 of mice. In this case the LD50/30 of C57BL/6 mice was 1.25 (1.14-1.38) times higher (10.08 Gy [confidence interval (c.i.): 9.62-10.56] vs. 8.05 Gy [c.i.: 7.64-8.42]) when KL (120 micrograms/kg) and IL-1 (40 micrograms/kg) were injected subcutaneously at 20 hours before TBI. It was also investigated whether the combined effects of KL and IL-1 resulted in changes in the intrinsic radiation sensitivity of different bone marrow subsets. Therefore, mice were irradiated and the survival of bone marrow subsets was determined at 4-6 hours after TBI by using the CFU-S assay and the competitive repopulation assay. The CFU-S subset displayed an increased Dzero value in KL and IL-1-treated mice (0.88 Gy vs. 0.72 Gy) and the protection factor was 1.22, close to the factor found for the hemopoietic syndrome (LD50/30). It may therefore be concluded that CFU-S are the target cell population involved in hemopoietic death. Additional protection of the more primitive stem cell subset with long-term repopulation ability (LTRA) could not be shown from the data we obtained with the competitive repopulation assay. Both Dzero and the extrapolation number (n) were increased, but not significantly. These data suggest that radioprotection by cytokines is caused mainly by the decreased radiation sensitivity of the CFU-S subset, although earlier subsets may also be protected (but to a lesser extent).

Animals↗

The fallacy of enrolling only high-risk subjects in cancer prevention trials: is there a "free lunch"?

BACKGROUND: There is a common belief that most cancer prevention trials should be restricted to high-risk subjects in order to increase statistical power. This strategy is appropriate if the ultimate target population is subjects at the same high-risk. However if the target population is the general population, three assumptions may underlie the decision to enroll high-risk subject instead of average-risk subjects from the general population: higher statistical power for the same sample size, lower costs for the same power and type I error, and a correct ratio of benefits to harms. We critically investigate the plausibility of these assumptions. METHODS: We considered each assumption in the context of a simple example. We investigated statistical power for fixed sample size when the investigators assume that relative risk is invariant over risk group, but when, in reality, risk difference is invariant over risk groups. We investigated possible costs when a trial of high-risk subjects has the same power and type I error as a larger trial of average-risk subjects from the general population. We investigated the ratios of benefit to harms when extrapolating from high-risk to average-risk subjects. RESULTS: Appearances here are misleading. First, the increase in statistical power with a trial of high-risk subjects rather than the same number of average-risk subjects from the general population assumes that the relative risk is the same for high-risk and average-risk subjects. However, if the absolute risk difference rather than the relative risk were the same, the power can be less with the high-risk subjects. In the analysis of data from a cancer prevention trial, we found that invariance of absolute risk difference over risk groups was nearly as plausible as invariance of relative risk over risk groups. Therefore a priori assumptions of constant relative risk across risk groups are not robust, limiting extrapolation of estimates of benefit to the general population. Second, a trial of high-risk subjects may cost more than a larger trial of average risk subjects with the same power and type I error because of additional recruitment and diagnostic testing to identify high-risk subjects. Third, the ratio of benefits to harms may be more favorable in high-risk persons than in average-risk persons in the general population, which means that extrapolating this ratio to the general population would be misleading. Thus there is no free lunch when using a trial of high-risk subjects to extrapolate results to the general population. CONCLUSION: Unless the intervention is targeted to only high-risk subjects, cancer prevention trials should be implemented in the general population.

Confidence Intervals↗

Surveys on mammography frequency in Geneva.

Two surveys were conducted in Geneva, in 1991 and 1995, to assess the coverage of mammography before the introduction of a breast cancer screening programme. Women who attended for mammographies did so at their own request, or were referred by doctors (more by gynaecologists than general practitioners). In 1995, the total female population was around 200,000, of which the target population for screening (age group 50 to 69) was 46,000 persons. The total number of mammographies observed increased by 23%, with a higher increase for "routine" mammographies (+35%). However, these figures hide certain trends, with a high proportion of educated women performing regular breast investigations. The two year coverage rate for mammography among the 50 to 69 age group is estimated at 38%, which means that about 20,000 women within this target population in Geneva still escape screening.

