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ORGANISATION OF TEACHING INTERNAL MEDICINE: The Department for Internal Medicine and Internal Clinics were founded in spring 1922. Dr. Radenko Stankovic and Dr. Dimitrije Antic were appointed as part-time Professors, while Dr. Aleksandar Ignjatovski, a former Full-time Professor of the Warsaw University, was appointed as professor under contract. A year later, Dr. Aleksandar Radosavljevic was appointed as Part-time Professor. In the General State Hospital and Military Hospital, certain wards were turned into clinics. II and III Internal Clinics were situated in the barracks, while the Propedeutic and I Internal Clinics were located in the Military Hospital. Upon the construction of the buildings of the Internal Clinic and General State Hospital, the Propedeutic and I Internal Clinics were permanently placed in the new building, and II and III Internal Clinics in the General State Hospital. Teaching of Internal Medicine started 31 October 1922. Dr. R. Stanko vic delivered a lecture in Propedeutics for students of the fifth term. This date marks the beginning of teaching internal medicine at the newly established School of Medicine, University of Belgrade. Dr. A. Ignjatovski started lecturing Internal medicine 23 March 1923, whereas Dr. D. Antic and and Dr. A. Radosavljevic also delivered lectures in the areas of Internal Medicine within their professional scope. At the beginning, the clinics belonged to the General State Hospital. It was impossible to teach successfully in hospital, therefore upon the professors' request, the clinics were separated and thus became the institutions belonging to the School of Medicine-educational institutions, while hospitals were health institutions. The rule was 'one professor--one clinic'. After the Second World War, teaching Internal Medicine was begun in demolished buildings in very difficult financial circumstances. The Propedeutic Internal clinic was renamed IV Internal Clinic, which continued dealing predominantly with cardiology. III and IV Internal Clinics were placed in the building of the Internal Clinic, II Internal Clinic remained in the General State Hospital and I Internal clinic was moved to the new building of the Institute for Oncology. REFORMS OF SCHOOL OF MEDICINE AND ITS CLINICS: Out of the School of Medicine, Veterinary Medicine, Pharmacy and Stomatology, the Grand Medical School was formed. After several years, it was closed down, and the schools were returned to the University. The most important alteration was made when, according to the Law, the Clinics were isolated from the School and proclaimed hospitals, health institutions and organised into the Clinical Centre of the School of Medicine, then University Clinical Centre, and finally the Clinical Centre of Serbia as the teaching base. Within city hospitals, later on Clinical Hospital Centres, the teaching bases for Internal Medicine and other subjects were established, with introducing self-management and the Law on Associated Labour with independent financing, there came hard times for the School of Medicine and Clinics. The Law had negative effects upon the Schools--University and it had to be abolished. The next step in the reform was merging of I and II Internal Clinics into the Internal B Clinic, within the Clinics, out of specialized departments for certain branches of Internal Medicine there were formed clinics (Clinic for Cardiology, Pulmonology, Endocrinology, Diabetes and Metabolic Diseases and so on). The Internal A Clinic was situated in the building of the General State Hospital and the Internal B Clinic in the building of the Internal Clinic, where there were also III and IV Internal Clinics. CONSTRUCTION OF CLINICAL CENTRE: After a long time, there were created conditions for constructing a new building for locating clinics--the Clinical Centre, the foundation stone was laid 20 October 1976, and the first phase including the polyclinics was completed 1 January 1983. The preliminary concept of the bed capacity of 30 to 50 at Internal Clinics was altered and the Institutes were established. Firstly, the Internal Clinics was altered and the Institutes were established. Firstly, the Internal A and B Clinics were joined into the Basic Organisation of Associated Labour Internal Medicine. Afterwards, certain specialized Internal Clinics with respective surgical branches were linked and the Institutes were established (Institute for Cardiovascular Diseases, Institute for Pulmonology and Tuberculosis, Institute for Endocrinology, Diabetes and Metabolic Diseases and so on). The Institutes were located at the former buildings of the clinics as well as the vacant buildings of the Military Medical Academy, which moved into the new modern building at Banjica. Thus, Internal Medicine was organisationally closed down, while assistants and professors were gathered at the Department for Internal Medicine which represented the organisation for teaching Internal Medicine. Professors and assistants from certain specialized Institutes taught certain disciplines, and at the Clinical Hospital Centre bases where teaching staff was deficient, the Clinical Centre professors were of assistance. A colossal Emergency Centre was established within the Clinical Centre, providing services for the whole of the Republic and beyond, which is completely illogical since it should be the Republic Health Institution rather than the part of the Clinical Centre. Also, the Clinical Centre as the health institution is enormous and represents the teaching base. The first directors were lawyers and, as of recently, professors of the School of Medicine. By separating Clinics from the School of Medicine, teaching and allied staff have a double working status as unique, so financially more potent health sector has gradually pushed aside the teaching one being rather underestimated in such organisation. Ministers for Health and Directors of the Clinical Centre great executive power for appointing directors. There started an uprecedented systematic degradation of teaching staff, since assistant professors or newly appointed associated professors were appointed as managers over their own teachers, full-time professors. It is unusual that those young people accepted their big, delicate roles to manage their professors in front of whom they had taken their board exams or defended their masters' and doctoral theses in not so distant past. There has only been one case of a junior professor refusing to be the director of his own professor. The stationary section of the Clinical Centre including the Internal Clinics was completely constructed but has not been equipped or occupied yet. Deans were authoriZed, by the University Law, to appoint professors and assistants. Thus, a large number of them were appointed without any high scientific and teaching quality standards, and afterwards promoted, while certain highly competent professors were dismissed from the University. By altering the system and passing the new University Law, the situation has improved and the University is returning to its roots. Today, such Clinical Centre as the teaching base of the School of Medicine and the School itself represent a big problem, primarily the financial one. Thus, it will be very hard to re-establish the right relationship between these two institutions.
