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At least 793 records · Page 44Linked to original sources
PubMed2002

Polymerisation of chemically cross-linked actin:thymosin beta(4) complex to filamentous actin: alteration in helical parameters and visualisation of thymosin beta(4) binding on F-actin.

The beta-thymosins are intracellular monomeric (G-)actin sequestering proteins forming 1:1 complexes with G-actin. Here, we analysed the interaction of thymosin beta(4) with F-actin. Thymosin beta(4) at 200 microM was chemically cross-linked to F-actin. In the presence of phalloidin, the chemically cross-linked actin:thymosin beta(4) complex was incorporated into F-actin. These mixed filaments were of normal appearance when inspected by conventional transmission electron microscopy after negative staining. We purified the chemically cross-linked actin:thymosin beta(4) complex, which polymerised only when phalloidin and the gelsolin:2-actin complex were present simultaneously. Using scanning transmission electron microscopy, the mass-per-length of control and actin:thymosin beta(4) filaments was found to be 16.0(+/-0.8) kDa/nm and 18.0(+/-0.9) kDa/nm, respectively, indicating an increase in subunit mass of 5.4 kDa. Analysis of the helical parameters revealed an increase of the crossover spacing of the two right-handed long-pitch helical strands from 36.0 to 40.5 nm. Difference map analysis of 3-D helical reconstruction of control and actin:thymosin beta(4) filaments yielded an elongated extra mass. Qualitatively, the overall size and shape of the difference mass were compatible with published data of the atomic structure of thymosin beta(4). The deduced binding sites of thymosin beta(4) to actin were in agreement with those identified previously. However, parts of the difference map might represent subtle conformational changes of both proteins occurring upon complex formation.

Actins↗
PubMed1999

Long-term effect of placental type on anthropometrical and psychological traits among monozygotic twins: a follow up study.

The long-term effect of differences in placentation in MZ twins is a controversial subject. An effect has been clearly established for birth weight but data on psychological traits are still under debate. We studied 20 pairs of monochorionic MZ (MC MZ) and 24 pairs of dichorionic MZ (DC MZ) twins. A chorion effect was observed for Block Design (WISC-R) confirming a previous report: MC MZ co-twins were more similar that DC MZ co-twins. For anthropometrical measures, an expected effect in the opposite direction was found. No chorion effect was significant for the other variables. A follow up was undertaken 3 years later using cognitive, national academic evaluations, and personality variables. The sample included 16 pairs of MC MZ and 22 pairs of DC MZ twins. Again a chorion effect was observed on anthropometrical variables but results on the Block Design were not replicated. However, the MC MZ co-twins were more similar than the DC MZ co-twins for two other cognitive variables: Perceptual Organization Index from the WISC-R and Global Visualisation from a Belgian reasoning test. Among the personality variables only one was sensitive to a chorion effect. The discussion focuses on the need for larger samples to achieve adequate power in statistical comparisons.

Adolescent↗
PubMed2002

Visualising microglial activation in vivo.

In health, microglia reside as quiescent guardian cells ubiquitously, but isolated without any cell-cell contacts amongst themselves, throughout the normal CNS. In disease, however, they act as swift "sensors" for pathological events, including subtle ones without any obvious structural damage. Once activated, microglia show a territorially highly restricted involvement in the disease process. This property, peculiar to microglia, confers to them diagnostic value for the accurate spatial localisation of any active disease process, acute or chronic. In the brain, the isoquinoline PK11195, a ligand for the peripheral benzodiazepine binding site (PBBS), binds with relative cellular selectivity to activated, but not resting, microglia. Labelled with carbon-11, (R)-PK11195 and positron emission tomography (PET) have been used for the study of inflammatory and neurodegenerative brain disease in vivo. These studies demonstrate meaningfully distributed patterns of regional [(11)C](R)-PK11195 signal increases that correlate with clinically observed loss of function. Increased [(11)C](R)-PK11195 binding closely mirrors the histologically well-described activation of microglia in the penumbra of focal lesions, as well as in the distant, anterograde, and retrograde projection areas of the lesioned neural pathway. There is also some indication that in long-standing alterations of a neural network with persistent abnormal input, additional signals of glial activation may also emerge in transsynaptic areas. These data suggest that the injured brain is less static than commonly thought and shows subtle glial responses even in macroanatomically stable appearing regions. This implies that glial activation is not solely a sign of tissue destruction, but possibly of disease-induced adaptation or plasticity as well. Whilst further technological and methodological advances are necessary to achieve routine clinical value and feasibility, a systematic attempt to image glial cells in vivo is likely to furnish valuable information on the cellular pathology of CNS diseases and their progression within the distributed neural architecture of the brain.