Adolescent↗

Probabilistic model for estimating field mortality of target and non-target bird populations when simultaneously exposed to avicide bait.

A probabilistic model was developed to estimate target and non-target avian mortality associated with the application of the avicide CPTH (3-chloro-p-toluidine hydrochloride) to minimize sprouting rice damage in the southern USA. CPTH exposures for individual birds were predicted by random sampling from species-specific non-parametric distributions of bait seed consumption and CPTH residues detected on individual bait seeds. Mortality was predicted from the species-specific exposure versus mortality relationship. Individual variations in this response were captured in the model by Monte Carlo sampling from species-specific distributions of slopes and median toxicity values (LD50) for each bird. The model was used to simultaneously predict mortality (percentage of exposed population and number of birds killed/weight of consumed bait) for a target (blackbird) and non-target (mourning dove) species feeding on bait sites for up to five consecutive days.

Animals↗

European multicenter study on propionyl-L-carnitine in intermittent claudication.

OBJECTIVES: This study was performed to identify a target population of claudicants for propionyl-L-carnitine treatment. BACKGROUND: Previous studies suggest that the efficacy of propionyl-L-carnitine in intermittent claudication is greater in patients with severe functional impairment than in those with mild walking disability. METHODS: After run-in, 485 claudicant patients were randomized to placebo or propionyl-L-carnitine (1 g bid, p.o.) and then stratified on the basis of maximal walking distance (cutoff point 250 m) and maximal walking distance variability (cutoff point 25%). Treatment lasted 12 months. Walking capacity was assessed by treadmill and quality of life by a questionnaire exploring various aspects of daily life. RESULTS: In the target population, that is, patients who at baseline walked < or = 250 m and showed a maximal walking distance variability < or = 25%, per-protocol analysis showed that the effect of propinyl-L-carnitine was significantly greater than that with placebo for both maximal walking distance and initial claudication distance (ICD). In the intention-to-treat population, maximal walking distance increased by 62 +/- 14% on propionyl-L-carnitine and by 46 +/- 9% (p < 0.05) on placebo, while no difference between treatments was observed for ICD. The beneficial effect of propionyl-L-carnitine was confirmed when data of the target population were pooled with those of patients who at baseline walked < or = 250 m and showed a > 25% maximal walking distance < 50% variability. Actually, maximal walking distance increased by 98 +/- 16% in the propionyl-L-carnitine group and by only 54 +/- 10% in the placebo group (p < 0.01). The corresponding values for ICD were 99 +/- 21% and 51 +/- 8% (p < 0.05). For patients with baseline maximal walking distance > 250 m, no difference between treatments was observed. CONCLUSIONS: Claudicants with maximal walking distance < or = 250 m benefited from the use of propionyl-L-carnitine, with improvement in walking distance and quality of life. However, patients with mild functional impairment (i.e., walking distance > 250 m) showed no response to propionyl-L-carnitine.

Cardiotonic Agents↗

Quality assurance in screening strategies.

The pre-requisites for successful screening programmes include understanding and acceptance of the necessity for tests with achieved high coverage of those at risk for the disease, provision of screening tests, provision of facilities for treatment of abnormalities, and acceptance by women of the necessity for further investigation of abnormalities, all requiring attention to quality assurance. Screening programmes for cancer of the cervix have been very effective in many developed countries but in very few developing countries. In general, the failures in developing countries can be directly related to failure to achieve adequate quality in one or other component of a programme. Some of these failures occur at the level of the laboratory, but in several Latin American countries, there are superb laboratories, but overall the programme has failed to achieve the expected impact. In some countries this has led to alternatives to the cytology smear being evaluated, without recognition that it is not the test that has failed, but another essential component of an effective programme. The solution is attention to management and organisation at all levels, with quality assurance at each. This is required at the level of: definition of the target population, identification of the individual women in the target population, recruitment of the at risk woman to screening, administration of the screening test, laboratory examination of the test, communication of results from the laboratory to the woman and her physician, ensuring the woman attends for investigation and management of abnormal screening tests, ensuring adequate therapy of lesions identified by the diagnostic process, ensuring adequate follow-up of treated women, ensuring women with negative screening tests return for re-screening at the appropriate intervals, and monitoring and evaluation of the programme.

