Repeat-exposure in vitro protocol to assess the risk of antimicrobial resistance (AMR) development from use of personal care products: Case study using an antibacterial liquid handwash

The global crisis we are facing with regard to antibiotic resistance has been largely attributed to the overuse and misuse of antibiotics in healthcare and agriculture. However, there is also growing global concern about cross-resistance between biocides and antibiotics. This has made clear the need for more research in this area along with easy-to-perform, but realistic, methods to characterise the potential risk associated with cross-resistance to antibiotics due to biocide use. The primary aim of this work was to develop a repeat-exposure method for predicting bacterial resistance to microbicides, including their cross-resistance to antibiotics. Realism is incorporated in the presented protocol through the use of relevant concentrations and contact times, validated neutralisers, appropriate test organisms and repeat-exposures. The protocol can be applied to formulated microbicides, as shown in the liquid handwash case study presented here. Five bacterial strains were included in the study: Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa ATCC 15442, Staphylococcus epidermidis ATCC 14990, Escherichia coli ATCC 10536 and Enterococcus hirae ATCC 10541. The protocol parameters used in the case study reflected a worst-case exposure scenario (in terms of contact time and concentration). The results demonstrated that repeated exposure to the liquid handwash would not be expected to lead to development of bacterial resistance or cross-resistance to antibiotics. It is envisaged that this protocol could be used by manufacturers of microbicidal formulations to assess whether repeated use of the test products would contribute to bacterial resistance development or cross-resistance to antibiotics.

Clinically applicable optical imaging technology for body size and shape analysis: comparison of systems differing in design

BACKGROUND/OBJECTIVES

Recent advances have extended anthropometry beyond flexible tape measurements to automated three-dimensional optical devices that rapidly acquire hundreds of body surface dimensions. Three new devices were recently introduced that share in common inexpensive optical cameras. The design, and thus potential clinical applicability, of these systems differ substantially leading us to critically evaluate their accuracy and precision.

SUBJECTS/METHODS

113 adult subjects completed evaluations by the three optical devices (KX-16 (16 stationary cameras), Proscanner (1 vertically oscillating camera), and Styku scanner (1 stationary camera)), air displacement plethysmography (ADP), dual-energy X-ray absorptiometry (DXA) and a flexible tape measure. Optical measurements were compared to reference method estimates that included results acquired by flexible tape, DXA and ADP.

RESULTS

Optical devices provided respective circumference and regional volume estimates that overall were well-correlated with those obtained from flexible tape measurements (for example, hip circumference: R2, 0.91, 0.90, 0.96 for the KX-16, Proscanner, and Styku scanner, respectively) and DXA (for example, trunk volume: R2, 0.97, 0.97, and 0.98). Total body volumes measured by the optical devices were highly correlated with those from the ADP system (all R2s, 0.99). Coefficient of variations obtained from duplicate measurements (n, 55) were larger in optical than in reference measurements and significant (P<0.05) bias was present for some optical measurements relative to reference method estimates.

CONCLUSIONS

Overall, the evaluated optical imaging systems differing in design provided body surface measurements that compared favorably with corresponding reference methods. However, our evaluations uncovered system measurement limitations, such as discrepancies in landmarking, that with correction have the potential to improve future developed devices.

Spine fracture prevalence in a nationally representative sample of US women and men aged ≥40 years: results from the National Health and Nutrition Examination Survey (NHANES) 2013-2014

Spine fracture prevalence is similar in men and women, increasing from <5 % in those <60 to 11 % in those 70-79 and 18 % in those ≥80 years. Prevalence was higher with age, lower bone mineral density (BMD), and in those meeting criteria for spine imaging. Most subjects with spine fractures were unaware of them.

INTRODUCTION

Spine fractures have substantial medical significance but are seldom recognized. This study collected contemporary nationally representative spine fracture prevalence data.

METHODS

Cross-sectional analysis of 3330 US adults aged ≥40 years participating in NHANES 2013-2014 with evaluable Vertebral Fracture Assessment (VFA). VFA was graded by semiquantitative measurement. BMD and an osteoporosis questionnaire were collected.

RESULTS

Overall spine fracture prevalence was 5.4 % and similar in men and women. Prevalence increased with age from <5 % in those <60 to 11 % in those 70-79 and 18 % in those ≥80 years. Fractures were more common in non-Hispanic whites and in people with lower body mass index and BMD. Among subjects with spine fracture, 26 % met BMD criteria for osteoporosis. Prevalence was higher in subjects who met National Osteoporosis Foundation (NOF) criteria for spine imaging (14 vs 4.7 %, P < 0.001). Only 8 % of people with a spine fracture diagnosed by VFA had a self-reported fracture, and among those who self-reported a spine fracture, only 21 % were diagnosed with fracture by VFA.