PURPOSE: To provide an understanding of the structure, role, and responsibility of the International Federation of Ophthalmological Societies, the International Council of Ophthalmology, and the International Congress of Ophthalmology. These established entities have recently codified their statutes and regulations and registered them in Zurich, Switzerland. METHODS: The International Council of Ophthalmology, which serves as the executive body of the International Federation of Ophthalmological Societies, used historical operating documents to prepare the statutes and regulations, which were reviewed and adopted by the International Federation of Ophthalmological Societies at the 28th International Congress of Ophthalmology in Amsterdam on June 23, 1998. RESULTS: The statutes and regulations of the International Federation of Ophthalmological Societies, the International Council of Ophthalmology, and the International Congress of Ophthalmology are available to supranational ophthalmological organizations, national ophthalmological societies, other ophthalmological organizations, and individual ophthalmologists. CONCLUSIONS: The statutes and regulations of the International Federation of Ophthalmological Societies, the International Council of Ophthalmology, and the International Congress of Ophthalmology provide a basis for an organizational structure in international ophthalmology. The International Congress of Ophthalmology, first held in 1857, is the longest continuing international meeting in medicine. The International Council of Ophthalmology was established in 1927, and the International Federation of Ophthalmological Societies was formed in 1933. These organizations coordinate the International Congress of Ophthalmology, which convenes with the International Federation of Ophthalmological Societies every 4 years. The International Council, as the executive body, meets annually. The International Council of Ophthalmology has for decades worked to coordinate and facilitate interchange, education, and standards in international ophthalmology. Currently, the International Council of Ophthalmology, working with other international organizations, is creating an international ophthalmology strategic plan, which includes focus on ophthalmic training, continuing education, advocacy for the preservation and restoration of vision, clinical guidelines, and research.
Grafting an internal thoracic artery to a coronary artery with moderate stenosis remains controversial. Competitive flow from the native coronary artery has been proposed as the cause of distal narrowing and ultimate failure of the internal thoracic artery graft. We investigated intraoperative phasic blood flow in internal thoracic arteries grafted to coronary arteries with various degrees of stenosis and the influence of stenosis on postoperative angiographic findings. One hundred patients who underwent coronary artery bypass grafting of an internal thoracic artery to the left anterior descending coronary artery were divided into three groups according to degree of coronary stenosis. Group 1 included 39 patients who had 75% or less stenosis, group 2 included 34 patients with stenosis from 76% to 90%, and group 3 included 27 patients with stenosis greater than 90%. Mean flow and peak systolic flow of internal thoracic artery graft in group 1 were lower than those in group 2 (p < 0.01, p < 0.05). Peak diastolic flow in group 1 showed no difference from flows in groups 2 and 3. In eight patients in group 1, internal thoracic artery flow showed a predominant diastolic peak with characteristic systolic reversal as a result of competitive flow from the native coronary artery. Angiography at 1 month showed that the internal thoracic artery graft was patent in every case. Relative contributions of native coronary artery and internal thoracic artery flow to distal perfusion differed among the three groups (p < 0.001). In group 1, 15% of patients showed native-dominant flow, 62% showed balanced flow, and 23% showed internal thoracic artery-dependent flow. In group 2, 9% of patients showed native-dominant flow, 29% showed balanced flow, and 62% showed internal thoracic artery-dependent flow. In group 3, 96% of patients showed internal thoracic artery-dependent flow. String sign of the internal thoracic artery graft developed in only three patients; in two of these patients internal thoracic arteries were grafted to coronary arteries with stenosis of 50% or less and in the other patient there was competitive flow from a diagonal vein graft. Eleven of 13 internal thoracic arteries grafted to coronary arteries with stenosis of 50% or less did not show string sign. Competitive flow from a moderately stenotic coronary artery did not predispose the patient toward string sign of the internal thoracic artery graft in the presence of substantial diastolic internal thoracic artery flow. We conclude that internal thoracic artery grafting is acceptable for a moderately stenotic coronary artery.