DNA, Viral↗

[Anesthesia and postoperative cognitive dysfunction in the elderly: a review of clinical and epidemiological observations].

Amnesic effects of anesthesia were first reported two hundred years ago, but the term postoperative cognitive dysfunction (POCD) has appeared only recently, covering a larger range of neuropsychological modifications resulting from surgical intervention. The clinical description of POCD is highly variable, ranging from concentration impairment to delirium. Significant short-term POCD is common in elderly persons, and can persist several months, varying both in time and intensity and affecting the full-range of cognitive functions (visual and auditory attention, primary and secondary memory, implicit memory, and visuospatial functioning). Incidence rates vary widely according to surgery type but also between studies for a given surgical procedure, as a result of methodological difficulties and limitations. Variability is largely attributable to the absence of a standardized POCD definition, the heterogeneity of procedures to measure cognitive deficits and the methods used for statistical analyses, but is also related to the disparity in targeted populations. The wide variation in study design and target populations precludes the application of formal meta-analysis procedures. We review the definition, epidemiology, etiology, pathophysiology and the clinical and public health implications of POCD. The effects of anesthetics are described in relation to ageing-related physiological changes. It is concluded that the complex interaction of etiological factors makes it difficult to determine at this point of time to what extent POCD may be attributed specifically to anesthetic agents.

Aged↗

Population monitoring: experience with residents exposed to uranium mining/milling waste.

More emphasis should be placed upon using biomarkers to address potential health risk among populations exposed to high concentrations of environmental toxicants. Among these studies, those which integrate exposure measurements with analyses of validated biomarkers may provide more reliable information for risk assessment and disease prevention. We have used a multidisciplinary approach to elucidate potential health hazards in a population living around uranium mining/milling facilities. The study included 24 target and 24 control residents who were matched for age and gender and selected based on time of residence in the study areas and proximity to mining/milling sites. Environmental samples were analyzed for uranium-238 (238U) concentrations and lead isotope ratios using inductively coupled plasma-mass spectrometry (ICP-MS) procedures, and blood samples were collected for cytogenetic analysis. We found that the 238U concentrations in soil samples were significantly higher than those in the control areas. In addition, the concentrations in the surface soil were significantly higher than in the subsurface soil (p<0.05) from target areas indicating environmental contamination by the mining/milling activities. Lead isotope data from soil samples taken near a railroad transfer location was significantly different from those of other sites, indicating contamination by non-native ore transported from sources outside of the region to local milling facilities for processing. Therefore, local residents have been exposed to low levels of radioactive contamination from the mining/milling activities on a daily basis for many years. From our cytogenetic analysis, the target population had more chromosome aberrations than the controls, although the differences were not significant (p<0.05). However, using our challenge assay, cells from the target population had a significantly abnormal DNA repair response, compared to cells from the same control population. In conclusion, the observed environmental contamination by uranium is consistent with the observed genotoxic effects in the target residents. Therefore, the residents have increased health risk and some of the health problems will most likely be related to exposure to the radioactive contaminants. Since the chromosome aberration frequency revealed increased, but not significant differences between the exposed and the control populations, we conclude that the health risk among the exposed residents is similar to those among nuclear workers.

Anencephaly↗

Exposure to a community-level HIV prevention intervention: who gets the message.

As part of the evaluation of a community-level HIV prevention program for women, this study examined predictors of exposure to print media and community outreach and assessed the relationship between exposure to the intervention and condom use behavior. Data from interviews with 479 women randomly selected from the intervention community in 1995 and 1996 were examined. Analysis of demographic and risk characteristics were conducted to identify predictors of exposure to the project's HIV prevention messages. Additionally, logistic regression analyses were conducted to examine the effects of intervention exposure on condom use, controlling for factors related to exposure. The results revealed that the print media campaign reached the largest number of women. However, women at highest risk did not have high rates of exposure to print media, but had greater exposure to outreach. Exposure to print media had an effect on increased communication with a main partner about condom use, but was not significantly related to condom use last time had sex. There were no significant main effects for exposure to outreach on condom use behavior. An important finding of this analysis was that each intervention strategy was successful in reaching a different portion of the target population and that exposure had differential effects on the condom use behavior of particular segments of the target population.