CONCLUSION

Spine fracture prevalence is similar in women and men and increases with age and lower BMD, although most subjects with spine fracture do not meet BMD criteria for osteoporosis. Since most (>90 %) individuals were unaware of their spine fractures, lateral spine imaging is needed to identify these women and men. Spine fracture prevalence was threefold higher in individuals meeting NOF criteria for spine imaging (∼1 in 7 undergoing VFA). Identifying spine fractures as part of comprehensive risk assessment may improve clinical decision making.

Trends in osteoporosis and low bone mass in older US adults, 2005-2006 through 2013-2014

This study examined trends in osteoporosis and low bone mass in older US adults between 2005 and 2014 using bone mineral density (BMD) data from the National Health and Nutrition Examination Survey (NHANES). Osteoporosis and low bone mass appear to have increased at the femur neck but not at the lumbar spine during this period.

INTRODUCTION

Recent preliminary data from Medicare suggest that the decline in hip fracture incidence among older US adults may have plateaued in 2013-2014, but comparable data on BMD trends for this time period are currently lacking. This study examined trends in the prevalence of osteoporosis and low bone mass since 2005 using BMD data from NHANES. The present study also updated prevalence estimates to 2013-2014 and included estimates for non-Hispanic Asians.

METHODS

Femur neck and lumbar spine BMD by DXA were available for 7954 adults aged 50 years and older from four NHANES survey cycles between 2005-2006 and 2013-2014.

RESULTS

Significant trends (quadratic or linear) were observed for the femur neck (mean T-score and osteoporosis in both sexes; low bone mass in women) but not for the lumbar spine. The trend in femur neck status was somewhat U-shaped, with prevalences being most consistently significantly higher (by 1.1-6.6 percentage points) in 2013-2014 than 2007-2008. Adjusting for changes in body mass index, smoking, milk intake, and physician's diagnosis of osteoporosis between surveys did not change femur neck trends. In 2013-2014, the percent of older adults with osteoporosis was 6% at the femur neck, 8% at the lumbar spine, and 11% at either site.

CONCLUSIONS

There was some evidence of a decline in femur neck BMD between 2005-2006 and 2013-2014, but not in lumbar spine BMD. Changes in the risk factors that could be examined did not explain the femur neck BMD trends.

Trabecular bone scores and lumbar spine bone mineral density of US adults: comparison of relationships with demographic and body size variables

This study examines demographic patterns and body size relationships in trabecular bone score and lumbar spine BMD of US adults from NHANES 2005-2008.

INTRODUCTION

Limited data exist on demographic and body size relationships for trabecular bone score (TBS), a new variable derived from bone texture analysis of lumbar spine dual-energy X-ray absorptiometry (DXA) scans. This study compares demographic patterns and correlations with body size (body mass index (BMI), weight, waist circumference, total body fat, trunk fat, trunk lean) between TBS and lumbar spine bone mineral density (LSBMD) for adults age ≥20 years from the National Health and Nutrition Examination Survey (NHANES) 2005-2008 with BMI in the optimal range for TBS (15-37 kg/m(2)).

METHODS

LSBMD, TBS, body fat, and lean were obtained by DXA. Weight, height, and waist circumference were measured. BMI was calculated from height and weight.

RESULTS

Sex differences in TBS varied by age and race/ethnicity (p sex X age interaction and p sex X race/ethnicity interaction < 0.001). In most of the nine demographic subgroups examined, TBS did not differ by sex (four subgroups) or was significantly higher in women (three subgroups). TBS differences by race/ethnicity were inconsistent in men; in women, non-Hispanic whites (NHWs) had higher TBS than non-Hispanic blacks (NHBs) or Mexican Americans (MAs) in all age groups. In contrast, LSBMD was either significantly higher in men (five subgroups) or did not differ by sex (four subgroups). Race/ethnic differences in LSBMD were consistent across age and sex (NHB > NHW > MA). All body size variables were negatively related to TBS but positively related to LSBMD.

CONCLUSIONS

Demographic patterns and body size relationships differed between TBS and LSBMD.

Adolescent Endogenous Sex Hormones and Breast Density in Early Adulthood

During adolescence the breasts undergo rapid growth and development under the influence of sex hormones. Although the hormonal etiology of breast cancer is hypothesized, it remains unknown whether adolescent sex hormones are associated with adult breast density, which is a strong risk factor for breast cancer. METHODS: Percentage of dense breast volume (%DBV) was measured in 2006 by magnetic resonance imaging in 177 women aged 25–29 years who participated in the Dietary Intervention Study in Children from 1988–1997 and had sex hormones and sex hormone binding globulin (SHBG) measured in serum collected on 1–4 occasions between 8 and 17 years of age. Multivariable linear mixed-effect regression models were used to evaluate the associations of adolescent sex hormones and SHBG with %DBV. RESULTS: Dehydroepiandrosterone sulfate (DHEAS) and SHBG measured in premenarche serum samples were significantly positively associated with %DBV (all Ptrend ≤ 0.03) but not when measured in postmenarche samples (all Ptrend ≥ 0.42). The multivariable geometric mean of %DBV across quartiles of premenarcheal DHEAS and SHBG increased from 16.7% to 22.1% and from 14.1% to 24.3%, respectively. Estrogens, progesterone, androstenedione, and testosterone were not associated with %DBV pre- or post-menarche (all Ptrend ≥ 0.16). CONCLUSIONS: Our results suggest that higher DHEAS and SHBG levels during adolescence, particularly before the onset of menarche, are associated with higher%DBV in young women. Whether this association translates into an increased risk of breast cancer later in life is currently unknown.

