Accumulation and transport of cadmium by tolerant and susceptible strains of Mycobacterium scrofulaceum.

Cadmium accumulation and transport were studied in two strains of Mycobacterium scrofulaceum differing in their susceptibility to Cd2+ toxicity. A 10-fold excess of either Zn2+ or Mn2+ partially antagonized inhibition of growth by Cd2+. 109Cd2+ uptake by both the tolerant and susceptible strains was temperature dependent and inhibited by a 10-fold excess of either Zn2+ or Mn2+. There were no significant differences in either the kinetics of 109Cd2+ uptake or the retention of accumulated 109Cd2+ by the tolerant and susceptible strains. Both tolerant and susceptible strains removed most of the cadmium from the culture medium, but significantly more was removed by cells of the tolerant strain. Most of the accumulated Cd2+ in the tolerant strain was in the particulate fraction, rather than in the soluble fraction. Intracellular accumulated Cd2+ was primarily in the soluble fraction of the susceptible strain. Increased Cd2+ in culture medium resulted in decreased Mn2+ and Zn2+ in cells of the susceptible strain but did not reduce the Mn2+ and Zn2+ content of cells of the tolerant strain.     

Cardiac MRI in Congenital Heart Disease – Our Experience

A significant recent advance that has occurred world over in the continuously evolving field of Magnetic Resonance Imaging (MRI) practice is the introduction of Cardiac applications. Cardiac MRI has moved to the centre stage of clinical management strategy by non-invasively imaging the structure as well as function of the heart. It has a wide range of specific applications such as delineation of morphological anatomy, quantification of flow and pressure across cardiac valve dysfunction, evaluation of myocardial function, assessment of infarcts, mapping coronary arteries and so on. Evaluation of congenital heart disease (CHD) is an important application of Cardiac MRI since the morphological details of chambers, septum, defects and anomalous connections are depicted accurately. Besides, flow information across valves, chambers, outflow tracts and shunts are also provided. This article describes our experience in the use of cardiac MRI in congenital heart disease.Key Words: Cardiac MRI, Congenital heart disease, Cyanotic and Acyanotic heart disease     

Ultrasound for the early diagnosis of clinically suspected scaphoid fracture

PURPOSE: To test the ability of ultrasound to diagnose clinically suspected occult scaphoid fractures. METHODS: Eighteen wrists in 18 patients with an average age of 35 years (range, 10-77 years) were seen in the emergency room, each with a single traumatic wrist injury, snuffbox tenderness, swelling, and a negative wrist x-ray result. They were evaluated in this prospective, blind, controlled study by physical examination, x-ray, and high-resolution ultrasound. One hand surgeon performed the examination, and ultrasounds were read by a musculoskeletal radiologist. Patients were immobilized in a thumb spica splint and then seen in the office 1 to 14 days after the emergency room visit, at which time a repeat physical examination, wrist x-ray, and the single investigative ultrasound were done using the opposite wrist as a control. All patients were immobilized and evaluated until symptoms resolved or x-ray showed scaphoid fracture site resorption or callus, in which case they were kept immobilized until healed. RESULTS: Ultrasound identified correctly 7 of 9 cases that were eventually positive for scaphoid fracture on plain x-ray. Ultrasound was read correctly as negative in 8 of 9 x-ray-negative cases; this was statistically significant. The 1 false-positive case had radioscaphoid arthrosis and radial wrist swelling. Sensitivity was 78% and specificity was 89%. The positive predictive value was 88% and negative predictive value was 80%. CONCLUSIONS: We recommend that high-frequency ultrasound be used to investigate occult suspected scaphoid fractures because of its ability to allow early diagnosis and to eliminate the need for a more invasive or expensive diagnostic test in most cases.     

Xanthophylls and alpha-tocopherol decrease UVB-induced lipid peroxidation and stress signaling in human lens epithelial cells

Epidemiological studies suggest that consumption of vegetables rich in the xanthophylls lutein (LUT) and zeaxanthin (ZEA) reduces the risk for developing age-related cataract, a leading cause of vision loss. Although LUT and ZEA are the only dietary carotenoids present in the lens, direct evidence for their photoprotective effect in this organ is not available. The present study examined the effects of xanthophylls and alpha-tocopherol (alpha-TC) on lipid peroxidation and the mitogen-activated stress signaling pathways in human lens epithelial (HLE) cells following ultraviolet B light (UVB) irradiation. When presented with LUT, ZEA, astaxanthin (AST), and alpha-TC as methyl-beta-cyclodextrin complexes, HLE cells accumulated the lipophiles in a concentration- and time-dependent manner with uptake of LUT exceeding that of ZEA and AST. Pretreatment of cultures with either 2 micromol/L xanthophyll or 10 micromol/L alpha-TC for 4 h before exposure to 300 J/m(2) UVB radiation decreased lipid peroxidation by 47-57% compared with UVB-treated control HLE cells. Pretreatment with the xanthophylls and alpha-TC also inhibited UVB-induced activation of c-JUN NH(2)-terminal kinase (JNK) and p38 by 50-60 and 25-32%, respectively. There was substantial inhibition of UVB-induced JNK and p38 activation for cells containing <0.20 and approximately 0.30 nmol xanthophylls/mg, respectively, whereas >2.3 nmol alpha-TC/mg protein was required to significantly decrease UVB-induced stress signaling. These data suggest that xanthophylls are more potent than alpha-TC for protecting human lens epithelial cells against UVB insult.     

