By H. Yugul. Salisbury State University. 2018.
This activity is expressed by the open probability (Po) cheap super p-force oral jelly 160mg overnight delivery, that is discount super p-force oral jelly 160mg mastercard, the probability that effective 160 mg super p-force oral jelly, at any given time purchase 160mg super p-force oral jelly with visa, the channel is open (or order super p-force oral jelly 160mg free shipping, in other words, the proportion of time the channel spends in the open state). There are many hundreds or thousands of such channels in the entire membrane of a single ganglion cell. The currents through all of these channels add up to give the whole-cell current. This can be recorded using the patch pipette by filling the pipette with a solution of similar ionic composition to that of the cytoplasm (i. In the former case, the solution in the pipette is in direct contact with the cytoplasm, so substances in the cytoplasm diffuse into the pipette and vice versa; nystatin and amphotericin conduct small ions such as Na and K across the cell membrane under the pipette tip, so providing good electrical contact with the cytoplasm, but do not permit total mixing of the two solutions. An older, but still useful, method is to insert one or more fine micro-electrodes filled with a strong K solution into the cell and then let them seal into the membrane. At a hyperpolarised potential (À75 mV), a current injection produces a brief burst of action potentials superimposed whereas at À53 mV the cell responds with a sustained train of action potentials. Each record show voltage-trace (top), injected current pulse (middle) and T-type Ca2 current (bottom). At a depolarised potential (b and d), the T-channels are fully inactivated so depolarisation does not initiate a T- current (record d) and now evokes a train of Na spikes instead of a burst (record b). Published by Oxford University Press, New York Ð see Further Study) 50 NEUROTRANSMITTERS, DRUGS AND BRAIN FUNCTION Figure 2. At (4) the depolarisation has closed (deactivated) the h- channels and has inactivated the T-channels. This hyperpolarisation now removes T-channel in-activation and activates Ih (6), to produce another pacemaker potential CONTROL OFNEURONAL ACTIVITY 51 Figure 2. Reproduced by permission of The Royal Society) 52 NEUROTRANSMITTERS, DRUGS AND BRAIN FUNCTION Figure 2. However, they do not open instantly but instead take many milliseconds to open Ð that is, their voltage-gating is relatively slow compared to that of (say) a Na channel. The time taken by any individual channel to assume its new level of open probability varies stochastically about a mean. This can be estimated for a single channel, or for the small cluster of channels seen in Fig. As one might expect, the time-course of the whole-cell current is quite similar to that of the ensemble of the currents through the small cluster of channels. In a normal cell, however, the voltage is not fixed: the effect of the current is to change the voltage, and signals are normally seen as voltage signals. When the cell (a frog ganglion cell) was artificially hyperpolarised to À90 mV (left column) so that all of the M-channels were shut, very little current flowed when the voltage was changed (i. Membrane capacitance is determined by the lipid composition of the membrane and is relatively constant at around 1 mF/cm2 membrane. A hyper- polarising step closes some of the channels, giving a slow decline in current, whereas depolarisation opened more, giving a slow increase in current Ð the gating of M- channels being characteristically slow, as shown in Fig. So now when depolarising current is injected into the cell (bottom record), the membrane begins to depolarise as before but the depolarisation opens more M-channels, and the K current through these extra M-channels hyperpolarises the membrane nearly back to where it started. Conversely, if one tries to hyperpolarise the membrane by injecting hyperpolarising current, the outward flux of K ions diminishes as M-channels close, so the membrane CONTROL OFNEURONAL ACTIVITY 53 Figure 2. Upper traces in each record show currents (I), lower traces show voltage V). Note that the effect of activating the current is to severely reduce the voltage response to current injection. Hence, because M-channels are voltage- sensitive, changes in voltage affect current through M-channels and changes in current through M-channels in turn affect voltage, in such a manner as to stabilise the membrane potential Ð a negative feedback effect. The bottom trace shows a synaptic current recorded under voltage clamp at a preset voltage of À60 mV from a ganglion cell on giving a single shock to the preganglionic fibres. The synaptic current is generated by acetylcholine released from the preganglionic fibres, which opens nicotinic cation channels in the ganglion cell membrane to produce an inward cation current. The top trace shows what happens when the voltage-clamp circuit is switched off, to allow the membrane potential to change. The inward synaptic current now generates a depolarisation (the synaptic potential), which in turn initiates an action potential. This is exactly what synaptic potentials should do, of course, but no Na current is seen under voltage clamp because the membrane potential is held below the threshold for Na channel opening. This threshold is readily exceeded when the clamp circuit is turned off.