OBJECTIVE: To examine the scope of intern prescribing practices by determining: the proportion of prescriptions that interns chart compared with other medical staff; the proportion of intern-charted prescriptions for which interns are sole decision-makers; whether or not intern-initiated prescribing varies with respect to the specialty to which they are attached, the shifts they are working and the types of charts they are using; the types of clinical conditions for which interns initiate prescribing decisions; and the drug classes that interns use for their self-initiated prescribing. DESIGN: Prospective study of a random sample of intern-charted prescriptions. SETTING: Two teaching hospitals of the Hunter Area Health Service, Newcastle, Australia. The study was conducted from the fifth to the eighth month of the intern training year. MAIN OUTCOME MEASURES: The proportion of prescriptions charted by interns that resulted from their own decision-making, the circumstances relating to this, clinical conditions for which they prescribe and drugs prescribed. RESULTS: A total of 17,895 prescriptions were examined--3437 (19%) were intern-charted. Interns reported they were the sole decision-makers for 19% (95% CI: 14 -24%) of prescriptions they had charted. Interns were more likely to initiate decisions in accident and emergency (OR=7.5, 95% CI: 2.2- 25.2) and obstetric and gynaecology (OR=2.3, 95% CI: 1.6 -3.2) rotations than in medicine and were more likely to initiate decisions on night (OR=7.3, 95% CI: 3.4- 15.5) and weekend (OR=1.7, 95% CI: 1.0 -3.2) shifts than during the day. They were also more likely to prescribe on the "as required" (OR=36.6, 95% CI: 20.6-65.0), "statim" (OR=26.1, 95% CI: 17.0- 40.1) and "intravenous" (OR=7.2, 95% CI: 4.3-12.3) charts compared with "regular" charts. A total of 52% of intern-initiated prescriptions were for symptom relief; pain, insomnia and nausea; and 75% of the drugs for which interns made independent decisions were analgesics, antithrombotic agents, psycholeptics, antispasmodics, laxatives and anti-asthmatic agents. CONCLUSION: Interns have a limited role with respect to independent prescribing and take the sole responsibility for only one-fifth of the prescriptions they chart. This limited, albeit safe, approach to prescribing may impact significantly on an intern's opportunity to acquire the skills necessary to become an independent, rational prescriber.
This publication contains the pediatric and neonatal sections of the 2005 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations (COSTR). The consensus process that produced this document was sponsored by the International Liaison Committee on Resuscitation (ILCOR). ILCOR was formed in 1993 and consists of representatives of resuscitation councils from all over the world. Its mission is to identify and review international science and knowledge relevant to cardiopulmonary resuscitation (CPR) and emergency cardiovascular care (ECC) and to generate consensus on treatment recommendations. ECC includes all responses necessary to treat life-threatening cardiovascular and respiratory events. The COSTR document presents international consensus statements on the science of resuscitation. ILCOR member organizations are each publishing resuscitation guidelines that are consistent with the science in this consensus document, but they also take into consideration geographic, economic, and system differences in practice and the regional availability of medical devices and drugs. The American Heart Association (AHA) pediatric and the American Academy of Pediatrics/AHA neonatal sections of the resuscitation guidelines are reprinted in this issue of Pediatrics (see pages e978-e988). The 2005 evidence evaluation process began shortly after publication of the 2000 International Guidelines for CPR and ECC. The process included topic identification, expert topic review, discussion and debate at 6 international meetings, further review, and debate within ILCOR member organizations and ultimate approval by the member organizations, an Editorial Board, and peer reviewers. The complete COSTR document was published simultaneously in Circulation (International Liaison Committee on Resuscitation. 2005 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. 2005;112(suppl):73-90) and Resuscitation (International Liaison Committee on Resuscitation. 2005 International Consensus Conference on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Resuscitation. 2005;67:271-291). Readers are encouraged to review the 2005 COSTR document in its entirety. It can be accessed through the CPR and ECC link at the AHA Web site: www.americanheart.org. The complete publication represents the largest evaluation of resuscitation literature ever published and contains electronic links to more detailed information about the international collaborative process. To organize the evidence evaluation, ILCOR representatives established 6 task forces: basic life support, advanced life support, acute coronary syndromes, pediatric life support, neonatal life support, and an interdisciplinary task force to consider overlapping topics such as educational issues. The AHA established additional task forces on stroke and, in collaboration with the American Red Cross, a task force on first aid. Each task force identified topics requiring evaluation and appointed international experts to review them. A detailed worksheet template was created to help the experts document their literature review, evaluate studies, determine levels of evidence, develop treatment recommendations, and disclose conflicts of interest. Two evidence evaluation experts reviewed all worksheets and assisted the worksheet reviewers to ensure