Human CD99L2 Regulates a Unique Step in Leukocyte Transmigration

CD99-like 2 (CD99L2 [L2]) is a highly glycosylated 52-kDa type 1 membrane protein that is important for leukocyte transendothelial migration (TEM) in mice. Inhibiting L2 using function-blocking Ab significantly reduces the recruitment of leukocytes to sites of inflammation in vivo. Similarly, L2 knockout mice have an inherent defect in leukocyte transmigration into sites of inflammation. However, the role of L2 in inflammation has only been studied in mice. Furthermore, the mechanism by which it regulates TEM is not known. To study the relevance to human inflammation, we studied the role of L2 on primary human cells in vitro. Our data show that like PECAM and CD99, human L2 is constitutively expressed at the borders of endothelial cells and on the surface of leukocytes. Inhibiting L2 using Ab blockade or genetic knockdown significantly reduces transmigration of human neutrophils and monocytes across endothelial cells. Furthermore, our data also show that L2 regulates a specific, sequential step of TEM between PECAM and CD99, rather than operating in parallel or redundantly with these molecules. Similar to PECAM and CD99, L2 promotes transmigration by recruiting the lateral border recycling compartment to sites of TEM, specifically downstream of PECAM initiation. Collectively, our data identify a novel functional role for human L2 in TEM and elucidate a mechanism that is distinct from PECAM and CD99.

Optimised polymer trapped-air lenses for ultrasound focusing in water exploiting Fabry-Pérot resonance

The concept of employing air volumes trapped inside polymer shells to make a lens for ultrasound focusing in water is investigated. The proposed lenses use evenly-spaced concentric rings, each having an air-filled polymer shell construction, defining concentric water-filled channels. Numerical simulations and experiments have shown that a plane wave can be focused, and that the amplification can be boosted by Fabry-Pérot resonances within the water channels with an appropriate choice of the lens thickness. The effect of the polymer shell thickness and the depth of the channels is discussed, as these factors can affect the geometry and hence the frequency of operation. The result was a lens with a Full Width at Half Maximum value of 0.65 of a wavelength at the focus. Results obtained on a metal-based counterpart are also shown for comparison. An advantage of this polymeric design is that it is easily constructed via additive manufacturing. This study shows that trapped-air lenses made of polymer are suitable for ultrasound focusing in water near 500 kHz.

Holey-structured tungsten metamaterials for broadband ultrasonic sub-wavelength imaging in water

Metamaterials exhibiting Fabry-Pérot resonances are shown to achieve ultrasonic imaging of a sub-wavelength aperture in water immersion across a broad bandwidth. Holey-structured metamaterials of different thickness were additively manufactured using a tungsten substrate and selective laser melting, tungsten being chosen so as to create a significant acoustic impedance mismatch with water. Both broadband metamaterial behavior and sub-wavelength imaging in water are demonstrated experimentally and validated with finite element simulations over the 200-300 kHz range.

High Incidence of Barotrauma in Patients With Severe Coronavirus Disease 2019

Objective.:

To report the high incidence of barotrauma in critically ill patients admitted to the intensive care unit (ICU) with coronavirus disease 2019 (COVID-19) and to discuss its implications.

Design.:

Retrospective cohort study.

Setting.:

ICU of an academic county hospital in Los Angeles, CA admitted from March 15-June 20, 2020.

Patients.:

77 patients with COVID-19 pneumonia. 75 patients met inclusion criteria.

Results.:

21% of patients with severe COVID-19 sustained barotrauma (33% of patients receiving IMV, 8% of patients receiving (NIV). There were no differences between the barotrauma and non-barotrauma groups regarding demographics, illness severity, or medications received, nor tidal volume or average/peak airway pressures in those receiving IMV. In the barotrauma group there was a greater proportion of patients receiving therapeutic anticoagulation (81% vs. 47%, p = 0.023) and ventilated using airway pressure release ventilation mode (13% vs. 0%, p = 0.043). Barotrauma was associated with increased likelihood of receiving a tracheostomy (OR 2.58 [0.23-4.9], p = 0.018]), longer median ICU length of stay (17 days vs. 7 days, p = 0.03), and longer median length of hospitalization (26 days vs. 14 days, p < 0.001). There was also a trend toward prolonged median duration of IMV (12.5 days vs 7 days, p = 0.13) and higher average mortality (56% vs 37%, p = 0.25).

Conclusions.:

Barotrauma is seen in 5-12% of patients with ARDS receiving IMV and is exceedingly rare in patients receiving NIV. We report a high incidence of barotrauma observed in critically ill patients with COVID-19 requiring either NIV or IMV. While there was a trend toward increased mortality in patients with barotrauma, this did not reach statistical significance. The increased incidence of barotrauma with COVID-19 may be a product of the pathophysiology of this disease state and a heightened inflammatory response causing rampant acute lung injury. Evidence-based medicine and lung-protective ventilation should remain the mainstay of treatment.

Ultrasonic Propagation in Highly Attenuating Insulation Materials

Experiments have been performed to demonstrate that ultrasound in the 100-400 kHz frequency range can be used to propagate signals through various types of industrial insulation. This is despite the fact that they are highly attenuating to ultrasonic signals due to scattering and viscoelastic effects. The experiments used a combination of piezocomposite transducers and pulse compression processing. This combination allowed signal-to-noise levels to be enhanced so that signals reflected from the surface of an insulated and cladded steel pipe could be obtained.