Which of the following alternating movements purchase 160 mg super p-force oral jelly visa, is seen most commonly in cerebellar dis- represents the most likely location of the lesion in this boy? Answer E: One possible cause of trigeminal neuralgia (tic (B) Cochlea douloureux) is compression of the trigeminal root by the superior (C) External ear cerebellar artery or its main branches; surgical relocation of the (D) Inferior colliculus aberrant vessel (neurovascular decompression) relieves the symp- (E) Middle ear toms super p-force oral jelly 160mg generic. Hemifacial spasm may be caused by compression of the fa- cial nerve by the anterior inferior cerebellar artery (commonly 84 effective super p-force oral jelly 160 mg. Which of the following laminae of the lateral geniculate nucleus called AICA) order 160 mg super p-force oral jelly fast delivery. The other choices do not cause trigeminal neuralgia receive input from the contralateral retina? Answer E: The rostral interstitial nucleus of the medial longitu- (D) 2 effective super p-force oral jelly 160mg, 3, 5 dinal fasciculus receives cortical input from the frontal eye ﬁeld on (E) 3, 4, 5, 6 the ipsilateral side and projects to the ipsilateral (heavy) and con- tralateral (light) oculomotor and trochlear nuclei. A 12-year-old girl is brought to the pediatrician by her mother regarded as the vertical gaze center. The paramedian pontine who explains that the girl has started to “act funny”. The oculomotor reveals that the girl was treated for a hemolytic streptococcus in- and abducens nuclei do not receive direct input from the frontal fection 4 weeks before the appearance of her symptoms; the eye ﬁeld and the Edinger-Westphal is a visceromotor nucleus con- mother states that the girl has had this problem for 3 weeks. Answer C: The absence of, or the aberrant development of, This girl is most likely suffering from which of the following? Mesoderm of the (E) Weber syndrome head outside of the pharyngeal arches gives rise to the extraocular muscles and muscles of the tongue. The muscles of mastication Q & A’s: A Sampling of Study and Review Questions with Explained Answers 287 (plus the tensor tympani, tensor veli palati, mylohyoid, anterior ing of written or printed words. Aphonia is a loss of the voice fre- belly of the digastric) arise from arch 1, the stylopharyngeus from quently due to disease of, or injury to, the larynx. Aphasia is seen arch 3, and striated muscles of the pharynx, larynx, and upper in individuals with a lesion in the dominant hemisphere, and is esophagus from arch 4. Answer C: Hypothalamocerebellar ﬁbers that project to the cerebellar nuclei and cortex contain histamine. Answer C: The Korsakoff syndrome is a constellation of deﬁcits several neurons that are located in the cerebellar cortex, and in the include memory loss, confabulation, amnesia, and dementia Purkinje cells glutamate is found in many pontocerebellar ﬁbers that is seen in chronic alcoholics; the manifestations are related, in and in granule cells of the cerebellar cortex; and noradrenalin is part, to excessive alcohol consumption and malnutrition. Serotonin is found in cells of the peutic doses of thiamine are used to treat this disease. Broca apha- reticular formation and in some raphe cells that project to the sia (nonﬂuent or expressive aphasia) results from lesions in the cerebellum. The Klüver-Bucy syndrome is related to bilateral lesions to the amygdaloid complex, and Pick disease is de- 8. Answer C: The best localizing sign in this patient is the paucity mentia related to atrophy of the frontal and temporal lobes. Mun- of eye movement and dilated pupil on the left; this indicates a le- chausen syndrome is the fabrication or feigning of illness or disease sion of the midbrain on the left at the level of the exiting oculo- to gain attention or control. The red nucleus is found at the same level and, more importantly, immediately lateral to the red nucleus is a compact 14. Answer B: Cell bodies in the nucleus ambiguus innervate mus- bundle of cerebellothalamic ﬁbers. The ataxia and tremor are re- cles of the pharynx and larynx, including what is commonly called lated primarily to damage to these cerebellar efferent ﬁbers. A lesion of this nucleus is one cause of motor deﬁcit is contralateral to the lesion because the corti- dysarthria. The solitary tract and nuclei are concerned with vis- cospinal ﬁbers, through which the deﬁcit is expressed, cross at the ceral afferent information including taste, and the spinal trigemi- motor (pyramidal) decussation. Lesions at the other choices nal tract is made the central processes of primary sensory ﬁbers would not result in a paucity of eye movement and are, therefore, conveying general somatic afferent (GSA) information from the not potential candidates. Proprioceptive infor- mation from the ipsilateral upper extremity is transmitted via the 9. Answer C: The lesion on the exiting oculomotor ﬁbers (on the cuneate nucleus; the vestibular nuclei are related to balance, equi- left) damages the preganglionic ﬁbers from the Edinger-Westphal librium, and control of eye movement. Consequently, the intact postganglionic sympathetic ﬁbers from the ipsilateral su- 15. Answer C: The area of the brainstem that contains the nucleus perior cervical ganglion predominate, and the pupil dilates.