Spatially modulated illumination microscopy: online visualization of intensity distribution and prediction of nanometer precision of axial distance measurements by computer simulations

During the last years, measurements considerably beyond the conventional "Abbe-Limit" of optical resolution in far field light microscopy were realized by several light microscopical approaches. Point spread function (PSF) engineering, spectral precision distance microscopy (SPDM), and related methods were used to demonstrate the feasibility of such measurements. SPDM allows the measurement of position and multiple distances between point-like fluorescent objects of different spectral signatures far below the optical resolution criterion as defined by the full width at half maximum of the PSF. Here, we report a software method to obtain online visualization of light distribution in the lateral and axial direction of any object detected in a spatially modulated illumination (SMI) microscope. This strongly facilitates routine application of SMI microscopy. The software was developed using Microsoft Visual C++ running on Windows NT. Furthermore, some aspects of the theoretical limits of the SPDM method were studied by virtual microscopy. For the case of SMI microscopy the precision of axial distance measurements was studied, taking into account photon statistics and image analysis procedures. The results indicate that even under low fluorescence intensity conditions typical for biological structure research, precise distance measurements in the nanometer range can be determined, and that axial distances in the order of 40 nm are detectable with such precision.     

Progression of large artery structural and functional alterations in Type I diabetes

Aims/hypothesis. Type I (insulin-dependent) diabetes mellitus is accompanied by reduced arterial distensibility and increased arterial wall thickness even in normotensive subjects with no micro-macrovascular complications. It is not known whether, and how fast, these subclinical markers of vascular damage develop over time. Methods. We measured arterial wall distensibility in radial, common carotid artery and abdominal aorta in 60 normotensive patients (aged 35.0 ± 1.2 years, means ± SE) with Type I diabetes with no microvascular or macrovascular complications and in 20 healthy control subjects matched for age. Arterial distensibility was determined by continuous measurements of arterial diameter through echotracking techniques and by using either the Langewouters (radial artery) or the Reneman formula (carotid artery and aorta). The same echotracking techniques allowed us to ascertain the radial and carotid artery wall thickness. Data were collected before and after 23 ± 1 months. Results. In the first study, carotid artery distensibility was similar but radial artey and aortic distensibility was less (p < 0.01) in patients with diabetes than in control subjects (–39 % and 25 % respectively). This was accompanied by an increase (p < 0.01) in both radial (42 %) and carotid artery wall thickness (46 %). After 23 ± 1 months diabetic subjects showed a further reduction in arterial distensibility (radial–12 %, p < 0.05; carotid–8 %, NS; aorta–20 % p < 0.05) and an increase in arterial wall thickness (radial + 15 %; carotid 14 %, p < 0,05). No change in distensibility and wall thickness values occurred in control subjects. Conclusion/interpretation. The early reduction in arterial distensibility and increase in arterial wall thickness characterizing uncomplicated normotensive Type I diabetes patients shows a measurable worsening over the short term. [Diabetologia (2001) 44: 203–208] Received: 20 May 2000 and in revised form: 20 September 2000     

Safety assessment of recombinant green fluorescent protein orally administered to weaned rats

Several proposed biotechnological applications of green fluorescent protein (GFP) are likely to result in its introduction into the food supply of domestic animals and humans. We fed pure GFP and diets containing transgenic canola expressing GFP to young male rats for 26 d to evaluate the potential toxicity and allergenicity of GFP. Animals (n = 8 per group) were fed either AIN-93G (control), control diet plus 1.0 mg of purified GFP daily, modified control diet with 200 g/kg canola (Brassica rapa cv Westar), or control diet with 200 g/kg transgenic canola containing one of two levels of GFP. Ingestion of GFP did not affect growth, food intake, relative weight of intestine or other organs, or activities of hepatic enzymes in serum. Comparison of the amino acid sequence of GFP to known food allergens revealed that the greatest number of consecutive amino acid matches between GFP and any food allergen was four, suggesting the absence of common allergen epitopes. Moreover, GFP was rapidly degraded during simulated gastric digestion. These data indicate that GFP is a low allergenicity risk and provide preliminary indications that GFP is not likely to represent a health risk.     

Nutrition: a reservoir for integrative science

In the last twenty years, powerful new molecular techniques were introduced that made it possible to advance knowledge in human biology using a reductionist approach. Now, the need for scientists to deal with complexity should drive a movement toward an integrationist approach to science. We propose that nutritional science is one of the best reservoirs for this approach. The American Society for Nutritional Sciences can play an important role by developing and delivering a cogent message that convinces the scientific establishment that nutrition fills this valuable niche. The society must develop a comprehensive strategy to develop our image as the reservoir for life sciences integration. Our efforts can start with our national meeting and publications, with the research initiatives for which we advocate, with our graduate training programs and with the public relations image we project for ourselves. Defining the image and future directions of nutrition as the discipline that can integrate scientific knowledge from the cell and molecule to the whole body and beyond to populations can be the most important task that our society undertakes. If we do not effectively meet this challenge, a golden opportunity will pass to others and nutritional scientists will be left to follow them.