that the worksheets met a consistently high standard. A total of 281 experts completed 403 worksheets on 275 topics, reviewing more than 22000 published studies. In December 2004 the evidence review and summary portions of the evidence evaluation worksheets, with worksheet author conflict of interest statements, were posted on the Internet at www.C2005.org, where readers can continue to access them. Journal advertisements and e-mails invited public comment. Two hundred forty-nine worksheet authors (141 from the United States and 108 from 17 other countries) and additional invited experts and reviewers attended the 2005 International Consensus Conference for presentation, discussion, and debate of the evidence. All 380 participants at the conference received electronic copies of the worksheets. Internet access was available to all conference participants during the conference to facilitate real-time verification of the literature. Expert reviewers presented topics in plenary, concurrent, and poster conference sessions with strict adherence to a novel and rigorous conflict of interest process. Presenters and participants then debated the evidence, conclusions, and draft summary statements. Wording of science statements and treatment recommendations was refined after further review by ILCOR member organizations and the international editorial board. This format ensured that the final document represented a truly international consensus process. The COSTR manuscript was ultimately approved by all ILCOR member organizations and by an international editorial board. The AHA Science Advisory and Coordinating Committee and the editor of Circulation obtained peer reviews of this document before it was accepted for publication. The most important changes in recommendations for pediatric resuscitation since the last ILCOR review in 2000 include: Increased emphasis on performing high quality CPR: "Push hard, push fast, minimize interruptions of chest compression; allow full chest recoil, and don't provide excessive ventilation" Recommended chest compression-ventilation ratio: For lone rescuers with victims of all ages: 30:2 For health care providers performing 2-rescuer CPR for infants and children: 15:2 (except 3:1 for neonates) Either a 2- or 1-hand technique is acceptable for chest compressions in children Use of 1 shock followed by immediate CPR is recommended for each defibrillation attempt, instead of 3 stacked shocks Biphasic shocks with an automated external defibrillator (AED) are acceptable for children 1 year of age. Attenuated shocks using child cables or activation of a key or switch are recommended in children <8 years old. Routine use of high-dose intravenous (IV) epinephrine is no longer recommended. Intravascular (IV and intraosseous) route of drug administration is preferred to the endotracheal route. Cuffed endotracheal tubes can be used in infants and children provided correct tube size and cuff inflation pressure are used. Exhaled CO2 detection is recommended for confirmation of endotracheal tube placement. Consider induced hypothermia for 12 to 24 hours in patients who remain comatose following resuscitation. Some of the most important changes in recommendations for neonatal resuscitation since the last ILCOR review in 2000 include less emphasis on using 100% oxygen when initiating resuscitation, de-emphasis of the need for routine intrapartum oropharyngeal and nasopharyngeal suctioning for infants born to mothers with meconium staining of amniotic fluid, proven value of occlusive wrapping of very low birth weight infants <28 weeks' gestation to reduce heat loss, preference for the IV versus the endotracheal route for epinephrine, and an increased emphasis on parental autonomy at the threshold of viability. The scientific evidence supporting these recommendations is summarized in the neonatal document (see pages e978-e988).
Cloned mammalian type II GnRH receptors have a carboxyl-terminal tail in contrast to the mammalian type I GnRH receptors, which uniquely lack a carboxyl-terminal tail. Because this domain mediates internalization of many serpentine receptors, the internalization pathway of the marmoset monkey type II GnRH receptor and the functional role of the carboxyl-terminal tail in internalization was studied. The internalization pathway of the type II GnRH receptor was investigated in COS-1 cells by coexpressing G protein-coupled receptor kinases (GRKs), dynamin-1, and beta-arrestins. Internalization of the receptor requires GRKs and dynamin but does not require beta-arrestin. The type II GnRH receptor can also internalize via beta-arrestin in the presence of exogenous beta-arrestins, suggesting that the receptor can use two distinct internalization pathways. Receptor internalization appears to occur via clathrin-coated pits and caveolae because disruption of either structure inhibits internalization. Progressive truncations of the carboxyl-terminal tail identified a region containing serine residues 338 and 339 as critical for receptor internalization. Substitution of these serine residues with alanine residues inhibited internalization, whereas substitutions with glutamic acid residues rescued internalization. Furthermore, a dominant-negative GRK2 did not inhibit internalization of receptors having these serine substitutions, although it inhibited internalization of the wild-type receptor. These results together identify serine residues 338 and 339 in the carboxyl-terminal tail as critical for internalization of the type II GnRH receptor and suggest that these residues undergo phosphorylation by GRKs. However, neither of these residues, nor the carboxyl-terminal tail, is required for beta-arrestin-dependent internalization.