Adolescent↗

[How to reach the right size?].

Very little is known about how the size of an organism, or a specific tissue in an organism, is regulated. Coordinating and regulating the size of tissues is necessary for proper development, wound healing, and regeneration. Defects in a tissue-size regulation mechanism could lead to birth defects or cancer. In addition, there is a strong psychological aspect to some areas of tissue size regulation, as many cosmetic surgery procedures involve enlarging or reducing the size of some body parts. This review addresses the little bit that we know about size regulation. A key concept is that the size of a tissue is the size of the component cells multiplied by the number of those cells. This breaks the size regulation problem down to two parts. The size of cells can be regulated by nutrient sensing and secreted factors, and may have an upper limit due to an upper limit of a genome's ability to produce mRNA's and thus proteins. To regulate the number of cells in a tissue, there are several simple theoretical models involving secreted factors. In one case, the cells can secrete a characteristic factor and the concentration of the factor will increase with the number of cells secreting it, allowing the tissue to sense its own size. In another scenario, a specific cell secretes a limited amount of a factor necessary for the survival of a target population, and this then limits the size of the target population. There are currently several examples of secreted factors that regulate tissue size, including myostatin, which regulates the amount of muscles, leptin, which regulates adipose tissue, and growth hormone and insulin-like growth factors which regulate total mass. In addition, there are factors such as the < > found in Dictyostelium that regulate the breakup of a tissue into sub-groups. A better understanding of how these factors regulate size will hopefully allow us to develop new therapeutic procedures to treat birth defects or diseases that affect tissue size.

Animals↗

Hormone replacement therapy in the post-Women's Health Initiative era. Report a a meeting held in Funchal, Madeira, February 24-25, 2003.

Over 24-25 February 2003 in Funchal, Madeira, Novo Nordisk gathered together 25 of the top international hormone replacement therapy (HRT) experts, in order to debate the results of the Women's Health Initiative (WHI) and interpret its possible implications for the future use of HRT. The meeting covered many interesting and controversial areas, addressing the complex and multifaceted issues with insight and realism. Some of the areas covered at the meeting were the use of HRT as a short- or long-term therapy for hot flushes, for general menopausal symptom relief and in osteoporosis prevention; the overall risk-benefit profile and specific breast cancer concerns were also discussed. The WHI data were reviewed and summarized, and, although it was generally agreed that the study was well designed and executed, its relevance to standard hormone therapy for clinical practice must be seriously called into question. The target population used in the WHI is not representative of the target population for whom menopausal HRT is normally considered. It is important to note that randomized controlled trials such as the WHI are really scientific tools for a group of research participants, not a form of individualized medical management. Since their publication, the relevance of the WHI study results for everyday clinical practice has been the subject of controversy. The WHI targeted a group of women who were much older than those normally treated and who had numerous other risk factors. These were not women for whom a practicing clinician would think about initiating hormone therapy with the regimen that was used. Putting a high-risk 70-year-old woman on 0.625 mg conjugated equine estrogens (CEE) plus 2.5 mg medroxyprogesterone acetate would not seem appropriate for any indication. With this in mind, we reviewed statements and guidance that followed the release of the WHI to the media, putting them in context with the actual results. Focusing on data taken out of context and without reference to subject profiles, the media created an emotive wave of uncertainty for patients and physicians, which needs to be addressed through realistic, factual communication. It is clear that hormone therapy is effective for postmenopausal symptoms and osteoporosis prevention. Timing is critical for the initiation of therapy and length of treatment. The individual's unique personal profile must be assessed. This leads to the paradox of osteoporosis prevention: therapy should be long-term, but it is long-term therapy that may increase breast cancer risk. The meeting reviewed the uncertain nature of the risks for breast cancer, although the evidence is becoming stronger that combinations of estrogen and progestogen cause a modest increase in risk after 5 years, while this seems not to be true for estrogen alone. Cardiovascular disease issues were also reviewed and discussed. This is perhaps the most misinterpreted result that came out of the WHI, given the population of women studied. Considering the vascular biology and effects of early interventions, the WHI finding that hormone therapy has no place in primary cardiovascular protection is an unwarranted conclusion. Other issues regarding the risk-benefit profile of HRT for the individual patient were also discussed. Additionally, presenters explored the possibility of class effects against the potential risk factors associated with particular estrogen and progestogen types. It is quite clear that CEE and 17beta-estradiol differ with respect to their source and composition; pharmacokinetic and metabolic data indicate that they differ in their total estrogenic potency, with CEE possessing greater estrogenic potency. Using 17beta-estradiol at the lowest dosage level can provide safe and effective therapy for most indications. The evidence for progestogen differences is even more clear. Medroxyprogesterone acetate and norethisterone acetate have different pharmacokinetic profiles and different activities on steroid receptors. Evidence from preclinical and clinical studies supports the conclusion that these differences result in different pharmacological and clinical effects in favor of norethisterone acetate. Having comprehensively discussed and reviewed all available evidence, a consensus was achieved with regard to appropriate therapy: HRT should be given to women with menopausal complaints to meet their individual needs, taking into account their individual risk profile and the overall therapeutic objectives.