Anthropometric models of bone mineral content and areal bone mineral density based on the bone mineral density in childhood study

New models describing anthropometrically adjusted normal values of bone mineral density and content in children have been created for the various measurement sites. The inclusion of multiple explanatory variables in the models provides the opportunity to calculate Z-scores that are adjusted with respect to the relevant anthropometric parameters.

INTRODUCTION

Previous descriptions of children's bone mineral measurements by age have focused on segmenting diverse populations by race and sex without adjusting for anthropometric variables or have included the effects of a single anthropometric variable.

METHODS

We applied multivariate semi-metric smoothing to the various pediatric bone-measurement sites using data from the Bone Mineral Density in Childhood Study to evaluate which of sex, race, age, height, weight, percent body fat, and sexual maturity explain variations in the population's bone mineral values. By balancing high adjusted R(2) values with clinical needs, two models are examined.

RESULTS

At the spine, whole body, whole body sub head, total hip, hip neck, and forearm sites, models were created using sex, race, age, height, and weight as well as an additional set of models containing these anthropometric variables and percent body fat. For bone mineral density, weight is more important than percent body fat, which is more important than height. For bone mineral content, the order varied by site with body fat being the weakest component. Including more anthropometrics in the model reduces the overlap of the critical groups, identified as those individuals with a Z-score below -2, from the standard sex, race, and age model.

CONCLUSIONS

If body fat is not available, the simpler model including height and weight should be used. The inclusion of multiple explanatory variables in the models provides the opportunity to calculate Z-scores that are adjusted with respect to the relevant anthropometric parameters.

Lumbar spine bone mineral density in US adults: demographic patterns and relationship with femur neck skeletal status

This analysis examines lumbar spine bone mineral density (BMD) of US adults from NHANES 2005-2008 by age, sex, and race/ethnicity. Prevalence of low spine BMD and agreement between the prevalence of low BMD at the spine and femur neck in older adults are also assessed.

INTRODUCTION

Lumbar spine BMD data from a representative sample of the US population have not been previously available.

METHODS

We used data from the National Health and Nutrition Examination Survey 2005-2008 to examine demographic patterns in lumbar spine BMD among US adults age ≥20 years and the prevalence of low lumbar spine BMD in adults age ≥50 years. Agreement between the prevalence of low BMD at the femur neck and spine in older adults was also assessed. Dual-energy X-ray absorptiometry was used to measure lumbar spine and femur neck BMD. World Health Organization definitions were used to categorize skeletal status as normal, osteopenia, or osteoporosis.

RESULTS

Compared to non-Hispanic whites, non-Hispanic blacks had higher and Mexican Americans had lower lumbar spine BMD. Lumbar spine BMD declined with age in women, but not in men. Approximately 4.7 million (10%) older US women and 1 million (3%) older men had lumbar spine osteoporosis in 2005-2008. Roughly one third of them differed in skeletal status at the spine and hip but most were normal at one site and osteopenic at the other. Only 3-10%, depending on sex, had osteoporosis at one skeletal site but not at the other skeletal site. Between 76% and 87% with discordant skeletal status had lumbar spine T-scores within 1 unit of the category threshold.

CONCLUSIONS

These findings suggest that measuring either the femur neck or the lumbar spine will correctly classify the majority of individuals who present for care as osteoporotic or not.

Changes in femur neck bone density in US adults between 1988-1994 and 2005-2008: demographic patterns and possible determinants

SUMMARY

This analysis compares femur neck bone mineral density (FNBMD) and bone determinants in adults between National Health and Nutrition Examination Survey (NHANES) III (1988-1994) and NHANES 2005-2008. FNBMD was higher in NHANES 2005-2008 than in NHANES III, but between-survey differences varied by age, sex, and race/ethnicity. The likelihood that FNBMD has improved appears strongest for older white women.

INTRODUCTION

Recent data on hip fracture incidence and femur neck osteoporosis suggest that the skeletal status of older US adults has improved since the 1990s, but the explanation for these changes remains uncertain.

METHODS

The present study compares mean FNBMD of adults ages 20 years and older between the third (NHANES III, 1988-1994) and NHANES 2005-2008. Dual-energy X-ray absorptiometry systems (pencil beam in NHANES III, fan beam in NHANES 2005-2008) were used to measure hip BMD, and several bone determinants are compared between surveys to assess their potential role in explaining observed FNBMD differences.

