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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↗

[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↗

[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↗

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↗

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↗

Structural determinants of substrate selection by the human insulin-receptor protein-tyrosine kinase.

Using NMR spectroscopy to visualise tyrosine phosphorylation kinetics in real time, we have investigated the sequence-dependent determinants of the selectivity of the human insulin receptor protein-tyrosine kinase for different tyrosine residues. The peptides used encompass the multiple-tyrosine-containing autophosphorylation site sequences from the insulin receptor kinase core domain (Tyr1158, Tyr1162 and Tyr1163) and from its specific C-terminal tail domain (Tyr1328 and Tyr1334). Comparison of the phosphorylation kinetics with those found for the tyrosine residues on a peptide comprising the regulatory tyrosine phosphorylation site of cdc2 points to the role of the primary sequence context of the phosphate acceptor. The particularly deleterious influence of a basic residue immediately C-terminal to the tyrosine is discussed in relation to the autophosphorylation properties of the regulatory loop regions of the insulin and epidermal growth factor receptor kinases. The data further suggest that receptor tyrosine kinase active sites and their substrate targets act in concert to ensure that specific downstream effects are activated.

Amino Acid Sequence↗

The microanatomy of the alveolar duct of the human lung imaged by confocal microscopy and visualised with computer-based 3D reconstruction.

The most widely accepted model of human lung alveolar duct systems is that they are constructed from central helical fibres between the turns of which lie alveolar opening. Experimental difficulties of handling and sectioning lung tissue have made it difficult to confirm this. Confocal laser scanning microscopy (CLSM) was therefore used to generate optical serial sections of the lung that were reconstructed in three dimensions and displayed using volume rendering techniques. From images of the reconstructions, a new structure is proposed in which alveolar ducts consist of collections of connected oval, twisted loop structures with eccentric openings.

Adult↗

Assessment of the influence of subacute phenobarbitone administration on multi-tissue cell proliferation in the rat using bromodeoxyuridine immunocytochemistry.

The effects of daily administration of phenobarbitone on the mitotic rates of several tissues were investigated by bromodeoxyuridine (BrdU) immunocytochemistry. Phenobarbitone (80 mg/kg per day) was dosed to AP Wistar male rats for up to 7 days and BrdU (10 mg/ml) was given by infusion at a rate of 10 microliters/h via subcutaneously implanted osmotic minipumps for 2 days prior to necropsy on days 1, 2, 3, 5 and 7. BrdU-labelled nuclei were visualised by peroxidase-antiperoxidase immunocytochemistry and counts of the numbers of labelled cells (labelling index, LI%) made from at least 1000 cells per tissue section(s). The LIs of several tissues (testis, adrenal cortex and medulla, kidney distal convoluted tubule and exocrine pancreas) showed no statistical difference by comparison with controls. Several tissues exhibited characteristic responses to phenobarbitone administration. Pituitary and endocrine pancreas LIs were decreased while those of thyroid, liver and kidney proximal convoluted tubule were increased. The pattern of LI increase was unique to each tissue with liver (median and lateral lobes) increased two-fold on day 3 and returning to control levels thereafter while kidney proximal tubule LI rose gradually with time and remained elevated on day 7. Thyroid LI on day 1 was almost double that of day 0 control and increased steadily thereafter. These data illustrate the varied responses of different tissues to phenobarbitone exposure, namely, depression and stimulation of mitosis. The causation of these functional changes is discussed in relation to direct and indirect effects on functional parameters, especially enzyme induction, alterations in hormonal and growth factor status and receptor regulation.

Adrenal Glands↗

Direct diagnosis of carriers of Duchenne and Becker muscular dystrophy by amplification of lymphocyte RNA.

Rapid detection of deletion and duplication mutations that cause Duchenne and Becker muscular dystrophy was achieved in patients and carriers after amplification of small amounts of mRNA from peripheral blood lymphocytes. The entire coding region of the dystrophin mRNA was amplified in 10 sections by reverse transcription and nested polymerase chain reaction, and the products were directly visualised on acrylamide minigels with ethidium staining. Major structural gene mutations were identified by the appearance of a band of different size to that of the wild type. The altered band was readily detected in all patients and heterozygous relatives. This non-radioactive test of venous blood samples can be used for unambiguous and rapid identification of virtually all carriers of deletions or insertions within the dystrophin gene.

