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Biomedical subjects

N de Jong

Publications and source records attributed to N de Jong.

At least 37 records · Page 2Linked to original sources
PubMed2001

Nutrient-dense foods and exercise in frail elderly: effects on B vitamins, homocysteine, methylmalonic acid, and neuropsychological functioning.

BACKGROUND: Frail elders are at risk of suboptimal micronutrient status, functional decline, and neurologic disorders. The influence of oral multimicronutrients in physiologic doses and of moderately intense physical exercise on homocysteine (Hcy), methylmalonic acid (MMA), and neurologic functioning have not yet been investigated. OBJECTIVE: Our goal was to determine the effects of enriched foods and exercise on blood vitamins, Hcy, MMA, and neuropsychological functioning in the frail. DESIGN: A 17-wk randomized controlled intervention trial was used to study 1) enriched foods plus a social program, 2) regular foods plus exercise, 3) enriched foods plus exercise, and 4) regular foods plus a social program. Enriched foods contained multiple micronutrients (25-100% of the Dutch recommended dietary allowances); exercises focused on strength, coordination, flexibility, and endurance. Vitamin (cobalamin, red blood cell folate, and pyridoxal 5'-phosphate), Hcy, and MMA concentrations were measured and 2 neuropsychological tests were conducted. RESULTS: Vitamin concentrations were higher in the supplemented groups than in the unsupplemented groups (P < 0.001; total n = 130). Compared with baseline, cobalamin in the supplemented groups was increased by 22%, plasma folate by 101%, red blood cell folate by 87%, and pyridoxal 5'-phosphate by 68%. Concentrations in the unsupplemented groups changed by -2%, -6%, 1%, and -13%, respectively. Hcy decreased by 25% and MMA by 30% in the supplemented groups, compared with a small increase in Hcy (2%) and decrease in MMA (9%) in the unsupplemented groups. Exercise did not significantly affect vitamin, Hcy, or MMA concentrations. No significant effect of either intervention was observed on the neuropsychological tests. CONCLUSIONS: The decrease in Hcy and MMA in frail elders confirms a subclinical metabolic deficiency state. Enriched foods containing physiologic amounts of micronutrients have a beneficial effect on these metabolites. No effects of B vitamins on mental health were identified.

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PubMed2001

Selenium and zinc status are suboptimal in a sample of older New Zealand women in a community-based study.

The importance of selenium and zinc in the immune functioning of the aged is widely recognized. Seniors in New Zealand are at particularly high risk of low selenium status because of the low selenium soil environment. The zinc status of the New Zealand elderly has never been assessed. In this cross-sectional study, the biochemical selenium, zinc and lipid levels, physical functional capacity and dietary intakes of 103 randomly selected free-living New Zealand women (mean age +/- SD, 75 +/- 3 y) were assessed. Among nonusers of selenium supplements (n = 80), 80% [95% confidence interval (CI): 70; 88%] had plasma selenium levels (0.85 +/- 0.23 micromol/L) below 1.00 micromol/L [ approximately 10% below mean plasma selenium necessary for full expression of glutathione peroxidase (GPx) activity in New Zealand subjects]. Plasma selenium was strongly correlated with GPx: r = 0.56; P < 0.0001. For nonusers of zinc supplements (n = 88), serum zinc concentrations were 12.4 +/- 1.4 micromol/L, with 12% (95% CI: 6; 21%) having levels below the cut-off value (10.7 micromol/L). Estimated mean daily selenium and zinc intakes were 34 +/- 10 microg and 8.7 +/- 2.0 mg, respectively. Subjects in the highest tertile of a functional capacity index had higher biochemical zinc and selenium values than those in the lowest tertile (P < 0.05). The correlation between plasma selenium and GPx indicates that selenium intake in these women is still insufficient for full expression of GPx activity. Lower serum zinc levels also appear to be prevalent. Because a suboptimal trace element status may be more common among those with a poor physical functioning, promotion of the consumption of nutrient dense foods or supplements to improve selenium and zinc status of elderly women in New Zealand may be beneficial.