Animals↗
PubMedDate not supplied

[LithoRisk: A software for calculating and visualising nephrolithiasis risk profiles].

BACKGROUND: The pathogenesis of nephrolithiasis, based on the anomalies of the urinary environment, demands metabolic and physicochemical assessment for the medical management of patients. Standard metabolic protocols include the measurement of pertinent urine chemistry values and the calculation of the extent of saturation in stone-forming salts. However, patients are often given fragmentary and hard-to-consult reports and so this weakens the strength of the therapeutic recommendations. This paper introduces LithoRisk, a dedicated software which graphically represents risk profiles of stone formation, including the extent of saturation. METHODS: LithoRisk uses the results of 24-h urine chemistry values widely available in hospital laboratories, i.e., sodium, potassium, calcium, magnesium, ammonia, phosphate, sulphate, citrate, oxalate, chloride, pH and urine volume. Uric acid and cystine are optional. The relative supersaturation (beta), estimated according to our own ab initio calculation, is given in a scale whereby beta=1 is saturation, beta < 1 under - and beta > 1 oversaturation. LithoRisk is available as a CD-ROM and can be loaded on Windows 95/98/Millenium/XP. Colour or laser printers are suitable for printed records. RESULTS: LithoRisk is easily loaded on any PC by following video instructions. Once the loading of the program is completed a grey icon LithoRisk appears on the Desktop. The program can be opened by clicking twice on the icon. The patients data page first appears on the screen and is followed by the evaluation page for the input of variables. This generates the graph representing the diagnostic lithorisk profile, which is drawn as a line connecting different values, according to a specific scale and related to an arbitrary normal point. Normal values are shown as green lines, whereas abnormal ones are red. The beta values for calcium oxalate and phosphate, uric acid and cystine are instantaneously calculated and reported on the graph. CONCLUSIONS: LithoRisk produces a complete, unique and easy to understand report that includes all relevant parameters, it therefore expresses the overall risk of stone formation. It requires the results of chemistry tests done on the same 24-h urine collection, and carried out using suitable preservatives. If the tests for unusual parameters, i.e. sulphate and ammonia, are unavailable, one can use default values with minimal alterations on beta calculation. In spite of being arbitrary, the normal thresholds values are based on widely accepted literature data. The risk profile recognises the most relevant abnormalities and enables the establishment of individual targets aimed at reducing the propensity towards stone formation.

Humans↗
PubMed1997

Insufficient and absent acoustic temporal bone window: potential and limitations of transcranial contrast-enhanced color-coded sonography and contrast-enhanced power-based sonography.

The aim of this study was to investigate the diagnostic potential of contrast-enhanced transcranial color-coded sonography (CE-TCCS) and contrast-enhanced transcranial power-based sonography (CE-TPS) in patients with insufficient or absent acoustic bone windows (IABW). Due to temporal bone thickness, the basal cerebral circulation could not be insonated in 21 of 172 patients using unenhanced transcranial color-coded real-time sonography (TCCS) and transcranial power-based sonography. Additional CE-TCCS and CE-TPS were performed after application of 400 mg/ml galactose microbubble suspension. In both modalities, the use of echo-contrast agents allowed visualisation of the first segment of the middle cerebral artery (MCA) in all patients. The A1 segment of the anterior cerebral artery (67% in CE-TCCS; 81% in CE-TPS), P1 segment of the posterior cerebral artery (71% in CE-TCCS; 76% in CE-TPS) and the basilar artery (48% in CE-TCCS; 67% in CE-TPS) were depictable in the majority of the examinations. The M3 (5% in CE-TCCS; 33% in CE-TPS; p < 0.05), P2 (24% in CE-TCCS; 71% in CE-TPS; p < 0.005), P3 segments (0% in CE-TCCS; 43% in CE-TPS; p < 0.005) and the posterior communicating artery (5% in CE-TCCS; 33% in CE-TPS; p < 0.05) were detected in a significantly greater proportion of subjects using power Doppler. In conclusion, CE-TCCS and CE-TPS appear to be sensitive ultrasonic tools that provide reliable data regarding the basal cerebral circulation in patients with IABW. Furthermore, CE-TPS offers advantages over CE-TSSC in the identification of small-caliber arteries and vessels that run at unfavorable angels to the ultrasound beam. Both methods can overcome hyperostosis of the skull that is a major hindrance in transcranial ultrasonography, and may be helpful in the diagnosis of occlusive diseases of intracranial vessels.

