Michael R. Lewis

Incidence, manifestations, and predictors of brain infarcts defined by serial cranial magnetic resonance imaging in the elderly: the Cardiovascular Health Study.

Background and Purpose— MRI-defined infarcts are common in the elderly. We sought to explore incidence, manifestations, and predictors of such infarcts. Methods— The Cardiovascular Health Study (CHS) is a population-based, longitudinal study of 5888 people aged ≥65 years. Participants have had extensive baseline and follow-up evaluations; 1433 participants underwent 2 MRI scans separated by 5 years and had no infarcts on initial MRI. Results— On follow-up MRI, 254 participants (17.7%) had 1 or more infarcts. Most were single (75.6%), subcortical (79.9%), and small (3 to 20 mm in 87.0%). Only 11.4% of those with infarcts experienced a documented transient ischemic attack or stroke between the scans. Although participants were similar at initial MRI, those with MRI-defined infarcts on follow-up experienced greater decline than those without infarcts on the Modified Mini-Mental State Examination and Digit-Symbol Substitution test (both P <0.01). Severity of white matter changes on initial MRI was the strongest predictor of incident infarcts. When it was excluded from stepwise multivariable models, predictors were serum creatinine, age, and ankle-arm index. Conclusions— Incident MRI-defined infarcts commonly affect the elderly. Most are small, subcortical, and not associated with acute symptoms recognized as a transient ischemic attack or stroke. Nonetheless, they cannot be considered silent because of their association with subtle cognitive deficits. These covert infarcts are associated with white matter changes, which may share a common pathophysiology. Whether control of vascular risk factors, such as blood pressure, would reduce the risk of developing these infarcts and associated cognitive decline deserves further investigation.

Effect of Two-Year Caloric Restriction on Bone Metabolism and Bone Mineral Density in Non-Obese Younger Adults: A Randomized Clinical Trial

Although caloric restriction (CR) could delay biologic aging in humans, it is unclear if this would occur at the cost of significant bone loss. We evaluated the effect of prolonged CR on bone metabolism and bone mineral density (BMD) in healthy younger adults. Two-hundred eighteen non-obese (body mass index [BMI] 25.1 ± 1.7 kg/m(2) ), younger (age 37.9 ± 7.2 years) adults were randomly assigned to 25% CR (CR group, n = 143) or ad libitum (AL group, n = 75) for 2 years. Main outcomes were BMD and markers of bone turnover. Other outcomes included body composition, bone-active hormones, nutrient intake, and physical activity. Body weight (-7.5 ± 0.4 versus 0.1 ± 0.5 kg), fat mass (-5.3 ± 0.3 versus 0.4 ± 0.4 kg), and fat-free mass (-2.2 ± 0.2 versus -0.2 ± 0.2 kg) decreased in the CR group compared with AL (all between group p < 0.001). Compared with AL, the CR group had greater changes in BMD at 24 months: lumbar spine (-0.013 ± 0.003 versus 0.007 ± 0.004 g/cm(2) ; p < 0.001), total hip (-0.017 ± 0.002 versus 0.001 ± 0.003 g/cm(2) ; p < 0.001), and femoral neck (-0.015 ± 0.003 versus -0.005 ± 0.004 g/cm(2) ; p = 0.03). Changes in bone markers were greater at 12 months for C-telopeptide (0.098 ± 0.012 versus 0.025 ± 0.015 μg/L; p < 0.001), tartrate-resistant acid phosphatase (0.4 ± 0.1 versus 0.2 ± 0.1 U/L; p = 0.004), and bone-specific alkaline phosphatase (BSAP) (-1.4 ± 0.4 versus -0.3 ± 0.5 U/L; p = 0.047) but not procollagen type 1 N-propeptide; at 24 months, only BSAP differed between groups (-1.5 ± 0.4 versus 0.9 ± 0.6 U/L; p = 0.001). The CR group had larger increases in 25-hydroxyvitamin D, cortisol, and adiponectin and decreases in leptin and insulin compared with AL. However, parathyroid hormone and IGF-1 levels did not differ between groups. The CR group also had lower levels of physical activity. Multiple regression analyses revealed that body composition, hormones, nutrients, and physical activity changes explained ∼31% of the variance in BMD and bone marker changes in the CR group. Therefore, bone loss at clinically important sites of osteoporotic fractures represents a potential limitation of prolonged CR for extending life span. Further long-term studies are needed to determine if CR-induced bone loss in healthy adults contributes to fracture risk and if bone loss can be prevented with exercise.