Base Sequence↗

Radiological determination of the posterior limits of the temporal lobe for volumetric analysis.

The posterior peri-Sylvian area is the most highly lateralized part of the human brain due to its specialised role in language. Currently, there is no clearly defined posterior boundary of the temporal lobe which takes account of language lateralization and which can be reliably determined radiologically. However, there have been a number of recent advances in magnetic resonance technology including volume visualisation techniques which have as their goal the realistic three-dimensional representation of the brain which is acquired in two-dimensional slices. These have enabled the identification of precise macroanatomical and cytoarchitectural boundaries from which an efficient and reproducible posterior limit may be demarcated. Such limit standardisation is important for volumetric investigations of both neurological and psychiatric disease. Magnetic resonance imaging (MRI) scans of 20 normal subjects (10 male and 10 female), aged between 18 and 42 years, were acquired as part of a study of normal temporal lobe volume variation. In order to demonstrate the method of posterior limit placement, a thin slice (1.5 mm) 3D spoiled gradient magnetic resonance image of the brain of a 30 year-old right-handed male, without neurological disease, was acquired on a 1.5 tesla GE magnetic resonance machine. The data set was transferred via network to the hard disk of a 166 MHz Pentium processor PC. A software package called MEASURE allowed reformation of the data set in all three orthogonal planes. Then, using a high resolution algorithm, the brain was aligned along the newly proposed posterior plane which runs from the limit of the Sylvian fissure, identified on a 3D rendering, to the posterior/inferior splenium. It is hoped that this procedure will be utilised as a standard method for radiological determination of the limit of the posterior temporal lobe in order to allow volumetric measurements of this structure to be compared in a meaningful way.

Adolescent↗

Combined use of proacrosin immunocytochemistry and autosomal DNA in situ hybridisation for evaluation of human ejaculated germ cells.

The recently reported human pregnancies and births after fertilising oocytes with round spermatids recovered from the ejaculate of men with non-obstructive azoospermia have underscored the need for a more accurate evaluation of the nuclear and cytoplasmic maturation status of ejaculated germ cells. In this study we describe our first experience with a method combining the immunocytochemical visualisation of proacrosin with autosomal DNA fluorescence in situ hybridisation (FISH) to assess ejaculated germ cells from patients with a spermiogenesis defect. The proacrosin immunoreactivity, analysed with the use of the monoclonal antibody 4D4, has been detected in cells of round spermatid size presenting a haploid FISH figure as well as in larger cells whose ploidy corresponds to primary and secondary spermatocytes. These observations are in agreement with previously published results obtained, with the use of the same antibody, by immunocytochemical analysis of histological sections of testicular tissue. All the cells of round spermatid size possessing proacrosin immunoreactivity were found to be haploid by FISH. On the other hand, some of the haploid cells of round spermatid size did not possess proacrosin immunoreactivity. The structural pattern of proacrosin immunoreactivity was highly variable both in spermatids and in younger spermatogenic cells. These data show that cell size is the main criterion to be used for the identification of ejaculated round spermatids, whereas the presence of the developing acrosome represents only an auxiliary criterion. The scoring of acrosomal development in ejaculated spermatids may be useful as part of pre-treatment diagnosis before the inclusion of infertile couples in a spermatid conception programme.

Acrosin↗

Stress induced changes in transmitter release from sympathetic varicosities of the mouse vas deferens.

