By I. Curtis. College of Mount Saint Vincent.
Before a new method can contribute to industrial radionu- clide production it has to be demonstrated that its product satisfes the established quality criteria and ofen the new method has to be included in the drug master fles of the respective radiopharmaceuticals repaglinide 2mg low cost. Te administrative efort of validating and adding a new method is only justifed if it can contribute substantially to regional or global demand buy discount repaglinide 0.5mg on-line. Nuclear medicine is today recognised as an essential and cost-efcient method of supporting a variety of disciplines in medicine or achieving therapeutic success where other methods fail. Expected Mo production capacity and demand end (kerosene) that is brought by dangerous goods of 2016. Canada is assumed self-suffcient by cyclotron production of 99mTc, reducing the demand for 99Mo accordingly. Note that both activities are highly regulated, subject doses while exercising their profession. While fuel costs represent about a quarter of the expenses in aviation, in nuclear medicine they are less than 1% in the case for 99mTc scans. Tis suggests that perhaps the value of radionuclides, the fuel in nuclear medicine, is not widely appre- ciated. In many countries the radionuclides used in a nuclear medicine procedure are not reimbursed directly, but are considered as a simple auxiliary material similar to disposable syringes, plasters of bandages. It is mainly this economic aspect, and not physical or technical problems, that has been the root cause for occasional radionuclide supply dis- ruptions in the past. When discussing the prospects of other promising radionuclides that have advan- tageous properties for the patient, for radiation protection issues, and for overall cost-efective- ness, it must be made clear that these cannot be introduced or reach the use they deserve unless the essential value of radionuclides in nuclear medicine 135 therapies is better recognised and acknowledged by healthcare systems! A more selective pharmaceutical (right side) provides a a Tc diagnostic procedure given above are largely larger therapeutic window, i. Interestingly none of these countries therapeutic result the side efects are reduced or at supports at present their own 99Mo or 99mTc produc- a given level of side efects the therapeutic success tion. Tese general con- the market would favour delivery to certain non- siderations are valid for all types of therapy, but in producers if no political action is taken. Only the dose makes Tus uptake into the tumour can be visualised and that a thing is not poisonous. Only afer this verifcation the therapy dose does not cause a durable therapeutic efect since dose consisting of a therapeutic isotope coupled to the cancer cell s repair mechanisms recover from the same targeting vector is injected. A sufciently high dose that only those patients are treated who will most can destroy all cells without the possibility of recov- likely beneft from the treatment. With medium doses a proportion of the cells a quantitative analysis of the scout dose, i. Any therapy tries to stay in to adapt the therapy dose individually, thereby mak- the middle range, the so-called therapeutic window ing optimum use of the therapeutic window. Tis where a good therapeutic efect is achieved with method of personalised medicine is called theranos- acceptable side efects. If real matched pairs are not available one ofen resorts to nearly matched pairs of radio- isotopes from chemically similar elements, e. However, the degree of chemical resemblance has to be validated by in vivo experiments for every targeting vector and chelator combination. Usually such therapies are fractionated into smaller administered activities that are repeated regularly. Tus deviations in the uptake can be compensated for in the subsequent treatment cycle. Principle of theranostics: the distribution of pharmaceuticals varies from patient to patient, thus for a given administered amount (mass of normal pharmaceuticals, activity for radiopharmaceuticals) the resulting dose scatters correspondingly 3. With patient-specifc theranostics the scatter of the dose is reduced and a better therapeutic effect can be achieved. By measuring the real distribu- ture on enriched 176Lu targets in high fux reactors tion in an individual patient before the therapy, the provides a specifc activity of about 20 Ci/mg at the administered amount can be tailored accordingly to moment of production. Tus, afer delivery the ratio achieve the optimum dose and improve the success of radioactive 177Lu to total Lu is about 1:6 to 1:8. Ideally one should use