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PubMed2001

A new ultrasound contrast imaging approach based on the combination of multiple imaging pulses and a separate release burst.

A new ultrasound contrast imaging technique is described that optimally employs the rupture of the contrast agent. It is based on a combination of multiple high frequency, broadband, imaging pulses and a separate release burst. The imaging pulses are used to survey the target before and after the rupture and release of free gas bubbles. In this way, both processes (imaging and release) can be optimized separately. The presence of the contrast agent is simply detected by correlating or subtracting the signal responses of the imaging pulses. Because the time delay between the imaging pulses can be very short, the subtraction is less affected by tissue motion and can be done in real time. In vitro measurements showed that by using a release burst, the detection sensitivity increased 12 to 43 dB for different types of contrast agents. In the presence of a moving phantom, the increase in sensitivity was 22 dB. This new method is very sensitive for contrast agent detection in fundamental imaging mode and, therefore, non-linear propagation effects do not limit the maximum obtainable agent-to-tissue ratio. However, because of the inherent destruction of the contrast agent, it has to operate in an intermittent way. Through experiments, we have demonstrated the potential of the method to achieve simultaneous high sensitivity for contrast detection, i.e., high agent-to-tissue ratio, and high spatial resolution performance for different types of contrast agents.

Contrast Media↗
PubMed2001

Three-stage approach to ultrasound contrast detection.

A new method for detecting ultrasound contrast agents using a three-stage pulsing sequence is proposed. The method is based on observations showing that the scattering properties of contrast agents are modified by ultrasonic insonation at high power, but remain unchanged at low power. The objective of the first stage of the pulsing sequence is to use low power pulses to obtain a high resolution reference image without altering the agent. Higher power pulses in the second stage modify the contrast agent. The third stage detects the changes imposed to the contrast agent using low power pulses. A temporal filter is proposed to discriminate contrast response from clutter signal. The method is similar to power Doppler methods in that it uses several pulses to survey the target while destroying the agent. The new idea is to separate detection and destruction to circumvent a trade-off between sensitivity and resolution. Results from in vitro experiments with three different contrast agents are presented. The results are compared with harmonic power Doppler processed from the same data and show that an improvement in sensitivity is achievable by including the high power burst in the pulsing sequence. The results also show that the proposed filter reduces clutter artifacts from moving tissue.

Biomedical Engineering↗
PubMed2001

Appraisal of 4 months' consumption of nutrient-dense foods within the daily feeding pattern of frail elderly.

OBJECTIVES: The appraisal and acceptance of micronutrient-dense versus identical regular foods among frail elderly are described. METHODS: Four types of dairy and four types of fruit products, either enriched with multiple micronutrients or not, were consumed by 150 frail elders for 4 months. In the first 2 and last 2 weeks of the intervention, hedonic aspects were assessed. Afterward, evaluation forms were completed. RESULTS: At the start, small but consistent differences existed between the enriched and the regular foods concerning the scores on pleasantness, desire to eat the product, and attitude toward the product. At the end, those ratings dropped slightly or stayed equal. Significant differences between groups emerged from the overall evaluation score: 6.4 plus or minus 1.6 and 7.7 plus or minus 1.7 respectively (p <.001). DISCUSSION: Optimization of the hedonic parameters of nutrient-dense foods and major long-term attention for application in the daily elderly feeding pattern is of essential importance.

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PubMed2000

Detection procedures of ultrasound contrast agents.

In the early days, it was believed that ultrasound contrast agents (UCA) could be sufficiently detected and imaged with the conventional imaging methods nowadays referred to as fundamental imaging. Newer imaging techniques proved to be more sensitive and are based on specific properties of the UCA. In general, these new characteristics involve non-linear and transient characteristics of contrast agents that appear at the high end of the diagnostic acoustic intensity. Imaging modalities used today for UCA are, besides fundamental imaging, second harmonic imaging, power Doppler, harmonic power Doppler, pulse inversion and pulse inversion Doppler, multi-pulse imaging and subharmonic imaging. Although the results of conventional second harmonic imaging are still not optimal for perfusion imaging applications, in combination with Doppler techniques (colour Doppler, power Doppler) it is one of the most sensitive techniques currently available in terms of agent-to-tissue ratio. Further improvements in current and future detection methods demand a complete understanding of the ultrasound-UCA interaction.

