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Professional exposition of how to write feature articles for newspapers and magazines generic toprol xl 100 mg line. Journals All over the world thousands of journals are published each year discount toprol xl 25 mg without prescription, most run by commercial organizations buy cheap toprol xl 25mg on line, but some in partnership with professional associations. They contain a blend of material, such as editorials, review articles, letters, obitu- aries and news, but what distinguishes them from magazines is that they include scientific papers sent out for peer review. More recently, through the development of peer review, they have played a key role in validating science (and scientists). In the last few years electronic publishing has challenged a number of assumptions, such as the fact that space to publish is limited and that reviewing can be done only before publication. One of the most likely scenarios seems to be the increasing use of electronic publishing to validate science, and (with luck) the return of journals to their original purpose of communicating exciting advances of knowledge. Whatever happens, the need to understand effective writing will not go away. BOOKLIST: journals • Journal publishing by Gillian Page, Robert Campbell and Jack Meadows, Cambridge: Cambridge University Press, 1997. Unlikely to help anyone with their writing problems, but will delight the fans of peer review. Published to mark the retirement of Stephen Lock as editor of the BMJ, this book has a range of provocative and entertaining articles on all aspects of medical 69 THE A–Z OF MEDICAL WRITING journals. It is particularly interesting to look back at how Richard Smith, the current editor, predicted the development of journals. Journalology The word used to describe the study of matters of interest to editors of learned journals. Key words These are the half dozen or so words that you need to include with an article in order to aid electronic retrieval. Terms from the medical subject head- lines (MeSH) list of Index Medicus should be used. Kill fee If a commissioned article is returned unused authors will sometimes receive a kill fee to compensate them for the time spent (see commissioning). Latin education Not a good preparation for those who want to be able to write effective contemporary English. Finally, Latin is no longer a developing language and therefore can encourage the delusion that language has immutable rules (see pub test). Law of late literals At least one mistake in every piece of writing will be discovered once it is too late to do anything about it. The only consolation is to think of all the things you did get right (see proofreading; spelling). Lawyers It is usually best to avoid their interventions (see copyright; libel) – but beware falling into the trap of defensive writing. Lay person A put-down by those in one group to describe members of another. The difference is usually made to seem greater than it is by the use of jargon. Layout How we lay out what we write on a page has an enormous influence on how it will be received, and you can ruin much hard work by thoughtless presentation. Many people like to feel that they need to exercise their individuality and therefore must ignore any style laid down by the organization they work for. Resist this temptation, partly because it is in both your interests and those of your organization to keep a consistent image. Those who have decided on your corporate image will usually have had training in design and therefore will probably have a better idea of what works (not that you will believe them). Make sure the margins round the outside of the page are wide enough to give an air of organization. In the old days, if you made a mistake, you had to get out a bottle of correcting fluid or simply tear out the sheet and start again. So there should be no excuse for submitting copy with handwritten amendments: it looks messy, and sends a strong message that the writing and thinking will be messy, too.

