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At least 397 records · Page 22Linked to original sources
PubMed1999

Fatal head injury in children: a new approach to scoring axonal and vascular damage.

As part of a multidisciplinary study of brain damage in children fatally injured in motor vehicle accidents, a simple method to quantify and visualise the distribution and extent of injury has been developed. Vascular and axonal injury were assessed using coronal brain sections stained for haematoxylin and eosin, or reacted immunohistochemically for beta-amyloid precursor protein. Subsequent analysis was carried out using NIH Image software, and the resulting information is displayed in schematic diagrams. These summary diagrams simply and clearly show the distribution of injury in both the coronal and horizontal planes. This technique offers an advantage over previous scoring methods in that it provides both a quantitative and a visual summary of the distribution and extent of brain injury. This information can then be used to compare the injury distribution and severity with estimated impact points and acceleration data.

Accidents, Traffic↗
PubMed1994

[New data in cardiology: the electric charge of the heart].

This study emerging from profound consideration of the basis of vectorcardiography reveals a new electric model of the heart, the starting point for a computer programme of which only the principle is described. Noting inadequacies of vectorcardiography linked to necessary but possibly excessive simplifications, the author suggests a solution based only on Einthoven's postulate of a single dipole: at each instant during the cardiac revolution, the positions of point N, the centre of negative charges and origin of the dipole, of point P, the centre of positive charges and extremity of the dipole, and the value of the load borne by this dipole are calculated. The classical orientations of septal, parietal and basal vectors are thus found. It is shown that electric charge follows a bell-shaped curve and that the velocity of the dipole is compatible with that of the depolarisation wave, in contrast to velocities given by vectorcardiography. The trajectory of the dipole, a veritable "dipologram" visualises breaks in continuity which are interpreted. This new method has the advantage of being entirely confirmable: the dipole provided by the programme enables the calculation of potentials. Comparison between measured potentials and calculated potentials ensures the reliability of results provided by this programme. This method is totally in contrast with conventional vectorcardiography: the dipole is entirely mobile regarding both its origin and extremity, its site in the thorax is precisely identified, and its length is calculated, together with its velocity and the charge which it carries.(ABSTRACT TRUNCATED AT 250 WORDS)

Electricity↗
PubMed2000

Characterisation of three-dimensional anatomic shapes using principal components: application to the proximal tibia.

The objective of the research is to determine if principal component analysis (PCA) provides an efficient method to characterise the normative shape of the proximal tibia. Bone surface data, converted to analytical surface descriptions, are aligned, and an auto-associative memory matrix is generated. A limited subset of the matrix principal components is used to reconstruct the bone surfaces, and the reconstruction error is assessed. Surface reconstructions based on just six (of 1452) principal components have a mean root-mean-square (RMS) reconstruction error of 1.05% of the mean maximum radial distance at the tibial plateau. Surface reconstruction of bones not included in the auto-associative memory matrix have a mean RMS error of 2.90%. The first principal component represents the average shape of the sample population. Addition of subsequent principal components represents the shape variations most prevalent in the sample and can be visualised in a geometrically meaningful manner. PCA offers an efficient method to characterise the normative shape of the proximal tibia with a high degree of dimensionality reduction.

Adult↗
PubMed1994

High-resolution magnetic resonance imaging of arthritic pathology in the rat knee.

High-resolution magnetic resonance imaging (MRI) has been used to visualise the changes that occur in both soft tissue and bone during antigen-induced, monoarticular arthritis (AIMA) of the rat knee. Extensive optimisation studies were performed in order to minimise the time of the experiments and to maximise both the signal-to-noise ratio and the contrast in the MR images. The study was cross-sectional rather than longitudinal and at each of the 13 time points studied during the progression of the disease, corresponding X-radiographs and histological sections were obtained. Interpretation of the spin echo MR images was aided by the use of chemical shift-selective imaging, magnetisation transfer contrast and relaxation time experiments, as well as by correlation with the histology and X-radiography data. The MR images clearly show invasion of the synovium by an inflammatory pannus which spreads over the articular cartilage and invades the bone, leading to erosion and later remodelling. Two distinct types of bony erosion were observed: focal erosions, especially at the margins of the joint, and subchondral erosions. It is concluded that MRI provides a sensitive, non-invasive method for investigating both early-stage inflammatory changes and late-stage bony changes in the knee joints of the arthritic rat.