Adult↗
PubMed1994

Consideration of time-dose-patterns in 3D treatment planning. An approach towards 4D treatment planning.

PURPOSE: The rendering of the 3D dose distribution together with anatomical information and the volumes of interest (VoI) is essential to get a visual impression of the treatment plan and to find modifications for the optimization of the dose distribution. The integration of biological effects into the 3D treatment planning is of interest for the assessment of different time-dose patterns. MATERIALS AND METHODS: One way of taking into account biological data is to relate the physical dose in critical structures to the corresponding tolerance dose. For that purpose the applied time-dose pattern has to be converted into the standard fractionation scheme being the basis of the tolerance dose. Generally any model can be used for these calculations. Here a modified incomplete repair model is used to calculate the relative biological dose distribution (RBD). The visualization of these biologically isoeffective dose distributions can be performed in the same manner as the physical dose so that the physical and biological dose distributions can by displayed side by side. As this is equivalent to introducing the time as a fourth dimension into 3D treatment planning this is called 4D treatment planning. RESULTS: From 3D dose matrices the biologically isoeffective dose distributions are calculated for the organs at risk. The changes introduced by different time-dose patterns are displayed using the same technique as for rendering 3D treatment plans. The visualisation of the three-dimensional biological dose distributions is shown by means of a patient with an oesophagus carcinoma. The RBD related to the tolerance dose of the organs at risk is displayed for different time-dose fractionations. CONCLUSION: The RBD distribution on a 3D treatment plan can be displayed in the same mode as the physical dose distribution. This offers additionally valuable information in a 3D treatment planning process about the dose to critical organs and the influence of different time-dose patterns.

Color↗
PubMed2002

Insights into the sites of X ray and neutron induced chromosomal aberrations in human lymphocytes using COBRA-MFISH.

A multi-colour fluorescence in situ hybridisation (MFISH) assay has been developed, for simultaneous visualisation of all human chromosomes in 24 different colours. This assay is based on the simultaneous use of combinatorial labelling and ratio labelling, the so called combined binary ratio labelling (COBRA). This technique is used to study the spectra of chromosomal exchanges induced by X ray and neutrons in human lymphocytes. With X rays the dose-effect relationships for both dicentrics and translocations were linear-quadratic, whereas with neutrons these were linear. Among aberrant cells, average estimates of the minimum number of breaks was higher for neutrons than for X rays. Moreover, the induced chromosomal exchange patterns were more complex following neutron irradiation in comparison with X rays. COBRA-MFISH was found to have a greater resolving power over partial labelling for the accurate detection of complex translocations and insertions. With neutrons the frequencies of both were higher than those induced by X rays, and their relative proportions to the total frequencies were independent of dose. These data suggest insertions can be used as the 'signature' of high LET radiation.

Cells, Cultured↗
PubMed2002

Does fetal tracheal fluid flow during fetal breathing movements change before the onset of labour?