Acoustics↗
PubMed2000

A fast rotating scanning unit for real-time three-dimensional echo data acquisition.

Most three-dimensional (3-D) echocardiography (3-DE) systems today are based on off-line methods where a large number of cross-sectional 2-D scans have to be acquired sequentially before a 3-D image can be reconstructed. Because acquisition is done step-by-step based on ECG triggering plus respiratory gating, this introduces motion artefacts and takes significant acquisition time. Another 3-D approach is based on 2-D transducers and parallel beam-forming. Such a system is very complex. In this manuscript, a fast continuously-rotating scanning unit, based on a 64-element phased-array transducer, is described. Typical rotation speed of the 3-D unit is 8 rotations per s. Therefore, 16 3-D volume datasets can be acquired per s in real-time. The first clinical examples as acquired with this probe are presented.

Artifacts↗
PubMed2000

Ultrasound contrast imaging: current and new potential methods.

For 10 years, it was thought that ultrasound (US) contrast agents could be sufficiently detected and imaged with the conventional imaging techniques, now referred to as fundamental imaging. However, it turned out that fundamental imaging was not sensitive enough to detect the contrast agents in the presence of tissue. New imaging techniques that are based on specific properties of the contrast agents, such as nonlinear and transient scattering, proved to be more sensitive. US contrast imaging modalities used today are fundamental, second harmonic, harmonic power Doppler, and pulse inversion; new modalities, such as release burst and subharmonic imaging are emerging. Second harmonic imaging is still not optimal for perfusion imaging applications. However, in combination with Doppler techniques such as power Doppler, it is one of the most sensitive techniques currently available. A complete understanding of the US-contrast agent interaction is essential for further improvements of current detection methods, and the development of new imaging techniques.

Contrast Media↗
PubMed2000

Optical imaging of contrast agent microbubbles in an ultrasound field with a 100-MHz camera.

Ultrasound (US) contrast agents, used in the field of medical diagnosis, contain small microbubbles of a mean diameter of about 3 microm. The acoustic behavior of these bubbles in US field has been subject to many investigations. In this study, we propose a method to visualize the behavior of the bubbles in a 0.5-MHz US field under a microscope with a frame rate of 4 MHz. For low acoustic pressures (peak negative pressure of 0.12 MPa), the radius-time curve as measured from the optical images is in agreement with the theory. For higher acoustic pressures (peak negative pressure of 0.6 MPa), the recorded radius is significantly larger than predicted by theory and sudden change in the bubbles shapes has been noticed. The proposed method enables the study and characterization of individual bubbles and their encapsulation. It is expected that this will open new areas for quality control, US contrast imaging and US-guided drug delivery.

Contrast Media↗
PubMed2000

Effect of dietary supplements and physical exercise on sensory perception, appetite, dietary intake and body weight in frail elderly subjects.