Activation of the sympathetic nervous system is an important component of the response to stress, but the effects of prolonged stress on sympathetic neurotransmission have not been assessed. In the present study we have examined the effect of 3 to 10 days exposure to stress induced by frequent handling and sham injections on neurotransmitter release from sympathetic varicosities of the mouse vas deferens. DiOC2(5)-fluorescence was used to visualise the sympathetic varicosities so that extracellular electrodes could be placed over known numbers of varicosities to monitor transmitter release using electrophysiological techniques. The frequency of excitatory junction currents (EJCs) increased with increasing duration of exposure to stress. The mean and maximum EJC amplitude significantly increased by 107% and 43%, respectively after 10 days of exposure to stress. The density of sympathetic varicosities innervating smooth muscle of the mouse vas deferens was not changed throughout the duration of the exposure to stress. The findings from this study demonstrate that the efficacy of transmitter release from the sympathetic varicosities is altered by repeated exposure of mice to stressful stimuli, such as handling and sham injections. Since such procedures are routine in many pharmacological experiments, it is important that investigators are aware of these changes so that due consideration is given when interpreting the data obtained from animals treated in this way.

Animals↗

Multiple mitochondrial DNA deletions in an elderly human individual.

We have used the polymerase chain reaction (PCR) to study deletions in the mitochondrial DNA (mtDNA) of an elderly human individual. An extended set of PCR primers has been utilised to identify 10 mitochondrial DNA deletions in a 69-year-old female subject with no known mitochondrial disease. The particular deletions visualised as PCR products depended on the primer pairs used, such that the more distantly separated PCR primers enabled visualisation of larger deletions. Some deletions were common to the heart, brain and skeletal muscle, whereas others were apparently specific to individual tissues. DNA sequencing analysis of PCR products showed that short direct repeat sequences (5 to 13 bp) flanked all deletion breakpoints; in most cases one copy of the repeat was deleted. It is proposed that the accumulation of such multiple deletions is a general phenomenon during the ageing process.

Aged↗

Echo-planar magnetic resonance imaging of Gaviscon alginate rafts in-vivo.

Liquid Gaviscon and Gaviscon Advance are established reflux suppressant formulations. This study describes the use of echo-planar magnetic resonance imaging (EPI) to visualise non-invasively intragastric alginate rafts of Liquid Gaviscon and Gaviscon Advance in healthy subjects. Secondly, the feasibility of using relaxation rate (T2(-1)) measurements to monitor changes in the physicochemical properties of the rafts in-vivo is evaluated. Six subjects ingested 500 mL of a liquid meal and received a single dose of 20 mL Liquid Gaviscon or 10 mL Gaviscon Advance on 2 separate visits each and were imaged every 15 min. An alginate raft was observed in the stomach for all subjects and both treatments. The raft was observed to consist of a few large fragments on the majority of the scans for both products. At t = 60 min a raft was still present in all cases. Three-dimensional volume reconstructions showed, for the first time, the spatial distribution of the rafts within the gastric lumen. The T2(-1) data showed potential for assessment of dynamic changes in the physicochemical properties of the alginate rafts in-vivo. We conclude that EPI shows great potential in assessing alginate rafts formation in-vivo.

Adult↗

Natural course of Crohn's disease after ileocolic resection: endoscopically visualised ileal ulcers preceding symptoms.

Forty two Crohn's disease patients were followed up after ileocolic resection with regard to symptoms and endoscopic appearance of the ileocolic anastomosis. Twenty eight patients resected because of colonic neoplasm served as controls. In all the Crohn's disease patients the ileal resection margin was disease free macroscopically at operation. In addition, intraoperative ileoscopy was performed in 13 and no sign of residual inflammation in the neoterminal ileum was seen. Endoscopy soon after surgery often showed preanastomotic ileal ulceration before symptoms appeared, whereas no anastomotic lesions were observed in the controls. Thus, 22 of 30 Crohn's disease patients examined had ulceration of the anastomotic area after three months, but only 10 had developed symptoms indicating relapse (73 v 33%). Corresponding figures in the 30 patients examined after one year were 93 v 37%, and in 14 patients after three years they were 100 and 86% respectively. The inflammatory lesions in all cases were preanastomotic, in the neoterminal ileum, and showed time related progression from aphthae to larger ulcers and stricture. The study suggests that endoscopically observed inflammatory lesions that appear soon after ileocolic resection for Crohn's disease signify new inflammation and not residual, persistent disease or incomplete anastomotic healing. The data further suggest that despite clinical remission after apparently radical intestinal resection, the bowel is permanently inflamed in Crohn's disease.