RESULTS

FNBMD was higher overall in NHANES 2005-2008 than in NHANES III, but between-survey differences varied by age, sex, and race/ethnicity. Although FNBMD differences in several groups were small enough (≤3%) to be attributable to use of different dual-energy X-ray absorptiometry (DXA) systems in the two surveys, variability in size and direction of the differences does not support artifactual differences in DXA methodology as the sole explanation. Several FNBMD determinants (body size, smoking, selected bone-active medications, self-reported health status, calcium intake, and caffeine consumption) changed in a bone-improving direction in older adults, but FNBMD in older non-Hispanic white women remained significantly higher in 2005-2008 even after adjusting for DXA methodology or for the selected bone determinants.

CONCLUSION

The likelihood that FNBMD has improved appears strongest for older white women, but the reason for the improvement in this group remains unclear.

P5-08-03: How Reader's Training, Software, and Image Formats Impact Percent Dense Area Measures

BACKGROUND: Mammographic percent dense area, the percent ratio of dense to total breast area in a mammogram, is one of the strongest measures of a woman's risk of breast cancer. However, systematic differences have been observed between readers and mammography technologies (film and digital) that could cause clinically inconsistent associations with risk. The purpose of this study was to evaluate inter- and intra-reproducibility of percent dense area between readers and between film and digital technologies.

METHODS: One hundred digitized film mammograms were randomly selected with 25 films in each of quartile of percent density and read by two readers at two different sites (Mayo Clinic and UCSF). The readers had extensive experience and were also jointly trained at university of Toronto using Cumulus software. After training, all films were read twice with at least one year between duplicate readings. The Mayo clinic reading used Cumulus while UCSF used custom semiautomatic software to estimate total and dense tissue area. In addition, digitized films and unprocessed full field digital mammograms of the same women were assessed by one reader. The time between the film and digital acquisitions ranged from nine to twenty-four months. Interclass correlation coefficient (ICC) was calculated for each comparison.

RESULTS: The intra- and inter-observer ICCs, consistency for film images, were 0.96 (UCSF) and 0.97 (Mayo), and 0.96 (UCSF vs. Mayo). We found ICC between film and digital mammograms for percent dense area was 0.88. The digital mammogram had 9% significantly higher total breast area and 5% significantly lower percent density area compared to film.

CONCLUSIONS: Similarly trained readers had a high reproducibility regardless of the software used. Our results suggest centralized reader training should enable pooling of film breast density results from different clinics. However, pooling film and digital results would need careful calibration due to lower measured percent dense areas than on film.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-08-03.

Fitting of bone mineral density with consideration of anthropometric parameters

A new model describing normal values of bone mineral density in children has been evaluated, which includes not only the traditional parameters of age, gender, and race, but also weight, height, percent body fat, and sexual maturity. This model may constitute a better comparative norm for a specific child with given anthropometric values.

INTRODUCTION

Previous descriptions of children's bone mineral density (BMD) by age have focused on segmenting diverse populations by race and gender without adjusting for anthropometric variables or have included the effects of anthropometric variables over a relatively homogeneous population.

METHODS

Multivariate semi-metric smoothing (MS(2)) provides a way to describe a diverse population using a model that includes multiple effects and their interactions while producing a result that can be smoothed with respect to age in order to provide connected percentiles. We applied MS(2) to spine BMD data from the Bone Mineral Density in Childhood Study to evaluate which of gender, race, age, height, weight, percent body fat, and sexual maturity explain variations in the population's BMD values. By balancing high adjusted R (2) values and low mean square errors with clinical needs, a model using age, gender, race, weight, and percent body fat is proposed and examined.

RESULTS

This model provides narrower distributions and slight shifts of BMD values compared to the traditional model, which includes only age, gender, and race. Thus, the proposed model might constitute a better comparative standard for a specific child with given anthropometric values and should be less dependent on the anthropometric characteristics of the cohort used to devise the model.

CONCLUSIONS

The inclusion of multiple explanatory variables in the model, while creating smooth output curves, makes the MS(2) method attractive in modeling practically sized data sets. The clinical use of this model by the bone research community has yet to be fully established.

Improved precision with Hologic Apex software

The precision of Hologic Apex v2.0 analysis software is significantly improved from Hologic Delphi v11.2 software and is comparable to GE Lunar Prodigy v7.5 software. Apex and Delphi precisions were, respectively, 1.0% vs. 1.2% (L1-L4 spine), 1.l % vs. 1.3% (total femur), 1.6% vs. 1.9% (femoral neck), and 0.7% vs. 0.9% (dual total femur).

INTRODUCTION

Precision of bone mineral density (BMD) measurements by dual-energy X-ray absorptiometry (DXA) is known to vary by manufacturer, model, and technologist. This study evaluated the precision of three analysis versions: Apex v2.0 and Delphi v11.2 (Hologic, Inc.), and Prodigy v7.5 (GE Healthcare, Inc.) independent of technologist skill.