This present study investigated the effect of a 17-week intervention programme with nutrient-dense foods (enriched with vitamins and minerals at 25-100% of the Dutch recommended dietary allowance) and/or physical exercise in 159 frail elderly subjects (forty-six men, 113 women, mean age 78.7 (SD 5.6) years). Subjects were randomized into four groups: (1) control, (2) nutrition intervention, (3) exercise or (4) both nutrition intervention and exercise. Main outcome variables were sensory perception (smell test and questionnaire), appetite (questionnaire), energy intake (3 d food record) and body weight (on a weighing scale and with dual energy X-ray absorptiometry measurements). At baseline, moderate but significant correlations were found between appetite and energy intake (r 0.30, P < 0.0001), between smell test and smell perception assessed by questionnaire (r 0.40, P < 0.0001) and between lean body weight and energy intake (r 0.50, P < 0.0001). Results after 17-weeks intervention revealed neither change in smell test scores (P = 0.19) nor in appetite (P = 0.17). A slight positive effect of exercise compared with non-exercising groups on energy intake (difference 0.5 MJ, P = 0.05) was shown next to a preserving effect of exercise on lean body mass (+0.08 kg) compared with a decrease (-0.4 kg) in non-exercisers (P < 0.02). The correlation between the change in lean body mass and change in energy intake was 0.18 (P = 0.05). In conclusion, an interesting preserving effect on lean body mass in frail elderly subjects due to 17 weeks of exercise was shown. Since a decline in lean body mass was observed in the non-exercisers, effects may be attributable to change in activity pattern. Changes in lean mass were also slightly, but significantly, correlated with changes in energy intake. In turn, energy intake was not related to a change in reported appetite or sensory perception. Nutrient-dense foods were not able to improve any of the outcome variables in this study.

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PubMed2000

Variability of micronutrient content in enriched dairy and fruit products. Executive Group for Development of Nutrient Dense Foods for Frail Elderly.

Accurate measures of micronutrient levels in newly developed enriched foods are indispensable for valid labelling, for determination of ultimate levels for possible claimed health effects and for safety. To date, only a limited amount of public literature is available on the reproducibility of laboratory analysis and on the similarity within novel fortified or enriched foods. Within the framework of an intervention trial in frail elderly, the micronutrient content of eight different types of enriched foods were repeatedly examined. The variance in concentrations of the vitamins B1, B2, B6, folic acid, B12, C, D, and E was studied, in addition to levels of the minerals zinc, iodine, calcium, iron and magnesium. Four main factors, possibly contributing to the variability of these micronutrient levels, were investigated: (1) type of product, (2) type of laboratory (between-laboratory) reproducibility), (3) time of the year (month) in which analyses were carried out (May-October) and (4) freshness of the product. The type of product and laboratory emerged as factors contributing mostly to the total variability in concentrations of vitamins (on average approximately 50% explained). However, none of the products consistently contained higher or lower levels compared to the other products and most target levels were met except for vitamin B2 in both dairy and fruit products and for folic acid and vitamin C in some fruit products. Differences between products were regarded as acceptable. Extensive evaluation of multiple lab results should be emphasised within the manufacturing process of enriched foods.

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PubMed2000

Immunity in frail elderly: a randomized controlled trial of exercise and enriched foods.

OBJECTIVE: To examine the effects of 17-wk physical exercise and enriched foods on cellular immune response (CIR) in frail elderly. METHODS: A total of 112 independently living, frail elderly men and women (mean age 79.2 +/- 5.9) received: twice weekly comprehensive, moderate intensity, progressive group exercise (group A, N = 26); daily enriched foods (group B, N = 31); both (group C, N = 29); or neither (group D, N = 26). Exercises focused on skills training. Foods were enriched with micronutrients with a high prevalence of deficiency in older people (at 25-100% the RDA). A social program and identical regular foods were offered as a control. CIR was measured by delayed-type hypersensitivity skin test response (DTH) against seven recall antigens expressed as the total number of positive responses and sum of diameters of all positive responses. RESULTS: No independent or interactive effect of enriched foods was observed. Therefore, exercise (groups A + C) was compared with no exercise (groups B + D). Nonexercising subjects showed an average decline of 0.5 responses compared with an unchanged responsiveness among exercising subjects (difference = 0.5, 95% CI: 0.04-0.89, P = 0.03 adjusted for baseline DTH, activity level, and micronutrient status). Nonexercising subjects had a larger decline in the sum of diameters of all positive responses than exercising subjects but the difference did not reach significance (adjusted difference = 2.1 mm, 95% CI:-1.0-4.8). CONCLUSION: Exercise may prevent or slow the age-related decline in immune response. Micronutrient enriched foods showed no effect. As infectious diseases can have debilitating or even fatal consequences for the elderly, prevention of the age-related decline in CIR could significantly improve their quality of life.

