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As predicted by Moore in 1965 discount 100mg viagra sublingual with visa, central processing units (CPUs) nearly double in speed of operation every 12 to 18 months purchase viagra sublingual 100mg with amex. While some in the industry predict an 162 Shahram Ghandeharizadeh end to this trend with compound semiconductors, there are alternatives, such as the superconducting metal niobium that can support 100-GHz processors (Brock et al. Second, the cost of storing data is dropping by approxi- mately a factor of 2 every 12 to 18 months, with industry o¤ering smaller devices. At the time of this writing, 200-gigabyte disk drives are common- place. With rapid advances in disk head technology that can pack magnetic disks with a large amount of data per square centimeter (Comerford, 2000), magnetic disks that o¤er terabytes of storage should be available in a few years. Third, rapid ad- vances in both wire-based and wireless communication technology enable devices to exchange data rapidly. One may observe bandwidths on the order of tens of megabits per second from 802. Fourth, the power consumption of these devices decreases every year, in turn reducing the amount of heat produced. One area that deserves greater scrutiny is the mechanical nature of haptic devices. First, they should be designed to minimize the likelihood of physical injury to their users. Second, they should become more reliable and user friendly in order to be accepted for general use. In the next section we describe tech- niques to support data retrieval and the spatiotemporal characteristics of data. Continous Media and Haptic Devices The data generated by each sensor of a haptic glove consist of continuous media with a prespeciﬁed bit rate requirement. If a system delivers a movement more slowly than its prespeciﬁed rate without special precautions, the user might observe logical errors that result in undesirable behavior; for example, with chopsticks, either one or both sticks might fall out of place. A second important characteristic of the haptic glove is the temporal constraints that exist between multiple streams. Moreover, during the play mode, the system must ensure that the retrieval and rendering of data respect these temporal constraints. Otherwise, once again, the resulting motor activity might fail to perform the required task, for example, causing one or both chopsticks to fall. Both types of Real-Time Spatiotemporal Databases 163 logical errors are collectively termed hiccups (Ghandeharizadeh and Ramos, 1993). In the following discussion, we start by describing a scalable server to store the stream generated by a haptic glove and support hiccup-free displays. Next, we focus on how to capture the temporal relationships between the di¤erent streams (i. Finally, we explain how we intend to relate the di¤erent streams to the di¤erent joints and muscle groups in a hand to facilitate query processing. MITRA: A Scalable Continuous Media Server From 1993 to 1999, we conducted pioneering research to support a multimedia server that can store and retrieve continuous media. This research focused on multi- user systems that (1) employ o¤-the-shelf hardware; (2) have a software architecture that can scale as a function of the underlying hardware platform to support thou- sands of simultaneous streams; (3) utilize hierarchical storage structures to minimize cost; (4) use intelligent data placement techniques, disk scheduling algorithms, and bu¤ering schemes to enhance either the cost-e¤ectiveness of a conﬁguration (compet- itive cost per stream) or experience by minimizing latency, that is, the amount of delay incurred from the time a user requests a stream to the start of a display. Attached to each PC is an Adaptec small computer system interface (SCSI) card with several magnetic disks. The system can show audio and video data encoded in di¤erent for- mats, for example, Motion Picture Experts Group (MPEG). Simultaneous with our implementation e¤orts, other investigators conducted pioneering research on fault-tolerant techniques to support continuous media, for example, Berson et al. MITRA implements a simple mirroring technique to ensure the availability of data when these are disk failures. However, it can be extended to incorporate the more elaborate designs found in the literature. To minimize the cost of storage with large datasets, MITRA is designed to support a hierarchical storage structure consisting of either one or multiple tertiary storage devices, D disks, and M megabytes of memory (Ghandeharizadeh et al. Streams are materialized on the disk drives on demand (and deleted when the disk storage capacity is exhausted). A small fraction of a stream is staged in memory to support its display (see next para- graph for details). We have analyzed pipelining algorithms that stage portions of a 164 Shahram Ghandeharizadeh stream intelligently from the tertiary storage onto magnetic storage to minimize the latency incurred when displaying a stream (Ghandeharizadeh et al. At the ﬁle system level, each stream that constitutes a task is partitioned into a se- quence of blocks. When the task is referenced, a block of each stream is staged from disk into memory for display, assuming that they are resident on a disk; otherwise, they must be either staged or pipelined from tertiary; see Ghandeharizadeh et al. Moreover, resources are scheduled intelligently to prevent data starvation. This ensures the availability of the right block at the right time for rendering (Ghandeharizadeh and Muntz, 1998; Gemmell et al. Moreover, it maximizes the number of simultaneous streams supported by a system conﬁgured with a ﬁxed amount of resources. With D disks, the data blocks that constitute a stream are dispersed across all disks to distribute the load imposed by the retrieval of that stream evenly across the D disks (this is an important consid- eration when scalability is an objective).