radioisotopes of the targeting with higher specifc activity. Tis explains the particular interest for branch of the neutron capture reaction leads not to so-called matched pairs of one diagnostic and the useful 7/2+ ground state of 177Lu (T =6. In 2007, a century afer the discovery of 1/2 relative activity of 177mLu, or more when the decay lutetium, large-scale radiochemical separation was of 177gLu during transport is considered. In principle all (n,) reactions A long and tedious challenge for chemists could be replaced by (d,p) reactions with the same Ytterbium was frst chemically separated, and target/product combination. However, the (d,p) thus discovered as a new chemical element, in cross-sections are generally lower and so are the 1878. It took nearly thirty years until chemists deuteron currents available from accelerators and managed to separate the chemically very similar sustainable by the targets. For indirect production 137 lutetium from ytterbium, thus demonstrating paths the fnal product populated by (n,)- is also its existence as separate element. Te excitation century afer discovery of lutetium, a large- functions for 176Yb(d,p) and 176Yb(d,n) were recently scale radiochemical separation was developed measured [Man11]. Irradiating the same target (about 2 g mass) for a week in a thermal neutron fux Tus, depending on the free limit and local leg- of 1014 cm-2s-1 would produce ten times more 177Lu. Tis may represent a serious bottleneck for the application of this promising radioisotope. Here the spin selection and nuclear physics rules of beta decay ensure that 9/2+ 177Yb decays only to the wanted ground state and does not popu- Since its inception, nuclear medicine has been late the high-spin state 177mLu. Lu/Yb separation is particularly challenging since When the efects of ionising radiation were dis- these are neighbouring, chemically very similar covered, these were rapidly introduced into medical lanthanides. Afer ytterbium was frst chemically practice for treatments via brachytherapy (in French separated, and thus discovered as a new chemical still called Curie therapie) with 226Ra sources. In turn the industrial availability thus demonstrating its existence as separate element. Te separation of pure lutetium became possible, thus close collaboration of nuclear physicists and nuclear medicine and radiology physicians enabled many of laboratories is seen as a general pattern, which is the ground-breaking discoveries of the 20th century: worth remembering when considering the future Discovery of the neutron by Chadwick. Tis universal Te discovery of neutron moderation and its use workhorse of medical isotope production origi- for more efcient transmutation by Fermi was nated at the University of California Radiation based on a Rn/Be source with the 222Rn recovered Laboratory and the entire feld of cyclotron design from medical 226Ra sources. It seems an this fssionable material would be allocated to serve almost universal truth that the experimental scien- the peaceful pursuits of mankind. Experts would tist in basic physics sooner or later starts to think of be mobilised to apply atomic energy to the needs of medical applications. Tis food chain of innovation agriculture, medicine and other peaceful activities.
Conversely generic 2mg repaglinide visa, an elevated hematocrit is consistent with hemoconcentration such as occurs from dehydration or polycythemia generic 2 mg repaglinide mastercard. The white blood count may be elevated from epinephrine (white blood cell demargination from vessel walls), systemic corticosteroids (demargination and release from bone marrow), or infection. In the absence of prior systemic corticosteroids, the acutely ill patient with allergic or nonallergic asthma often has peripheral blood eosinophilia. However, in the management of most patients with asthma, both those with acute symptoms and long-term sufferers, eosinophil counts are not of value. The presence of eosinophilia in patients receiving long-term systemic corticosteroids should suggest noncompliance or possibly rare conditions, such as Churg-Strauss syndrome, allergic bronchopulmonary aspergillosis, or chronic eosinophilic pneumonia ( 136). Usually, the eosinophilia in asthma does not exceed 10% to 20% of the differential. Sputum examination reveals eosinophils, eosinophils plus polymorphonuclear leukocytes (asthma and purulent bronchitis or bacterial pneumonia), or absence of eosinophils. In severely ill patients with asthma, the sputum is thick, tenacious, and yellow or green. Dipyramidal hexagons from eosinophil cytoplasm may be identified and are called Charcot-Leydon crystals. Curschmann spirals are