OBJECTIVE: To examine changes in intra-tracheal fluid flow parameters during fetal breathing movements throughout the second half of pregnancy in the normally developing human fetus. DESIGN: Prospective cross-sectional study. SETTING: Fetal medicine unit at the Charité University Hospital in Berlin. METHODS: Assessment of tracheal fluid flow was attempted in 340 healthy fetuses (GA 20-40 weeks) in which fetal breathing movements were seen by B-mode scan. Colour Doppler was applied to visualise the tracheal fluid flow, followed by spectral Doppler to record the velocity waveforms. The records of 53 fetuses divided into five gestational age groups (20-23, 24-27, 28-31, 32-35 and 36-40 weeks of gestation) containing 40 or more continuous breathing cycles (inspiration and expiration) were considered for analysis. Only regular breathing phases were examined and the volume obtained by integration of the tracheal fluid flow displaced during fetal breathing movements was calculated. RESULTS: The intra-tracheal flow volume moved during inspiration (Vi) and expiration (Ve) increased until 36 weeks of gestation after which there was a flattening until term. This suggests either a reduction of lung liquid production or a diminished lung liquid volume. The median difference between Vi and Ve was positive in the first four age groups and negative in the last one suggesting that, in mature fetuses, the effect of fetal breathing movements no longer results in an influx. CONCLUSIONS: Our data demonstrate a modification in fetal behaviour that manifests itself during the last four weeks before birth and has the potential to reduce lung liquid volume.

Body Fluids↗
PubMed1992

Immunoperoxidase labelling of albumin at the endothelial cell surface of frog mesenteric microvessels.

Albumin was visualised at the endothelial cell surface of perfused frog mesenteric microvessels using immuno-peroxidase labelling. Vessels in the mesenteries of pithed frogs were washed free of blood and then perfused with frog Ringer solutions containing bovine serum albumin (BSA) at a concentration of 20 mg BSA ml-1, followed by a brief Ringer flush to remove excess albumin from the vessel lumen. The tissues were fixed in 1% glutaraldehyde and a double antibody labelling technique used to identify albumin within the tissue. A dense layer of peroxidase reaction product was seen, which extended 25-50 nm into the vessel lumen. It appeared as a continuous layer lining the luminal openings of interendothelial cell clefts and vesicles open to the luminal cell surface. In some vessels a more irregular layer of peroxidase labelled albumin was seen extending 150 to 200 nm into the vessel lumen, whilst in others clumps of peroxidase labelled albumin were also seen within the vessel lumen. These data offer direct evidence that BSA does interact with the endothelial cell surface of perfused frog mesenteric microvessels but suggest that a proportion is loosley or non-specifically bound to the cell surface and can be removed by a brief Ringer flush. The remainder appears more tightly bound and resistant to Ringer flush.

Animals↗
PubMed1995

Rapid identification of mycobacteria from AIDS patients by capillary electrophoretic profiling of amplified SOD gene.

Aim-Rapid differentiation of mycobacterial species at the genomic level.Methods-The manganese superoxide dismutase (SOD) gene (464 bp) and 16SrRNA (353 bp) from 104 isolates (18 species) of mycobacteria were amplified using polymerase chain reaction (PCR). Products were sequenced and a phenogram of SOD sequences derived. PCR products of SOD gene were digested with HaeIII, and restriction fragment profiles visualised using capillary electrophoresis.Results-Novel SOD sequences were found for M szulgai, M marinum, M phlei, M smegmatis, M chelonei, M paratuberculosis, M malmoense, M intracellulare serotype 7, M intracellulare serotype 18, and M celatum types 1, 2, and 3. Phylogenetic analysis indicated that 18 of 19 species studied had 8-29% interspecies and <6% intraspecies sequence diversity in the SOD gene. No consistent differences were detected between AIDS and non-AIDS isolates. M paratuberculosis showed a unique SOD sequence with a 1.1% (SD 0.5%) diversity from M avium. Capillary electrophoresis profiles were able to differentiate 16 of 18 species within 24 hours.Conclusions-A phenogram of SOD sequences clearly delineated all mycobacterial species and showed two distinct clusters, fast growing species, and the M avium complex (MAC). Within the MAC, M avium (five types), M intracellulare (five types), M scrofulaceum (two types), and M paratuberculosis (one type) could be demonstrated. Phylogenetic diversity of M celatum from MAC, previously suggested by 16SrRNA data, was confirmed. This simple and rapid method for DNA extraction, in conjunction with capillary electrophoresis of SOD restriction fragments, allows rapid identification of mycobacterial isolates.