Estrogen Replacement Therapy↗

Different cell volume with high target cell population between liver disease and homozygous hemoglobin E.

Blood samples with increased percentage of target cells were collected from liver disease, thalassemia, homozygous hemoglobin E (E/E), and nonidentified cases. Normal cases who had no history of liver disease and normal hemoglobin typing were also included in the study for control. Patients with liver disease had increased target cell percentage with normal MCV, whereas, the other three groups had increased target cell percentage and reduced MCV. The difference was more obvious when compared with liver disease and homozygous Hb E cases. These two groups had comparable target cell percentage (14.36 +/- 4.77 in liver disease, and 14.22 +/- 1.59 in homozygous Hb E) and comparable degree of anemia (Hb level in liver disease = 11.19 +/- 0.39, and 11.30 +/- 0.16 in homozygous Hb E) but they showed a statistical significance (p less than 0.0001) between MCV (79.66 +/- 2.18 fL in liver disease, and 60.40 +/- 0.75 fL in homozygous Hb E).

Diagnosis, Differential↗

Using central cancer-registry data to monitor progress in early detection of breast and cervical cancer (Illinois, United States).

Cases of breast and cervical cancer account for almost 40 percent of all cancers diagnosed in Illinois (United States) women. Information on screening rates, however, is not collected routinely for the populations at risk. This paper reports on surveillance indicators designed to identify target populations and evaluate programs. All cases of cancers of the breast (n = 38,824, including in situ) and invasive cervix (n = 2,763) with a known stage, among women aged 40 to 74, were identified through the population-based Illinois State Cancer Registry for 1986 to 1992. The proportion of breast cancer cases with in situ disease-stage and cervical cancer cases with a late invasive stage were selected as surveillance indicators. Differences by age and race were evaluated, as were age- and race-specific trends. The data suggest that Black women, aged 40 to 74 years, and White women, aged 65 to 74 years, should be targeted for breast-cancer-screening interventions. All women, aged 40 to 74, should be targeted for enhanced cervical-cancer-screening interventions. Significant trends in in situ breast cancer diagnoses were apparent in all age-race groups, however no significant decline in invasive cervical cancer was found for any age-race group. The indicators identified the age- and race-specific disparities among potential target populations for breast and cervical cancer screening.

Adult↗

[The limits of health reporting in health planning].

Health reporting differs from traditional health statistics in (1) its claim to prospectively determine priorities and goals in the health sector, and (2) the expansion of the target group to include political decision makers and interested citizens. To date, neither has the prognostic element of health reporting been developed to satisfaction, nor has satisfactory access to the target population been gained. Forecasting requires suitable methods, an in-focus description of problems and targets, and performance control with regard to its aims. Effective access to a target population is a general problem not unique to health reporting. Forecasting and successful communication with target groups are crucial to the influence of health reporting on health planning. Both factors should be prominent goals in the future development of health reporting.

Germany↗

Prevalence and correlations of lower urinary tract symptoms, erectile dysfunction and incontinence in men from a multiethnic Asian population: Results of a regional population-based survey and comparison with industrialized nations.