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PubMed2000

Dietary supplements and physical exercise affecting bone and body composition in frail elderly persons.

OBJECTIVES: This study determined the effect of enriched foods and all-around physical exercise on bone and body composition in frail elderly persons. METHODS: A 17-week randomized, controlled intervention trial, following a 2 x 2 factorial design--(1) enriched foods, (2) exercise, (3) both, or (4) neither--was performed in 143 frail elderly persons (aged 78.6 +/- 5.6 years). Foods were enriched with multiple micronutrients; exercises focused on skill training, including strength, endurance, coordination, and flexibility. Main outcome parameters were bone and body composition. RESULTS: Exercise preserved lean mass (mean difference between exercisers and non-exercisers: 0.5 kg +/- 1.2 kg; P < .02). Groups receiving enriched food had slightly increased bone mineral density (+0.4%), bone mass (+0.6%), and bone calcium (+0.6%) compared with groups receiving non-enriched foods, in whom small decreases of 0.1%, 0.2%, and 0.4%, respectively, were found. These groups differed in bone mineral density (0.006 +/- 0.020 g/cm2; P = .08), total bone mass (19 +/- g; P = .04), and bone calcium (8 +/- 21 g; P = .03). CONCLUSIONS: Foods containing a physiologic dose of micronutrients slightly increased bone density, mass, and calcium, whereas moderately intense exercise preserved lean body mass in frail elderly persons.

Absorptiometry, Photon↗
PubMed1999

Comparison of native and contrast-enhanced harmonic echocardiography for visualization of left ventricular endocardial border.

Our study was designed to compare the utility of fundamental and second harmonic imaging (SH) for visualization of the left ventricular (LV) endocardial border. SH is a new imaging modality using nonlinear acoustic response, which may provide better endocardial border delineation. Standard apical views were studied in 42 patients using fundamental frequency (FF), SH without contrast (1.6- to 1.8-MHz and 2.1- to 2.5-MHz transmission frequencies), and SH after an intravenous injection of 2.5 g of Levovist. The quality of endocardial delineation in 16 standard segments was scored from 0 to 2. The endocardial visualization index was calculated as a mean of the scores. SH with and without contrast significantly improved LV endocardial border detection (endocardial visualization index 1.25+/-0.53, 1.64+/-0.67, 1.55+/-0.69, and 1.73+/-0.28 for fundamental, lower, and higher frequency harmonic and contrast-harmonic mode, respectively, p <0.005). Improvement was found in all LV segments. The number of invisible segments decreased from 142 (FF) to 54, 112, and 61 (in lower, higher, and contrast SH mode, respectively, p <0.001). Endocardial delineation in the apical segments using SH was optimal after contrast injection. In the basal LV area, contrast-enhanced images were less informative because of signal attenuation. Thus, SH significantly improves visualization of the LV endocardial border. Contrast enhancement with Levovist improves imaging of the apical segments but has no additional advantage in the basal segments. SH emerges as first-line modality for studies of LV function.

Contrast Media↗
PubMed1999

Noninvasive measurement of the hydrostatic pressure in a fluid-filled cavity based on the disappearance time of micrometer-sized free gas bubbles.

A new method for noninvasive pressure measurement, based on the disappearance time of micrometer-sized free gas bubbles, is described in this article. An ultrasound (US) contrast agent, consisting of encapsulated gas bubbles, is used as a vehicle to transport the free gas bubbles to the desired region where the pressure is to be measured. The small free gas bubbles are generated at the region of interest (e.g., heart chambers), from the encapsulated gas bubbles, which rupture when they are exposed to a single low-frequency (e.g., 0.5 MHz), high acoustic amplitude US burst. The released gas bubbles persist for only a few ms and dissolve in the liquid, depending on their size, the gas, the liquid characteristics and ambient parameters such as temperature, gas concentration and pressure. A pressure-disappearance time relationship is determined using a sequence of high-frequency (e.g., 10 MHz), low acoustic amplitude US pulses. From in vitro experiments, reproducible results show a significant difference between the disappearance time of the bubbles as function of the local pressure, resulting in a quicker disappearance of the bubble for higher values of the pressure. The sensitivity of the method to small pressure changes (50 mmHg) is demonstrated.

