Measuring guided waves in long bones: modeling and experiments in free and immersed plates

Guided waves, consistent with the A0 Lamb mode, have previously been observed in bone phantoms and human long bones. Reported velocity measurements relied on line fitting of the observed wave fronts. Such an approach has limited ability to assess dispersion and is affected by interference by other wave modes. For a more robust identification of modes and determination of phase velocities, signal processing techniques using the fast Fourier transform (FFT) were investigated. The limitations of FFT because of spatial resolution were addressed to improve the precision of the measured modes. An inversion scheme was developed for determining the plate thickness from the measured velocity. Experiments were performed on free and immersed plates, mimicking bone without and with an overlying tissue. With group velocity filtering, modes could be identified reliably with precise phase velocities and thicknesses. These methods were essential for the immersed plates and they should lead to more reliable in vivo measurements.

Multi-locus candidate gene polymorphisms and risk of myocardial infarction: a population-based, prospective genetic analysis

BACKGROUND

Polymorphisms in candidate genes related to lipid metabolism, thrombosis, hemostasis, cell-matrix adhesion, and inflammation have been suggested clinically useful in risk assessment of cardiovascular disease.

METHODS

We evaluated a panel of 92 candidate gene polymorphisms, using a multiplex polymerase chain reaction-immobilized probe assay amongst 523 individuals who subsequently developed myocardial infarction (MI), and amongst 2092 individuals who remained free of reported cardiovascular disease over a mean follow-up period of 13.2 years.

RESULTS

Of the 92 polymorphisms tested, three that we previously reported on were associated with risk of MI, [pro12ala in the peroxisome proliferator activated-receptor gamma gene (odds ratio, OR = 0.75, P = 0.02); thr164ile in the beta-2 adrenergic receptor gene (OR = 0.14, P = 0.007); and ala23thr polymorphism in the eotaxin gene (OR = 1.87, P = 0.01)]. However, when adjusted for the other 89 polymorphisms evaluated, these findings were no longer statistically significant. Further, in contrast to reports from other investigators, we found little evidence for association of a C677T polymorphism in the 5,10-methylenetetrahydrofolate reductase gene, the angiotensin-I-converting enzyme 1 insertion/deletion polymorphism, a 4G/5G polymorphism in the serine/cysteine proteinase inhibitor-clade E-member 1 gene, the factor V Leiden mutation, the G20210A factor II mutation, a -455G>A polymorphism in the beta-fibrinogen gene, the cys112arg/arg158cys apolipoprotein E gene polymorphism, a gly460trp polymorphism in the alpha-adducin gene, and a -629C>A polymorphism in the cholesteryl ester transfer protein gene with risk of MI.

CONCLUSIONS

After correction for multiple comparisons, the addition of genetic information observed in the present study had little impact on risk prediction models for MI. The present investigation highlights the importance of replication and validation of findings from genetic association studies.

Noninvasive assessment of coronary stenosis

Invasive coronary angiography (ICA) has been the gold standard in the diagnosis of coronary artery disease (CAD) for a long time and angiographic procedures performed annually in the United States have steadily increased during the last 25 years. The unmatched temporal and spatial imaging resolution, the high level contrast between the coronary lumen and the adjacent structures, and the ability to concurrently perform percutaneous coronary interventions (PCI) are the technical advantages of coronary angiography. However, the isolated intraluminal imaging, the relatively high financial cost of the procedure, and the risks associated with catheterization may be limitations to its use. Moreover, a better selection of patients really in need of ICA and PCI is necessary since many patients referred for ICA are found not to have significant CAD. Therefore, a remarkable technical progress has been achieved by both cardiac magnetic resonance and cardiac computed tomography in this regard for the noninvasive detection of coronary stenoses.