2007. Impact of Combining Rapid Diagnostics with an Interpretation Guide on Vancomycin Usage for Contaminant Blood Cultures Growing Coagulase-Negative Staphylococci (CoNS)

Background

Contaminant blood cultures can lead to unnecessary antibiotic use, longer admissions and increased costs. Rapid diagnostics, like the BioFire® FilmArray® Blood Culture Identification (BCID) Panel, can potentially lessen these harms. BioFire BCID was implemented at VA Greater Los Angeles in 7/2017. When providers review BCID results, they are also directed to an interpretation guide developed by our antimicrobial stewardship program. This study aimed to determine the impact of BioFire BCID with this interpretation guide on unnecessary vancomycin use for contaminant blood cultures growing CoNS.

Methods

This was a retrospective cohort study on adult inpatients with contaminant blood cultures positive for CoNS. We evaluated cases before BCID (April 2016–July 2017) and after BCID (July 7/2017–December 2018) implementation. Cases with patients who died or were discharged prior to preliminary results, polymicrobial cultures, no empiric vancomycin use, or where vancomycin was indicated were excluded. We defined a “case” as anytime a provider concurrently ordered blood cultures and empiric antibiotics. Our primary outcome was the duration of unnecessary vancomycin. Secondary outcomes were time to discontinuation/modification of any empiric antibiotic, length of stay (LOS), LOS in ICU and 30-day mortality.

Results

A total of 99 cases were included (N = 45 pre-BCID; N = 54 post-BCID). Demographics between the 2 groups were largely similar except the post-BCID group had more patients with end-stage renal disease (ESRD) (14 vs. 4, P = 0.037) and more frequent infectious disease (ID) consultation (21 vs. 8, P = 0.027). The post-BCID group had shorter mean duration of unnecessary vancomycin (53.0 hours vs. 38.1 hours, P = 0.0029). After controlling for ESRD and ID involvement, the mean duration of unnecessary vancomycin was not significantly different between the 2 groups (P = 0.30 and P = 0.49, respectively). There was no difference in time to modification/discontinuation of any empiric antibiotic (44.6 hr vs. 35.0 hr, P = 0.36). There was no difference in mean LOS, mean LOS in ICU, or 30-day mortality.

Conclusion

Shorter duration of unnecessary vancomycin for CoNS bacteremia after BCID implementation and provision of an interpretation guide may have been driven in part by more frequent ID consultation.

Disclosures

All authors: No reported disclosures.

Lack of improvement in antimicrobial prescribing after a diagnosis of Clostridium difficile and impact on recurrence

BACKGROUND

Antimicrobial use is one of the largest modifiable risk factors for development of Clostridium difficile infection (CDI). We sought to determine if a recent diagnosis of CDI affected the appropriateness of subsequent antimicrobial prescribing.

METHODS

This study is a retrospective electronic chart review of the Greater Los Angeles Veterans Administration. Medication administration records were reviewed for all patients with new CDI from 2015-2016 to determine the appropriateness (drug choice, duration, and dosage) of all non-CDI antimicrobials prescribed within 90 days pre- and post-initial CDI (iCDI) positive testing.

RESULTS

Of the 210 patients diagnosed with new-onset iCDI, 140 met inclusion criteria. Of antimicrobial courses prescribed, 40.6% of pre-iCDI were inappropriate compared with 43.1% of post-iCDI, demonstrating no difference in prescribing habits (P = .717). Thirty-three patients developed recurrent CDI (rCDI). After adjustment for other known risk factors, inappropriate antimicrobial use was associated with a significant increased risk of recurrence compared with appropriate use alone (odds ratio [OR], 6.19; 95% confidence interval [CI], 1.45-26.42). Antimicrobial use in general was associated with increased recurrence compared with no antimicrobial use post-iCDI (OR, 2.6; 95% CI, 1.16-5.84); however, after adjustment, it was no longer significant (OR, 2.13; 95% CI, 0.90-5.04).

CONCLUSIONS

The appropriateness of antimicrobial prescribing was not affected by the diagnosis of recent CDI. Inappropriate antimicrobial use after iCDI was associated with higher risk of rCDI.

Nebulization of RNS60, a Physically-Modified Saline, Attenuates the Adoptive Transfer of Experimental Allergic Encephalomyelitis in Mice: Implications for Multiple Sclerosis Therapy

Developing a new and effective therapeutic approach against multiple sclerosis (MS) is always an important area of research. RNS60 is a bioactive aqueous solution generated by subjecting normal saline to Taylor-Couette-Poiseuille flow under elevated oxygen pressure. Recently we have demonstrated that RNS60, administered through intraperitoneal injection, ameliorated clinical symptoms and disease progression of experimental allergic encephalomyelitis (EAE), an animal model of MS. Since the intravenous route is not preferred for treating a chronic condition, we tested if nebulization of RNS60 could attenuate the disease process of adoptively-transferred EAE in mice. Although we could not directly image RNS60 after nebulization, nebulized Alexa680 reached spleen, spinal cord and different parts of the brain. Nebulization of RNS60 starting from the acute phase attenuated clinical symptoms of relapsing-remitting EAE in female SJL/J mice. RNS60 nebulization also inhibited perivascular cuffing, maintained the integrity of blood-brain and blood-spinal cord barriers, suppressed inflammation, normalized the expression of myelin genes, and blocked demyelination in the CNS of EAE mice. On the immunomodulatory front, nebulization of RNS60 to EAE mice led to the enrichment of anti-autoimmune regulatory T cells (Tregs) and suppression of autoimmune Th17 cells. Together, these results suggest that nebulization of RNS60 may be used to control aberrant immune responses in MS and other autoimmune disorders.