Animals↗
PubMed1991

A novel protein antigen of the malaria parasite Plasmodium falciparum, located on the surface of gametes and sporozoites.

A Plasmodium falciparum cDNA clone was isolated of which the insert is transcribed at high rates as a 1.4-kb mRNA in the sexual stages of the malaria parasite. The cDNA clone contains a copy of a non-interrupted gene which codes for a protein of 157 amino acids (Mr = 16607). This 16-kDa protein does not contain repetitive sequences and is characterised by a putative N-terminal signal sequence, a hydrophobic membrane anchor sequence and a highly hydrophilic C-terminal region suggesting that it is an integral membrane protein. Rabbit antisera raised against a synthetic peptide covering amino acids 31-47 of the 16-kDa protein and against recombinant fusion proteins recognised the 16-kDa antigen in protein extracts of gametocytes, macrogamete/zygotes and sporozoites by Western blot analysis. The rabbit antisera also reacted with gametes, gametocytes and sporozoites in a standard immunofluorescence assay. By immunoelectron microscopy using the protein A-gold method the 16-kDa protein could be clearly visualised on the surface of macrogametes and sporozoites, whereas the antigen was not detectable in the asexual erythrocytic stages of the parasite. The 16-kDa antigen of P. falciparum therefore might have the potential to elicit a dual protective immune response against the sporozoite and sexual stage parasites.

Amino Acid Sequence↗
PubMed1992

Laparoscopic laser cholecystectomy: our first 200 patients.

A series of 200 consecutive patients were considered for laparoscopic laser cholecystectomy. Laparoscopic laser cholecystectomy was attempted in 195 cases and was performed in 192 cases. Laparoscopy was performed in five patients, but laparoscopic cholecystectomy was not attempted owing to dense adhesions (3), cholangiocarcinoma (1) and an absent gallbladder (1). The indications for operation were symptomatic gallstones which included biliary colic (142), acute cholecystitis (49) and gallstone pancreatitis (9). The median duration of operation was 75 min. Operative cholangiography was attempted in 151 (77%) of cases, and was successful in 85% of attempts. Laparoscopic common bile duct visualisation was performed three times with successful stone extraction twice. The other common bile duct was normal. The median duration of postoperative hospital stay was 2 days, for return to normal activity 6 days, and for return to work 10 days. Mean analgesic and antiemetic requirements were approximately one-third of those for open cholecystectomy. Of the patients, 94% reported good or excellent overall satisfaction and 96% reported excellent cosmetic results. Seven complications occurred (4%). Three patients had immediate conversion to laparotomy owing to haemorrhage (2) and gallbladder rupture (1). Four patients required laparotomy for postoperative complications (common bile duct damage, slipped clips from cystic duct, perforated duodenum and leaking accessory hepatic duct). No complications occurred in the last 140 cases. These data suggest that laparoscopic laser cholecystectomy reduces the discomfort of laparotomy and allows a shorter postoperative recovery. The operation has a learning curve, but will ultimately be applicable to the majority of patients with symptomatic gallstones.

Adult↗
PubMed1997

Characterisation of basic proteins from Spiroplasma melliferum using novel immobilised pH gradients.

Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) has become the method of choice for efficient separation of complex protein mixtures. Previously, analysis of the Spiroplasma melliferum proteome (protein complement of a genome) has been performed with pH 3-10 and narrow range pH 4-7 IPG gel strips. We report here on the use of novel 18 cm basic (pH 6-11) immobilised pH gradients (IPG) to increase the resolution of protein spots visible within 2-D gels. These gradients were synthesised to emulate the gradient of commercially available IPG gel strips in a 5 cm region of overlap so as to attempt construction of a more complete map of cellular protein expression. Approximately 50 additional gene products were detected from S. melliferum that were not previously well-resolved or visible using wide-range pH 3-10 IPG gel strips. Twenty-seven of these were electrotransferred to polyvinylidene difluoride (PVDF) membrane and analysed by N-terminal protein microsequencing. Protein spots with an initial peak yield of as little as 100 femtomoles (fm) were sequenced to 5-10 amino acid residues, demonstrating the importance of improved sample handling procedures and analytical technologies. Many essential metabolic enzymes were shown to have basic pI, including: glyceraldehyde-3-phosphate dehydrogenase, pyruvate kinase, carbamate kinase and lactate dehydrogenase. A very basic protein (pI approximately 11.0) was identified as uridylate kinase, an enzyme indirectly associated with pyrimidine biosynthesis and thought be absent in some members of the bacterial class Mollicutes. The advent of novel basic (pH 6-11) IPGs has allowed the visualisation of a significantly greater percentage of the 'functional proteome', that portion of the total protein complement of a genome actively translated within a specific time frame, on 2-D electrophoresis gels. This will aid in the characterisation of translated gene products in conjunction with genome sequencing initiatives.