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Dysrhyth- Each heartbeat or cardiac cycle occurs at regular intervals mias buy generic toprol xl 25 mg line, also called arrhythmias generic toprol xl 25 mg without a prescription, are abnormalities in heart rate and consists of four events discount toprol xl 25 mg overnight delivery. They become significant when they interfere with electrical impulse, transmission of the electrical impulse to cardiac function and ability to perfuse body tissues. To aid in adjacent conductive or contractile tissue, contraction of understanding of dysrhythmias and antidysrhythmic drug atria and ventricles, and relaxation of atria and ventricles, therapy, the physiology of cardiac conduction and contractil- during which they refill with blood in preparation for the ity is reviewed. Any part of the conduction system can sponta- and conduct an electrical impulse. Although impulses are neously start an impulse, but the sinoatrial (SA) node nor- conducted through muscle cells, the rate is much slower. With its faster SA node Intra-atrial tract rate of electrical discharge or depolarization than other parts of the conduction system, the SA node serves as pacemaker Bundle of His and controls heart rate and rhythm. Internodal tracts Initiation of an electrical impulse depends on the move- Main stem of ment of sodium and calcium ions into a myocardial cell and left bundle AV node branch movement of potassium ions out of the cell. Normally, the cell membrane becomes more permeable to sodium and opens pores or channels to allow its rapid movement into AV junction the cell. As sodium and calcium ions move into cells, Right bundle Anterior branch branch of left bundle potassium ions move out of cells. The movement of the ions branch changes the membrane from its resting state of electrical Purkinje fibers Inferior branch of neutrality to an activated state of electrical energy buildup. In these calcium-respondent cells, which are found mainly in the SA and atrioventricular (AV) nodes, the electrical impulse is conducted more slowly and recovery CARDIAC DYSRHYTHMIAS of excitability takes longer than in sodium-respondent cells. Overall, activation of the SA and AV nodes depends on a slow Cardiac dysrhythmias can originate in any part of the con- depolarizing current through calcium channels, and activation duction system or from atrial or ventricular muscle. They re- of the atria and ventricles depends on a rapid depolarizing cur- sult from disturbances in electrical impulse formation rent through sodium channels. These two types of conduction (automaticity), conduction (conductivity), or both. The char- tissues are often called slow and fast channels, respectively, acteristic of automaticity allows myocardial cells other than and they differ markedly in their responses to drugs that affect the SA node to depolarize and initiate the electrical impulse conduction of electrical impulses. This may The ability of a cardiac muscle cell to respond to an electri- occur when the SA node fails to initiate an impulse or does cal stimulus is called excitability or irritability. When the electrical impulse arises anywhere must reach a certain intensity or threshold to cause contraction. If After contraction, sodium and calcium ions return to the extra- the ectopic focus depolarizes at a rate faster than the SA node, cellular space, potassium ions return to the intracellular space, the ectopic focus becomes the dominant pacemaker. Ectopic muscle relaxation occurs, and the cell prepares for the next pacemakers may arise in the atria, AV node, Purkinje fibers, electrical stimulus and contraction. They may be activated by hypoxia, Following contraction there is also a period of decreased ex- ischemia, or hypokalemia. Ectopic foci indicate myocardial citability (called the absolute refractory period) during which the cell cannot respond to a new stimulus. Before the resting irritability (increased responsiveness to stimuli) and potentially membrane potential is reached, a stimulus greater than normal serious impairment of cardiac function. This period is called the rela- A common mechanism by which abnormal conduction tive refractory period. During nor- mal conduction, the electrical impulse moves freely down the conduction system until it reaches recently excited tissue that Conductivity is refractory to stimulation. The SA node then recovers, fires spontaneously, Conductivity is the ability of cardiac tissue to transmit elec- and the conduction process starts over again. Although the electrophysiology of a single tion means that an impulse continues to reenter an area of the myocardial cell can assist understanding of the process, the or- heart rather than becoming extinguished. For this to occur, derly, rhythmic transmission of impulses to all cells is needed the impulse must encounter an obstacle in the normal con- for effective myocardial contraction. The obstacle is usually an area of damage, Normally, electrical impulses originate in the SA node and such as myocardial infarction. The damaged area allows con- are transmitted to atrial muscle, where they cause atrial con- duction in only one direction and causes a circular movement traction, and then to the AV node, bundle of His, bundle of the impulse (Fig.