expectorated yellow or clear mucus threads that are remnants or casts of small bronchi. Expectorated ciliated and nonciliated bronchial epithelial cells can also be identified that emphasize the patchy loss of bronchial epithelium in asthma. On a related basis, high-molecular-weight neutrophil chemotactic activity has been identified in sera from patients with status asthmaticus ( 137). Serum electrolyte abnormalities may be present and should be anticipated in the patient presenting to the emergency department. Recent use of oral corticosteroids can lower the potassium concentration (as can b 2-adrenergic agonists) and cause a metabolic alkalosis. Oral corticosteroids may raise the blood glucose in some patients, as can systemic administration of b-adrenergic agonists. Because intravenous fluids will be administered, it is necessary to determine the current status of electrolytes and serum chemistry values. After prolonged high-dose corticosteroids, hypomagnesemia or hypophosphatemia may occur. Rarely, a patient younger than 30 years of age may be thought to have asthma when the underlying condition is a 1-antitrypsin deficiency. A properly performed sweat chloride test is essential, as is proper performance of other laboratory tests. In the outpatient management of asthma, determination of the presence or absence of antiallergen IgE is of value. For decades, skin testing for immediate cutaneous reactivity has been the most sensitive and specific method. One cannot emphasize enough the need for high quality control for both skin testing and in vitro testing. The experienced physician should use either method of demonstration of antiallergen IgE as adjunctive to, rather than a substitute for, the narrative history of asthma. More patients have immediate cutaneous reactivity or detectable in vitro IgE than have asthma that correlates with exposure to the specific allergen. Some patients develop psychological abnormalities because of the burden of a chronic illness such as asthma. Ineffectively treated asthma in children can result in chest wall abnormalities, such as pigeon chest, because of sustained hyperinflation of the chest. In general, long-term asthma does not result in irreversible obstructive lung disease. However, an occasional patient with long-term asthma develops apparently irreversible disease in the absence of cigarette smoking, a 1-antitrypsin disease, or other obvious cause ( 141). Usually, these patients have childhood-onset asthma and are dependent on oral corticosteroids. Nevertheless, pulmonary physiologic studies do not reveal return of parameters to the expected normal ranges. Asthma patients are not deficient in antiproteases that can be measured, and they do not have bullous abnormalities on chest radiographs. Pneumomediastinum or pneumothorax can occur in patients presenting in status asthmaticus. Neck, shoulder, or chest pain is common, and crepitations can be detected in the neck or supraclavicular fossae. Rupture of distal alveoli results in dissection of air proximally through bronchovascular bundles. The air can then travel superiorly in the mediastinum to the supraclavicular or cervical areas. At times, the air dissects to the face or into the subcutaneous areas over the thorax. Fatalities from asthma are unnecessary because asthma is not an inexorably fatal disease. Uncontrolled asthma can lead to mucus plugging of airways and frank collapse of a lobe or whole lung segment. Cough syncope or cough associated cyanosis occurs in patients whose respiratory status has deteriorated and in whom status asthmaticus or need for emergency therapy has occurred. During severe airway obstruction from asthma, during inspiration, intrathoracic pressure is negative because the patient must generate very high negative pressures to apply radial traction on bronchi in an attempt to maintain their patency. During expiration, the patient must overcome severe airway resistance and premature airways collapse. Increases in intrathoracic pressure during expiration with severe coughing, as compared with intraabdominal pressure, causes a decline in venous return to the right atrium. There may also be increased blood flow to the lung during a short inspiration, but that is accompanied by pooling in the pulmonary vasculature from the markedly elevated negative inspiratory pressure. There will be reduced blood flow to the left ventricle with temporary decreases in cardiac output and cerebral blood flow. Pulsus paradoxus is present when there is greater than a 10-mm Hg decline in systolic blood pressure during inspiration. The most frequent electrocardiographic findings during acute asthma are sinus tachycardia followed by right axis deviation, clockwise rotation, prominent R in lead V1 and S in lead V5, and tall peaked P waves consistent with cor pulmonale (151).