Adolescent↗

CT data sets surface extraction for biomechanical modeling of long bones.

In modelling applications such as custom-made implants design is useful to have a surface representation of the anatomy of bones rather than the voxel-based representation generated by tomography systems. A voxel-to-surface conversion process is usually done by a 2D segmentation of the images stack. However, other methods allow a direct 3D segmentation of the CT or MRI data set. In the present work, two of these methods, namely the Standard Marching Cube (SMC) and the Discretized Marching Cube (DMC) algorithms, were compared in terms of local accuracy when used to reconstruct the geometry of a human femur. The SMC method was found to be more accurate than the DMC method. The SMC method was capable of reconstructing the inner and outer geometry of a human femur with a peak error lower than 0.9 mm and an average error comparable to the pixel size (0.3 mm). However, the large number of triangles generated by the algorithm may limit its adoption in many modelling applications. The peak error of the DMC algorithm was 1.6 mm but it produced approximately 70% less triangles than the SMC method. From the results of this study, it may be concluded that three dimensional segmentation algorithms are useful not only in visualisation applications but also in the creation of geometry models.

Algorithms↗

ER quality control can lead to retrograde transport from the ER lumen to the cytosol and the nucleoplasm in plants.

Quality control in the secretory pathway is a fundamental step in preventing deleterious effects that may arise by the release of malfolded proteins into the cell or apoplast. Our aims were to visualise and analyse the disposal route followed by aberrant proteins within a plant cell in vivo using fluorescent protein technology. A green fluorescent protein (GFP) fusion was detected in the cytosol and the nucleoplasm in spite of the presence of an N-terminal secretory signal peptide. In contrast to secreted GFP, the fusion protein was retained in the cells where it was degraded slowly, albeit at a rate much higher than that of the endoplasmic reticulum (ER)-retained derivative GFP-HDEL. The fusion protein could not be stabilised by inhibitors of transport or the cytosolic proteasome. However, the protein is a strong lumenal binding protein (BiP) ligand. Complete signal peptide processing even after long-term expression in virus-infected leaves rules out the possibility that the documented accumulation in the cytosol and nucleoplasm is because of the bypassing of the translocation pores. The data are consistent with the hypothesis that the fusion protein is disposed off from the ER via a retrograde translocation back to the cytosol. Moreover, accumulation in the nucleoplasm was shown to be microtubule dependent unlike the well-documented diffusion of cytosolically expressed GFP into the nucleoplasm. The apparent active transport of the GFP fusion into the nucleoplasm may indicate an as yet undiscovered feature of the ER-associated degradation (ERAD) pathway and explain the insensitivity to degradation by proteasome inhibitors.

Biological Transport↗

Cross sectional echocardiographic assessment of great artery diameters in infants and children.

The pulmonary trunk and aortic root were measured on cross sectional echocardiograms in 173 normal subjects aged from one day to 15 years. Fifteen neonates were reexamined 3-6 days later. The great vessels were visualised in the parasternal long axis and short axis views. All measurements were made in end diastole and end systole by the leading edge method. The internal diameter (inner surface to inner surface) of the pulmonary trunk was also measured. The diameters of the great vessels correlated best with the square root of body surface area. Individual variability in cardiac growth gave a wide scatter of normal values. This was controlled for by calculating the ratio of the pulmonary trunk to aortic root for each subject. This ratio showed little individual variability and, except for the neonatal period, was remarkably constant throughout infancy and childhood (1.06 (0.06)). In the first 24 hours of life the ratio of the pulmonary trunk to the aortic root was significantly larger (1.29 (0.12)) but within one week it decreased to the "normal" ratio found in the older age groups. These normal data should be useful in assessing patients with congenital heart disease, particularly those in whom pulmonary blood flow is abnormal.

Adolescent↗