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PubMed1996

Enhanced expression of microtubule-associated protein 2 in large neurons of cortical dysplasia.

To evaluate neuronal cytoarchitectural changes in cortical dysplasia, we examined microtubule-associated protein 2 (MAP2) expression in surgically resected specimens obtained from 20 patients (age range, 3 months to 10 years) treated for intractable epilepsy. Large neurons were investigated in the specimens from all patients and showed significantly strong immunoreactivity with antibodies against MAP2 in the perikaryon and proximal portion of their processes. In situ hybridization with MAP2 antitense riboprobe showed increased hybridization signal intensities in the large neurons, which correlated with the pattern of immunoreactivity for MAP2. We conclude that MAP2 is strongly expressed in the large neurons in cortical dysplasia. The results of preliminary immunoblotting in 1 patient with focal cortical dysplasia showed that the low-molecular-weight form of MAP2 (MAP2c) was strongly expressed in the dysplastic cortex, suggesting that MAP2c may be a major component contributing to the increased expression of MAP2 in the large neurons of cortical dysplasia. Since it has been suggested that MAP2 plays a crucial role in the branching and remodeling of neuronal processes, increased expression of MAP2 may reflect activated plasticity of the large neurons in cortical dysplasia.

Base Sequence↗
PubMed2004

Surgically revascularized dual LAD.

Dual left anterior descending artery (or dual anterior interventricular artery, LAD) is a rare coronary artery anomaly. Dual but normally originated LAD has been usually reported to have no clinical significance. In this case report, we present a case of 75 year old male with anginal symptoms in whom coronary arteriography showed normally originated dual LAD with two branches of almost equal caliber. The course of both branches were supplying the usual territory of LAD and both of the branches had significant proximal stenosis. The patient underwent a coronary artery bypass grafting operation and both branches were grafted. This normally originated dual LAD case may be considered to be interesting, because dual LAD branches were symmetrically involved with the atherosclerotic process in their proximal segments. In addition, this condition was demonstrated intraoperatively and the two branches were revascularized with bypass grafting.

Aged↗
PubMed1991

Two systems of branching axons in monkey's retina.

Several monkey retinae were stained, by using the reduced silver technique, in order to analyse long-distance intraretinal connections. Long, bifurcating processes covering very large areas were identified. Morphological investigation of these processes suggest that they are members of two different systems of branching axons. The first population of these processes originates as axon collaterals from cell in the ganglion cell layer. These cells have a relatively large, elongated soma and straight, sparsely branching dendrites, stratified in the vitreal half of the inner plexiform layer. The main axon (0.6 microns average diameter) passes along the optic fibre bundles, disappearing into the optic disk, whilst its collaterals run mainly in the inner plexiform layer. A cell showing similar morphology has also been found in the ganglion cell layer of a cat retina. The second population of processes consists of very thick fibres (2.1 microns average diameter) apparently originating from the optic disk. The main branches run in the space between the optic fibre layer and the ganglion cell layer, with short, secondary processes crossing the ganglion cel layer orthogonally. Many higher-order processes originate from the second-order branches; these run almost horizontally in the inner plexiform layer. The ganglion cells generating axon collaterals may constitute an intraretinal firing synchronization system, or they may be a residual feature of retinal development. The centrifugal fibres may be related to the sensitivity control during retinal dark adaptation.

Animals↗
PubMed1980

Ruffed cell: a new type of neuron with a distinctive initial unmyelinated portion of the axon in the olfactory bulb of the goldfish (Carassius auratus): II. Fine structure of the ruffed cell.