Journal Article↗
PubMed1995

[2-dimensional mapping and retinal and papillary microcirculation using scanning laser Doppler flowmetry].

PURPOSE: To present clinical applications of a new non-invasive method imaging in a high-definition the topography of perfused retinal vessels. METHOD: By a combination of a laser Doppler flowmeter with a scanning laser system the perfusion of the retina and the optic nerve head is visualized and quantified. The principles of measuring blood flow by Laser Doppler Flowmetry are based on the optical Doppler effect: laser light scattered by a moving particle is shifted in frequency by an amount delta f. Our data acquisition and evaluation system is a modified laser scanning tomograph. The technical data are: retinal area of measurement 2.7 mm x 0.7 mm, 10 degree-field with 256 points x 64 lines, measurement accuracy 10 microns, wavelength 670 nm and 790 nm, light power 100 microW, data acquisition time 2,048 s. Every line is scanned 128 times by a line-sampling rate of 4,000 Hz. By performing a discrete Fast Fourier Transformation over 128 intensities of each retinal point the laser Doppler-shift is calculated for each retinal point. With these data a 2-D map with 256 x 64 points of the retinal perfusion is created. The brightness of the picture-point is coded by the value of the Doppler shift. We estimated the reliability and the validity of the method. Perfusion-pictures of the superficial retinal layer and in the optic nerve head were presented. RESULTS: The reliability-coefficients r1 of "Flow", "Volume" and "Velocity" were 0.85, 0.83, and 0.85 respectively. The blood flow measurements by the presented method ("Scanning Laser Doppler Flowmetry") in an artificial capillary gave a linear relationship (r-value 0.973, p < 0.00001) between defined blood velocities and the measured blood flow. By the confocal technique, dependent on the focus, capillaries of the retinal superficial vasculature of the optic nerve head became visible with a high resolution. Off line the blood flow of areas of 110 microns x 110 microns were calculated in terms of laser Doppler flowmetry. CONCLUSION: "Scanning Laser Doppler Flowmetry" facilitates the visualisation of perfused retinal capillaries and vessels in high resolution. The representation of the function of the retinal circulation by SLDF leads to an image similar to the anatomical situation. The 2-dimensional mapping of local blood flow leads to a physiological picture of the retinal perfusion with visible vessels and capillaries.

Adult↗
PubMed2002

A simple method for serving Web hypermaps with dynamic database drill-down.

BACKGROUND: HealthCyberMap http://healthcybermap.semanticweb.org aims at mapping parts of health information cyberspace in novel ways to deliver a semantically superior user experience. This is achieved through "intelligent" categorisation and interactive hypermedia visualisation of health resources using metadata, clinical codes and GIS. HealthCyberMap is an ArcView 3.1 project. WebView, the Internet extension to ArcView, publishes HealthCyberMap ArcView Views as Web client-side imagemaps. The basic WebView set-up does not support any GIS database connection, and published Web maps become disconnected from the original project. A dedicated Internet map server would be the best way to serve HealthCyberMap database-driven interactive Web maps, but is an expensive and complex solution to acquire, run and maintain. This paper describes HealthCyberMap simple, low-cost method for "patching" WebView to serve hypermaps with dynamic database drill-down functionality on the Web. RESULTS: The proposed solution is currently used for publishing HealthCyberMap GIS-generated navigational information maps on the Web while maintaining their links with the underlying resource metadata base. CONCLUSION: The authors believe their map serving approach as adopted in HealthCyberMap has been very successful, especially in cases when only map attribute data change without a corresponding effect on map appearance. It should be also possible to use the same solution to publish other interactive GIS-driven maps on the Web, e.g., maps of real world health problems.

Journal Article↗
PubMed1998

Nucleotide-dependent structural changes in dimeric NCD molecules complexed to microtubules.