PURPOSE: Bilateral ligation of the internal iliac arteries has been reported to be a safe procedure in pelvic surgery because there are five collateral pathways. Some of the five pathways are surgically interrupted after resection of the rectum and two cases in which necrosis developed in the perineum were reported. The aim of the study was to assess the degree of safety and blood flow reducing efficacy of internal iliac artery ligation in rectal cancer surgery. METHODS: The subjects were 23 patients with advanced rectal cancer. Tissue blood flow on the surface of the bladder was measured using a laser Doppler flow meter when unilateral or bilateral internal iliac artery were clamped at a central site or at a peripheral site. RESULTS: Tissue blood flow of the bladder before clamping the internal iliac artery was 6 to 74 ml/min/100 g. Blood flow in the right half of the bladder decreased significantly when the right and both internal iliac arteries were clamped (both, P < 0.01), but it did not decrease significantly when only the left internal iliac artery was clamped. The results were the same whether the central site or peripheral site was clamped. When the central site was clamped, there was no difference between the decrease in blood flow in the right half of the bladder whether the right internal iliac artery was clamped or both internal iliac arteries were clamped. By contrast, when the peripheral site was clamped, the decrease in blood flow in the right half of the bladder was much greater when both internal iliac arteries were clamped than when the right internal iliac artery alone was clamped (P < 0.01). The results in the left half were the same as in the right half. Blood flow became 33 to 110 (mean, 73; median, 75) percent of the value before clamping when both internal iliac arteries were clamped at the central site, and 18 to 114 (mean, 52; median, 47) percent when both internal iliac arteries were clamped at the peripheral site. No changes in the color of the bladder or other pelvic organs were observed while the internal iliac arteries were clamped. CONCLUSION: Our study suggests that bilateral internal iliac artery ligation causes a temporary decrease in blood flow to the pelvic organs, but the reduction is not great enough to induce necrosis histologically. We recommend the ligation of the internal iliac arteries at the point below the takeoff of the superior gluteal artery to gain a considerable blood flow reducing effect on the pelvic organs.
1. Receptor-dependent internalization of somatostatin (SRIF) agonists has been a matter of controversy probably because [125I]Tyr11-SRIF-14 is rapidly degraded. We have studied the internalization of a stable somatostatin analogue, [125I]-BIM-23027, in a neuronal cell line, Neuro2A, which natively expresses somatostatin sst2 receptors. 2. Incubation of Neuro2A cells with [125I]-BIM-23027 at 37 degrees C resulted in a time-dependent internalization of the ligand, which reached a maximum at 30 min. Acid-washing showed that cell-surface binding of the ligand accounted for only 34% of total binding at this time. Internalization was dramatically reduced at 15 degrees C. 3. Internalization of [125I]-BIM-23027 was prevented by inclusion of unlabelled somatostatin receptor agonists in a concentration-dependent manner. The IC50 values for inhibition of [125I]-BIM-23027 internalization were approximately 100 fold lower than for inhibition of [125I]-BIM-23027 binding to membrane homogenates but followed the same rank order of potencies. 4. Disruption of G-protein coupling by treatment with pertussis toxin caused a 60% reduction in internalization of ligand. A combination of antimycin (50 nM) and deoxyglucose (50 mM) pretreatment, which leads to a depletion of cellular ATP, decreased internalization of [125I]-BIM-23027 by 66% of control and increased the proportion of surface-bound ligand. Hypertonic sucrose, which prevents clathrin-mediated endocytosis, reversibly abolished the internalization of ligand without increasing the proportion bound at the cell surface. 5. After internalization of [125I]-BIM-23027, approximately half of the ligand was recycled back to the extracellular medium within 20 min at 37 degrees C. This finding suggests that the intracellular content of [125I]-BIM-23027 reaches a steady state which is determined by the rates of both internalization and recycling of the ligand. In contrast to studies in which the internalization of [125I]-Tyr11-SRIF-14 was examined, neither internalized nor recycled [125I]-BIM-23027 was degraded to its component amino acids. 6. These findings indicate that the somatostatin agonist, [125I]-BIM-23027, is internalized in a receptor-dependent manner which involves clathrin-coated pits in Neuro2A cells. Furthermore, much of the internalized ligand is rapidly recycled back to the extracellular medium without undergoing significant degradation.