OBJECTIVE: To determine, in a population-based survey, the prevalence of lower urinary tract symptoms (LUTS), erectile dysfunction (ED) and incontinence in community-dwelling men in multiethnic Malaysia, as currently available Western demographic data might not be applicable in the Asian population. SUBJECTS AND METHODS: A cross-sectional population-based survey was carried out in the State of Penang, Malaysia, with a target population of men aged > or = 40 years. Using a multistage study design, random systematic sampling was used to represent the target population, who were weighted based on ethnicity and rural-urban ratios so as to represent the general population distribution. Trained field-workers conducted direct interviews and administered the American Urological Association Symptom Index (AUA-SI), the International Index of Erectile Function (IIEF-5) questionnaire and questions on incontinence based on the International Continence Society 2002 definition. RESULTS: In all, 418 men aged > or = 40 years were interviewed, of whom 353 completed the AUA-SI questionnaire (84.5% response rate). The prevalence of mild, moderate and severe LUTS was 80.6%, 6% and 0.3%, respectively. The prevalent symptoms were frequency and nocturia. There was moderate and severe ED in 45.9% of men, whereas incontinence was reported by 8.2%. The AUA-SI correlated strongly with age (R = 0.291, P < 0.001), IIEF-5 (R = - 0.265, P < 0.001) and diabetes mellitus. CONCLUSION: The prevalence and severity of LUTS, ED and incontinence increased with age in this multiethnic Asian population, in which ED correlated strongly with LUTS. Compared to the Western population, the prevalence of LUTS was significantly lower, while the prevalence of ED and incontinence were comparable.

Adult↗

Validation of serological assays for diagnosis of infectious diseases.

Assay validation is a series of the following interrelated processes: an experimental process: reagents and protocols are optimised by experimentation to detect the analyte with accuracy and precision, and to ensure repeatability and reproducibility in the assay. a relative process: its diagnostic sensitivity and diagnostic specificity are calculated relative to test results obtained from reference animal populations of known infection/exposure status. a conditional process: classification of animals in the target population as infected or uninfected is conditional upon how well the reference animal population used to validate the assay represents the population to which the assay will be applied (accurate predictions of the infection status of animals from test results and predictive values of positive and negative test results are conditional upon the estimated prevalence of disease/infection in the target population) an incremental process: confidence in the validity of an assay increases over time when use confirms that it is robust as demonstrated by accurate and precise results (the assay may also achieve increasing levels of validity as it is upgraded and extended by adding reference populations of known infection status) a continuous process: the assay remains valid only insofar as the assay continues to provide accurate and precise results as proved through statistical verification. Therefore, validation of diagnostic assays for infectious diseases does not end with a time-limited series of experiments based on a few reference samples. Rather, it is a process that also requires constant vigilance and maintenance, along with reassessment of its performance characteristics for each population of animals to which it is applied. It is certain that the current movement to develop and implement accreditation criteria for veterinary diagnostic laboratories may be of little worth unless there is some assurance that the assays conducted in such laboratories are properly validated. Fully accredited laboratories may generate highly reproducible test results, but the results may still misclassify animals as to their infection status due to an improper assay validation process. Therefore, assay validation is foundational to the core product of veterinary diagnostic laboratories--test results and their interpretation.

Animals↗

Evidence for a third component in neutrophil aggregation: potential roles of O-linked glycoproteins as L-selectin counter-structures.

The homotypic aggregation of neutrophils requires the participation of L-selectin and the beta 2-integrins, but it has not been clear whether the two receptors recognize one another as counter-structures or whether other adhesion molecules are involved. We have examined aggregation of live neutrophils with target populations, manipulated to alter expression of adhesive epitopes, using flow cytometry. A target population depleted of both L-selectin and activatable beta 2-integrin displayed an ability to aggregate with live neutrophils, suggesting that these two molecules are not counter-structures. We also found that an O-sialoglycoprotease (GCP) from Pasteurella haemolytica is capable of inhibiting homotypic aggregation. Neutrophils treated with GCP lose O-glycosylated proteins but retain L-selectin and activatable beta 2-integrin. One or more of the GCP substrates appears to function in L-selectin-dependent binding but not in beta 2-integrin-dependent binding. Together the data suggest a mechanism of aggregation that is analogous to leukocyte-endothelial cell adhesion in which a low-affinity carbohydrate-dependent interaction precedes a high-affinity integrin-dependent adhesion.

Cell Adhesion Molecules↗