Intravenous saline is often needed because which predisposes to cardiac arrhythmias generic 2mg repaglinide visa. It may also many patients feel too nauseous to tolerate sufcient cause refractory hypotension and neuromuscular prob- oral uids and polyuria is common due to nephro- lems include tetany buy cheap repaglinide 1 mg line, seizures and emotional lability or genic diabetes insipidus. The preoperative assessment Neuromuscular manifestations Underlying any decision to perform surgery is a recog- Early symptoms include circumoral numbness, paraes- nition of the balance between the risk of the procedure thesiae of the extremities and muscle cramps. All patients un- but less specic symptoms include fatigue, irritability, dergo a preoperative assessment (history, examination confusion and depression. Myopathy with muscle weak- and appropriate investigations) both to review the diag- ness and wasting may be present. Carpopedal spasm nosis and need for surgery, and to identify any coexisting and seizures are signs of severe hypocalcaemia. Elici- disease that may increase the likelihood of perioperative tation of Trousseau s sign and Chvostek s signs should complications. In general any concerns regarding coex- be attempted, although it can be negative even in severe isting disease or tness for surgery should be discussed hypocalcaemia: with the anaesthetist who makes the nal decision re- r Trousseau s sign: Carpal spasm induced by ination of garding tness for anaesthesia. Cardiac disease by history, examination and, where appropriate, failure may occur. Elective surgery should be deferred by at caemia to guide management and to look for the under- least 6 months wherever possible. The serum calcium should be checked and r Hypertension should be controlled prior to any elec- corrected for serum albumin (see above). Blood should tive surgery to reduce the risk of myocardial infarction also be sent for magnesium, phosphate, U&Es and for or stroke. Chronic or complex arrhythmias should be Management discussedwithacardiologistpriortosurgerywherever This depends on the severity, whether acute or chronic possible. Mild hypocalcaemia is treated r Patients with signs and symptoms of cardiac failure with oral supplements of calcium and magnesium should have their therapy optimised prior to surgery where appropriate. Severe hypocalcaemia may be life- and require special attention to perioperative uid threatening and the rst priority is resuscitation as balance. Calcium gluconate contains only a third of the with a history of bacterial endocarditis should have amount of calcium as calcium chloride but is less irritat- prophylactic oral or intravenous antibiotic cover for ing to the peripheral veins. Patients must be asked pulmonary embolism, is a signicant postoperative about smoking and where possible should be encour- risk. Risk factors include previous history of throm- aged to stop smoking at least 6 weeks prior to surgery. Wherever possi- cated unless there are acute respiratory signs or severe ble, risk factors should be identied and modied (in- chronic respiratory disease with no lm in the last cluding stopping the combined oral contraceptive pill 12 months. Preop- coagulant or antiplatelet medication and chronic liver eratively all therapy should be optimised; pre- and disease may cause perioperative bleeding. Postopera- with known coagulation factor or vitamin K decien- tive analgesia should allow pain free ventilation and cies may require perioperative replacement therapy. Coagulation deciencies should be corrected tervention, but should have perioperative blood glu- prior to surgery and careful uid balance is essential. The patient s alcohol intake should be elicited; symp- r Patients on oral hypoglycaemic agents should omit toms of withdrawal from alcohol may occur during a their drugs on the morning of surgery (unless under- hospital admission. In more major surgery, or Pre-existing renal impairment predisposes to the devel- when patients are to remain nil by mouth for a pro- opment of acute tubular necrosis. Hypotension should longed period, intravenous dextrose and variable dose be avoided and urinary output should be monitored so intravenousshortactinginsulinshouldbeconsidered. Close In patients requiring emergency surgery there may not monitoring of blood sugar and urine for ketones is be enough time to identify and correct all coexistent essential. It is however essential to identify any cardiac, should convert back to regular subcutaneous insulin respiratory, metabolic