The drugs are also associated with less thrombocy- with standard heparin or LMWHs purchase viagra sublingual 100 mg amex. CHAPTER 57 DRUGS THAT AFFECT BLOOD COAGULATION 839 Fondaparinux produces anticoagulant effects by directly drugs usually are not used for antiplatelet effects cheap viagra sublingual 100mg without prescription. However, binding to circulating and clot-bound factor Xa, accelerating clients who take an NSAID daily (eg, for arthritis pain) may the activity of antithrombin and inhibiting thrombin produc- not need to take additional aspirin for antiplatelet effects. It is used in the prevention of DVT in clients having Acetaminophen does not affect platelets in usual doses. Adenosine Diphosphate Receptor Antagonists Lepirudin, bivalirudin, and argatroban are direct throm- bin inhibitors that prevent blood coagulation by inactivating Ticlopidine inhibits platelet aggregation by preventing ADP- thrombin. They are used as a heparin substitute for clients who induced binding between platelets and ﬁbrinogen. The drug is indicated for prevention of thrombotic stroke in people who have had Antiplatelet Drugs stroke precursor events (eg, TIAs) or a completed thrombotic stroke. Ticlopidine is considered a second-line drug for Antiplatelet drugs prevent one or more steps in the pro- clients who cannot take aspirin. As described previously, tropenia, diarrhea, skin rashes) and greater cost make it pro- platelet activity is very important in both physiologic hemo- hibitive for use by many clients. Arterial thrombi, which active bleeding disorders (eg, GI bleeding from peptic ulcer are composed primarily of platelets, may form on top of ath- or intracranial bleeding), neutropenia, thrombocytopenia, se- erosclerotic plaque and block blood ﬂow in the artery. It is Drugs used clinically for antiplatelet effects act by a variety highly protein bound (98%), extensively metabolized in the of mechanisms to inhibit platelet activation, adhesion, aggre- liver, and excreted in urine and feces. These include drugs that block drugs, there is increased risk of bleeding with ticlopidine. It is indicated for reduction of myocardial in- farction, stroke, and vascular death in clients with atheroscle- rosis and reportedly causes fewer or less severe adverse Thromboxane A2 Inhibitors effects than ticlopidine. Aspirin is a commonly used analgesic–antipyretic–anti- inﬂammatory drug (see Chap. Aspirin exerts pharmacologic actions by inhibiting synthesis of prostaglandins. In this instance, aspirin acetylates Abciximab is a monoclonal antibody that prevents the bind- cyclooxygenase, the enzyme in platelets that normally synthe- ing of ﬁbrinogen, von Willebrand factor, and other molecules sizes thromboxane A2, a prostaglandin product that causes to GP IIb/IIIa receptors on activated platelets. A single dose of 300 to 600 mg nary angioplasty or removal of atherosclerotic plaque to pre- or multiple doses of 30 mg (eg, daily for several days) inhibit vent rethrombosis of treated arteries. It is used with aspirin the cyclooxygenase in circulating platelets almost completely. Aspirin may be used long term for prevention contraindications include active bleeding, thrombocytopenia, of myocardial infarction or stroke, and in clients with pros- history of a serious stroke, surgery or major trauma within the thetic heart valves. It is also used for the immediate treatment previous 6 weeks, uncontrolled hypertension, or hypersensi- of suspected or actual acute myocardial infarction, for transient tivity to drug components. Ad- Eptiﬁbatide and tiroﬁban inhibit platelet aggregation by verse effects are uncommon with the small doses used for preventing activation of GP IIb/IIIa receptors on the platelet antiplatelet effects. However, there is an increased risk of surface and the subsequent binding of ﬁbrinogen and von bleeding, including hemorrhagic stroke. Antiplatelet effects occur dur- mately 85% of strokes are thrombotic, the beneﬁts of aspirin ing drug infusion and stop when the drug is stopped. The or other antiplatelet agents are thought to outweigh the risks of drugs are indicated for acute coronary syndrome (eg, unsta- hemorrhagic strokes (approximately 15%). Their antiplatelet effects subside and 2 hours for tiroﬁban; the drugs are cleared mainly by when the drugs are eliminated from the circulation and the renal excretion. With tiroﬁban, plasma clearance is approxi- 840 SECTION 9 DRUGS AFFECTING THE CARDIOVASCULAR SYSTEM mately 25% lower in older adults and approximately 50% boembolism after cardiac valve replacement and is given lower in clients with severe renal impairment (creatinine with warfarin. The drugs are contraindicated in clients with hypersen- sitivity to any component of the products; current or previ- Thrombolytic Agents ous bleeding (within the previous 30 days); a history of thrombocytopenia after previous exposure to tirofiban; a Thrombolytic agents are given