The report responded to a request from the Secretary of Health and Human Services for innovative approaches to five areas of health care: chronic care buy super p-force oral jelly 160 mg without prescription, primary care order super p-force oral jelly 160 mg without a prescription, information technology discount super p-force oral jelly 160 mg, health insurance coverage order super p-force oral jelly 160 mg without prescription, and liability generic super p-force oral jelly 160 mg amex. The liability recommendation included two options for “patient-centered, safety-focused, non-judi- cial compensation”: provider-based early payment and statewide administrative resolution. Under the first option, provider organizations that elected to participate in a given state would receive limited immu- nity from tort suits and federal subsidies for excess liability coverage in exchange for establishing systems for detecting and preventing medical errors and promptly paying economic loss and predefined noneconomic damages for identified classes of avoidable injuries. Under the second option, all health care providers in the state would be subject to a fed- Chapter 17 / New Directions in Liability Reform 273 erally funded, state-run administrative adjudication system for avoid- able injuries based on predetermined schedules of noneconomic dam- ages, which would replace open-ended tort liability. The IOM recommendation draws heavily on prior research—nota- bly “early offers,” ACEs, and enterprise liability—and is sketchy on details. Still, it has five virtues that distinguish it from other reform proposals. First, it explicitly addresses malpractice reform as a compo- nent of overall health care reform (74). Second, it recognizes the need for targeted financial support to help relieve the current malpractice crisis. Third, it seeks to make compensation for avoidable injury faster and more predictable and not simply to reduce the volume of litigation. Fourth, it fosters sound medical relationships by emphasizing apology and explanation (29,75) and involving patients in the process of iden- tifying and preventing medical errors. Finally, it allows for variation and choice in the health care system rather than assuming that all health care providers, however organized, have the same capacity to improve patient safety (76). A MALPRACTICE SYSTEM FOR MEDICARE AND MEDICAID Getting the Medicare program off the sidelines in the malpractice debate is the surest way to connect the liability and health insurance markets and potentially relieve the strain on the health care system created by the current malpractice crisis. The federal Centers for Medi- care and Medicaid Services (CMS) undoubtedly recognize the potential for malpractice liability to destabilize access to care for Medicare ben- eficiaries in the short term and increase program costs in the long term. However, its forays into medical malpractice reform have essentially been limited to supporting the Bush Administration’s overall prefer- ences for restrictions on general tort litigation (44). Instead, CMS should propose a system of error identification, fair compensation, and dispute resolution that would apply specifically to Medicare and Medicaid patients. The framework of such a system could be adopted by administrative rulemaking, although making it fully operational would likely require congressional action. Because of the voting power of the elderly, converting malpractice liability into a Medicare issue is politically perilous. Since its enactment, Medicare has been largely responsible for funding medical progress, promoting industrialization, and (more recently) imposing cost constraints—the forces described earlier as being prima- rily responsible for the current malpractice crisis: Medicaid has become the largest government health program, and pays for roughly half of 274 Sage U. Therefore, Medicare and Medicaid offer the most visible forum for debating the relationship between what America invests in health care and what it expects to receive when health care goes awry. Moreover, a system that provided immediate information and prompt compensation would have substantial advantages over conventional litigation for elderly claimants. EMPLOYER-SPONSORED HEALTH CARE AND THE WORKERS COMPENSATION ANALOGY Employer-sponsored private health insurance covers most Ameri- cans. Therefore, the current malpractice crisis affects the ability of businesses to attract and retain workers. Active involvement in health care purchasing also has made business better attuned to employees’ experiences as users of medical services. Moreover, industry’s contin- ued tolerance of avoidable physical harm in the health care system, especially when it is traceable to faulty systems design, contrasts sharply with general regulatory and self-regulatory changes since the 1960s, which have created a corporate culture exquisitely sensitive to health and safety issues and their relationship to productivity. Finally, health care is an economic engine throughout the country; liability crises reduce present-day prosperity and jeopardize future prospects. To address these issues, the business community could broker a com- promise approach to malpractice mirroring workers’ compensation, that limits liability but retains incentives for safety and assures prompt, reasonable payment in the event of injury. To accomplish this, employ- ers would need to set aside their parochial interests in using the mal- practice crisis as a poster child for general business tort reform to further their workers’ interests in safe, reliable health care. CONCLUSION This chapter analyzes the first medical malpractice insurance crisis of the 21st century in light of significant changes that have occurred in the health care system since previous crises. It concludes that the established debate over traditional tort reform incompletely defines current problems and leads to ineffective solutions. The chapter began by analogizing the malpractice crisis to the legend of Rip van Winkle and concludes with a different literary parallel.