This convergence is quite specific because no when the peroneal stimulus intensity was increased convergence has been detected between femoral Ia far above 1 × MT (Marque buy discount toprol xl 100mg online, Pierrot-Deseilligny & afferents and low-threshold afferents in the poster- Simonetta-Moreau buy discount toprol xl 50mg line, 1996) purchase toprol xl 100 mg visa, argues against an IPSP ior tibial and plantar nerves or various cutaneous evoked in motoneurones, because an IPSP should afferents. This finding, together with the potency of depress the H reflex as well (see pp. It is the group I excitation, raises the question whether therefore suggested that the suppression seen in the the organisation of the excitation of quadriceps presence of corticospinal stimulation is due to disfa- motoneurones from the pretibial flexors is unique cilitation resulting from inhibition of propriospinal in the lumbar enlargement. Peripheral inhibitory inputs to lumbar Cutaneous effects propriospinal neurones Cutaneous inhibition has only been disclosed in the presence of cortical stimulation (p. The absence of depression these effects were mediated through propriospinal was observed in 95% of motor units and contrasts neurones. Projections of group I afferents from intrinsic foot muscles to motoneurone pools of TA, quadriceps and triceps surae. Ia afferents from intrinsic plantar foot muscles have monosynaptic Ia and non-monosynaptic excitatory projections to tibialis anterior (TA) motoneurones (MN), and monosynaptic Ia excitatory and non-monosynaptic inhibitory projections to quadriceps (Q) and gastrocnemius-soleus (GS) MNs. Vertical dashed and dotted lines indicate the latency of the monosynaptic excitation and of the non-monosynaptic effect, respectively. Evidence has been presented that heteronymous group I excitation, it is likely to be this suppression presumably reflects disfacilitation of group I origin. Here again, the low threshold and of the motoneurone due to inhibition of excitatory abrupt onset of the inhibition (see Fig. Group I inhibition from foot muscles Medium-latency reciprocal inhibition Stimulation of the tibial nerve at the ankle elicits During voluntary dorsiflexion of the foot, group aweak heteronymous monosynaptic Ia facilitation Ivolleys in the common peroneal nerve evoke a in all leg and thigh muscles, followed by inhibi- medium-latency inhibition of the soleus H reflex tion 3–5 ms later in triceps surae and quadriceps (1–3 ms longer than disynaptic reciprocal Ia inhi- (Fig. This medium-latency inhibition is super- suppresses the H reflexes of soleus and quadriceps imposed on the disynaptic reciprocal Ia inhibition at rest (Fig. Because it is not produced whereitappears∼50msbeforetibialisanteriorEMG by separate stimulation of cutaneous afferents and activity, and is correlated with the strength of tonic has the same low threshold as the monosynaptic dorsiflexion (Crone & Nielsen, 1989). Because of its 498 Lumbar propriospinal system low threshold, it was again assumed that this inhibi- verge onto premotoneurones interposed in the cor- tion could be mediated through a disynaptic path- ticospinal pathway to quadriceps motoneurones way with interneurones located at different spinal (Marchand-Pauvert, Simonetta-Moreau & Pierrot- segments than motoneurones. It is readily facilitates the quadriceps MEP, sparing the initial facilitatedduringtonicvoluntarydorsiflexion(Crone part of the MEP (Fig. This is than the sum of effects of separate stimuli and, here anotherindicationthatthegroupIinputtothispath- again, the initial part of the corticospinal peak was wayisrelativelyweakandthesupraspinalinputrela- not facilitated (Fig. Finally,spa- ever, there is no evidence that these interneurones tial facilitation between corticospinal and group I belong to the system of short-axoned lumbar pro- volleys has also allowed the disclosure of excitatory priospinal neurones located rostral to motoneu- connections between leg muscles (from gastrocne- rones. Indeed, the central delay of the tibial nerve- mius medialis to tibialis anterior, and vice versa), induced inhibition of extensors, assessed with the connectionsthatwererarelydetectedintheabsence Hreflex (Fig. It was therefore not possible to be cer- tain of the central delay of the extra facilitation of Corticospinal control of peripheral excitation thecorticospinalpeak,andtodeterminewhetherthe centraldelayislongerthemorecaudalthemotoneu- Spatial facilitation between peripheral and rone pool. Thus, so far, it has not been demon- corticospinal volleys strated that the premotoneurones transmitting cor- The same spatial facilitation technique as in the ticospinal excitation are lumbar propriospinal neu- upper limb has been used to demonstrate that rones, even though this is probable. The finding that corticospinal and common peroneal volleys con- peripheral inhibition of propriospinal neurones can Organisation and pattern of connections 499 MEP H Reflex MEP (a) 150 (b) (c) 20 Corticospinal 100 0 Inhibitory 50 IN 0 2 4 6 25 30 35 40 45 ISI CPN-TMS (ms) PN Latency (ms) 7 9 11 13 ISI CPN-FN (ms) Ia Q Q MN VL MU 12 10 Group I (d ) (e) FN CPN 0 0 TA 28. Corticospinal fibres have monosynaptic excitatory projections to quadriceps (Q) motoneurones (MNs), propriospinal neurones (PN) and feedback inhibitory interneurones (IN) (the latter projection being the more potent, as indicated by the thickest line). The conditioned responses (expressed as a percentage of the control responses) are plotted against the interstimulus interval (ISI) between CPN and TMS (upper abscissa) and CPN and femoral nerve (FN) stimuli (lower abscissa, in italics), the two abscissae being aligned to start at the simultaneous arrival of conditioning and test volleys at the segmental level of the Q MN pool. Dashed and dotted lines in (c)–(e) indicate the onset of the MEP (c)orthe corticospinal peak ((d), (e)) and of the extra facilitation on combined stimulation, respectively. Modified from Marchand-Pauvert, Simonetta-Moreau & Pierrot-Deseilligny (1999), with permission. Overall the dominant effect of corticospinal volleys on the lumbar propriospinal Convergence of corticospinal and peripheral system seems to be excitation of feedback inhibi- volleys onto inhibitory interneurones tion.