METHODS

Duplicate spine and dual hip scans on 90 women were acquired on both Delphi and Prodigy DXA systems at three clinics. BMD measures were converted to standardized BMD (sBMD) units. Precision errors were described as a root-mean-square (RMS) standard deviations and RMS percent coefficients of variation across the population.

RESULTS

Apex and Delphi values were highly correlated (r ranged from 0.90 to 0.99). Excluding the right neck, the Apex precision error was found to be 20% to 25% lower than the Delphi (spine: 1.0% versus 1.2% (p < 0.05), total hip: 1.1% versus 1.3% (p < 0.05), right neck: 2.3% versus 2.6% (p > 0.1)). No statistically significant differences were found in the precision error of the Apex and Prodigy (p > 0.05) except for the right neck (2.3% versus 1.8% respectively, p = 0.03).

CONCLUSION

The Apex software has significantly lower precision error compared to Delphi software with similar mean values, and similar precision to that of the Prodigy.

Comparison of BMD precision for Prodigy and Delphi spine and femur scans

INTRODUCTION

Precision error in bone mineral density (BMD) measurement can be affected by patient positioning, variations in scan analysis, automation of software, and both short- and long-term fluctuations of the densitometry equipment. Minimization and characterization of these errors is essential for reliable assessment of BMD change over time.

METHODS

We compared the short-term precision error of two dual-energy X-ray absorptiometry (DXA) devices: the Lunar Prodigy (GE Healthcare) and the Delphi (Hologic). Both are fan-beam DXA devices predominantly used to measure BMD of the spine and proximal femur. In this study, 87 women (mean age 61.6+/-8.9 years) were measured in duplicate, with repositioning, on both systems, at one of three clinical centers. The technologists were International Society for Clinical Densitometry (ISCD) certified and followed manufacturer-recommended procedures. All scans were acquired using 30-s scan modes. Precision error was calculated as the root-mean-square standard deviation (RMS-SD) and coefficient of variation (RMS-%CV) for the repeated measurements. Right and left femora were evaluated individually and as a combined dual femur precision. Precision error of Prodigy and Delphi measurements at each measurement region was compared using an F test to determine significance of any observed differences.

RESULTS

While precision errors for both systems were low, Prodigy precision errors were significantly lower than Delphi at L1-L4 spine (1.0% vs 1.2%), total femur (0.9% vs 1.3%), femoral neck (1.5% vs 1.9%), and dual total femur (0.6% vs 0.9%). Dual femur modes decreased precision errors by approximately 25% compared with single femur results.

CONCLUSIONS

This study suggests that short-term BMD precision errors are skeletal-site and manufacturer specific. In clinical practice, precision should be considered when determining: (a) the minimum time interval between baseline and follow-up scans and (b) whether a statistically significant change in the patient's BMD has occurred.

Metacarpal index and bone mineral density in healthy African-American women

Bone mineral density (BMD) reference data of non-Caucasian women is scarce but greatly needed for African-American women. The objective of this study was to establish a metacarpal normative reference database for African-American women using digital X-ray radiogrammetry (DXR) and hand radiographs and compare these values to existing Caucasian data. Two hundred and fifty healthy African-American women between the ages of 20 and 79 years old, 14 of whom were excluded, were recruited to participate from four different clinical sites. The study population was recruited in approximately equal number into the following groups: 20-29, 30-39, 40-49, 50-59, 60-69 and 70-79 years of age. A radiograph was acquired of each subject's non-dominant hand. The radiographs were scanned and analyzed using radiogrammetric techniques, and the BMD, MCI (Metacarpal Index), bone width and cortical thickness were calculated. The regression curve that best fit the data was a second order polynomial. The BMD and MCI of young adult women (20-40 years of age) were used to calculate T-score parameters. The young reference BMD and MCI with their associated standard deviations were found to be 0.6045 g/cm2+/-0.0529 g/cm2 and 0.5096 and 0.0792, respectively. However, the MCI was found to be approximately 2.5% lower (-0.0118) compared to Caucasian women. The African-American metacarpal BMD was found to be 3.5% (0.0207 g/cm2) higher across all ages when compared to existing Caucasian reference data acquired in a similar way. The differences were found to be entirely due to larger bone size, cortical diameter and bone width in the African-American women.