4D intravital microscopy uncovers critical strain differences for the roles of PECAM and CD99 in leukocyte diapedesis

Leukocyte transendothelial migration (TEM) is an essential component of the inflammatory response. In vitro studies with human cells have demonstrated that platelet/endothelial cell adhesion molecule (PECAM) functions upstream of CD99 during TEM; however, results in vivo with mice have been apparently contradictory. In this study we use four-dimensional (4D) intravital microscopy to demonstrate that the site and order of function of PECAM and CD99 in vivo are dependent on the strain of mice. In FVB/n mice, PECAM functions upstream of CD99, as in human cells in vitro, and blocking antibodies against either molecule arrest neutrophils before they traverse the endothelium. However, in C57BL/6 mice, PECAM and CD99 appear to function at a different step, as the same antibodies arrest leukocyte migration through the endothelial basement membrane. These results are the first direct comparison of PECAM and CD99 function in different murine strains as well as the first demonstration of the sequential function of PECAM and CD99 in vivo.

Functional food microstructures for macronutrient release and delivery

There is a need to understand the role of fat, protein and carbohydrate in human health, and also how foods containing and/or structured using these macronutrients can be designed so that they can have a positive impact on health. This may include a reduction in fat, salt or sugar, the protection and targeted release of micronutrients or active ingredients from/to particular parts of the digestive system, improvement of gastrointestinal health or satiety enhancing properties. Such foods can be designed with various macro- and microstructures that will impact on macronutrient release and delivery. These include simple and double emulsions, the use of Pickering particles and shells, nanoparticles, liposomes, gelled networks, fluid gels and gel particles, foams, self-assembled structures, and encapsulated systems. In order to design foods that deliver these benefits understanding of how these structures behave in the gastrointestinal tract is also required, which should involve utilising both in vitro and in vivo studies. This review aims to draw together research in these areas, by focusing on the current state of the art, but also exciting possibilities for future research and food development.

Cutting Edge: CD99 Is a Novel Therapeutic Target for Control of T Cell-Mediated Central Nervous System Autoimmune Disease

Leukocyte trafficking into the CNS is a prominent feature driving the immunopathogenesis of multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis. Blocking the recruitment of inflammatory leukocytes into the CNS represents an exploitable therapeutic target; however, the adhesion molecules that specifically regulate the step of leukocyte diapedesis into the CNS remain poorly understood. We report that CD99 is critical for lymphocyte transmigration without affecting adhesion in a human blood-brain barrier model. CD99 blockade in vivo ameliorated experimental autoimmune encephalomyelitis and decreased the accumulation of CNS inflammatory infiltrates, including dendritic cells, B cells, and CD4(+) and CD8(+) T cells. Anti-CD99 therapy was effective when administered after the onset of disease symptoms and blocked relapse when administered therapeutically after disease symptoms had recurred. These findings underscore an important role for CD99 in the pathogenesis of CNS autoimmunity and suggest that it may serve as a novel therapeutic target for controlling neuroinflammation.

Endothelial CD99 signals through soluble adenylyl cyclase and PKA to regulate leukocyte transendothelial migration

CD99 is a critical regulator of leukocyte transendothelial migration (TEM). Watson et al. describe the CD99 signaling pathway responsible. This involves a complex of CD99 with the A-kinase anchoring protein ezrin and soluble adenylyl cyclase that activates protein kinase A during leukocyte TEM.

CD99 is a critical regulator of leukocyte transendothelial migration (TEM). How CD99 signals during this process remains unknown. We show that during TEM, endothelial cell (EC) CD99 activates protein kinase A (PKA) via a signaling complex formed with the lysine-rich juxtamembrane cytoplasmic tail of CD99, the A-kinase anchoring protein ezrin, and soluble adenylyl cyclase (sAC). PKA then stimulates membrane trafficking from the lateral border recycling compartment to sites of TEM, facilitating the passage of leukocytes across the endothelium. Pharmacologic or genetic inhibition of EC sAC or PKA, like CD99 blockade, arrests neutrophils and monocytes partway through EC junctions, in vitro and in vivo, without affecting leukocyte adhesion or the expression of relevant cellular adhesion molecules. This is the first description of the CD99 signaling pathway in TEM as well as the first demonstration of a role for sAC in leukocyte TEM.

Assessment of single versus twice daily dosing of ramipril by ambulatory blood pressure monitoring in patients similar to those included in the HOPE study

Ramipril has been used in twice daily dose of 5 mg in most heart failure trials, whereas the dose used in Heart Outcomes Prevention Evaluation (HOPE) study was 10 mg once at bedtime. The HOPE investigators in an ambulatory blood pressure (ABP) substudy observed a fall of nighttime but not daytime blood pressure (BP). We examined the effects of once daily ramipril 10 mg versus 5 mg twice a day. Twenty-nine patients were recruited based on the original criteria for the HOPE study and were given ramipril either in twice-daily dose (5 mg b.d.) or once daily (10 mg o.d.) each morning in randomized, prospective crossover trial. Twenty-four hour ABP recordings were taken just before commencement of ramipril therapy and after treatment with twice-daily and once-daily ramipril. Our results show that ramipril causes a significant reduction of BP over 24-h period as compared with baseline. The mean baseline ABP was 124/73 mm Hg, which reduced to 117/69 mm Hg for the twice-a-day regimen (P<0.001) and 115/68 mm Hg for the once a day regimen (P<0.001). Both regimes effectively lower BP to a similar extent. Ramipril causes significant BP reduction in both once- and twice-daily dosing. The fall in BP after daytime dosing is greater than that observed in the HOPE study (including ABP substudy). Once-daily dosing in the morning seems to be effective in causing a significant reduction in the ABP profile of patients at high-risk of a future vascular event.