Contrast Media↗
PubMed1999

Impaired sensory functioning in elders: the relation with its potential determinants and nutritional intake.

This study assessed the relation of an impaired taste and smell perception with (a) potential determinants and (b) nutritional intake and status in elderly people. Determinants examined were age, gender, functional category (institutionalized vs independently living), dental state, illnesses, smoking behavior, drug usage, and saliva excretion and composition. Nutritional intake and status were measured by an "appetite and hunger" questionnaire, a food frequency questionnaire, and body mass index (BMI). In order to have access to a large heterogeneous group, two different categories of elderly people were studied. We enrolled independently living elders (n=89) assumed to have a relatively good taste and smell perception, and institutionalized elders (n=67) with a potential poorer taste and smell perception. Scores at the smell identification (range: 0-10) and taste perception (range: 0-4) test were, respectively, 5.7 (independently living) versus 3.5 (institutionalized); p < .0001 and 3.3 versus 3.0; p < .05. Correlation between smell test scores and outcomes of the "appetite and hunger" questionnaire ranged from r: .19 to .50; p values < .05. There was, however, no clear correlation of any sensory outcome with energy and food intake, nor with BMI. Regression analyses revealed that age and the functional category were the most important determinants of the scores on the taste perception and smell identification tests. It is concluded that a poor performance on sensory tests is related to a poor appetite but not necessarily to low energy intake or low BMI. Age-related factors and smoking are important determinants of impaired sensory functioning.

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PubMed1999

Functional biochemical and nutrient indices in frail elderly people are partly affected by dietary supplements but not by exercise.

A decline in dietary intake due to inactivity and, consequently, development of a suboptimal nutritional status is a major problem in frail elderly people. However, benefits of micronutrient supplementation, all-round physical exercise or a combination of both on functional biochemical and hematologic indicators of nutritional and health status in frail elderly subjects have not been tested thoroughly. A 17-wk randomized controlled trial was performed in 145 free-living frail elderly people (43 men, 102 women, mean age, 78 +/- 5.7 y). Based on a 2 x 2 factorial design, subjects were assigned to one of the following: 1) nutrient-dense foods, 2) exercise, 3) both (1) and (2) or 4) a control group. Foods were enriched with micronutrients, frequently characterized as deficient [25-100% of the recommended daily allowance (RDA)] in elderly people. Exercises focused on skill training, including strength, endurance, coordination and flexibility. Dietary intake, blood vitamin levels and nutritional and health indicators, including (pre)albumin, ferritin, transferrin, C-reactive protein, hemoglobin and lymphocytes were measured. At baseline, 28% of the total population had an energy intake below 6.3 MJ, up to a maximum of 93% having vitamin intakes below two thirds of the Dutch RDA. Individual deficiencies in blood at baseline ranged from 3% for erythrocyte glutathione reductase-alpha to 39% for 25-hydroxy vitamin D and 42% for vitamin B-12. These were corrected after 17 wk in the two groups receiving the nutrient-dense foods, whereas no significant changes were observed in the control or exercise group. Biochemical and hematologic indicators at baseline were within the reference ranges (mean albumin, 46 g/L; prealbumin, 0.25 g/L; hemoglobin, 8.6 mmol/L) and were not affected by any of the interventions. The long-term protective effects of nutrient supplementation and exercise, by maintaining optimal nutrient levels and thereby reducing the initial chance of developing critical biochemical values, require further investigation. Other indicative functional variables for suboptimal nutritional status, in addition to those currently selected, should also be explored.

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