Previous studies by our laboratory demonstrated that internalization of fibrinogen-bound alphaIIbbeta3 correlated with both a loss of aggregation and a loss of bound fibrinogen from the platelet surface. However, these studies do not address whether cellular activation, receptor activation and/or receptor occupancy are responsible for the observed internalization of alphaIIbbeta3. The present studies were designed to evaluate the roles of cellular and receptor activation states on the alphaIIbbeta3 internalization process. In these studies, washed platelets were allowed to bind FITC-D57, an antialphaIIb monoclonal antibody, and were subsequently treated with ADP, thrombin receptor activation peptide (TRAP) or antiLIBS6 monoclonal antibody. Following flow cytometric analyses for log green fluorescence, rabbit antifluorescein was added, and the samples were re-analyzed for residual/unquenched fluorescence. Because access of the quenching antibody is limited to extracellular/surface-associated fluorescein, protection from quenching by antifluorescein is taken as evidence of internalization. Stimulation of platelets with ADP or TRAP resulted in a significant increase in the percent internalization of alphaIIbbeta3 compared to control (8.7% and 12.8% vs. 2.9%). Addition of cytochalasin E prior to stimulation resulted in a greater than 90% inhibition of both TRAP and ADP-induced internalization, suggesting that activation-dependent internalization is mediated by the actin cytoskeleton. To investigate whether receptor activation increases the extent of alphaIIbbeta3 internalization, platelets were treated with anti-LIBS6, which directly activates alphaIIbbeta3. Stimulation with anti-LIBS6 caused an approximate 8-fold increase in the extent of alphaIIbbeta3 internalization. To evaluate whether the activated pool of alphaIIbbeta3 is preferentially internalized, platelets were incubated with PAC-1, an antibody specific for activated alphaIIbbeta3. Platelets stimulated with TRAP, demonstrated a dose-dependent internalization of PAC-1. However, approximately 29% of total PAC-1 binding was internalized, irrespective of TRAP concentration, suggesting that a constant proportion of activated alphaIIbbeta3 is selectively internalized in platelets. Collectively, these data suggest that alphaIIbbeta3 is internalized to a greater extent in activated platelets in a cytoskeleton-dependent manner. Furthermore, the active conformer of alphaIIbbeta3 is preferentially internalized which may act as a mechanism for downregulating adhesiveness of activated platelets in the circulation.
Beta-arrestins are key negative regulators and scaffolds of G protein-coupled receptor (GPCR) signalling. Beta-arrestin1 and beta-arrestin2 preferentially bind to the phosphorylated GPCRs in response to agonist stimulation, resulting in receptor internalization and desensitization. The critical roles of GPCR kinases (GRKs)-catalyzed receptor phosphorylation and interaction of beta-arrestins with the phosphorylated receptor in receptor internalization are well established. However, emerging evidence suggests that an agonist-stimulated internalization mechanism that is independent of receptor phosphorylation may also be employed in some cases, although the molecular mechanism for the phosphorylation-independent GPCR internalization is not clear. The current study investigated the role of receptor phosphorylation and the involvement of different beta-arrestin subtypes in agonist-induced delta-opioid receptor (DOR) internalization in HEK293 cells. Results from flow cytometry, fluorescence microscopy, and surface biotin labelling experiments showed that elimination of agonist-induced DOR phosphorylation by mutation GRK binding or phosphorylation sites only partially blocked agonist-induced receptor internalization, indicating the presence of an agonist-induced, GRK-independent mechanism for DOR internalization. Fluorescence and co-immunoprecipitation studies indicated that both the wild-type DOR and the phosphorylation-deficient mutant receptor could bind and recruit beta-arrestin1 and beta-arrestin2 to the plasma membrane in an agonist-stimulated manner. Furthermore, internalization of both the wild-type and phosphorylation-deficient receptors was increased by overexpression of either type of beta-arrestins and blocked by dominant-negative mutants of beta-arrestin-mediated internalization, demonstrating that both phosphorylation-dependent and -independent internalization require beta-arrestin. Moreover, double-stranded RNA-mediated interference experiments showed that either beta-arrestin1 or beta-arrestin2 subtype-specific RNAi only partially inhibited agonist-induced internalization of the wild-type DOR. However, agonist-induced internalization of the phosphorylation-deficient DOR was not affected by beta-arrestin1-specific RNAi but was blocked by RNAi against beta-arrestin2 subtype. These data indicate that endogenous beta-arrestin1 functions exclusively in the phosphorylation-dependent receptor internalization, whereas endogenous beta-arrestin2, but not beta-arrestin1, is required for the phosphorylation-independent receptor internalization. These results thus provide the first evidence of different requirement for beta-arrestin isoforms in the agonist induced phosphorylation-dependent and -independent GPCR internalization.