Rheofluorescence Technique for the Study of Dilute MEH-PPV Solutions in Couette Flow

A novel rheofluorescence technique has been developed that permits the study of fluorescent polymers in a near-uniform shear field. The system has been used to examine the effects of shear flow on dilute solutions of two commercially available samples of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) in toluene and xylene. A detailed description of the instrument is provided, along with data that confirm a small probe molecule, Rhodamine 6G, is not affected by simple shear flow. MEH-PPV solutions were examined over two decades of concentration for rheochromism indicative of changes in segment length, and shear-induced orientation revealed by measurements of the steady state emission anisotropy. It is demonstrated that these dilute samples were not influenced by shear rates in the range 100-1000 s(-1). In contrast, MEH-PPV dispersed in a concentrated polystyrene solution showed evidence of shear-induced orientation and rheochromism. This new technique shows promise for investigating the impact of shear flow on the conformation of conjugated polymers employed in organic optoelectronic devices.

Alcohol consumption and the risk of type 2 diabetes mellitus: atherosclerosis risk in communities study

Evidence regarding the association between alcohol consumption and type 2 diabetes risk remains inconsistent, particularly with regard to male-female differences. The authors conducted a prospective study of type 2 diabetes risk associated with alcohol consumption in a cohort of 12,261 middle-aged participants of the Atherosclerosis Risk in Communities Study (1990-1998), who were followed between 3 and 6 years. Alcohol consumption at baseline was characterized into lifetime abstainers, former drinkers, and current drinkers of various levels. Incident diabetes was determined by blood glucose measurements and self-report. After adjustment for potential confounders, an increased risk of diabetes was found in men who drank >21 drinks/week when compared with men who drank < or =1 drink/week (odds ratio = 1.50, 95% confidence interval: 1.02, 2.20) while no significant association was found in women. This increased diabetes risk among men who drank >21 drinks/week was predominantly related to spirits rather than to beer or wine consumption. The relative odds of incident diabetes in a comparison of men who drank >14 drinks of spirits per week with men who were current drinkers but reported no regular use of spirits, beer, or wine were 1.82 (95% confidence interval: 1.14, 2.92). Results of this study support the hypothesis that high alcohol intake increases diabetes risk among middle-aged men. However, more moderate levels of alcohol consumption do not increase risk of type 2 diabetes in either middle-aged men or women.

Neighborhood of residence and incidence of coronary heart disease

BACKGROUND

Where a person lives is not usually thought of as an independent predictor of his or her health, although physical and social features of places of residence may affect health and health-related behavior.

METHODS

Using data from the Atherosclerosis Risk in Communities Study, we examined the relation between characteristics of neighborhoods and the incidence of coronary heart disease. Participants were 45 to 64 years of age at base line and were sampled from four study sites in the United States: Forsyth County, North Carolina; Jackson, Mississippi; the northwestern suburbs of Minneapolis; and Washington County, Maryland. As proxies for neighborhoods, we used block groups containing an average of 1000 people, as defined by the U.S. Census. We constructed a summary score for the socioeconomic environment of each neighborhood that included information about wealth and income, education, and occupation.

RESULTS

During a median of 9.1 years of follow-up, 615 coronary events occurred in 13,009 participants. Residents of disadvantaged neighborhoods (those with lower summary scores) had a higher risk of disease than residents of advantaged neighborhoods, even after we controlled for personal income, education, and occupation. Hazard ratios for coronary events in the most disadvantaged group of neighborhoods as compared with the most advantaged group--adjusted for age, study site, and personal socioeconomic indicators--were 1.7 among whites (95 percent confidence interval, 1.3 to 2.3) and 1.4 among blacks (95 percent confidence interval, 0.9 to 2.0). Neighborhood and personal socioeconomic indicators contributed independently to the risk of disease. Hazard ratios for coronary heart disease among low-income persons living in the most disadvantaged neighborhoods, as compared with high-income persons in the most advantaged neighborhoods were 3.1 among whites (95 percent confidence interval, 2.1 to 4.8) and 2.5 among blacks (95 percent confidence interval, 1.4 to 4.5). These associations remained unchanged after adjustment for established risk factors for coronary heart disease.

CONCLUSIONS

Even after controlling for personal income, education, and occupation, we found that living in a disadvantaged neighborhood is associated with an increased incidence of coronary heart disease.

Alcohol consumption with age: a cross-sectional and longitudinal study of the Atherosclerosis Risk in Communities (ARIC) study, 1987-1995

Previous cross-sectional and longitudinal studies assessing the association between age and drinking are inconsistent. Evaluating 15,425 Black and White men and women from four communities, this study sought to determine whether there was a consistent relation between age and drinking in cross-sectional and longitudinal analyses and to determine change in drinking status and level of consumption (occasional, light to moderate, and heavier drinkers) at follow-up. Cross-sectional analyses of drinking were performed for Atherosclerosis Risk in Communities examinations 1 (1987-1989) and 3 (1993-1995). The changes in drinking status and level were determined for the 12,565 persons with information at both examinations. Prevalence of drinking was generally inversely associated with age in the cross-sectional analyses for all ethnic/gender groups, and drinking prevalence decreased over the 6 years of follow-up for all except Black women. Only among Black drinkers was younger age associated with a higher level of alcohol consumption in both cross-sectional and prospective analyses. Thus, whether drinking prevalence declines, the amount consumed by drinkers is decreased, or whether both factors contribute to the decrease appears to vary with ethnicity and gender. The change in drinking level was substantial with more than 40% of baseline drinkers reporting drinking cessation or a different level of consumption at follow-up.

Sensitivity and specificity of the indicators of sincere effort of the EPIC lift capacity test on a previously injured population

STUDY DESIGN

Randomized control post-test only.