Towards standardization of dual X-ray absorptiometry (DXA) at the forearm: a common region of interest (ROI) improves the comparability among DXA devices

Manufacturer-implemented regions of interest (ROIs) to determine the bone mineral density (BMD) at the forearm are currently not standardized across dual X-ray absorptiometry (DXA) devices. We hypothesized that their differences introduce considerable variation in measurement results for forearm BMD when taken on different devices, and that a ROIs common to all devices with standardized placement and size significantly improve device comparability. The common ROI was defined to have a fixed length of 2 cm and to extend proximally from the location where the ulna and radius bones superimpose on the DXA image. The effects of universal standardization of forearm BMD were combined with and compared to those of the common ROI. They were drawn on 91 female study participants (ages 20-80 years, 10 per decade) who were scanned on Hologic QDR-4500, Aloka DCS-600EX, GE Lunar PIXI and Norland pDEXA DXA scanners. For all device combinations, manufacturer-implemented ROI root mean-square errors were significantly higher than for the common ROI, suggesting that implementing an ROI with common design on all scanners is a good way to reduce interdevice variability. When manufacturer-implemented ROIs were universally standardized root mean-square error (RMSE) values were less different from that of the nonstandardized Common ROI, suggesting that universal standardization can further improve interdevice comparability even when a common ROI such as the one implemented here is used. ROI standardization dramatically improves interdevice comparability.

Does osteoporosis classification using heel BMD agree across manufacturers?

The lack of standardization in bone mineral density (BMD) measurements is known. Several studies have been carried out to cross-calibrate the axial dual X-ray absorptiometry (DXA) devices. Recently, a number of peripheral DXA (pDXA) densitometers have been introduced. In this study we evaluated the agreement between two heel DXA devices on BMD and T-scores. A total of 99 females aged 21-78 years (ca. 16 per decade) had their non-dominant heel BMD measured using the PIXI (Lunar Inc.) and the Apollo (Norland Medical) pDXA scanners. The mean BMD values were 0.492 and 0.607 g/cm(2) and the mean T-scores using manufacturers' specified reference data were -0.07 and -0.25 for the PIXI and Apollo, respectively. Both the BMD and T-score intermachine relationships were highly correlated but showed significant nonidentity slopes and non-zero offsets. The diagnostic comparison on T-scores resulted in 86% agreement between the instruments (weighted kappa score of 0.550). Normalizing the reference peaks and SDs using this study's young adult population BMD results removed the systematic T-score disagreement. We found that PIXI and Apollo are highly correlated. Differences in BMD values are mainly due to different region of interest (ROI) definitions and additional T-score disagreement reflects the difference in normative databases.

Evaluation of a gel-coupled quantitative ultrasound device for bone status assessment

OBJECTIVE

To evaluate a new gel-coupled calcaneal quantitative ultrasound system, Osteospace (Medilink, Montpellier, France), which was designed to assess the status of bone in the calcaneus.

METHODS

The study group consisted of 215 healthy white women aged 20 to 85 years and 51 white women aged 60 to 86 years with osteoporotic fractures. Fifty-two healthy women aged 50 to 85 years were randomly selected from the healthy cohort as the control group. All the women had calcaneal quantitative ultrasonic measurements. The women with osteoporotic fractures and the control group also had proximal femur and lumbar anteroposterior spine bone mineral density measurements using dual X-ray absorptiometry. Bone mineral density was also measured in a subgroup of 54 women at the calcaneus.

RESULTS

There was a significant inverse correlation of broadband ultrasound attenuation and speed of sound with age (P < .001). Short-term measurement precision values expressed as coefficients of variation were 1.72% for broadband ultrasound attenuation and 0.64% for speed of sound, and standardized short-term precision values were 6.09% for broadband ultrasound attenuation and 3.87% for speed of sound. The correlations between the quantitative ultrasonic parameters and calcaneal bone mineral density were 0.69 (P = .0001) for broadband ultrasound attenuation and 0.45 (P = .0008) for speed of sound. Both quantitative ultrasonic parameters and all bone mineral density measurements of the hip and spine differed significantly between the control and osteoporotic fracture groups (P < .01). Age-, weight-, and height-adjusted odds ratios per SD decrease were as follows: broadband ultrasound attenuation, 1.79; speed of sound, 1.83; spine bone mineral density, 2.34; femoral neck bone mineral density, 1.69; and total hip bone mineral density, 1.85. The areas under the receiver operating characteristic curve for quantitative ultrasound parameters and bone mineral density measurements were close, ranging from 0.75 to 0.80.

CONCLUSIONS

This new quantitative ultrasound system can detect age- and menopause-related influences on skeletal status and can discriminate healthy women from those with osteoporotic fractures in a manner comparable with that of bone mineral density measurement by dual X-ray absorptiometry.