QUALITY ASSESSMENT OF ATOMIC FORCE MICROSCOPY PROBES BY SCANNING ELECTRON MICROSCOPY : CORRELATION OF TIP STRUCTURE WITH RENDERED IMAGES

While image quality from instruments such as electron microscopes, light microscopes, and confocal laser scanning microscopes is mostly influenced by the alignment of optical train components, the atomic force microscope differs in that image quality is highly dependent upon a consumable component, the scanning probe. Although many types of scanning probes are commercially available, specific configurations and styles are generally recommended for specific applications. For instance, in our area of interest, tapping mode imaging of biological constituents in fluid, double ended, oxide‐sharpened pyramidal silicon nitride probes are most often employed. These cantilevers contain four differently sized probes; thick‐ and thin‐legged 100 μm long and thick‐ and thin‐legged 200 μm long, with only one probe used per cantilever. In a recent investigation [Taatjes et al. (1997) Cell Biol. Int. 21:715–726], we used the scanning electron microscope to modify the oxide‐sharpened pyramidal probe by creating an electron beam deposited tip with a higher aspect ratio than unmodified tips. Placing the probes in the scanning electron microscope for modification prompted us to begin to examine the probes for defects both before and after use with the atomic force microscope. The most frequently encountered defect was a mis‐centered probe, or a probe hanging off the end of the cantilever. If we had difficulty imaging with a probe, we would examine the probe in the scanning electron microscope to determine if any defects were present, or if the tip had become contaminated during scanning. Moreover, we observed that electron beam deposited tips were blunted by the act of scanning a hard specimen, such as colloidal gold with the atomic force microscope. We also present a mathematical geometric model for deducing the interaction between an electron beam deposited tip and either a spherical or elliptical specimen. Examination of probes in the scanning electron microscope may assist in interpreting images generated by the atomic force microscope. Microsc. Res. Tech. 44:312–326, 1999.

Long-term moderate calorie restriction inhibits inflammation without impairing cell-mediated immunity: a randomized controlled trial in non-obese humans

Calorie restriction (CR) inhibits inflammation and slows aging in many animal species, but in rodents housed in pathogen-free facilities, CR impairs immunity against certain pathogens. However, little is known about the effects of long-term moderate CR on immune function in humans. In this multi-center, randomized clinical trial to determine CRs effect on inflammation and cell-mediated immunity, 218 healthy non-obese adults (20-50 y), were assigned 25% CR (n=143) or an ad-libitum (AL) diet (n=75), and outcomes tested at baseline, 12, and 24 months of CR. CR induced a 10.4% weight loss over the 2-y period. Relative to AL group, CR reduced circulating inflammatory markers, including total WBC and lymphocyte counts, ICAM-1 and leptin. Serum CRP and TNF-α concentrations were about 40% and 50% lower in CR group, respectively. CR had no effect on the delayed-type hypersensitivity skin response or antibody response to vaccines, nor did it cause difference in clinically significant infections. In conclusion, long-term moderate CR without malnutrition induces a significant and persistent inhibition of inflammation without impairing key in vivo indicators of cell-mediated immunity. Given the established role of these pro-inflammatory molecules in the pathogenesis of multiple chronic diseases, these CR-induced adaptations suggest a shift toward a healthy phenotype.