The fine structure and synaptic features of the ruffed cell, especially those of the initial unmyelinated portion of its axon (IP), were investigated by means of electron microscopy. The round or oval cell body is 10 to 20 micrometers in diameter. Near the cell body, there is a specialized region of the IP, about 20 to 40 micromerters in diameter, which consists of branched protrusions from the IP. Many neuronal processes end on these protrusions, and the whole assembly reminds one of a bird's nest. The nest has a little higher electron density than the surrounding field. The nucleus of the cell itself is round or oval with irregular undulations, and measures 7 to 10 micrometers in diameter. The perikaryon contains the usual cell organelles; especially many clusters of free ribosomes. Two kinds of dendrites arise from the cell body: thick dendrites, about 4 micrometers thick, which appear to be extensions of the perikaryon; and thinner dendrites, about 1 to 2 micrometers in diameter. In addition to these two, processes resembling those of glia arise from the cell body or from the thick dendritic trunk. Some of the dendritic branches enter the glomerulus. The IP arises from the cell body as a protrusion-bearing process about 0.8 to 1.5 micrometer in diameter. The IP is divided into three parts: part 1, where many elaborate protrusions arise to constitute a nest; part 2, where several scattered protrusions arise; and part 3, which has no protrusions. Part 1 of the IP is further subdivided into three portions according to the fine structure of its shaft. The first portion, about 10 to 15 micrometers long, is rather straight and exhibits the two characteristics of the conventional initial segment, i.e., membrane undercoating and fascicles of microtubules. The second portion, about 10 to 20 micrometer long, shows the membrane undercoating, but no fascicles of microtubules. The third portion of part 1 as well as parts 2 and 3 exhibits neither of the two distinguishing characteristics of the initial segment. Synapses are encountered on the cell body, the dendrites, and the IP. Most of them are formed with granule cell dendrites. The ruffed cell is presynaptic in asymmetrical synapses whose postsynaptic elements are the granule cell dendrites and other kinds of neuronal processes of unknown origins. It is also postsynaptic in symmetrical synapses from the granule cell dendrites. Reciprocal pairs of these two types of synapses are also seen, both on the dendrite and the IP. The numbers of synapses on the dendrite and the cell body seem far less than on the IP. The number of synapses on one IP is roughly estimated to be 1,000 to 2,000. The ratios of the synaptic types are as follows: asymmetrical synapses from the IP, 63%; symmetrical synapses onto the IP, 12%; and reciprocal pairs of synapses, 25%. Gap junctions are also seen between protrusions of the ruffed cell IP and dendrites of the perinest cell, which is a small neuron located at the periphery of the nest...

Animals↗
PubMed2005

Vascular-specific growth factor angiopoietin 1 is involved in the organization of neuronal processes.

Neuronal processes and vessels have similar branching and bifurcation patterning in the adult body and appear to use many of the same molecules during their development, including vascular endothelial growth factor, Notch, neuropilin, and ephrins/Ephs. We were interested in determining whether the endothelial growth factor angiopoietin (Ang) has a unique role in the nervous system in addition to its angiogenic role. By using a mouse molecular genetics approach, we overexpressed Ang1 in the mouse forebrain and observed increases in overall vascularization, consistent with prior reports describing the role of Ang1. Nonvascular events, involving alterations in the dendritic organization of layer II motor cortex neurons, dentate granule cells, and pyramidal cells of CA1, were seen, suggesting that Ang1 was able to influence the growth of these processes. The angiopoietin tyrosine kinase receptor Tie2 was not found on neurons or their processes, but beta1 integrin was and has previously been found to act as an Ang receptor. Our findings provide some of the first data evaluating the interactions between the developing nervous system and the vascular protein Ang1. Understanding interactions between the developing nervous and vascular systems will lead to novel insight into how the two systems interact throughout development, during senescence, and in disease.

Angiopoietin-1↗
PubMed2001

Regulation of prostate branching morphogenesis by activin A and follistatin.