OBJECTIVES

To investigate the reliability and validity of the EPIC Lift Capacity test's indicators of sincere effort.

SUMMARY OF BACKGROUND DATA

The EPIC Lift Capacity test (ELC) (Employment Potential Improvement Corp., Santa Ana, CA) is a functional evaluation tool used to identify physical limitations involved in lifting and manual materials handling. Identification of insincere effort is an integral component of such functional testing because of the potential secondary gain issues surrounding the various populations typically involved in this form of testing. The purpose of this study was to determine the sensitivity and specificity of the "indicators of sincere effort" of the EPIC Lift Capacity test when used on a previously injured population typical of subjects for which the test is designed.

METHODS

Subjects consisted of 41 volunteers (age 22 to 58 years) with a previously diagnosed musculoskeletal pathology of the spine or extremities. Volunteers were randomized into either the control group, instructed to give a sincere maximum effort, or the experimental group, instructed to give an insincere effort at 50% of their perceived maximum effort. All tests were administered by certified clinical evaluators according to the standardized EPIC Lift Capacity test protocol.-

RESULTS

Overall accuracy in identifying participants' level of effort was 86.84%. The indicators of valid effort exhibited both high positive (94.44%) and negative (80.00%) predictive values. The indicators of valid effort accounted for 94.9% of the total variance in the determination of the subjects' overall effort level. Interrater reliability for agreement of subjects' overall effort was good (interclass correlation coefficient = 0.82).

CONCLUSIONS

Through use of standardized indicators of sincere effort, certified EPIC Lift Capacity test evaluators were able to predict sincerity of effort with a high degree of reliability and validity. The rater's systematicobservational evaluation of effort was shown to be the single best indicator of sincere effort.

Incident type 2 diabetes mellitus in African American and white adults: the Atherosclerosis Risk in Communities Study

CONTEXT

Although the excess prevalence of type 2 diabetes mellitus in African Americans is well established, few studies have compared incident diabetes in African American and white persons.

OBJECTIVES

To compare risk of incident diabetes in African American vs white adults and to identify explanatory factors for racial disparities.

DESIGN

Prospective cohort study using baseline data collected from 1986 to 1989 from the ongoing Atherosclerosis Risk in Communities (ARIC) Study, with 9 years of follow-up.

SETTING AND PARTICIPANTS

A total of 2646 African American and 9461 white adults aged 45 to 64 years without diabetes at baseline, sampled from 4 US communities.

MAIN OUTCOME MEASURES

Incident type 2 diabetes, ascertained by self-report of physician diagnosis, use of diabetes medications, or fasting glucose level of at least 7.0 mmol/L (126 mg/dL), compared among white and African American subjects and by presence of potentially modifiable risk factors.

RESULTS

Diabetes incidence per 1000 person-years was about 2.4-fold greater in African American women (25.1 [95% confidence interval [CI], 22.4-28.1] vs 10.4 [95% CI, 9.4-11.4]) and about 1.5-fold greater in men (23.4 [95% CI, 19.9-27.2] vs 15.9 [95% CI, 14.6-17.2]) than in their white counterparts (P<.001). Results from proportional hazards regression models indicated that racial differences in potentially modifiable risk factors, particularly adiposity, accounted for 47.8% of the excess risk in African American women but accounted for little excess risk in African American men. Compared with their white counterparts, African American men and women had higher blood pressures before diabetes onset (diastolic blood pressure difference=5.6 mm Hg in women and 8.4 mm Hg in men; P=.005).

CONCLUSIONS

Our data indicate that compared with their white counterparts, middle-aged African Americans are at greater risk of developing type 2 diabetes and have higher blood pressure prior to development of diabetes. In women, almost 50% of this excess risk might be related to potentially modifiable factors.

Antimicrobial use for pediatric upper respiratory infections: reported practice, actual practice, and parent beliefs

BACKGROUND

In response to the dramatic emergence of resistant pneumococci, more judicious use of antibiotics has been advocated. Physician beliefs, their prescribing practices, and the attitudes of patients have been evaluated previously in separate studies.

METHODS

This 3-part study included a statewide mailed survey, office chart reviews, and parent telephone interviews. We compared survey responses of 366 licensed pediatricians and family physicians in Georgia to recently published recommendations on diagnosis and treatment of upper respiratory infections (URIs). We further evaluated 25 randomly selected pediatricians from 119 surveyed in the Atlanta metropolitan area. For each, charts from the first 30 patients between the ages of 12 and 72 months seen on a randomly selected date were reviewed for encounters during the preceding year. A sample of parents from each practice were interviewed by telephone.

RESULTS

In the survey, physicians agreed that overuse of antibiotics is a major factor contributing to the development of antibiotic resistance (97%), and that they should consider selective pressure for resistance in their decisions on providing antibiotic treatment for URIs in children in their practices (83%). However, many reported practices do not conform to the recently published principles for judicious antibiotic use. For example, 69% of physicians considered purulent rhinitis a diagnostic finding for sinusitis; 86% prescribed antibiotics for bronchitis regardless of the duration of cough; and 42% prescribed antibiotics for the common cold. Reported practices by family physicians were more often at odds with the published principles: they were significantly more likely than pediatricians to omit pneumatic otoscopy (46% vs 25%); to omit the requirement for prolonged symptoms to diagnose sinusitis (median 4 vs 10 days); and to omit laboratory testing for pharyngitis (27% vs 14%). Of the 7531 encounters analyzed in the chart review, 43% resulted in an antibiotic prescription, including 11% of checkups, 18% of telephone calls, and 72% of visits for URIs. There was wide variability in the overall antibiotic use rates among the 25 physicians (1-10 courses per child per year). There was an even wider variability in some diagnosis-specific rates; bronchitis and sinusitis in particular. Those with the highest antibiotic prescribing rates had up to 30% more return office visits. Physicians who prescribed antibiotics for purulent rhinitis were more likely to see parents who believed that their children should be evaluated for cold symptoms.