or endocrine disease, which may therapy. Any anaemia, uid and nutrition may cause signicant injury if extravasation electrolyte imbalance or cardiac failure should be cor- occurs. Other complications of parenteral nutrition rected prior to surgery wherever possible. Specic guidelines regarding the use of perioperative an- tibiotic prophylaxis vary between hospitals but these are Postoperative complications generally used if there is a signicant risk of surgical site infection. Prophylaxis for immunod- sions, wound dehiscence) and complications secondary ecient patients requires expert microbiological advice. It requires aggressive management and may necessitate return Nutritional support in surgical patients to theatre. Reactive haemorrhage occurs from small Signicantnutritionaldeciencyimpairshealing,lowers vessels, which only begin to bleed as the blood pres- resistance to infection and prolongs the recovery period. Blood replacement may be Malnutrition may be present preoperatively particularly required and in severe cases the patient may need to in the elderly and patients with malignancy. Enteral nutrition is the treatment of choice in all pa- r Alow-grade pyrexia is normal in the immediate post- tients with a normal, functioning gastrointestinal tract. Liquid feeds either as a supplement or replacement pletion, renal failure, poor cardiac output or urinary may be taken orally, via a nasogastric tube or via a gas- obstruction. Liquid feeds may be whole protein, oligopep- isation (or ushing of the catheter if already in situ) tide or amino acid based. These also provide glucose, and a clinical assessment of cardiovascular status in- essential fats, electrolytes and minerals. Mixed Early postoperative complications occur in the subse- preparations of amino acid, glucose and lipid are used quent days. Parenteralnutritionishypertonic,irritantandthrom- High-risk patients should receive prophylaxis (see bogenic. Intestinal stulae may be managed con- including cannulae) and Streptococci or mixed organ- servatively with skin protection, replacement of uid isms. The organisms responsible for organ or space and electrolytes and parenteral nutrition. If such con- infections are dependent on the site and the nature servative therapy fails the stula may be closed surgi- of the surgical condition, e.
C5a (a fragment of C5) attracts neutrophils and macrophages to the site of interest buy 2 mg repaglinide with amex. C3a (a fragment of C3) causes smooth muscle contraction and stimulates basophils cheap 1mg repaglinide fast delivery, mast cells, and platelets to release histamine and other chemicals contributing to inflammation. C3b (another fragment of C3) stimulates the ingestion (opsonization) of the cells onto which the C3b is bound by monocytes and other phagocytic cells. Antigen Antibody Complexes Binding of antigen with antibody is noncovalent and reversible. The strength of the interaction is termed affinity and determines the relative concentrations of bound versus free antigen and antibody. The formation of antigen antibody complexes results into lattice-like aggregates of soluble antigen and antibody, and the efficiency of such binding is affected by the relative concentrations of antigen and antibody ( 2,3 and 4,47). When there is an excess of either antibody or antigen, the antigen antibody complexes tend to remain small and in solution. The optimal binding, producing large aggregates that fall out of solution, occurs when the concentrations of antibody and antigen are in equivalence. B lymphocytes mature in the bone marrow, and those destined to become T lymphocytes migrate to the thymus, where they mature. The bone marrow and thymus thus constitute the primary lymphoid organs of the immune system, as opposed to the secondary organs (e. The ability of the immune system to identify so many different antigens is based on a division of labor each lymphocyte (or clone of lymphocytes) is able to identify only one epitope or determinant. Thereafter, that cell and all of its clonal descendants express receptors with the same antigenic specificity. Other surface molecules and secreted products serve to define functional subsets of lymphocytes ( Table 1. The specificity of an immune response lies in the fact that the entry of a foreign antigen into the body stimulates only those lymphocytes whose receptors recognize and bind the determinants expressed on the antigen. Recognition of antigen by binding to the receptors of lymphoid cells often manifested by clonal proliferation of the stimulated cells 2. Differentiation and maturation of the stimulated cells to mature functional capacity 3. Establishment of immunologic