Amino Acid Sequence↗
PubMed1990

Immunohistochemical localisation of nerve growth factor in a subpopulation of chick spinal ganglion neurons.

We have previously isolated and sequenced the chicken nerve growth factor (NGF) gene and now, from the deduced amino acid sequence, selected and produced peptides suitable for use as antigens. Anti-sera raised against these peptides inhibit the biological activity of a partially purified preparation of native chicken NGF and, when used in immunocytochemical studies, allow the visualisation of sensory neurons accumulating endogenous NGF. Immunoreactive cells form a distinct population of small neurons which may correspond to the well-described neurons generated in the dorsomedial area of spinal ganglia. We conclude that two subpopulations of neurons exist within dorsal root ganglia, whose requirements for, and use of, NGF may be quite distinct.

Amino Acid Sequence↗
PubMed2000

Iterative reconstruction: an improvement of technetium-99m MIBI SPET for the detection of parathyroid adenomas?

The purpose of this study was to assess the value of technetium-99m methoxyisobutylisonitrile (MIBI) single-photon emission tomography (SPET) and an iterative reconstruction algorithm for the preoperative localisation of parathyroid adenomas (PTAs). Seventy-two patients (26 male, 46 female, mean age 58+/-16 years) with known primary hyperparathyroidism were examined preoperatively. First, a thyroid examination was performed to detect possible MIBI-accumulating thyroid lesions. Planar scans were then acquired 15 and 120 min and tomographic images 120 min after intravenous injection of 740 MBq 99mTc-MIBI, using a triple-head gamma camera (Picker Prism 3000). Additionally, 99mTc-MIBI/ 99mTc-pertechnetate subtraction scintigraphy of the early planar images was performed. The SPET data were evaluated using an iterative reconstruction (multiplicative iterative SPET reconstruction: MISR) as well as a standard algorithm (FBP: filtered back-projection with application of a 3-D low-pass postfilter). The weight of the resected PTAs ranged from 110 mg to 5 g. Using planar MIBI scans, correct localisation of the side of the PTA was possible in 81% of cases (58% for PTAs weighing less than 500 mg). Sensitivity increased to 94% using SPET and FBP, while with MISR it rose further, to 97%. Patients with PTAs weighing less than 500 mg showed a sensitivity of 88% with MISR and 81% with FBP. Furthermore, there was a clear improvement in image quality using MISR. None of the normal parathyroid glands were visualised. This study indicates that, in comparison with planar scintigraphy, 99mTc-MIBI SPET is a more sensitive and specific tool for topographical localisation of PTAs, especially those that are small. There is a further improvement in sensitivity and image quality when iterative reconstruction is used instead of FBP.

Adenoma↗
PubMed2000

RuvAB-mediated branch migration does not involve extensive DNA opening within the RuvB hexamer.