HCHs and DDTs in sediment-dwelling animals from the Yangtze Estuary, China

HCHs and DDTs in sediment-dwelling animals including mollusks and crabs from the Yangtze Estuary were determined by GC-ECD. Levels of t-HCH were in the range of 1.2-5.5 ng g(-1) and averaged 3.5 ng g(-1) in mollusks, while t-DDT concentrations ranged from 26.0 to 68.8 ng g(-1), with a mean of 34.5 ng g(-1). In crabs t-HCH concentrations varied from 2.0 to 25.7 ng g(-1) and averaged 13.8 ng g(-1), whereas the concentrations of t-DDT were in the range of 1.5-24.8 ng g(-1) with a mean value of 5.9 ng g(-1). The HCHs and DDTs levels depend on geographical position and sources, showing the high levels at fresh water area in the estuary, such as XP, CM and LHK sites, and lower at brackish water area, such as FX site, and little difference between species. Results also indicate there was no significant relationship between t-HCH (t-DDT) concentrations and lipid contents both in mollusks and crabs because of non-equilibrium state under a specific estuarine dynamics; smaller individuals accumulated more HCHs and DDTs than larger individuals of mollusks at LHK site, showing different uptake rate for these pesticides; moreover, HCHs and DDTs levels were lower in female crab bodies than male crab bodies suggesting that the release of spawning. BSAFs (Biota- Sediment Accumulation Factors) from sediment-dwelling animals for HCHs and DDTs show a significant "one high with two low" and "one low with two high" effect in the Yangtze Estuary.

HCHs and DDTs in salt marsh plants (Scirpus) from the Yangtze estuary and nearby coastal areas, China

HCHs and DDTs in salt marsh plants taken from intertidal flats in the Yangtze estuary and coastal area in April and July 2002 were determined by GC-ECD. A significant seasonal effect was observed for HCHs and DDTs in sources and concentration levels in different sample types including above-ground tissues and roots as well as the whole plants and rhizospheric sediments. The results indicated that the concentration of t-HCH was higher in the above-ground tissues than in their roots in April; however, the partitioning of DDTs between contaminated sediments and the roots showed the higher concentrations of t-DDT in their roots. HCHs and DDTs concentration levels were higher in above-ground tissues than in roots in July. BCFs of HCHs and DDTs exhibited lower values with higher levels of contaminants in sediments, and higher values with lower levels in sediments.

Knowledge of blood pressure levels and targets in patients with coronary artery disease in the USA

Little is known about patient awareness of nationally recommended blood pressure targets, especially among patients with cardiac disease. To examine this issue, we interviewed 738 patients hospitalized with coronary artery disease to assess their knowledge of their systolic and diastolic blood pressure levels as well as corresponding national targets. We used bivariate and multivariate analyses to determine if any patient demographic or clinical characteristics were associated with blood pressure knowledge. Only 66.1% of patients could recall their own systolic and diastolic blood pressure levels. Only 48.9% of all patients could correctly name targets for these values. Knowledge of target blood pressure levels was particularly poor among patients who were female (odds ratio (OR) 0.69; 95% confidence interval (CI) 0.49-0.98), aged > or =60 years (OR 0.70, CI 0.51-0.97), without any college education (OR 0.48, CI 0.35-0.65), without a documented history of hypertension (OR 0.57, CI 0.39-0.84), and with known diabetes (OR 0.46, CI 0.33-0.66). Patients in the highest risk group, according to Joint National Committee guidelines stratification, were no more knowledgeable about their blood pressure levels and targets than lower risk patients. A significant proportion of patients hospitalized with coronary artery disease do not know their own blood pressure levels or targets. Current blood pressure education efforts appear inadequate, particularly for certain patient subgroups in which hypertension is an important modifiable risk factor.