Ventral prostate development occurs by branching morphogenesis and is an androgen-dependent process modulated by growth factors. Many growth factors have been implicated in branching morphogenesis including activins (dimers of beta(A) and beta(B) subunits); activin A inhibited branching of lung and kidney in vitro. Our aim was to examine the role of activins on prostatic development in vitro and their localization in vivo. Organ culture of day 0 rat ventral prostates for 6 days with activin A (+/- testosterone) inhibited prostatic branching and growth without increasing apoptosis. The activin-binding protein follistatin increased branching in vitro in the absence (but not presence) of testosterone, suggesting endogenous activins may reduce prostatic branching morphogenesis. In vivo, inhibin alpha subunit was not expressed until puberty, therefore inhibins (dimers of alpha and beta subunits) are not involved in prostatic development. Activin beta(A) was immunolocalized to developing prostatic epithelium and mesenchymal aggregates at ductal tips. Activin beta(B) immunoreactivity was weak during development, but was upregulated in prostatic epithelium during puberty. Activin receptors were expressed throughout the prostatic epithelium. Follistatin mRNA and protein were expressed throughout the prostatic epithelium. The in vitro evidence that activin and follistatin have opposing effects on ductal branching suggests a role for activin as a negative regulator of prostatic ductal branching morphogenesis.

Activin Receptors↗
PubMed1995

Breathless, a Drosophila FGF receptor homolog, is required for the onset of tracheal cell migration and tracheole formation.

Breathless, a Drosophila FGF receptor homolog (DFGF-R1), was shown to be essential for the migration of the tracheal cells and the posterior midline glia cells. The temporal requirement for the activity of this receptor was dissected by a dominant-negative construct lacking a functional cytoplasmic tyrosine-kinase domain. Induction of the construct prior to the onset of tracheal or glial cell migration produced phenotypes that were similar to those observed in the corresponding tissues of breathless null mutant embryos. However, this effect is not detected if the dominant-negative receptor is induced after the initiation of tracheal cell migration, indicating that Breathless is required primarily at the onset of the migration process. Induction of the construct after the tracheal branches are completed, blocked the formation of tracheoles, i.e. extension of cellular processes by the terminal tracheal cells, demonstrating that Breathless plays an essential role in this process as well. The requirement for Breathless at the onset of migration and the diversity of processes in which it participates, suggest that the receptor is involved in triggering transcription factors, which may be distinct for each context.

Animals↗
PubMed2005

New insights into the mechanism of palladium-catalyzed allylic amination.

A comparative investigation into palladium-catalyzed allylic amination of unsubstituted aziridines and secondary amines has been carried out. The use of NH aziridines as nucleophiles favors formation of valuable branched products in the case of aliphatic allyl acetates. The regioselectivity of this reaction is opposite to that observed when other amines are used as nucleophiles. Our study provides evidence for the palladium-catalyzed isomerization of the branched (kinetic) product formed with common secondary amines into the thermodynamic (linear) product. In contrast, the branched allyl products obtained from unsubstituted aziridines do not undergo the isomerization process. Crossover experiments indicate that the isomerization of branched allylamines is bimolecular and is catalyzed by Pd(0). The reaction has significant solvent effect, giving the highest branched-to-linear ratios in THF. This finding can be explained by invoking the intermediacy of sigma-complexes, which is consistent with NMR data. The apparent stability of branched allyl aziridines towards palladium-catalyzed isomerization is attributed to a combination of factors that stem from a higher degree of s-character of the aziridine nitrogen compared to other amines. The reaction allows for regio- and enantioselective incorporation of aziridine rings into appropriately functionalized building blocks. The resulting methodology addresses an important issue of forming quaternary carbon centers next to nitrogen. The new insights into the mechanism of palladium-catalyzed allylic amination obtained in this study should facilitate synthesis of complex heterocycles, design of new ligands to control branched-to-linear ratio, as well as absolute stereochemistry of allylamines.

Journal Article↗
PubMed1999

Studying the careers of nurse diplomates: the importance of branch-specific questionnaires.