CONCLUSIONS

Physicians recognize the problem of antibiotic resistance but their reported practices are not in line with recently published recommendations for most pediatric URIs. The actual prescribing practices of pediatricians are often considerably different from their close colleagues. Patient beliefs are correlated with their own physician's practices.

Serum and dietary magnesium and the risk for type 2 diabetes mellitus: the Atherosclerosis Risk in Communities Study

BACKGROUND

Experimental studies in animals and cross-sectional studies in humans have suggested that low serum magnesium levels might lead to type 2 diabetes; however, this association has not been examined prospectively.

METHODS

We assessed the risk for type 2 diabetes associated with low serum magnesium level and low dietary magnesium intake in a cohort of nondiabetic middle-aged adults (N = 12,128) from the Atherosclerosis Risk in Communities Study during 6 years of follow-up. Fasting serum magnesium level, categorized into 6 levels, and dietary magnesium intake, categorized into quartiles, were measured at the baseline examination. Incident type 2 diabetes was defined by self-report of physician diagnosis, use of diabetic medication, fasting glucose level of at least 7.0 mmol/L (126 mg/dL), or nonfasting glucose level of at least 11.1 mmol/L (200 mg/dL).

RESULTS

Among white participants, a graded inverse relationship between serum magnesium levels and incident type 2 diabetes was observed. From the highest to the lowest serum magnesium levels, there was an approximate 2-fold increase in incidence rate (11.1, 12.2, 13.6, 12.8, 15.8, and 22.8 per 1000 person-years; P = .001). This graded association remained significant after simultaneous adjustment for potential confounders, including diuretic use. Compared with individuals with serum magnesium levels of 0.95 mmol/L (1.90 mEq/L) or greater, the adjusted relative odds of incident type 2 diabetes rose progressively across the following lower magnesium categories: 1.13 (95% CI, 0.79-1.61), 1.20 (95% CI, 0.86-1.68), 1.11 (95% CI, 0.80-1.56), 1.24 (95% CI, 0.86-1.78), and 1.76 (95% CI, 1.18-2.61) (for trend, P = .01). In contrast, little or no association was observed in black participants. No association was detected between dietary magnesium intake and the risk for incident type 2 diabetes in black or white participants.

CONCLUSIONS

Among white participants, low serum magnesium level is a strong, independent predictor of incident type 2 diabetes. That low dietary magnesium intake does not confer risk for type 2 diabetes implies that compartmentalization and renal handling of magnesium may be important in the relationship between low serum magnesium levels and the risk for type 2 diabetes.

A community-based study of explanatory factors for the excess risk for early renal function decline in blacks vs whites with diabetes: the Atherosclerosis Risk in Communities study

CONTEXT

The explanation for the excess risk for diabetic renal disease in blacks is uncertain.

OBJECTIVES

To compare the incidence of early renal function decline in black and white adults with diabetes and to examine possible explanatory factors for racial differences.

DESIGN

Prospective cohort study.

SETTING

Four US communities participating in the Atherosclerosis Risk in Communities study.

PARTICIPANTS

Community-based sample of 1434 diabetic adults aged 45 to 64 years.

MEASUREMENTS

Detailed baseline assessment using structured interview, results of physical examination, and laboratory measurements.

MAIN OUTCOME

Development of early renal function decline defined by an increase in serum creatinine of at least 35.4 micromol/L (0.4 mg/dL) during 3 years of follow-up.

RESULTS

During 3 years of follow-up, early renal function decline developed in 45 blacks (28.4 per 1000 person-years [PY]) and 25 whites (9.6 per 1000 PY). After adjustment for age, sex, and baseline serum creatinine level, early renal function decline was more than 3 times as likely to develop in blacks than whites (odds ratio, 3.15; 95% confidence interval, 1.86-5.33). Additional adjustment for education, household income, health insurance, fasting glucose level, mean systolic blood pressure, smoking history, and physical activity level reduced the relative odds in blacks to 1.38 (95% confidence interval, 0.71-2.69), corresponding to a 82% reduction in excess risk.

CONCLUSIONS

These data suggest that early renal function decline is 3 times more likely to develop in blacks than whites and that potentially modifiable factors, including lower socioeconomic status, suboptimal health behaviors, and suboptimal control of glucose level and blood pressure, account for more than 80% of this disparity.

Neighbourhood differences in diet: the Atherosclerosis Risk in Communities (ARIC) Study

STUDY OBJECTIVE

To investigate whether neighbourhood characteristics are related to dietary patterns independently of individual level variables.

DESIGN

A cross sectional analysis of the relation between neighbourhood median household income and food and nutrient intakes, before and after adjustment for individual level variables.

SETTING

Four United States communities (Washington Co, MD; Suburban Minneapolis, MN; Forsyth Co, NC, and Jackson, MS).

PARTICIPANTS

13,095 adults aged 45 to 64 years participating in the baseline examination of the Atherosclerosis Risk in Communities (ARIC) Study, a prospective study of atherosclerosis.

MEASUREMENTS AND MAIN RESULTS

Information on diet and individual level income was obtained from the baseline examination of the ARIC Study. Diet was assessed using a semi-quantitative food frequency questionnaire. Information on neighbourhood (census defined block groups) median household income was obtained from the 1990 US Census. Multilevel models were used to account for the multilevel structure of the data. Living in lower income neighbourhoods was generally associated with decreased energy adjusted intake of fruits, vegetables, fish, and increased intake of meat. Patterns generally persisted after adjustment for individual level income, but were often not statistically significant. Inconsistent associations were recorded for the intake of saturated fat, polyunsaturated fat, and cholesterol. Overall, individual level income was a more consistent predictor of diet than neighbourhood income.