Family-based association analysis implicates IL-4 in susceptibility to Kawasaki disease

Several compelling lines of evidence suggest an important influence of genetic variation in susceptibility to Kawasaki disease (KD), an acute vasculitis that causes coronary artery aneurysms in children. We performed a family-based genotyping study to test for association between KD and 58 genes involved in cardiovascular disease and inflammation. By analysis of a cohort of 209 KD trios using the transmission disequilibrium test, we documented the asymmetric transmission of five alleles including the interleukin-4 (IL-4) C(-589)T allele (P=0.03). Asymmetric transmission of the IL-4 C(-589)T was replicated in a second, independent cohort of 60 trios (P=0.05, combined P=0.002). Haplotypes of alleles in IL-4, colony-stimulating factor 2 (CSF2), IL-13, and transcription factor 7 (TCF7), all located in the interleukin gene cluster on 5q31, were also asymmetrically transmitted. The reported associations of KD with atopic dermatitis and allergy, elevated serum IgE levels, eosinophilia, and increased circulating numbers of monocyte/macrophages expressing the low-affinity IgE receptor (FCepsilonR2) may be related to effects of IL-4. Thus, the largest family-based genotyping study of KD patients to date suggests that genetic variation in the IL-4 gene, or regions linked to IL-4, plays an important role in KD pathogenesis and disease susceptibility.

Characterization of a 4-methylbenzoate-degrading methanogenic consortium as determined by small-subunit rDNA sequence analysis

A methanogenic consortium that degrades 4-methylbenzoate (MBA) as the sole carbon and energy source was successfully enriched in an upflow anaerobic sludge bed bioreactor and studied. Electron microscopic observation showed that long rods with a distinct collar feature resembling Desulfomonile tiedjei rods were the predominant population, and that these rods formed a close spatial orientation with Methanobrevibacter-like bacteria. In addition, thin filaments and bamboo-shaped filaments that highly resembled the acetoclastic Methanosaeta were also frequently observed. A 16S rDNA clone library was constructed for the domain Bacteria, and 20 sequence types or operational taxonomic units (OTUs) were found out of 139 clones screened. Phylogenetic analysis classified these 20 nearly full-length OTUs into the delta (50.3% of total clones) and gamma (4.3%) subdivisions of the division Proteobacteria, the green non-sulfur bacteria subdivision I (7.2%), Cytophagales (7.2%), Planctomycetes (5.7%), gram-positive low G + C group (8.6%), candidate divisions OP8, OP10 and OP11 (9.3%), and a novel candidate division MBA1 (7.2%) that had an interdivisional sequence similarity less than 75%. However, only 3 OTUs had a sequence similarity higher than 90% to known isolates or environmental 16S rDNA clones, suggesting that the microbial community was diversified and largely unidentified. In particular, those 8 OTUs found in the delta-Proteobacteria were either clustered into novel groups or showed a low sequence similarity to closely related bacteria. It is highly possible that the delta-Proteobacteria were the long rods with a distinct collar feature observed microscopically, and together with the methanogens were mainly responsible for the syntrophic degradation of MBA. The unique and novel microbial populations identified explained the requirement of a long start-up period of up to 426 d for the MBA-degrading consortium.

Assessment of the role of genetic polymorphism in venous thrombosis through artificial neural networks

PURPOSE

To assess the role of genetic polymorphisms in venous thrombosis events (VTE) using Artificial Neural Networks (ANNs), a model for solving non-linear problems frequently associated with complex biological systems, due to interactions between biological, genetic and environmental factors.

METHODS

A database was generated from a case-control study of venous thrombosis, using 238 patients and 211 controls. The database of 64 variables included age, gender and a panel of 62 genetic variants. Three different ANNs were compared, with logistic regression for the accuracy of predicting cases and controls.

RESULTS

ANNs yielded a better performance than the logistic regression algorithm. Indeed, through ANNs models, the 62 variables related to genetic variants were first reduced to a set of 9, and then of 3 (MTHFR 677 C/T, FV arg506gln, ICAM1 gly214arg).

CONCLUSIONS

The findings of this study illustrate the power of ANN in evaluating multifactorial data, and show that the different sensitivities of the models of elaboration are related to the characteristics of the data. This may contribute to a better understanding of the role played by genetic polymorphisms in VTE, and help to define, if possible, a test panel of genetic variants to estimate an individual's probability of developing the disease.