The Escherichia coli RuvA and RuvB proteins promote the branch migration of Holliday junctions during the late stages of homologous recombination and DNA repair (reviewed in [1]). Biochemical and structural studies of the RuvAB-Holliday junction complex have shown that RuvA binds directly to the Holliday junction [2] [3] [4] [5] [6] and acts as a specificity factor that promotes the targeting of RuvB [7] [8], a hexameric ring protein that drives branch migration [9] [10] [11]. Electron microscopic visualisation of the RuvAB complex revealed that RuvA is flanked by two RuvB hexamers, which bind DNA arms that lie diametrically opposed across the junction [8]. ATP-dependent branch migration occurs as duplex DNA is pumped out through the centre of each ring. Because RuvB possesses well-conserved helicase motifs and RuvAB exhibits a 5'-3' DNA helicase activity in vitro [12], the mechanism of branch migration is thought to involve DNA opening within the RuvB ring, which provides a single strand for the unidirectional translocation of the protein along DNA. We have investigated whether the RuvB ring can translocate along duplex DNA containing a site-directed interstrand psoralen crosslink. Surprisingly, we found that the crosslink failed to inhibit branch migration. We interpret these data as evidence against a base-by-base tracking model and suggest that extensive DNA opening within the RuvB ring is not required for DNA translocation by RuvB.

Adenosine Triphosphate↗
PubMed1997

Development of phrenic motoneuron morphology in the fetal rat.

This study examined the morphological changes that a homogeneous mammalian spinal motoneuron population undergoes during foetal development. Retrograde labelling of the phrenic nerve with the carbocyanine dye, DiI, was used to visualise developmental changes in phrenic motoneuron morphology within the cervical spinal cord of perinatal rats from embryonic day (E) 13.5 to birth (ca. E21). Groups of intimately associated phrenic somata had migrated into the ventromedial region of cervical segments C3-C6 by E14. This migration was followed by their progressive compaction into a tightly aligned column by E18. During this period, close contact was maintained between phrenic somata throughout the motor pool, suggestive of the presence of gap junctions. From E15 to E18, extensive dendritic arborisations fanned out dorsolaterally and ventromedially into the white matter and the floor plate. By E19, however, dendritic fasciculation and retraction and the extension of newly formed rostrocaudally projecting dendrites had resulted in the approximation of the dendritic morphology observed at birth. These data demonstrate that morphological maturation of phrenic motoneurons occurs subsequently to the onset of functional recruitment and the arrival of central processes of dorsal root ganglion neurons within the ventral horn (ca. E17). By birth, a number of immature features remain, including a larger proportion of neurites that project into the white matter and into the floor plate, the presence of growth cones on a number of dendrites, and close contact between populations of contralaterally derived dendrites.

Animals↗
PubMed1992

3-Oxoacyl-[ACP] reductase from oilseed rape (Brassica napus).

3-Oxoacyl-[ACP] reductase (E.C. 1.1.1.100, alternatively known as beta-ketoacyl-[ACP] reductase), a component of fatty acid synthetase has been purified from seeds of rape by ammonium sulphate fractionation, Procion Red H-E3B chromatography, FPLC gel filtration and high performance hydroxyapatite chromatography. The purified enzyme appears on SDS-PAGE as a number of 20-30 kDa components and has a strong tendency to exist in a dimeric form, particularly when dithiothreitol is not present to reduce disulphide bonds. Cleveland mapping and cross-reactivity with antiserum raised against avocado 3-oxoacyl-[ACP] reductase both indicate that the multiple components have similar primary structures. On gel filtration the enzyme appears to have a molecular mass of 120 kDa suggesting that the native structure is tetrameric. The enzyme has a strong preference for the acetoacetyl ester of acyl carrier protein (Km = 3 microM) over the corresponding esters of the model substrates N-acetyl cysteamine (Km = 35 mM) and CoA (Km = 261 microM). It is inactivated by dilution but this can be partly prevented by the inclusion of NADPH. Using an antiserum prepared against avocado 3-oxoacyl-[ACP] reductase, the enzyme has been visualised inside the plastids of rape embryo and leaf tissues by immunoelectron microscopy. Amino acid sequencing of two peptides prepared by digestion of the purified enzyme with trypsin showed strong similarities with 3-oxoacyl-[ACP] reductase from avocado pear and the Nod G gene product from Rhizobium meliloti.

3-Oxoacyl-(Acyl-Carrier-Protein) Reductase↗
PubMed1997

A multidimensional partition analysis of SSFP image pulse sequences.