CONCLUSION

Despite limitations in the definition and characterisation of neighbourhoods, this study found consistent (albeit small) differences across neighbourhoods in food intake, suggesting that more in depth research into potential neighbourhood level determinants of diet is warranted.

Is fasting insulin concentration inversely associated with rate of weight gain? Contrasting findings from the CARDIA and ARIC study cohorts

OBJECTIVE

To test whether a higher fasting insulin concentration is associated with a lower rate of weight gain over six to seven years.

DESIGN

Two longitudinal epidemiologic cohorts including blacks and whites.

SUBJECTS

The Coronary Artery Risk Development in Young Adults (CARDIA) Study examined subjects aged 18-30 y in 1985-86 and 1992-93 (n = 3636), and the Atherosclerosis Risk in Communities (ARIC) Study examined subjects aged 45-64 y in 1987-89 and 1993-95 (n = 11179).

MEASUREMENTS

In each study, fasting insulin at baseline and weight change during follow-up were measured in participants without diabetes.

RESULTS

In whites and black men in CARDIA, there was a positive age-adjusted association between baseline insulin and weight change, although weight change was not entirely monotonic across the insulin quartiles. In these race-gender groups, the linear regression coefficients indicated that each 50 pmol/L increment of baseline insulin was associated (P < 0.05) with approximately 0.10 kg/y greater rate of weight gain (95% confidence intervals (CI) for this estimate in kg/y were 0.023-0.187 for white women, 0.015-0.150 for black men, and 0.011-0.158 for white men). The association was eliminated entirely with adjustment for baseline weight. In contrast, among whites and black women in ARIC, the association was negative, with the linear regression coefficients suggesting that each 50 pmol/L higher fasting insulin concentration was associated (P < 0.05) with a 0.03-0.10 kg/y lower rate of weight gain (95% CI for this estimate in kg/y were -0.133 to -0.061 for black women, -0.106 to -0.054 for white women, and -0.055 to -0.009 for white men). This finding was generally strengthened by adjustment for baseline body mass index (BMI).

CONCLUSIONS

A higher fasting insulin concentration is associated modestly with a lower rate of weight gain in ARIC, but not in CARDIA.

Neighborhood environments and coronary heart disease: a multilevel analysis

The authors investigated whether neighborhood socioeconomic characteristics are associated with coronary heart disease prevalence and risk factors, whether these associations persist after adjustment for individual-level social class indicators, and whether the effects of individual-level indicators vary across neighborhoods. The study sample consisted of 12,601 persons in four US communities (Washington County, Maryland; Forsyth County, North Carolina; Minneapolis, Minnesota; and Jackson, Mississippi) participating in the baseline examination of the Atherosclerosis Risk in Communities Study (1987-1989). Neighborhood characteristics were obtained from 1990 US Census block-group measures. Multilevel models were used to estimate associations with neighborhood variables after adjustment for individual-level indicators of social class. Living in deprived neighborhoods was associated with increased prevalence of coronary heart disease and increased levels of risk factors, with associations generally persisting after adjustment for individual-level variables. Inconsistent associations were documented for serum cholesterol and disease prevalence in African-American men. For Jackson African-American men living in poor neighborhoods, coronary heart disease prevalence decreased as neighborhood characteristics worsened. Additionally, in African-American men from Jackson, low social class was associated with increased serum cholesterol in "richer" neighborhoods but decreased serum cholesterol in "poorer" neighborhoods. Neighborhood environments may be one of the pathways through which social structure shapes coronary heart disease risk.

Racial differences in risk factors for atherosclerosis. The ARIC Study. Atherosclerosis Risk in Communities

This paper describes black/white differences in risk factors for atherosclerosis in the large multicenter Atherosclerosis Risk in Communities (ARIC) Project sponsored by the National Heart, Lung, and Blood Institute. It is based on data collected at baseline in ARIC's four geographically distinct clinical centers. Participants were randomly selected (4264 black and 11,479 white men and women, ages forty-five to sixty-four years at entry). There were striking differences in obesity between black and white women, higher fasting glucose and greater prevalence of diabetes in blacks, and lower high-density lipoprotein values in white men. Not unexpectedly, blood pressure in black participants exceeded that in whites. Clustering of multiple risk factors was more common in the black population. Conversely, prevalence of no risk factors was greatest among whites. In conclusion, while African-Americans and Caucasians share much the same group of risk factors for atherosclerosis, there are clinically important racial differences in emphasis.

Clustering of dyslipidemia, hyperuricemia, diabetes, and hypertension and its association with fasting insulin and central and overall obesity in a general population. Atherosclerosis Risk in Communities Study Investigators

Clustering of elevated triglycerides, decreased high-density lipoprotein cholesterol (HDL-C), hyperuricemia, diabetes, and hypertension has been related to insulin resistance/high insulin levels and central and/or overall obesity. The extent to which these abnormalities cluster and whether hyperinsulinemia, central adiposity, and overall obesity each independently associate with this clustering were evaluated in 14,481 US whites and African-Americans 45 to 64 years of age. With the exception of hypertension, abnormalities rarely existed in isolated form. Clustering greatly exceeded chance association (P < .001). Although this clustering was greater in relative terms (ratio of observed to expected cluster frequency) in the lean and less centrally obese, it was greater in absolute terms (observed minus expected cluster frequency as a percent of total population) in the more centrally and more generally obese. The greatest excesses were found for clusters that included both hypertriglyceridemia and low HDL-C. Multiple logistic regression models showed strong and independent graded relationships of clusters with quintiles of fasting insulin (fifth quintile odds ratio, 10 to 54, P < .001) and to a lesser degree with quintiles of the waist to hip ratio (2.2 to 5.4, P < .001 for most) and of body mass index (1.6 to 4.5, P < .05 for most). In conclusion, all abnormalities cluster in excess of that predicted by chance, with clusters showing remarkable and graded independent associations with fasting hyperinsulinemia and to a lesser extent with central and overall obesity. Thus, a metabolic syndrome occurs in both lean and obese middle-aged US adults.