UNLABELLED: The uptake of radiolabeled somatostatin analogs by tumor cells through receptor-mediated internalization is a critical process for the in vivo targeting of tumoral somatostatin receptors. In the present study, the somatostatin receptor internalization induced by a variety of somatostatin analogs was measured with new immunocytochemical methods that allow characterization of trafficking of the somatostatin receptor subtype 2 (sst2), somatostatin receptor subtype 3 (sst3), and somatostatin receptor subtype 5 (sst5) in vitro at the protein level. METHODS: Human embryonic kidney 293 (HEK293) cells expressing the sst2, sst3, or the sst5 were used in a morphologic immunocytochemical internalization assay using specific sst2, sst3 and sst5 antibodies to qualitatively and quantitatively determine the capability of somatostatin agonists or antagonists to induce somatostatin receptor internalization. In addition, the internalization properties of a selection of these agonists have been compared and quantified in sst2-expressing CHO-K1 cells using an ELISA. RESULTS: Agonists with a high sst2-binding affinity were able to induce sst2 internalization in the HEK293 and CHO-K1 cell lines. New sst2 agonists, such as Y-DOTA-TATE, Y-DOTA-NOC, Lu-DOTA-BOC-ATE (where DOTA is 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid; TATE is [Tyr3, Thr8]-octreotide; NOC is [1-NaI3]-octreotide; and BOC-ATE is [BzThi3, Thr8]-octreotide), iodinated sugar-containing octreotide analogs, or BIM-23244 were considerably more potent in internalizing sst2 than was DTPA-octreotide (where DTPA is diethylenetriaminepentaacetic acid). Similarly, compounds with high sst3 affinity such as KE108 were able to induce sst3 internalization. In sst2- or sst3-expressing cell lines, agonist-induced receptor internalization was efficiently abolished by sst2- or sst3-selective antagonists, respectively. Antagonists alone had no effect on sst2 or sst3 internalization. We also showed that somatostatin-28 and somatostatin-14 can induce sst5 internalization. Unexpectedly, however, potent sst5 agonists such as KE108, BIM-23244, and L-817,818 were not able to induce sst5 internalization under the same conditions. CONCLUSION: Using sensitive and reproducible immunocytochemical methods, the ability of various somatostatin analogs to induce sst2, sst3, and sst5 internalization has been qualitatively and quantitatively determined. Whereas all agonists triggered sst2 and sst3 internalization, sst5 internalization was induced by natural somatostatin peptides but not by synthetic high-affinity sst5 agonists. Such assays will be of considerable help for the future characterization of ligands foreseen for nuclear medicine applications.
OBJECTIVES: In the last several years, there has been increasing interest in international emergency medicine (IEM) programs. A number of residency programs offer or encourage international opportunities during residency. The purpose of this study was twofold: 1) to determine whether the availability of international opportunities during residency affected the ranking of emergency medicine (EM) residency programs by graduating medical students and 2) to determine whether prior international health experience among medical students influences interviewing and ranking of residency programs with international opportunities. METHODS: An eight-question survey measuring interest in IEM and its effect on ranking of programs was mailed to all 1,205 first-year EM residents from 122 accredited allopathic EM residency programs in the United States. International opportunities were defined as any program that offered an international elective during residency or had an IEM fellowship. Data were analyzed using descriptive statistics and chi-square tests. RESULTS: Of the 1,205 mailed surveys, 34% were returned by the first-year residents. Of all respondents, 281/408 (69%) interviewed at programs with international opportunities. Study findings revealed 62% (164/264) of the students who interviewed at programs with international opportunities considered the availability of international opportunities a positive factor in ranking residency programs. Analysis revealed that applicants with previous international health experience, 68% (104/152), were more likely to rank EM residency programs with international opportunities higher than those that did not. CONCLUSIONS: This study suggests that the availability of international opportunities during residency positively affected residency ranking. This relationship was stronger in medical students with prior international health experience.