Questionnaire design is considered in the context of a longitudinal panel study focusing on the careers of people qualifying from all four branches of the UK nurse diploma course. Separate, but comparable, questionnaires were developed for each branch in order to produce information which reflected the differences between branches, and the experiences of the cohort as a whole. This approach ensured that participants from the smaller branches did not feel their interests and concerns were overshadowed by those of the largest (adult) branch, as is often the case during the diploma course's Common Foundation Programme. The elements that needed to be tailored to each branch emerged during a three-stage piloting process used to develop and test the questionnaires. Differences were found between branches in their use of terminology; in certain issues being more relevant to some branches than others; and in questions which concerned all branches benefiting from the inclusion of branch-specific examples. The effectiveness of this approach to questionnaire design is borne out by the study's high response rates.

Career Choice↗
PubMed2001

Tts, a processive beta-glucosyltransferase of Streptococcus pneumoniae, directs the synthesis of the branched type 37 capsular polysaccharide in Pneumococcus and other gram-positive species.

The type 37 capsule of Streptococcus pneumoniae is a homopolysaccharide built up from repeating units of [beta-d-Glcp-(1-->2)]-beta-d-Glcp-(1-->3). The elements governing the expression of the tts gene, coding for the glucosyltransferase involved in the synthesis of the type 37 pneumococcal capsular polysaccharide, have been studied. Primer extension analysis and functional tests demonstrated the presence of four new transcriptional start points upstream of the previously reported tts promoter (ttsp). Most interesting, three of these transcriptional start points are located in a RUP element thought to be involved in recombinational events (Oggioni, M. R., and Claverys, J. P. (1999) Microbiology 145, 2647-2653). Transformation experiments using either a recombinant plasmid containing the whole transcriptional unit of tts or chromosomal DNA from a type 37 pneumococcus showed that tts is the only gene required to drive the biosynthesis of a type 37 capsule in S. pneumoniae and other Gram-positive bacteria, namely Streptococcus oralis, Streptococcus gordonii, and Bacillus subtilis. The Tts synthase was overproduced in S. pneumoniae and purified as a membrane-associated enzyme. These membrane preparations used UDP-Glc as substrate to catalyze the synthesis of a high molecular weight polysaccharide immunologically identical to the type 37 capsule. In addition, UDP-Gal was also a substrate to produce type 37 polysaccharide since a strong UDP-Glc-4'-epimerase activity is associated to the membrane fraction of S. pneumoniae. These results indicated that Tts has a dual biochemical activity that leads to the synthesis of the branched type 37 polysaccharide.

Bacterial Proteins↗
PubMed1999

In vivo observations of terminal Schwann cells at normal, denervated, and reinnervated mouse neuromuscular junctions.

We found a low-molecular-mass, fluorescent dye, Calcein blue am ester (CB), that labels terminal Schwann cells at neuromuscular junctions in vivo without damaging them. This dye was used to follow terminal Schwann cells at neuromuscular junctions in the mouse sternomastoid muscle over periods of days to months. Terminal Schwann cell bodies and processes were stable in their spatial distribution over these intervals, with processes that in most junctions were precisely aligned with motor nerve terminal branches. Three days after nerve cut, the extensive processes elaborated by terminal Schwann cells in denervated muscle were labeled by CB. The number and length of CB-labeled terminal Schwann cell processes decreased between 3 days and 1 month after denervation, suggesting that terminal Schwann cell processes are only transiently maintained in the absence of innervation. During reinnervation after nerve crush, however, terminal Schwann cell processes were extended in advance of axon sprouts, and these processes persisted until reinnervation was completed. By viewing the same junctions twice during reinnervation, we directly observed that axon sprouts used existing Schwann cell processes and chains of cell bodies as substrates for outgrowth. Thus, CB can be used to monitor the dynamic behavior of terminal Schwann cells, whose interactions with motor axons and their terminals are important for junction homeostasis and repair.

Animals↗
PubMed2005

Morphometric study of the nerves entering into the coracobrachialis muscle.