A metabolic syndrome in whites and African-Americans. The Atherosclerosis Risk in Communities baseline study

OBJECTIVE

To describe clustering of hypertriglyceridemia, low HDL cholesterol, hypertension, diabetes, and hyperuricemia and its association with fasting insulin, waist-to-hip ratio (WHR), and BMI for African-American and white men and women.

RESEARCH DESIGN AND METHODS

Observed frequencies of clusters were compared with those expected in 14,481 participants, 45-64 years of age, of the Atherosclerosis Risk in Communities (ARIC) baseline survey, 1987-1989. Associations of clusters with insulin, central adiposity, and overall obesity, as well as with abnormalities, were analyzed through multiple logistic regression.

RESULTS

Clustering beyond chance was observed in all four sex/ethnic groups (P < 0.001), with 7% of the sample presenting 30% of the abnormalities in large clusters (> or = 3 abnormalities per individual). The odds ratio (OR) for the association of each abnormality with clustering of the remaining four ranged from 1.6 to 8.8 (P < 0.01). These odds of clustering were notably large in white women. Of the abnormalities, hypertriglyceridemia demonstrated the highest OR (5.0-8.8) and diabetes had the lower OR in African-American subjects than in white subjects (P < 0.001). Insulin, WHR, and BMI were statistically associated with clustering in all groups (P < 0.001, except for BMI in African-Americans.

Fasting hyperinsulinemia and cardiovascular disease risk factors in nondiabetic adults: stronger associations in lean versus obese subjects. Atherosclerosis Risk in Communities Study Investigators

The association between hyperinsulinemia and atherogenic risk factors has not been well studied in blacks and may be different for obese versus lean individuals. To investigate this possibility and to confirm the associations of hyperinsulinemia with cardiovascular disease risk factors in blacks and whites, we analyzed the joint associations of fasting serum insulin and obesity with risk factors in the Atherosclerosis Risk in Communities (ARIC) Study (1,293 black men, 4,797 white men, 2,033 black women, and 5,445 white women). Insulin values > or = 90th percentile (> or = 21 microU/mL) constituted hyperinsulinemia; body mass index (BMI) values > or = 27.3 kg/m2 for women and > or = 27.8 for men constituted obesity. Participants with hyperinsulinemia in all four race-sex groups had more atherogenic levels of most risk factors studied than those with normoinsulinemia. Among black men and women, mean levels of triglycerides, low-density lipoprotein cholesterol (LDL-C), apolipoprotein (apo) B, glucose, and fibrinogen (men only) were higher in hyperinsulinemic lean participants as compared with the normoinsulinemic obese group. Furthermore, most associations between insulin level and risk factors were stronger among lean versus obese subjects. For example, among lean black men, the difference in mean triglyceride concentration between those with hyperinsulinemia and those with normoinsulinemia was 147 - 99 = 48 mg/dL; among obese black men, the difference was 155 - 121 = 34 mg/dL (P < .05 for the interaction). Generally, similar negative interactions between BMI and insulin concentration were also observed among whites.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipoprotein(a) as a correlate of stroke and transient ischemic attack prevalence in a biracial cohort: the ARIC Study. Atherosclerosis Risk in Communities

Although both mean lipoprotein(a) [Lp(a)] concentration and national stroke prevalence estimates are consistently higher in American blacks than in whites, no information exists on the relationship of Lp(a) and stroke prevalence in African-Americans. Associations of Lp(a) with stroke or transient ischemic attack (TIA) are addressed in this report for 15,160 participants--4160 blacks and 11,000 whites--in the Atherosclerosis Risk in Communities (ARIC) Study. Lp(a) was measured in ARIC as its total protein component by double-antibody enzyme-linked immunosorbent assay (ELISA) for apo(a) detection. Self-reported stroke/TIA history was assessed as part of a standardized questionnaire, and resulted in age-adjusted stroke/TIA prevalences of 3.0% in blacks (n = 120) and 2.0% in whites (n = 222). Overall, mean Lp(a) protein levels were markedly higher for blacks than for whites (160.5 versus 81.6 micrograms/mL, respectively), and were statistically significantly higher among individuals reporting stroke/TIA history for both races (191.3 versus 159.6 micrograms/mL in blacks; 100.6 versus 81.2 micrograms/mL in whites). Multivariable logistic regression analysis for the association of Lp(a) protein with stroke/TIA status yielded a prevalence odds ratio (OR) (95% confidence intervals) of 1.17 (1.05, 1.30) overall (based on one standard deviation difference, 108.2 micrograms/mL, in Lp[a] protein). Race-specific ORs, after adjustment for the same covariates, were equivalent for blacks [OR = 1.17 (0.99, 1.39)] and whites [OR = 1.19 (1.04, 1.36)]. These data suggest that Lp(a) is an independent risk factor for stroke/TIA in both blacks and whites, and that the relative risk of stroke/TIA associated with Lp(a) protein does not vary by race.(ABSTRACT TRUNCATED AT 250 WORDS)