22 research outputs found
Typed letter, signed
No full textG. J. Bertocchini, South China Island Union Mission of Seventh-day Adventists, Hong Kong, to Elder H. E. McClure, Home Missionary Department, General Conference of SDA, Singapore, January 12, 1959, TLS, 2 pp.
-- Regarding General Conference film and his order for projectors to be shipped to various missions. As soon as the projectors are in hand, they will begin promoting the Bible Study plan
Branchial cleft and pouch anomalies in childhood: a report of 50 surgical cases
No full textBranchial abnormalities occur when there is disturbance in the maturation of the branchial apparatus during fetal development. Branchial anomalies are congenital lesions usually present in childhood, even if they can be diagnosed later for enlargement or infection. A correct diagnosis will lead to proper management: complete surgical excision is the treatment of choice. The purpose of this article is to present clinical features, diagnostic methods and surgical treatment of branchial anomalies in childhood, based on a series of 50 patients
carbon copy Typed Letter
No full textH. E. McClure, Home Missionary Secretary, to Elder G. J. Bertocchini, South China Island Union Mission, SDA, Hong Kong, January 15, 1959, ccTL, 2 pp.
-- Acknowledging Bertocchini’s letter of the 12th and the order for Hope For Today material. Informs Bertocchini that the Chinese and English filmstrips are not quite ready
Pancreaticoduodenectomy for malignancies in children
No full textMalignant tumors of the common bile duct or of the pancreas head are uncommon in childhood [Perez EA, Gutierrez JC, Koniaris LG, Neville HL, Thompson WR, Sola JE. Malignant pancreatic tumors: incidence and outcome in 58 pediatric patients. J Pediatr Surg. 2009; Jan; 44 (1): 197-203]. With radical surgery being the standard cure for nonmetastatic diseases, pancreaticoduodenectomy (PD) is the best choice when the tumor is localized in the head of the pancreas, or in the lower portion of the common bile duct. The purpose of the present study is to describe five consecutive children managed by PD, and reviewing the particular aspects and results of this rare procedure in children
Intrahepatic portal venous systems in children with noncirrhotic prehepatic portal hypertension: anatomy and clinical relevance
No full textChildren with extrahepatic portal hypertension typically present with cavernomatous transformation of the portal vein and a poorly defined intrahepatic portal vein system on conventional imaging. With the Meso-Rex Bypass becoming the gold-standard intervention for a cure, a precise assessment of the intrahepatic portal vein system provides helpful data for deciding whether a Meso-Rex Bypass is feasible or not
Anatomy of the Intrahepatic Portal Venous System in Children with Non-Cirrhotic Pre-Hepatic Portal Hypertension. Results of Wedged Retrograde Portography Imaging and Proposal for an Anatomo-Radiological Classification.
No full textPrehepatic portal hypertension with aneurysm of the portal vein: unusual but treatable malformative pattern
No full textPortal vein aneurysms (PVAs) are usually located at the vein trunk or at its bifurcation, rarely intra-hepatic, or at the umbilical portion. Etiology remains unclear
A proposed screening algorithm for bone remodelling
No full text14 p.-10 fig.One of the most remarkable aspects of human homeostasis is bone remodeling. This term denotes the continuous renewal of bone that takes place at a microscopic scale and ensures that our skeleton preserves its full mechanical compliance during our lives. We propose here that a renewal process of this type can be represented at an algorithmic level as the interplay of two different but related mechanisms. The first of them is a preliminary screening process, by means of which the whole skeleton is thoroughly and continuously explored. This is followed by a renovation process, whereby regions previously marked for renewal are first destroyed and then rebuilt, in such a way that global mechanical compliance is never compromised. In this work we pay attention to the first of these two stages. In particular we show that an efficient screening mechanism may arise out of simple local rules, which at the biological level are inspired by the possibility that individual bone cells compute signals from their nearest local neighbors. This is shown to be enough to put
in place a process which thoroughly explores the region where such mechanism operates.CFA, MAH and GEO have been partially supported by MINECO Grant MTM2017-
85020-P. JML was partially supported by grants PI18/01757 from Instituto de Salud
Carlos III (Madrid, Spain). FB is grateful to the Roechling Foundation for its support.Peer reviewe
Structure-function analysis on the level of individual synapses
No full textExcitatory synapses in the mammalian brain are made on small protrusions of the postsynaptic cell called dendritic spines. Dendritic spines are highly variable in their morphology and in their microanatomy (e.g. presence of subsynaptic organelles). It is unclear whether and how variability in spine morphological and anatomical properties translates into differences in synaptic function. Using two photon imaging, we analyzed how spine properties can affect synaptic signals and the potential for synaptic plasticity at single identified spine synapses. We show that synaptic signals can be tightly regulated on the level of individual synapses and that differences in spine morphology and microanatomy regulate synaptic function. We also provide evidence for the existence of functionally distinct populations of synapses in regard to their potential for synaptic plasticity. The present thesis is subdivided into three main sections. The first section is dedicated to the analysis of the function of specialized subsynaptic organelles in regulating synaptic plasticity. In the second section we studied the impact of spine morphology on synaptic signals and in the third section we examined whether critical proteins can be tagged to individual synapses in response to plasticity inducing stimuli.