The nerves entering into the coracobrachialis muscle are the musculocutaneous nerve (MC) and the nerve (usually consists of several thin branches) branches to the coracobrachialis. These thin branches enter the coracobrachialis proximal to the MC. The thin branches and the MC are susceptible to injury during coracoid process transfer. The purpose of this study is (1) to reveal the number and origin of the thin branches and (2) especially to report the morphometric information about the two distances between the coracoid process and the points where the first thin branch and the MC enter the coracobrachialis. These distances were named as the "distance T1" and the "distance D," respectively. Forty-two cadaver upper extremities were used and the distance between the coracoid process and the medial epicondyle of the humerus as the "arm length" was measured. The "ratio T1" was calculated by dividing the distance T1 by the arm length. The "ratio D" was calculated by dividing the distance D by the arm length. The number of the thin branches varied between one and four. In the most common type, there were two thin branches (45%). All of the thin branches originated from the MC. The mean distance T1, distance D and arm length were found as 41.5, 62 and 304.5 mm, respectively. The mean ratio T1 and ratio D were determined as 0.13 (approximately 1/8) and 0.20 (=1/5), respectively. The findings about the number and origin of the thin branches may contribute to the anatomy of the nerve to the coracobrachialis. The shoulder surgeon may calculate the predicted distance T1 and distance D of any upper extremity, dividing its arm length by eight and five, respectively.

Adult↗
PubMed1990

Uridine branch acceptor is a cis-acting element involved in regulation of the alternative processing of calcitonin/CGRP-l pre-mRNA.

The human calcitonin/CGRP-I (CALC-I) gene contains 6 exons and encodes two polypeptide precursors. In thyroid C-cells, calcitonin (CT) mRNA is produced by splicing of exons 1-2-3 to exon 4 (CT-encoding) and polyadenylation at exon 4. CGRP-I mRNA is produced in particular neural cells by splicing of exons 1-2-3 to exon 5 (CGRP-I-encoding) and the polyadenylated exon 6. We previously reported that model precursor RNAs containing the exon 3 to exon 5 region of the CALC-I gene are processed predominantly into CGRP-I mRNA in vitro, in nuclear extracts of several cell types (neural and non-neural). Using truncated precursor RNAs containing only the exon 3 to exon 4 region of the CALC-I gene it was shown that CT splicing is an inefficient reaction in which a uridine residue serves as the major site of lariat formation. Here we report that the low CT splicing efficiency and the dominance of CGRP-I splicing over CT splicing in vitro are primarily due to the usage of the CT-specific uridine branch acceptor. Mutation of this uridine residue into an adenosine residue resulted in a strong increase in CT splicing efficiency causing a reversal of the splicing pattern. In addition, it was shown that this point mutation also increased CT splicing efficiency in vivo. These results and data obtained from other experiments involving mutation of the CT splice acceptor site suggest that the uridine branch acceptor is a cis-acting element involved in regulation of the alternative processing of the CALC-I pre-mRNA.

Adenosine↗
PubMed1983

Structure as revealed by airway dissection. A comparison of mammalian lungs.

Microdissection of mammalian pulmonary airways demonstrates branching patterns and provides precisely defined tissue samples for morphologic study. The dissections are performed on lung fixed by airway infusion at standard pressures. Using fine scissors and a high resolution dual-viewing dissecting microscope, extrapulmonary and intrapulmonary airways are dissected down their axial pathways. The plane of dissection is chosen to include as many minor daughter (side) branches as possible. Lungs from 5 species: sheep, goat, cat, rabbit, and bonnet monkey have been dissected, photographed, successive generations numbered, and pieces of tissue processed for LM, TEM, and SEM. Branching patterns differ between lobes (cranial versus caudal) of the same species and between the same lobe in different species. Marked differences in epithelial population distribution within the airway tree are found between the same lobe of different species (i.e., cranial lobes of rabbit and sheep) and between different lobes in the same species (i.e., cranial and caudal lobes of the sheep). The dissection approach to pulmonary airway morphologic studies provides specimens of precisely defined branching history, generation number, and anatomic position within regions of the lung and within specific segments. This allows studies that compare: (1) different airway generations in the same pathway, (2) bifurcation points and the airway segments between them, (3) terminal airways of differing pathway lengths and numbers of branching, (4) terminal airways of different regions of same lobe, (5) same airway generations in different lobes, and (6) same airway generations from animal to animal and species to species.