memory Memory resides in a portion of the stimulated lymphocytes that do not carry out effector functions ( 51,52). Instead, they remain quiescent in the system, providing an enlarged pool of activated cells specific for the original stimulating epitope. As a result, subsequent exposures to that same epitope can produce faster and higher (secondary or anamnestic) responses than were seen in the initial (primary) response. Memory can persist for long periods of time and is primarily maintained by T lymphocytes. B Lymphocytes Immunoglobulins recognize and bind specific antigens and determinants. Each B cell, or clonally derived set of B cells, expresses only a single species of immunoglobulin and is capable of recognizing and binding to only a single epitope. Immunoglobulin can be either membrane bound or secreted, and these forms serve two different purposes: 1. When membrane-bound on a B-cell surface, immunoglobulin detects the antigen or epitope for which that particular B cell is specific. The binding of antigen to the surface immunoglobulin, together with help from T lymphocytes (proliferative and maturation factors), induces the B cell to proliferate and mature into a plasma cell that secretes large amounts of immunoglobulin or becomes a memory B cell (53). When secreted by plasma cells, immunoglobulin binds to the antigen of interest, tagging it for removal or for subsequent interaction with other cells and molecules (e. The binding specificity of the membrane-bound and secreted immunoglobulins from a single B cell or clonal set of B cells and plasma cells are essentially identical. However, as mentioned previously, mutations can occur and accumulate in the immunoglobulin-encoding genes of B lymphocytes undergoing proliferation after restimulation with antigen. Where the mutated immunoglobulins are capable of binding more tightly to the antigen, the cells producing those immunoglobulins are stimulated to proliferate more rapidly. In this way, an ongoing antibody response can generate new immunoglobulin varieties with higher affinity for the antigen in question, a process known as affinity maturation. T Lymphocytes T lymphocytes (T cells) also bear antigen-specific surface receptors. T cells include several different functional groups: Helper T cells initiate responses by proliferating and providing help to B cells and to other T cells (e. T-cell help consists of a variety of cytokines that are required for activation, proliferation, and differentiation of cells involved in the immune response, including the helper T cells themselves. These two particular subsets have been best characterized in mice, and comparable subsets are being identified in humans. The activated macrophages, which themselves have no specificity for antigen, then produce a localized inflammatory response arising 24 to 72 hours after antigenic challenge. The mechanisms by which T s cells carry out these + functions is currently a topic of intense debate, and some investigators question their existence altogether. The ontogeny, distribution, and functional roles of gd T lymphocytes are still not as well understood as those of ab T lymphocytes ( 65). K cells bear receptors capable of recognizing the Fc portion of bound immunoglobulins. The K cell has no specificity for the antigen that is bound to the antibody, only for the Fc portion of the bound antibody. Mast Cells and Granulocytes A variety of other cells are involved in some immune responses, particularly those involving inflammation ( Table 1. Neutrophils are drawn to sites of inflammation by cytokines, where their phagocytic activity and production of enzymes and other soluble mediators contribute to the inflammation. Eosinophils ( 75,76) are involved in immune responses against large parasites, such as roundworms, and are apparently capable of killing them by direct contact. These cells migrate to the fetal liver and then (beginning about 80 days after fertilization) to the bone marrow, where they remain for life. Primary lymphoid organs consist of the bone marrow and thymus, where B and T lymphocytes, respectively, mature. B cells undergo their development, including generation of immunoglobulin receptors, while in the bone marrow. This intimate contact between recirculating cells facilitates the close interactions needed to initiate immune responses and generate appropriately sensitized cells, whose activities may then be expressed throughout the body ( 2,3 and 4). B lymphocytes responding to T-dependent antigens require two signals for proliferation and differentiation: (a) the binding of their surface immunoglobulin by appropriate specific antigen, and (b) the binding of cytokines (e.