Vertebral fractures in osteoporosis: a new method for clinical assessment

Vertebral fractures are the most common consequence of osteoporosis, and are an important risk factor for subsequent fractures. Patients with reduced bone mineral density (BMD) and vertebral fractures have significantly increased risk for future fractures, indicating great potential for the combined use of fracture assessment and BMD in risk evaluation. Despite the established importance of fractures, however, vertebral assessment is not typically performed in the clinical evaluation of patients at risk for osteoporosis. Radiographs are the accepted standard for assessment of fractures, but are rarely obtained in osteoporosis assessment for a variety of practical reasons, including cost, radiation dose, and the lack of office-based radiological facilities. Clinical assessment of fractures is difficult because most are asymptomatic. Consequently, this strong risk factor for osteoporotic fractures is often overlooked. High-resolution lateral spine images, obtained on advanced fan-beam dual X-ray absorptiometry (DXA) systems, provide a practical, low-radiation dose, point-of-care methodology for assessment of vertebral fractures, and have the potential to address this important clinical need. In this article, we review the importance of vertebral fractures and the methods of assessing them. We also review clinical data supporting the feasibility of visual evaluation of lateral spine images obtained using a fan-beam DXA system, and discuss the potential positive impact of this new methodology on clinical patient evaluation.

Characterization of the COQ5 gene from Saccharomyces cerevisiae. Evidence for a C-methyltransferase in ubiquinone biosynthesis

Ubiquinone (coenzyme Q or Q) is a lipophilic metabolite that functions in the electron transport chain in the plasma membrane of prokaryotes and in the inner mitochondrial membrane of eukaryotes. Q-deficient mutants of Saccharomyces cerevisiae fall into eight complementation groups (coq1-coq8). Yeast mutants from the coq5 complementation group lack Q and as a result are respiration-defective and fail to grow on nonfermentable carbon sources. A nuclear gene, designated COQ5 was isolated from a yeast genomic library based on its ability to restore growth of a representative coq5 mutant on media containing glycerol as the sole carbon source. The DNA segment responsible for the complementation contained an open reading frame (GenBankTM accession number Z49210Z49210) with 44% sequence identity over 262 amino acids to UbiE, which is required for a C-methyltransferase step in the Q and menaquinone biosynthetic pathways in Escherichia coli. Both the ubiE and COQ5 coding sequences contain sequence motifs common to a wide variety of S-adenosyl-L-methionine-dependent methyltransferases. A gene fusion expressing a biotinylated form of Coq5p retains function, as assayed by the complementation of the coq5 mutant. This Coq5-biotinylated fusion protein is located in mitochondria. The synthesis of two farnesylated analogs of intermediates in the ubiquinone biosynthetic pathway is reported. These reagents have been used to develop in vitro C-methylation assays with isolated yeast mitochondria. These studies show that Coq5p is required for the C-methyltransferase step that converts 2-methoxy-6-polyprenyl-1, 4-benzoquinone to 2-methoxy-5-methyl-6-polyprenyl-1,4-benzoquinone.

Complementation of coq3 mutant yeast by mitochondrial targeting of the Escherichia coli UbiG polypeptide: evidence that UbiG catalyzes both O-methylation steps in ubiquinone biosynthesis

Ubiquinone functions in the mitochondrial electron transport chain. Recent evidence suggests that the reduced form of ubiquinone (ubiquinol) may also function as a lipid soluble antioxidant. The biosynthesis of ubiquinone requires two O-methylation steps. In eukaryotes, the first O-methylation step is carried out by the Coq3 polypeptide, which catalyzes the transfer of a methyl group from S-adenosylmethionine to 3,4-dihydroxy-5-polyprenylbenzoate. In Escherichia coli, 2-polyprenyl-6-hydroxyphenol is the predicted substrate; however, the corresponding O-methyltransferase has not been identified. The second O-methylation step in E. coli, the conversion of demethylubiquinone to ubiquinone, is carried out by the UbiG methyltransferase, which is 40% identical in amino acid sequence with the yeast Coq3 methyltransferase. On the basis of the chemical similarity of the first and last methyl-acceptor substrates and the high degree of amino acid sequence identity between Coq3p and UbiG, the ability of UbiG to catalyze both O-methylation steps was investigated. The current study shows that the ubiG gene is able to restore respiration in the yeast coq3 mutant, provided ubiG is modified to contain a mitochondrial leader sequence. The mitochondrial targeting of O-methyltransferase activity is an essential feature of the ability to restore respiration and hence ubiquinone biosynthesis in vivo. In vitro import assays show the mitochondrial leader sequence present on Coq3p functions to direct mitochondrial import of Coq3p in vitro and that processing to the mature form requires a membrane potential. In vitro methyltransferase assays with E. coli cell lysates and synthetically prepared farnesylated-substrate analogs indicate that UbiG methylates both the derivative of the eukaryotic intermediate, 3,4-dihydroxy-5-farnesylbenzoate, as well as that of the E. coli intermediate, 2-farnesyl-6-hydroxyphenol. The data presented indicate that the yeast Coq3 polypeptide is located in the mitochondria and that E. coli UbiG catalyzes both O-methylation steps in E. coli.

Chemical Control of Nematodes on Flue-cured Tobacco in Brazil, Canada, United States, and Zimbabwe

A survey was conducted in four major flue-cured tobacco producing countries to determine use of nematicides for control of plant-parasitic nematodes on flue-cured tobacco. Included in the survey were scientists from Brazil, Canada, the United States, and Zimbabwe. Nematicides were used on 60-95% of the flue-cured tobacco crop in these regions. The choice of fumigant and nonfumigant nematicides, however, varied greatly as influenced by the edaphic factors, nematode species, and other pests present. The major nematicides, application methods, and efficacy evaluation systems used in these countries were addressed.