to dissolve thrombi. They history of stroke within 30 days or any history of hemor- stimulate conversion of plasminogen to plasmin (also called rhagic stroke; major surgery or severe physical trauma ﬁbrinolysin), a proteolytic enzyme that breaks down ﬁbrin, within the previous month; severe hypertension (systolic the framework of a thrombus. The main use of thrombolytic blood pressure >180 mm Hg with tirofiban or >200 mm Hg agents is for management of acute, severe thromboembolic with eptifibatide, or diastolic blood pressure >110 mm Hg disease, such as myocardial infarction, pulmonary embolism, with either drug); a history of intracranial hemorrhage, neo- and iliofemoral thrombosis. Heparin and warfarin above (for the 180 mcg/kg bolus and the 2 mcg/kg/min in- are given after completion of thrombolytic therapy. Throm- fusion) or 4 mg/dL or above (for the 135 mcg/kg bolus and bolytic drugs are also used to dissolve clots in arterial or the 0. Alteplase, reteplase, and tenecteplase are tissue plas- Bleeding is the most common adverse effect, with most minogen activators used mainly in acute myocardial infarction major bleeding occurring at the arterial access site for car- to dissolve clots obstructing coronary arteries and re-establish diac catheterization. If bleeding occurs and cannot be con- perfusion of tissues beyond the thrombotic area. The drugs trolled with pressure, the drug infusion and heparin should bind to ﬁbrin in a clot and act locally to dissolve the clot. Phosphodiesterase Inhibitor Streptokinase and urokinase are enzymes that break down Cilostazol inhibits phosphodiesterase, an enzyme that me- ﬁbrin. They are used mainly to lyse coronary artery clots in tabolizes cyclic adenosine monophosphate (cAMP). Streptokinase may also be used to hibition increases intracellular cAMP, which then inhibits dissolve clots in vascular catheters and to treat acute, severe, platelet aggregation and produces vasodilation. Urokinase versibly inhibits platelet aggregation induced by various is recommended for use in clients allergic to streptokinase. As stimuli (eg, thrombin, ADP, collagen, arachidonic acid, epi- with other anticoagulants and thrombolytic agents, bleeding is nephrine, and shear stress).
Observe for therapeutic effects Therapeutic effects depend on the reason for use generic 100mg viagra sublingual amex. When nasal decongestants are given order viagra sublingual 100mg line, observe for decreased The goal of antitussive therapy is to suppress nonpurposeful nasal obstruction and drainage. With cold and allergy remedies, observe for decreased nasal congestion, rhinitis, muscle aches, and other symptoms. With nasal decongestants, observe for: (1) Tachycardia, cardiac dysrhythmias, hypertension These effects may occur with any of the adrenergic drugs (see Chap. When adrenergic drugs are used as nasal decongestants, cardiovascular effects are more likely to occur with oral agents. However, topically applied drugs also may be systemically ab- sorbed through the nasal mucosa or by being swallowed and ab- sorbed through the gastrointestinal tract. With antitussives, observe for: (1) Excessive suppression of the cough reﬂex (inability to This is a potentially serious adverse effect because retained secre- cough effectively when secretions are present) tions may lead to atelectasis, pneumonia, hypoxia, hypercarbia, and respiratory failure. When narcotics are given for antitussive effects, how- ever, they are given in relatively small doses and are unlikely to cause adverse reactions. With combination products (eg, cold remedies), observe for Adverse effects are rarely signiﬁcant when the products are used adverse effects of individual ingredients (ie, antihistamines, as prescribed. There may be subtherapeutic doses of one or more adrenergics, analgesics, and others) component drugs, especially in over-the-counter formulations. Also, the drowsiness associated with antihistamines may be offset by stimulating effects of adrenergics. Ephedrine, for example, has central nervous system (CNS)–stimulating effects. Drugs that increase effects of nasal decongestants: These interactions are more likely to occur with oral decongestants than topically applied drugs. Drugs that increase antitussive effects of codeine: (1) CNS depressants (alcohol, antianxiety agents, barbitu- Additive CNS depression. Codeine is given in small doses for anti- rates, and other sedative-hypnotics) tussive effects, and risks of signiﬁcant interactions are minimal. Drugs that alter effects of dextromethorphan: (1) MAO inhibitors This combination is contraindicated. Apnea, muscular rigidity, hyperpyrexia, laryngospasm, and death may occur. Drugs that may alter effects of combination products for Interactions depend on the individual drug components of each coughs, colds, and allergies: formulation. Risks of clinically significant drug interactions are increased with use of combination