In pyramidal cells, only a subset of dendritic spines contains endoplasmic reticulum (ER). Spine ER often forms a ‘spine apparatus’, a specialized organelle with unknown function. It is unclear whether these specialized subsynaptic structures can affect the function of the synapse on the spine head. The possible involvement of spine ER in shaping spine calcium transients, a key trigger for synaptic plasticity, raises the possibility that spine ER could modulate the potential of a given synapse to undergo activity dependent modifications. Using a genetic approach to label the ER in living neurons, we find that the ER preferentially localizes to spines containing strong synapses. We demonstrate that spine ER represents a specialized calcium signaling machinery required for the induction of metabotropic glutamate receptor dependent long term depression at individual synapses. We demonstrate that different subsets of synapses exist in regard to their potential to undergo specific forms of plasticity. Spine ER represents the anatomical correlate for a mechanism by which strong synapses can be retuned in an activity dependent manner.
Dendritic spines are separated from their parent dendrite by a thin spine neck. The spine neck slows down diffusion of molecules from the spine head to the parent dendrite, allowing spine-specific action of second messengers and activated enzymes. The resistance of the spine neck is crucial in determining whether spines can also be considered electrical compartments. Only a high enough spine neck resistance leads to electrical compartmentalization and activation of voltage gated channels in the spine in response to synaptic stimulation. We show that spine neck resistance can change in an activity dependent manner. Using single spine calcium imaging as a reporter of NMDA receptor activation and spine head depolarization, we show that spines can indeed act as electrical compartments. Using pharmacological experiments and modeling, we demonstrate that different voltage dependent channels cooperatively participate in shaping spine head depolarization and spine calcium transients. We also show that in vivo the spine neck resistance is higher compared to the situation in acutely sliced brain tissue, demonstrating that in the living animal a higher fraction of spines can be considered electrical compartments compared to the in vitro situation. We provide strong evidence that the spine neck can profoundly affect synaptic calcium signals. Biochemical and electrical compartmentalization is dynamically regulated in an activity dependent way.
Spine calcium signals can activate key signaling cascades responsible for the induction of synaptic plasticity. Long term potentiation (LTP) has been shown to require the activity of CaMKII, a serine/ threonine kinase. A chemical protocol leading to LTP has been shown to induce translocation of CaMKII to dendritic spines. It is however unclear whether this molecule acts at single synapses or whether it can spread and modulate neighboring synapses in response to more physiological protocols. Using a new optical approach to induce LTP at single visualized synapses, we show that LTP induction is accompanied by a long-lasting increase of CaMKII at the stimulated synapse. This increase was specific to the stimulated spine and did not spread to neighboring spines. We provide evidence that CaMKII acts locally, on the micrometer scale, to regulate plasticity. We show that the concentration of proteins involved in regulating synaptic plasticity can be tightly regulated at the level of single synapses
The role of ryanodine receptors in development
No full textPhDCalcium ions (Ca2+) are fundamental to the regulation of many cellular processes; however, the coordination of these signals during embryogenesis is not well understood. Ryanodine receptors (RyR) are a family of important intracellular ion channels that are responsible for the release of Ca2+ and they regulate the cytosolic Ca2+ concentration. Humans have three differentially expressed ryr genes (ryr1, ryr2 and ryr3) and mutations can cause both skeletal and cardiac diseases. Although the primary function of RyR is to mediate excitation-contraction coupling in muscle, they may also regulate Ca2+ signalling during developmental processes.
The project has addressed the role of RyR during embryonic development, using the zebrafish as an in vivo vertebrate model. Five zebrafish RyR genes (ryr1a, ryr1b, ryr2a, ryr2b and ryr3) were characterised and a comprehensive overview of their spatial and temporal expression in the embryo was determined. At 24 hours post-fertilisation (hpf), ryr1a, ryr1b and ryr3 are expressed in the skeletal muscle, ryr2a in specific neuronal populations and ryr2b in the cardiac muscle. Semi-quantitative PCR data and wholemount in situ hybridisation revealed strong maternal expression of ryr3 during the cleavage and blastula periods and into adulthood. The early expression of the ryr3 gene suggests that this receptor functions during the initial stages of development; a role that has not been described previously. The functional significance of RyR3 during early embryogenesis was investigated in a loss-of-
3
function model using antisense morpholino oligonucleotides. The ryr3 specific knockdown experiments appeared to affect the establishment of embryonic axis prior to the segmentation periods (before 10 hpf). In addition, by 19 to 20 hpf ryr3 morphants failed to exhibit spontaneous muscle contractions and displayed a defect in neuromuscular development.
In conclusion, this study has characterised the ryr genes and provided an overview on their temporal and spatial expression. The work provides evidence that ryr3 expression provides the Ca2+ vital for myofibrils organisation and that is required for the spontaneous movements during zebrafish embryonic development. The knowledge of RyR tissue distribution in zebrafish has provided a strong foundation for loss-of-function studies aimed at addressing their role in development. In the long term, the work will also facilitate more focused studies on disease.School of Biological and Chemical Sciences Queen Mary University of London.
Central Research Fund and Physiological Society Travel Grant