The k-space description, of MRI pulse sequences, has been combined with a partition model in order to model the image reconstruction and the contrast behaviour found in SSFP pulse sequences. A partition represents the magnetisation created, due to excitation by a given rf pulse. In the present model, it is visualised as a set of parameters rather than a vector sum taken over a collection of spins. A multidimensional parameter space, where each dimension is associated with one of the partition parameters, is introduced in order to describe the interaction between partitions and pulse sequence events (e.g., rf pulses and gradients). The three k-space dimensions form the first three dimensions and higher orders are used to handle phase dispersions due to diffusion and main field inhomogeneities. The model makes it possible to perform fast simulation of images resulting from general SSFP pulse sequences. A computer implementation generates images (256 matrix), containing more than 10 different T1/T2 combinations, in less than 45 s on a 120 MHz Pentium computer. The contrast behaviour and signal intensities found in simulated images show excellent agreement with data generated using a clinical MRI scanner system.

Computer Simulation↗
PubMed1992

Localization and function of the D3 dopamine receptor.

A novel dopamine receptor has been recently cloned, which differs from D1 and D2 receptors by its sequence, localization, pharmacology and possibly signalling system, hence its designation as D3 receptor. The D3 receptor cDNA was obtained by a combination of screenings of DNA libraries and PCR polymerase chain reaction experiments. It encodes a protein with a predicted structure consisting in 7 transmembrane domains indicating that it belongs to the G-protein coupled receptor family. Its global homology is 52% with the D2 receptor but 78% if only transmembrane domains are considered. Two shorter transcript variants, in addition to the full-length cDNA were detected by PCR in various rat brain regions. The shorter transcripts are generated by alternative splicing and encode two putative proteins respectively interrupted after the second transmembrane domain and lacking the second extracytoplasmic loop. After transfection of this latter isoform into cultured cells, no dopaminergic activity could be detected. These shorter splice variants may regulate the number of active D3 receptors. The human D3 receptor was also cloned using similar approaches with rat D3 receptor cDNA probes and was found highly homologous to the rat receptor, except in the third intracytoplasmic loop. The human D3 receptor gene was assigned to the chromosome 3 at q13.3 band. Visualisation of D3 receptor mRNA in rat brain by in situ hybridization indicated a predominant expression of the message in the ventral striatum and other "limbic" areas. There is no overlap in the distributions of D2 and D3 receptor mRNAs in discrete structures, suggesting that the two transcripts are expressed by different cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1998

[PET in neuroendocrine tumors].

With the radionuclide tracers available today, 50-90 per cent of neuroendocrine tumours of the gastro-intestinal tract can be visualised with PET (positron-emission tomography). PET also enables the effect of tumour treatment to be monitored in terms of biochemical and functional variables, which is not possible with other radiological techniques. Owing to the very good tumour resolution possible with PET, it serves as a complement to other routine methods such as computed tomography and ultrasonography, and can be used to screen the chest and abdomen for small primary tumours that can not be detected with other methods. In several pre-operative trials PET has been shown to demonstrate more changes in the pancreas and liver than was possible with other methods. In the near future it will be possible to demonstrate the presence of and quantify growth factor receptors, hormones, enzymes, DNA synthesis, mRNA synthesis and protein synthesis. Access to these tumour biological data will be of crucial importance to the individualisation of treatment.

Forecasting↗
PubMed1984

[2-dimensional echography in the preoperative evaluation of mitral stenosis].