Complexes consisting of motor domains of the kinesin-like protein ncd bound to reassembled brain microtubules were visualised using cryoelectron microscopy and helical image reconstruction. Different nucleotide-associated states of a dimeric construct (NDelta295-700) of ncd were analysed to reveal ADP-containing, AMP.PNP-containing and empty (rigor) conformations. In these three states, each thought to mimic a different stage in ATP turnover, the double-headed motors attach to the microtubules by one head only, with the free head tethered in relatively fixed positions. The three structures differ both in the way the attached heads interact with tubulin and in the position of the tethered heads. In the strongly binding rigor and AMP.PNP (ATP-like) states, the attached head makes close contact with both subunits of a tubulin heterodimer. In the weakly bound ADP state, the contact made by the attached head with the monomer closer to the plus end appears to be more loose. Also, in the ATP-like state, the free head tilts nearer to the plus end than in the other two states. The data argue against model mechanisms in which a conformational change in the bound head guides the free head closer to its next binding site; on the contrary, the transition from ADP-filled via rigor to the AMP.PNP (ATP-like) state of the bound head produces a small motion of the free head in the counter-productive direction. However, the observation that the tethered head points towards the minus end, in all three states, is consistent with the idea that the relative arrangement of the heads in a dimer is a major determinant of directionality.

Adenosine Diphosphate↗
PubMed1999

Scintigraphy for evaluating early aspiration after oral feeding in patients receiving prolonged ventilation via tracheostomy.

OBJECTIVE: In tracheotomised patients the incidence of aspiration is difficult to determine because investigators often apply different criteria. In this study a scintigraphic method was used to visualise feeding aspiration directly and the results were compared with clinical evidence of aspiration. DESIGN: Prospective study in difficult-to-wean patients with tracheostomy. SETTING: Respiratory ICU. PATIENTS AND METHODS: The study population consisted of 62 consecutive patients (16 females, age: 64.1+/-11.1 years). All patients were tracheotomised and had previously been long-term ventilated in other ICUs due to weaning failure. The scintigraphic test was performed during spontaneous breathing. The standard nutrition consisted of a liquid, semi-liquid and solid meal which was labelled with 100 MBq 99mTc-human serum albumin. MEASUREMENTS AND RESULTS: Scintigraphic aspiration (SA) was defined as positive if radioactivity was detected in the bronchial system using a scintillation camera. Furthermore, aspiration was proven clinically (CA). CA and SA yielded identical results in 54 of the 62 patients [10 positive (16%) and in 44 negative (71%)]. CA, but not SA, was seen in 4/62 (6.5%) and SA, but not CA, was found in 4/62 (6.5%) patients. CONCLUSIONS: Our data re-emphasise that aspiration in tracheotomised patients is common (in our study approximately 30%). The scintigraphic method failed to identify all tracheotomised patients with clinically significant aspiration; however, it did suggest that some patients had subclinical aspiration.

Aged↗
PubMed1995

Theileria annulata sporozoite antigen fused to hepatitis B core antigen used in a vaccination trial.

A C terminal fragment (SR1) of SPAG-1, a sporozoite surface antigen of Theileria annulata, has been expressed as a fusion protein in the e1 loop of hepatitis B core antigen (HBcAg). This recombinant antigen (HBcAg-SR1) is produced in the form of self-assembling polyhedral particles which have been visualised under the electron microscope. Cattle immunised with HBcAg-SR1 produced high titres of neutralising antibodies. A significant T cell response to both the HBcAg and SR1 determinants was observed but evidence of a T suppressor determinant in SR1 was also revealed. Immunised cattle showed some evidence of protection to sporozoite challenge as assessed by severity of the disease. The significance of these findings for the development of a sub-unit vaccine against T. annulata is discussed.

Animals↗
PubMed1997

Iopentol (Imagopaque 250) compared with diatrizoate (Urografin 219) in endoscopic retrograde cholangio-pancreatography (ERCP). A clinical trial assessing safety (adverse events and S-pancreatic iso-amylase) and diagnostic information (VAS).