Animals↗
PubMed2003

Role for ETS domain transcription factors Pea3/Erm in mouse lung development.

During the development of the mouse lung, the expression of a number of genes, including those encoding growth factors and components of their downstream signaling pathways, is enriched in the epithelium and/or mesenchyme of the distal buds. In this location, they regulate processes such as cell proliferation, branching morphogenesis, and the differentiation of specialized cell types. Here, we report that the expression of Pea3 and Erm (or Etv5, Ets variant gene 5), which encode Pea3 subfamily ETS domain transcription factors, is initially restricted to the distal buds of the developing mouse lung. Erm is transcribed exclusively in the epithelium, while Pea3 is expressed in both epithelium and mesenchyme. Erm/Pea3 are downstream of FGF signaling from the mesenchyme, but their responses toward different FGFs are not the same. The functions of the two proteins were investigated by transgenic expression of a repressor form of Erm specifically in the embryonic lung epithelium. When examined at E18.5, the distal epithelium of transgenic lungs is composed predominantly of immature type II cells, while no mature type I cells are observed. In contrast, the differentiation of proximal epithelial cells, including ciliated cells and Clara cells, appears to be unaffected. A model is proposed for the role of Pea3/Erm during the dynamic process of lung bud outgrowth and proximal-distal differentiation, in response to FGF signaling. Our results provide the first functional evidence that Pea3 subfamily members play a role in epithelial-mesenchymal interactions during lung organogenesis.

Animals↗
PubMed1993

Diagnostic and therapeutic applications of angiogenesis research.

Certain principles of the angiogenic process elucidated in the laboratory over the past 3 decades have now been translated to clinical application. These applications are in the areas of prognosis, inhibition of angiogenesis, and acceleration of angiogenesis. As more experience is gained from these studies we may begin to see the development of therapies for many other angiogenic diseases, including diabetic retinopathy, rheumatoid arthritis, and psoriasis. It may be possible to increase the rate of neovascularization of a myocardial infarction and perhaps even to stimulate the growth of coronary collateral vessels. From these laboratory and clinical studies it has become clear that angiogenesis is a fundamental process that dominates diseases in many different branches of medicine and surgery. A clear understanding of the biological and molecular aspects of this process will be critical to the successful treatment of a wide spectrum of "angiogenic diseases" [53].

Humans↗
PubMed1997

Processing of recombination intermediates by the RuvABC proteins.

The RuvA, RuvB, and RuvC proteins in Escherichia coli play important roles in the late stages of homologous genetic recombination and the recombinational repair of damaged DNA. Two proteins, RuvA and RuvB, form a complex that promotes ATP-dependent branch migration of Holliday junctions, a process that is important for the formation of heteroduplex DNA. Individual roles for each protein have been defined, with RuvA acting as a specificity factor that targets RuvB, the branch migration motor to the junction. Structural studies indicate that two RuvA tetramers sandwich the junction and hold it in an unfolded square-planar configuration. Hexameric rings of RuvB face each other across the junction and promote a novel dual helicase action that "pumps" DNA through the RuvAB complex, using the free energy provided by ATP hydrolysis. The third protein, RuvC endonuclease, resolves the Holliday junction by introducing nicks into two DNA strands. Genetic and biochemical studies indicate that branch migration and resolution are coupled by direct interactions between the three proteins, possibly by the formation of a RuvABC complex.

Animals↗