PURPOSE: The aim of lateral internal anal sphincterotomy when treating anal fissure is to divide the distal one-third to one-half of the internal anal sphincter. This study aimed to evaluate prospectively the extent of disruption to the internal anal sphincter following lateral anal internal sphincterotomy and also to establish the prevalence of symptoms of anal incontinence in these patients. METHODS: Fifteen patients with anal fissure (ten females and five males) had bowel symptoms assessed and anal endosonography performed preoperatively and two months after lateral internal anal sphincterotomy. RESULTS: Anal endosonography was normal preoperatively in all but two females who had anterior external sphincter defects (presumedly from previous obstetric trauma). Postoperatively, apart from one male in whom no defect could be identified, all had an internal anal sphincter defect corresponding to the site of lateral internal anal sphincterotomy. In nine of the ten females, the defect involved the full length of the internal anal sphincter, but in the other four males, the defect involved the distal internal anal sphincter only. All were continent preoperatively, but after lateral internal anal sphincterotomy, three females became incontinent to flatus (two of whom had a preoperative external sphincter defect). CONCLUSION: In contrast to lateral internal anal sphincterotomy in males, division of the internal anal sphincter in most females tends to be more extensive than intended. This is probably related to their shorter anal canal. In some females, lateral internal anal sphincterotomy may compromise sphincter function and precipitate anal incontinence, particularly in the presence of other sphincter defects. Care should be exercised especially in the presence of previous obstetric trauma, as internal anal sphincter division may further compromise sphincter function.
Many membrane-bound neurotransmitter receptors are known to be internalized by exposure to agonist. This agonist-induced receptor internalization is considered to play important roles in receptor-mediated signaling. Here we investigated the internalization of GAR-3, a Caenorhabditis elegans muscarinic acetylcholine receptor, using cultured mammalian cells. When Chinese hamster ovary cells stably expressing GAR-3 were treated with carbachol, GAR-3 was internalized in a dose- and time-dependent manner. Approximately 60% of the cell surface receptor was internalized by exposure to 1 mM carbachol for 1 h. Carbachol-induced GAR-3 internalization was suppressed by treatment with hypertonic sucrose, which blocks the formation of clathrin-coated pits. Overexpression of a dominant-negative dynamin mutant (DynK44A), but not of a dominant-negative beta-arrestin mutant (Arr319-418), substantially inhibited carbachol-induced internalization of GAR-3. Thus, these data suggest that GAR-3 undergoes agonist-induced internalization via a clathrin- and dynamin-dependent but beta-arrestin-independent pathway. Depletion of Ca2+ by simultaneous treatment of the cells with BAPTA/AM (Ca2+ mobilization blocker) and EGTA (Ca2+ influx blocker) almost completely blocked agonist-induced GAR-3 internalization. Moreover, treatment of the cells with the Ca2+ ionophore A23187 led to GAR-3 internalization in the absence of agonist. These results indicate that Ca2+ plays a critical role in GAR-3 internalization. We tested whether the third intracellular (i3) loop of GAR-3 is involved in agonist-stimulated receptor internalization. A GAR-3 deletion mutant lacking a large central portion of the i3 loop exhibited an internalization pattern comparable to that of the wild type, suggesting that the central i3 loop is not required for the internalization of GAR-3.
OBJECTIVE: To determine the relative risk of sternal dehiscence in patients undergoing bilateral internal thoracic artery harvesting and to assess whether and to what extent the technique of artery skeletonization might reduce this risk. METHODS: Prospectively collected data on patients undergoing coronary artery bypass operations with at least a single internal thoracic artery were reviewed. The last 450 patients receiving bilateral internal thoracic artery grafts were compared with 450 patients who received a single internal thoracic artery during the same period. The left internal thoracic artery was always harvested in a pedicled fashion. Among patients receiving a bilateral internal thoracic artery, both arteries were harvested in a pedicled fashion in 300 cases, whereas both internal thoracic arteries were skeletonized in the remaining 150 cases. RESULTS: Compared with a single internal thoracic artery, harvesting both internal thoracic arteries either in a skeletonized or in a pedicled fashion increased the chance of deep (1.1% vs 3.3% vs 4.7%; P = .01) or superficial (4.8% vs 7.8% vs 12%; P = .002) sternal infection. However, the technique of artery harvesting (odds ratio, 4.1; 95% confidence interval, 1.4-12.1); the presence of peripheral arteriopathy (odds ratio, 3.1; 95% confidence interval, 1.2-8.5), and resternotomy for bleeding (odds ratio, 8.2; 95% confidence interval, 2.0-33.6) were the only independent predictors for deep sternal infection, whereas the technique of artery harvesting (odds ratio, 3.0; 95% confidence interval, 1.6-5.4), female sex (odds ratio, 2.2; 95% confidence interval, 1.2-4.2), and diabetes (odds ratio, 1.7; 95% confidence interval, 1.0-2.9) were the only independent predictors of superficial sternal infection. In diabetic patients, there was no difference in the incidence of deep sternal infection among patients receiving a single internal thoracic artery or double skeletonized internal thoracic arteries ( P = .4). CONCLUSIONS: Bilateral internal thoracic artery harvesting carries a higher risk of sternal infection than harvesting a single internal thoracic artery. Skeletonization of both internal thoracic arteries significantly decreases this risk. A strategy of bilateral thoracic artery grafting can also be offered to patients at high risk for wound infection.