products. Review and Application Exercises Answer: Sudafed is an adrenergic agent whose use is contraindi- cated in hypertensive clients because it signiﬁcantly increases 1. Who should usually avoid OTC nasal decongestants and traindications to any medication she or he administers. When re- questing an order from a physician who does not know the patient cold remedies? What are advantages and disadvantages of multi-ingredient medications that may interact. Given a client who uses echinacea, vitamin C, or zinc lozenges and asks you what you think about the products as cold remedies, how would you reply? Nursing Notes: Apply Your Knowledge SELECTED REFERENCES Answer: Joan has the symptoms of a cold. Pathophysiology: Concepts of altered health getting adequate rest and drinking lots of ﬂuids. List cardiovascular disorders for which drug vessels, and blood in supplying oxygen and therapy is a major treatment modality. Describe the role of vascular endothelium in manage cardiovascular disorders. Discuss atherosclerosis as the basic disorder causing many cardiovascular disorders for which drug therapy is required. The right ventricle sends deoxygenated blood The cardiovascular or circulatory system is composed of the through the pulmonary circulation. The general functions of the because it contracts against minimal pressure. The left ventri- system are to carry oxygen, nutrients, hormones, antibodies, cle pumps oxygenated blood through the systemic circuit. It is and other substances to all body cells and to remove waste much more muscular and thick walled because it contracts products of cell metabolism (carbon dioxide and others). A muscular wall called the septum separates the right the quality and quantity of blood. HEART Layers The heart is a hollow, muscular organ that functions as a two- The layers of the heart are the endocardium, myocardium, and sided pump to circulate ﬁve to six liters of blood through the epicardium. It is continuous with the endothelial lining of blood described in the following sections. The myocardium is the strong muscular layer of the heart that provides the pumping power for circulation of blood. The right atrium receives de- oxygenated blood from the upper part of the body by way of Valves the superior vena cava, from the lower part of the body by way of the inferior vena cava, and from veins and sinuses within the Heart valves function to maintain the one-way ﬂow of blood heart itself. The mitral valve separates the left 739 740 SECTION 9 DRUGS AFFECTING THE CARDIOVASCULAR SYSTEM atrium and left ventricle. The tricuspid valve separates the muscle functions to maintain blood pressure and blood ﬂow. The pulmonic valve separates It contracts and relaxes in response to numerous stimuli, in- the right ventricle and pulmonary artery. Overall, regulation of tone in vascular smooth muscle depends on the intracellular con- Conduction System centration of calcium ions.
Describe general characteristics and functions adenosine monophosphate and calcium within of hormones purchase 100 mg viagra sublingual free shipping. Differentiate between physiologic and pharma- relation to site of action and pharmacokinetics buy 100mg viagra sublingual with visa. For example, lung tumors may produce corticotropin (adrenocorticotropic hormone [ACTH]), The endocrine system participates in the regulation of es- antidiuretic hormone, or parathyroid hormone; kidney tumors sentially all body activities, including metabolism of nutri- may produce parathyroid hormone. The usual effects are those ents and water, reproduction, growth and development, and of excess hormone secretion. This chapter focuses on the traditional endocrine organs The major organs of the endocrine system are the hypothal- and their hormones. Speciﬁc organs are discussed in the fol- amus, pituitary, thyroid, parathyroids, pancreas, adrenals, lowing chapters; general characteristics of the endocrine sys- ovaries, and testes. These tissues function through hormones, tem and hormones are described in the following sections and substances that are synthesized and secreted into body ﬂuids in Box 22–1. Hormones act as chemical messengers to transmit information between body cells and organs. Most hormones ENDOCRINE SYSTEM– from the traditional endocrine glands are secreted into the NERVOUS SYSTEM INTERACTIONS bloodstream and act on distant organs. In addition to the major endocrine organs, other tissues The endocrine and nervous systems are closely connected, also produce hormones. These endocrine-like cells intermin- anatomically and physiologically, and work in harmony to in- gle with nonendocrine cells in various organs. In general, the nervous mones are secreted into tissue ﬂuids and act locally on nearby system regulates rapid muscular and sensory activities by se- cells, as in the following examples: creting substances that act as neurotransmitters, circulating • Gastrointestinal