Antibacterial action of 2-bromo-2-nitropropane-1,3-diol (bronopol)

Patterns of growth inhibition of Escherichia coli in the presence of 2-bromo-2-nitropropane-1,3-diol (bronopol) indicate a period of biocide-induced bacteriostasis followed by growth at an inhibited rate. The length of the bacteriostatic period, but not the subsequent growth inhibition, was reduced by the addition of excess cysteine. Patterns of growth inhibition were unaffected by catalase or superoxide dismutase. The bactericidal concentrations (100 to 500 micrograms/ml) were considerably in excess of the MIC (13 micrograms/ml) and generally produced first-order reductions in viability. Bactericidal activity was considerably reduced by anoxic conditions and by the presence of catalase or superoxide dismutase. Results indicate that there are two distinct reactions between bronopol and thiols. Under aerobic conditions, bronopol catalytically oxidizes thiol-containing materials such as cysteine, with atmospheric oxygen as the final oxidant. By-products of this reaction are active oxygen species such as superoxide and peroxide, which are directly responsible for the bactericidal activity of the compound and for the reduced growth rate after the bacteriostatic period. The latter effect probably results from the oxidation of intracellular thiols such as glutathione and cysteine. Catalytic oxidation of thiols in the presence of excess thiol leads to the creation of an anoxic state. Under these conditions, the slower reaction with thiols, which consumes bronopol, predominates. Consumption of bronopol by its reaction with thiols, without the involvement of oxygen, leads to the eventual removal of bronopol from treated suspensions and the resumption of growth.

Lawson Tait-disciple of Charles Darwin

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Inhibition of prostaglandin E2 secretion. Failure to abolish autoregulation in the isolated dog kidney

We studied the role of renal prostaglandins in the regulation of glomerular filtration rate (GFR) and renal blood flow (RBF) in the isolated dog kidney. Indomethacin or meclofenamate, 2 mg/kg of body weight, suppressed renal prostaglandin E2 (PGE2) secretion, measured by radioimmunoassay, to zero within 20 minutes; the effect persisted for the duration of the study. When renal arterial pressure (PRA) was maintained at 104 mm Hg both drugs caused a sharp decrease in sodium excretion and RBF with redistribution of flow from inner to outer cortes we examined autoregulation of GFR and RBF over the pressure ranges of 150-100 and 150-75 mm Hg, respectively, after inhibition of PGE2 secretion and under control conditions. deltaGFR/deltaPRA (ml/min per mm Hg) was 0.020 +/- 0.017 in the indomethacin group, 0.152 +/- 0.055 in the meclofenamate group, and 0.086 +/- 0.017 in the control group. The change in GFR for the indomethacin group was significantly less than that for meclofenamate (P less than 0.01) and control groups (P less than 0.025); the latter two groups were not statistically different from each other (P greater than 0.1). There was no significant difference (P greater than 0.1) between the three groups with respect to deltaRBF/deltaPRA, which measured 0.288 +/- 0.046, 0.370 +/- 0.112, and 0.438 +/- 0.123 ml/min per mm Hg in the indomethacin, meclofenamate and control groups, respectively. Renal was lowered from 150 to 75 mm Hg. The observation that inhibition of prostaglandin synthesis promotes a redistribution of RBF from inner to outer cortex suggests that renal prostaglandins may participate in the regulation of medullary blood flow. However, since autoregulation of GFR and RBF remained intact despite inhibition of prostaglandin secretion, these data argue against a role for renal prostaglandins in regulating whole kidney GFR and RBF.

Amino- and carboxyl-terminal analyses of hepatoma lactate dehydrogenase isozymes

The M4 isozyme of lactate dehydrogenase was purified to homogeneity from normal rat liver and from two Morris hepatomas (7777 and 7793). Amino-terminal analyses with fluorodinitrobenzene failed to detect the presence of free amino-terminal residues in each enzyme studied. Each enzyme contained between 3.7 and 4.1 moles of protein-bound acetyl groups per mole of enzyme. The amino-terminal peptide, characterized as N-acetylalanylalanine, was isolated from Pronase digests of each isozyme preparation, and quantitative recovery experiments indicated that all acetyl residues were bound at the amino termini. Carboxylterminal analyses demonstrated phenylalanine to be the carboxyl-terminal residue in each enzyme studied. These data indicate no differences in either amino- or carboxyl-terminal regions of the hepatoma M4 isozymes compared to normal liver M4 isozyme.

Medical teaching in St. Andrews University 1413-1972

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Spencer Wells--Surgeon RN

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William Jeaffreson (1790-1865): surgical pioneer

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