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In general discount toprol xl 100mg free shipping, reduced doses are safer no significant problems occur during the drug-free pe- in older adults order toprol xl 25mg online. NURSING Central Nervous System Stimulants ACTIONS NURSING ACTIONS RATIONALE/EXPLANATION 1 purchase toprol xl 50mg on line. Give amphetamines and methylphenidate early in the day, To avoid interference with sleep. Do not crush or open and instruct clients not to bite or chew Breaking the tablets or capsules destroys the extended-release long-acting forms of methylphenidate (Concerta, Metadate feature and allows the drug to be absorbed faster. Observe for therapeutic effects Therapeutic effects depend on the reason for use. Improved behavior and performance of cognitive and psy- chomotor tasks with ADHD c. Observe for adverse effects Adverse effects may occur with acute or chronic ingestion of any CNS stimulant drugs. Excessive central nervous system (CNS) stimulation— These reactions are more likely to occur with large doses. Cardiovascular effects—tachycardia, other dysrhythmias, These reactions are caused by the sympathomimetic effects of the hypertension drugs. Gastrointestinal effects—anorexia, gastritis, weight loss, nausea, diarrhea, constipation (continued) 258 SECTION 2 DRUGS AFFECTING THE CENTRAL NERVOUS SYSTEM NURSING ACTIONS RATIONALE/EXPLANATION 4. Drugs that increase the effects of CNS stimulants: (1) Other CNS stimulant drugs Such combinations are potentially dangerous and should be avoided or minimized. Drugs that decrease effects of CNS stimulants: (1) CNS depressants IV diazepam or lorazepam may be used to decrease agitation, hyper- activity, and seizures occurring with stimulant overdose. Drugs that increase effects of amphetamines: (1) Alkalinizing agents (eg, antacids) Drugs that increase the alkalinity of the gastrointestinal tract in- crease intestinal absorption of amphetamines, and urinary alkalin- izers decrease urinary excretion. Increased absorption and decreased excretion serve to potentiate drug effects. These drugs thereby increase the risks of headache, subarachnoid hem- orrhage, and other signs of a hypertensive crisis. Drugs that decrease effects of amphetamines: (1) Acidifying agents Urinary acidifying agents (eg, ammonium chloride) increase uri- nary excretion and lower blood levels of amphetamines. De- creased absorption and increased excretion serve to decrease drug effects. Chlorpromazine (Thorazine) or haloperidol (Haldol) is sometimes used in treating amphetamine overdose. Drugs that increase effects of modafinil: (1) Itraconazole, ketoconazole These drugs inhibit cytochrome P450 3A4 enzymes that partly metabolize modafinil. Drugs that decrease effects of modafinil: (1) Carbamazepine, phenytoin, rifampin These drugs induce cytochrome P450 3A4 enzymes that partly metabolize modafinil. Drugs that increase effects of caffeine: (1) Enoxacin, fluvoxamine, mexilitene, theophylline These drugs inhibit the cytochrome P450 1A2 enzymes that par- ticipate in the metabolism of caffeine. Drugs that decrease effects of caffeine: (1) Carbamazepine, phenytoin, rifampin These drugs induce drug-metabolizing enzymes, thereby decreas- ing blood levels and increasing clearance of caffeine. CHAPTER 16 CENTRAL NERVOUS SYSTEM STIMULANTS 259 Drug facts and comparisons. What is the rationale for treating narcolepsy and ADHD tics: Drug and disease management, 7th ed. Efficacy of a mixed am- phetamine salts compound in adults with attention-deficit/hyperactivity disorder. Clinically significant pharmacokinetic interactions between dietary caffeine and medications.

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