Sickle Cell Trait and the Risk of ESRD in Blacks

Blacks, compared with whites, have an increased risk of progression to end-stage renal disease (ESRD). Emerging evidence suggests that, in addition to APOL1 high-risk genotypes, hemoglobin variants, including sickle cell trait (SCT) and hemoglobin C trait, have a role in kidney disease in blacks. However, the association between these hemoglobin traits and ESRD remains unknown. In a large population-based cohort, the REasons for Geographic and Racial Differences in Stroke (REGARDS) study, we evaluated 9909 self-reported blacks (739 with SCT and 243 with hemoglobin C trait). Incident ESRD occurred in 40 of 739 (5.4%) individuals with SCT, six of 243 (2.5%) individuals with hemoglobin C trait, and 234 of 8927 (2.6%) noncarriers. The incidence rate for ESRD was 8.5 per 1000 person-years for participants with SCT and 4.0 per 1000 person-years for noncarriers. Compared with individuals without SCT, individuals with SCT had a hazard ratio for ESRD of 2.03 (95% confidence interval, 1.44 to 2.84). Hemoglobin C trait did not associate with prevalent CKD or ESRD. The incidence rate for ESRD among participants with APOL1 high-risk genotypes was 6.6 per 1000 person-years, with a hazard ratio for ESRD of 1.77 (95% confidence interval, 1.31 to 2.38) for participants with, compared with those without, APOL1 high-risk genotypes. In this cohort, SCT strongly associated with risk of progression to ESRD in blacks, and this degree of risk for ESRD was similar to that conferred by APOL1 high-risk genotypes. These results may have important public policy implications for genetic counseling of SCT carriers.

The effect of testosterone on cardiovascular biomarkers in the testosterone trials

Context Studies of the possible cardiovascular risk of testosterone treatment are inconclusive. Objective To determine the effect of testosterone treatment on cardiovascular biomarkers in older men with low testosterone. Design Double-blind, placebo-controlled trial. Setting Twelve academic medical centers in the United States. Participants In all, 788 men ≥65 years old with an average of two serum testosterone levels <275 ng/dL who were enrolled in The Testosterone Trials. Intervention Testosterone gel, the dose adjusted to maintain the testosterone level in the normal range for young men, or placebo gel for 12 months. Main Outcome Measures Serum markers of cardiovascular risk, including lipids and markers of glucose metabolism, fibrinolysis, inflammation, and myocardial damage. Results Compared with placebo, testosterone treatment significantly decreased total cholesterol (adjusted mean difference, -6.1 mg/dL; P < 0.001), high-density lipoprotein cholesterol (adjusted mean difference, -2.0 mg/dL; P < 0.001), and low-density lipoprotein cholesterol (adjusted mean difference, -2.3 mg/dL; P = 0.051) from baseline to month 12. Testosterone also slightly but significantly decreased fasting insulin (adjusted mean difference, -1.7 µIU/mL; P = 0.02) and homeostatic model assessment‒insulin resistance (adjusted mean difference, -0.6; P = 0.03). Testosterone did not change triglycerides, d-dimer, C-reactive protein, interleukin 6, troponin, glucose, or hemoglobin A1c levels more than placebo. Conclusions and Relevance Testosterone treatment of 1 year in older men with low testosterone was associated with small reductions in cholesterol and insulin but not with other glucose markers, markers of inflammation or fibrinolysis, or troponin. The clinical importance of these findings is unclear and requires a larger trial of clinical outcomes.

Management of Hemoglobin Variants Detected Incidentally in HbA1c Testing: A Common Problem Currently Lacking a Standard Approach

Although HbA1c is widely used for diagnosis and management of diabetes in clinical practice and research studies, management of the incidental detection of hemoglobin variants (e.g., hemoglobin S [HbS], HbC) by common HbA1c methods, such as ion exchange high-performance liquid chromatography (HPLC), is not well established. Many clinical laboratories do not report the presence of hemoglobin variants, whereas others report them only if they interfere with HbA1c measurement (1). As routine HbA1c testing may incidentally yield information regarding hemoglobin variants that can affect clinical care, planning for appropriate management is warranted. The Vitamin D and Type 2 Diabetes (D2d) Study is a multicenter, randomized, placebo-controlled trial testing whether vitamin D supplementation reduces diabetes incidence in people at high risk (2). Adults meeting at least two of the three criteria for prediabetes established in 2010 by the American Diabetes Association are eligible for enrollment, and a racially and ethnically diverse study population is sought to ensure generalizability of results. HbA1c testing is performed using an HPLC method (Tosoh G8, Tosoh Bioscience, South San Francisco, CA) at the University of Vermont’s Laboratory for Clinical Biochemistry Research. Review of chromatograms can reveal unexpected peaks reflecting the presence of hemoglobin variants. Although HbS and HbC do not interfere with the assay, the presence of other variants, such as HbE, precludes reporting of HbA1c results. When an abnormal peak is seen, hemoglobin electrophoresis is performed to identify the hemoglobin variant. Because reporting of incidentally detected hemoglobin variants is not standardized, D2d investigators sought consultative opinions from …