The efficacy and safety of the non-ionic contrast medium iopentol, 250 mg I/ml (Imagopaque, Nycomed Imaging AS, Oslo, Norway) were evaluated and compared to those of the ionic contrast medium diatrizoate 219 mg I/ml (Urografin, Schering AG, Berlin, Germany). The trial was carried out as a randomized, double-blind comparative two-group study. One hundred and sixteen patients completed the study: 59 received iopentol and 57 received diatrizoate, the contrast medium used according to routine hospital procedure for ERCP. Demographic data and details of the ERCP procedure were comparable for the two contrast medium groups. Safety was assessed by monitoring serum pancreatic iso-amylase and by recording adverse events. Efficacy was evaluated through assessment of the diagnostic information and the quality of radiographs. Twenty-one of the patients receiving iopentol and 27 of the patients receiving diatrizoate reported adverse events during the ERCP procedure. Pain was the kind of procedure-related event most frequently reported. Three patients experienced serious adverse events with a fatal outcome 2, 10 and 12 days after the ERCP procedure, respectively. The principal investigator concluded for all three serious adverse events that any causal relationship with the contrast medium injected was unlikely. A mean change in serum pancreatic iso-amylase after contrast medium injection was noted in both contrast medium groups. However, statistical analysis did not show any significant difference between mean changes for the two groups. The efficacy results, both in terms of diagnostic information and quality of radiographic visualisation, were comparable for the two contrast media. In conclusion, the study did not show any statistically significant differences between the two contrast media as regards safety or efficacy in ERCP.

Amylases↗
PubMed2004

CMP-sialic acid synthetase of the nucleus.

Sialic acids of cell surface glycoconjugates play a pivotal role in the structure and function of animal cells and in some bacterial pathogens. The pattern of cell surface sialylation is species specific, and, in the animal, highly regulated during embryonic development. A prerequisite for the synthesis of sialylated glycoconjugates is the availability of the activated sugar-nucleotide cytidine 5'-monophosphate N-acetylneuraminic acid (CMP-NeuAc), which provides the substrate for sialyltransferases. Trials to purify the enzymatic activity responsible for the synthesis of CMP-NeuAc from different animal sources demonstrated that the major localisation of the enzyme is the cell nucleus. These earlier findings were confirmed when the murine CMP-NeuAc synthetase was cloned and the subcellular transport of recombinant epitope tagged forms visualised by indirect immunofluorescence. Today, the primary sequence elements that direct murine CMP-NeuAc synthetase into the cell nucleus are known, however, information regarding the physiological relevance of the nuclear destination is still not available. With this article, we provide a detailed review on earlier and recent findings that identified and confirmed the unusual subcellular localisation of the CMP-NeuAc synthetase. In addition, we take the advantage to discuss most recent developments towards understanding structure--function relations of this enzyme.

Amino Acid Sequence↗
PubMed2000

Visualisation of three-dimensional microcracks in compact bone.

Microdamage in bone contributes to the loss of bone quality in osteoporosis and is thought to play a major role in both fragility and stress fractures (Schaffler et al. 1995). In this study, in vivo microcracks in human ribs were bulk-stained in basic fuchsin and viewed in longitudinal section and in 3 dimensions using 2 different computer-based methods of reconstruction: (1) serial sectioning of methylmethacrylate embedded sections using a sledge macrotome and identification of microcracks using UV epifluorescence followed by computerised reconstruction of microcracks using software and (2) laser scanning confocal microscopy of thick sections followed by reconstruction of microcracks into a 3-D image. The size and shape of microcracks were found to be similar using both techniques. Both techniques of reconstruction showed microcracks to be approximately elliptical in shape. From the serial sectioning reconstructions (n = 9), microcracks were found to have a mean length of 404 +/- 145 microm (mean +/- S.D.) (in the longitudinal direction) and mean width of 97 +/- 38 microm (in the transverse direction). Using epifluorescence microscopy, 92 microcracks were identified; mean microcrack length was 349 +/- 100 microm in the longitudinal direction. This was consistent with other results (Burr & Martin, 1993) and with the theoretical prediction of an elliptical crack shape with aspect ratio (longitudinal: transverse) of 5:1 deduced from analysis of random 2-D sections (Taylor & Lee, 1998). The results obtained provide new data on the nature of microcracks in bone and the method has the potential to become a useful tool in the calculation of stress intensity values which indicate the probability of an individual microcrack propagating to cause a stress or fragility fracture.

Aged↗