2D echocardiography has become one of the most important investigations in the preoperative assessment of mitral stenosis. This study was undertaken to determine the reliability of the information so obtained, by comparison with the surgical appearances. The study population consisted of 104 patients (average age 45 years, 76% women) undergoing open heart surgery for pure mitral stenosis (72%) or mixed mitral valve disease (28%) between 1980 and 1981. All underwent 2D echo using a phased array Aloka SSD 800 80 degrees sector scanner. Cardiac catheterisation was performed in 102 cases and left ventricular angiography in 89 cases. The echocardiogramme was interpreted by an observer who had no knowledge of the surgical results. The mitral surface area, the condition of the valves and subvalvular apparatus and the predictive value of the possible surgical technique were analysed. The 2D echo mitral surface area was estimated by planimetry and quantitatively by using the Gorlin formula during catheterisation and by the surgical description preoperatively. 2D echo was more sensitive than M mode in the detection of severe mitral stenosis (90% vs 73%, p less than 0,01). The 2D echo-Gorlin correlation was quite good (R = 0,70, p less than 0,01) but was worse when the valves were very thickened. When compared with the surgical observations, 87% of the 2D echo data was correct. The thickness of the valves, their amplitude, the diastolic bowing of the anterior leaflet and the presence of calcification were assessed by 2D echo. The echo-surgical results matched perfectly in 76% of cases. The usual cause of error was underestimation of the degree of valvular damage. The valvular bowing and thickness were the most useful signs. Dense, brilliant echos of valvular calcification were found in only 58% of surgically proven cases of valvular calcification, but the error was often related to fine calcification, not visible on fluoroscopy, or to its localisation on the posterior leaflet. The subvalvular apparatus was evaluated in over 93% of patients, a complete study being possible in 73% of them. The 2D echo-surgical correlations were excellent in 90% of the cases in which it had been completely visualised. The chordal thickening was correctly predicted in 79% of cases. The surgical assessment was more pessimistic in 1/3 of cases in which the chordae appeared to be of normal thickness. The length of the chordae was correctly predicted in 68% of cases. The surgical assessment was more pessimistic in 1/2 of cases in which the chordae appeared to be of normal length.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1999

Measurement of clinical attachment levels using a constant-force periodontal probe modified to detect the cemento-enamel junction.

The handpiece of a Florida sleeve probe was modified to create a flange with the capability to detect the cemento-enamel junction (CEJ). This new instrument (the Pressure-controlled, Automated, Standardised Handpiece or Florida PASHA probe) was used to determine whether (a) the CEJ could be reproducibly detected in dried, human skulls and (b) clinical attachment levels could be reliably measured in human subjects. When using the Florida PASHA probe to detect the CEJ at 157 different sites in four dried, human skulls, there were no statistically significant (p > or = 0.15) differences in mean CEJ detection measurements for any of the three participating examiners; either when the CEJ was visualised or obscured. The mean differences between first and second replicates ranged from 0.00 to 0.08 mm. Intraclass correlation coefficients (ICCs) of repeated measures in both conditions ranged from 0.70 to 0.83 for tactile CEJ detection (CEJ obscured), and from 0.95 to 0.96 for visual detection (CEJ visible). In human studies, the Florida PASHA probe was used by two examiners to determine clinical attachment levels (CAL) at 660 sites in 5 human subjects undergoing supportive periodontal therapy. Intra-examiner agreement of replicate measurements recorded by the probe, as measured by calculating ICCs, ranged from 0.79 to 0.85 for the 2 examiners, respectively. A statistically significant inter-examiner difference in mean CAL measurements when using the Florida PASHA probe was found (p<0.001). Notwithstanding this difference, inter-examiner agreement was good, with an ICC of 0.83. These data suggest that the Florida PASHA probe can reproducibly detect the CEJ and is proposed as a tool for measuring CAL in humans.

Alveolar Bone Loss↗
PubMed1997

Numerical chromosomal aberrations in Hodgkin's disease detected by in situ hybridisation on routine paraffin sections.

AIMS: To visualise directly numerical chromosomal aberrations and polyploidy in both Hodgkin and Reed Sternberg (HRS) cells and background cells from cases of Hodgkin's disease using in situ hybridisation. METHODS: Non-isotopic DNA in situ hybridisation was applied to interphase cell nuclei of Hodgkin's disease within routine paraffin embedded tissue sections. Two a satellite DNA probes, specific for chromosomes 3 and 12, were used to evaluate the feasibility of this approach. Double labelling with immunocytochemical detection of the CD30 antigen was used to identify HRS cells. Cytogenetic normal diploid and triploid placental tissue served as controls. RESULTS: The eight cases of Hodgkin's disease investigated displayed frequent polysomy, while the majority of background cells showed disomy signals. CONCLUSIONS: Numerical chromosomal aberrations were detected in HRS cells from eight cases of Hodgkin's disease by in situ hybridisation. These data show that in Hodgkin's disease HRS cells frequently display polyploidy compared with background cells and are, therefore, probably the only neoplastic component in this disease. Correlations between polysomy and tumour type or grade could not be made from these data owing to the limited number of cases examined and to problems with interpreting data from truncated nuclei.

Adolescent↗