Safety and Feasibility of a Nocturnal Heart Rate Elevation—Exploration of a Novel Treatment Concept

BACKGROUND Diastolic dysfunction and heart failure with preserved ejection fraction (HFpEF) are associated with myocardial fibrosis and concentric left ventricular hypertrophy (LVH). In a preclinical model of LVH, we demonstrated that a moderate increase in heart rate can reduce interstitial fibrosis and improve LV compliance. We therefore hypothesized that moderately elevated heart rates can be used to beneficially modify the myocardial substrate in patients with diastolic dysfunction and HFpEF. As a preliminary step to test this hypothesis, we evaluated if patients can tolerate this novel pacemaker-based treatment approach without adverse effects. METHODS AND RESULTS A pacemaker-mediated increase in heart rate to 100 beats/min for 5 hours at night was tested over 4 weeks in 10 patients with diastolic dysfunction. The patients underwent a physical examination, biomarker collection, 6-minute walk test, heart failure questionnaire, and echocardiography before and after the pacing intervention. None of the patients reported any symptoms at night. No arrhythmias were induced. Eight patients completed the protocol. Three patients experienced unanticipated daytime pacing from an interfering pacemaker function. There were no detrimental changes in biomarkers or LV systolic function. CONCLUSIONS Nocturnal pacing at a rate of 100 beats/min appears to be safe and well tolerated in this small exploratory patient cohort.

Trends in Bone Marrow Sampling and Core Biopsy Specimen Adequacy in the United States and CanadaA Multicenter Study

Objectives To assess bone marrow (BM) sampling in academic medical centers. Methods Data from 6,374 BM samples obtained in 32 centers in 2001 and 2011, including core length (CL), were analyzed. Results BM included a biopsy (BMB; 93%) specimen, aspirate (BMA; 92%) specimen, or both (83%). The median (SD) CL was 12 (8.5) mm, and evaluable marrow was 9 (7.6) mm. Tissue contraction due to processing was 15%. BMB specimens were longer in adults younger than 60 years, men, and bilateral, staging, and baseline samples. Only 4% of BMB and 2% of BMB/BMA samples were deemed inadequate for diagnosis. BM for plasma cell dyscrasias, nonphysician operators, and ancillary studies usage increased, while bilateral sampling decreased over the decade. BM-related quality assurance programs are infrequent. Conclusions CL is shorter than recommended and varies with patient age and sex, clinical circumstances, and center experience. While pathologists render diagnoses on most cases irrespective of CL, BMB yield improvement is desirable.

Response to Comment on Lewis et al. Management of Hemoglobin Variants Detected Incidentally in HbA1c Testing: A Common Problem Currently Lacking a Standard Approach. Diabetes Care 2017;40:e8–e9

We thank Drs. Little and Rohlfing for their comments (1) regarding our article on the management of incidental detection of hemoglobin (Hb) variants in HbA1c testing (2). We agree that awareness of the potential for interference to affect HbA1c results is essential in research and clinical care. Multiple studies (including that of Lin et al. [3]) prior to the 2016 article by Rohlfing et al. (4) had yielded no evidence of clinically significant bias resulting from HbAS or HbAC variants in Tosoh G8 results. In the Vitamin D and Type 2 Diabetes (D2d) Study, we excluded potential participants with HbAE and HbAD because clinically significant bias had been demonstrated. In a recent article by Rohlfing et al. (4), HbA1c testing using a Tosoh G8 with software version 5.20 was found to show …