Food consumption and nutrient intakes with a special focus on milk product consumption in early pubertal girls in Central Finland

OBJECTIVE

To evaluate the current status of dietary intakes in early pubertal girls with a special focus on milk products.

DESIGN

Cross-sectional data using 3-day food records.

SUBJECTS

Eight hundred and sixty girls, aged 10-12 years, at Tanner maturation stage I-III.

RESULTS

The mean consumption of milk products (620 g day(-1)) was similar to that of a Finnish study in the 1980s, while the consumption of non-milk drinks (403 g day(-1)) had increased. Twelve per cent of the girls had a dairy-restricted diet and consumed significantly less milk products than girls with a non-restricted diet (465 vs. 644 g day(-1), P<0.001). Girls with low milk product consumption had the highest non-milk drinks consumption (P<0.001). The mean energy intake was 7.1 MJ day(-1). No major changes were found in the sources of nutrients. The shares of energy for nutrients were close to recommendations except for saturated fat (13.9 vs. 10% of energy) and carbohydrates (51.5 vs. 55-60% of energy). The mean calcium intake (1117 mg day(-1)) was above the recommendation, while the vitamin D intake (3.1 microg day(-1)) of 88% of the girls was below the recommendation.

CONCLUSIONS

The diet quality of early pubertal girls is close to the recommendations and has improved with respect to fat compared with the 1980s. Consumption of milk products is high although the consumption of non-milk drinks has increased. We found a subgroup of girls who compensate their low milk product consumption with a higher consumption of non-milk drinks. Following a dairy-restricted diet is the main reason for low consumption of milk products.

Influence of physical activity and maturation status on bone mass and geometry in early pubertal girls

This study aimed to evaluate the influence of leisure-time physical activity on the development of bone mass and density in early pubertal girls. Scores of physical activity were obtained from 242 Finnish girls (10-12 years old within Tanner Stages I-II) using a questionnaire. Bone mass and density were assessed using different densitometric techniques. At Tanner Stage I, active girls had significantly higher bone mineral mass (BMC) and areal bone mineral density (aBMD) of the whole body and cortical volumetric BMD and thickness of the tibial shaft compared with sedentary girls (P<0.05). On the other hand, the active girls at Tanner Stage II showed significantly higher values only in BMC and aBMD at the lumbar spine (P=0.017 and P=0.007, respectively). These indicated that girls at Tanner Stage I with higher leisure-time physical activity level benefited more from physical activity in terms of their bone development than their less active counterparts. Our results provide evidence that the most beneficial time for physical exercise to exhibit its effect on bone development is in the earlier pubertal period for normal school children, but the positive effect on the lumbar spine is also demonstrated in Tanner Stage II.

Comparison of three ultrasonic axial transmission methods for bone assessment

This study compared three approaches to bone assessment using ultrasonic axial transmission. In 41 fresh human radii, velocity of the first arriving signal was measured with a commercial device (Sunlight Omnisense) operating at 1.25 MHz, a prototype based on 1-MHz bidirectional axial transmission and a low-frequency (200 kHz) prototype, also measuring the velocity of a slower wave. Cortical and trabecular bone mineral density, cortical thickness and cross-sectional area were determined by peripheral quantitative computed tomography. Significant but modest correlation between velocities reflects differences in the nature of the propagating waves and methodological differences. Of the higher frequency devices, bidirectional measurements provided stronger correlations with bone properties than did conventional measurements. High-frequency devices were less sensitive to cortical thickness than was the low-frequency device, because higher frequency waves interrogate thinner cortical layers. The results suggest that different axial transmission approaches reflect different bone properties. Therefore, a multifrequency technique might be useful in probing different bone properties.