mucosa produces hormones that are hormones, and local hormones (eg, norepinephrine, epineph- important in the digestive process (eg, gastrin, entero- rine). The endocrine system regulates slow metabolic activities gastrone, secretin, and cholecystokinin). Thus, • Many body tissues produce prostaglandins and leuko- secretion of almost all hormones from the pituitary gland is trienes, which have a variety of physiologic effects. In endocrine tis- nating in the hypothalamus and ending in the posterior pitu- sues, neoplasms may be an added source of the hormone nor- itary gland control secretions of the posterior pituitary. In nonendocrine tissues, various hypothalamus secretes hormones called releasing and in- 321 322 SECTION 4 DRUGS AFFECTING THE ENDOCRINE SYSTEM BOX 22–1 MAJOR HORMONES AND THEIR GENERAL FUNCTIONS Anterior pituitary hormones are growth hormone (also called Thyroid hormones include triiodothyronine (T3 or liothyro- somatotropin), corticotropin, thyroid-stimulating hormone, follicle- nine) and tetraiodothyronine (T4 or thyroxine). Most regulate the metabolic rate of the body and greatly inﬂuence of these hormones function by stimulating secretion of other growth and development. Parathyroid hormone, also called parathormone or PTH, reg- Posterior pituitary hormones are antidiuretic hormone ulates calcium and phosphate metabolism. ADH helps maintain fluid Pancreatic hormones are insulin and glucagon, which regu- balance; oxytocin stimulates uterine contractions during child- late the metabolism of glucose, lipids, and proteins. Ovarian hormones (female sex hormones) are estrogens and Adrenal cortex hormones, commonly called corticosteroids, progesterone. Estrogens promote growth of speciﬁc body cells and include the glucocorticoids, such as cortisol, and the mineralocorti- development of most female secondary sexual characteristics. Glucocorticoids inﬂuence carbohydrate Progesterone helps prepare the uterus for pregnancy and the mam- storage, exert anti-inﬂammatory effects, suppress corticotropin se- mary glands for lactation. Mineralocorticoids help Testicular hormone (male sex hormone) is testosterone, which regulate electrolyte balance, mainly by promoting sodium retention regulates development of masculine characteristics. Placental hormones are chorionic gonadotropin, estrogen, The adrenal medulla hormones are epinephrine and norepinephrine progesterone, and human placental lactogen, all of which are con- (see Chap. The anterior pituitary, in turn, secretes hormones that mones can affect a single tissue or function (eg, catecholamines, act on target tissues, usually to stimulate production of other glucagon, secretin, and prolactin regulate lipolysis [release of hormones. For example, hypothalamic corticotropin-releasing fatty acids from adipose tissue]). For ex- cotropin, and corticotropin, in turn, stimulates the adrenal ample, ACTH, cortisol, and growth hormone are secreted in cortex to produce cortisol. This complex interrelationship is 24-hour (circadian) cycles, whereas estrogen and progestin often referred to as the hypothalamic–pituitary–adrenocortical secretion is related to the 28-day menstrual cycle. It functions by a negative feedback system, in which hormone secretion is stimulated when hormones are needed and inhibited when they are not needed. The hypothalamic– Hormone Pharmacokinetics pituitary–thyroid axis also functions by a negative feedback mechanism. Protein-derived hormones (amines, amino acids, peptides, and polypeptides) are synthesized, stored, and released into the bloodstream in response to a stimulus. The steroid hor- GENERAL CHARACTERISTICS mones, which are synthesized in the adrenal cortex and go- OF HORMONES nads from cholesterol, are released as they are synthesized. Most hormones are constantly present in the blood; plasma Hormones are extremely important in regulating body activ- concentrations vary according to body needs, the rate of syn- ities. Their normal secretion and function help to maintain the thesis and release, and the rate of metabolism and excretion. Steroid and thyroid hormones are trans- interactions with other hormones and nonhormone chemical ported by speciﬁc carrier proteins synthesized in the liver. If this occurs, hormone effects are en- all endocrine functions are complex processes that are inﬂu- hanced because more unbound, active molecules are avail- enced by more than one hormone. Several mecha- hormone) affect almost all cells, whereas others affect spe- nisms operate to eliminate hormones from the body. The ciﬁc target tissues (eg, corticotropin stimulates the adrenal water-soluble, protein-derived hormones have a short dura- cortex). In addition, one hormone can affect different tissues tion of action and are inactivated by enzymes mainly in the (eg, ovarian estrogen can act on ovarian follicles to promote liver and kidneys.
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