Interaction between metabolic syndrome and PON1 polymorphisms as a determinant of the risk of coronary artery disease

The enzyme serum paraoxonase plays an important role in antioxidant defences and prevention of atherosclerosis. Metabolic syndrome (MS) is a clinical condition associated with increased oxidant stress and cardiovascular mortality. Two common polymorphisms of serum paraoxonase, PON1 Leu(55)Met and Gln(192)Arg, have been postulated to modulate the cardiovascular risk. We studied 915 subjects with angiographic documentation: 642 subjects with coronary atherosclerosis and 273 with normal coronary arteries. Two hundred and twenty-four subjects met the diagnostic criteria of MS. We found a significant interaction between MS and both the PON1 polymorphisms in determining the risk of coronary artery disease (P<0.05 by likelihood-ratio test). The 55Leu and the 192Arg alleles, associated with reduced protection against lipid peroxidation, were associated with coronary artery disease only in the MS subgroup. Subjects with MS and both 55Leu and 192Arg alleles had significantly increased risk (OR=9.38 with 95% CI=3.02-29.13 after adjustment by multiple logistic regression) as compared to subjects without MS and with 55Met/Met-192Gln/Gln genotype. No increased risk was found for subjects with MS and the 55Met/Met-192Gln/Gln genotype. This study highlights a potential example of genetic (paraoxonase polymorphisms)-clinical (MS) interaction influencing cardiovascular risk.

Mortality in New Zealand workers exposed to phenoxy herbicides and dioxins

AIMS

To evaluate mortality in New Zealand phenoxy herbicide producers and sprayers exposed to dioxins.

METHODS

Phenoxy herbicide producers (n = 1025) and sprayers (n = 703) were followed up from 1 January 1969 and 1 January 1973 respectively to 31 December 2000. A total of 813 producers and 699 sprayers were classified as exposed to dioxin and phenoxy herbicides. Standardised mortality ratios (SMR) were calculated using national mortality rates.

RESULTS

At the end of follow up, 164 producers and 91 sprayers had died. Cancer mortality was reduced for sprayers (SMR = 0.82, 95% CI 0.57 to 1.14) and increased in exposed production workers (SMR = 1.24, 95% CI 0.90 to 1.67), especially for synthesis workers (SMR = 1.69), formulation and lab workers (SMR = 1.64), and maintenance/waste treatment/cleaning workers (SMR = 1.46). Lymphohaematopoietic cancer mortality was increased in exposed production workers (SMR = 1.65, 95% CI 0.53 to 3.85), especially for multiple myeloma (SMR = 5.51, 95% CI 1.14 to 16.1). Among sprayers, colon cancer (SMR = 1.94, 95% CI 0.84 to 3.83) showed increased mortality.

CONCLUSIONS

Results showed 24% non-significant excess cancer mortality in phenoxy herbicide producers, with a significant excess for multiple myeloma. Associations were stronger for those exposed to multiple agents including dioxin during production. Overall cancer mortality was not increased for producers and sprayers mainly handling final technical products, although they were likely to have been exposed to TCDD levels far higher than those currently in the general New Zealand population.

Assessment of Candida albicans genes expressed during infections as a tool to understand pathogenesis

Candida albicans is the most common fungal opportunistic pathogen of humans and causes mucocutaneous, bloodstream and deep organ infections. Screening for C. albicans genes that are preferentially expressed within infected hosts represents a strategy to identify novel virulence factors and define global expression patterns relevant to pathogenesis. Until recently, C. albicans has not been amenable to screening using existing technologies. This has begun to change with the development of new molecular genetic tools and the sequencing of the C. albicans genome. In this paper, we review studies using recently developed techniques to identify genes expressed by C. albicans during infections, as well as work from our laboratory using a human antibody-based strategy. Along with others, we have shown that selected in vivo expressed genes encode known and previously unrecognized candidal virulence factors. Future studies in this area will identify additional novel virulence factors, as well as advance our understanding of pathogenesis.