Patients whose claims are motivated mainly by a desire to understand what happened to them are denied that information for prolonged periods buy cheap super p-force oral jelly 160mg on line, and patients who were seriously injured by negligence seldom receive compensation when they most need it super p-force oral jelly 160mg otc. Many legitimate smaller claims are not brought or are dropped without resolution because the finan- cial or psychic cost of pursuing them exceeds the potential benefit super p-force oral jelly 160mg line. As the process crawls along buy 160 mg super p-force oral jelly mastercard, frustration mounts for both patient-plaintiffs (who want redress) and health professional defendants (who want vindication or at least closure) buy super p-force oral jelly 160mg fast delivery, positions harden, and interactions become increasingly adversarial and unpleasant. Delay less often places liability insurers and defense counsel at a disadvantage, which is why they allow it, but nonetheless it harms insurance markets. The “long tail” of malpractice insurance—a prod- uct of both prefiling and postfiling delay—impairs insurers’ ability to accurately estimate their exposure, makes insurer profits dependent on investment yields, and heightens the risk of insurer insolvency prior to claims resolution, all of which increase premium volatility and threaten availability and affordability of coverage during crisis periods. Finally, delay eliminates any possibility of the liability system sup- plying effective feedback to the health care system regarding patient safety. A judgment or settlement in a major case 5 or 10 years after an injury occurred is far less capable of conveying useful lessons to the professionals and institutions who were involved in the care being reviewed. POOR COMPENSATION The legal system is notoriously poor at compensating injured patients. As noted, most negligent injuries never generate legal claims, whereas payments are sometimes made in cases with poor medical Chapter 17 / New Directions in Liability Reform 259 outcomes but little evidence of substandard care. In cases where juries hold defendants liable for actual negligence, damage calculations are often uninformed and unguided, even when judges confront posttrial motions for remittitur. The fact that caps on damages have thus far proved the only way to stabilize malpractice insurance premiums makes matters worse. Statutes may place an absolute cap on total damages (as in Colorado); limit only damages for noneconomic injury such as physical or emotional pain and suffering (as in Ohio); or limit punitive damages (as in North Carolina). As of 2002, 21 states had placed caps ranging from $200,000 to $1 million on noneconomic damages. Noneconomic damage caps have been estimated to reduce the mean payout per claim by up to 40%; the effect on insurance premiums is smaller (9). In particular, flat caps on noneco- nomic or total damages may be unfair to young or severely injured plaintiffs but fail to constrain overly generous compensation for minor injuries because this compensation remains below the cap (25). The case of neonatal injury described in the preceding section illus- trates three additional limitations of a cap on noneconomic damages as a solution to the current malpractice crisis. First, economic damages can still be extremely high when prolonged medical care is required, and the money to pay them has to come from somewhere. Second, calculating those economic damages requires juries to evaluate com- plex and contentious expert testimony involving medical economics as well as clinical prognosis. Third, pain and suffering awards are increasing partly because long-term survival after serious injury has become more common. The implicit message in limiting damages for future suffering in these cases is that the patient should feel lucky to be alive. This approach is typical of “wrongful birth” claims, where physicians who do not cause but fail to diagnose congenital disease may be liable for the costs of caring for the child but not for its pain or suffering. A similar compromise also may be socially defensible in certain malpractice cases to preserve access to medical care that pro- longs life; however, its fairness should be debated openly. This example highlights the absence of a rational connection between what society invests in health care and what society expects to receive when health care goes awry. In part, this is an inevitable result of fund- ing the costs of malpractice through third-party liability insurance rather than first-party health and disability insurance. Insured health care pro- viders prefer that their carriers pay claims only as a last resort, and patient claimants see no direct link between the generosity of settle- 260 Sage ments and the cost of health care. The influence of medical cost-contain- ment on the malpractice system is similarly unplanned. Tort reformers cite a 10-fold increase in average annual liability premiums per long- term care bed over the past decade as evidence of a litigation explosion. Rising liability costs for today’s skilled nursing facilities are more accurately explained by two health policy developments. First, changes in Medicare reimbursement for acute care hospitals channeled younger but sicker patients requiring real medical treatment into what previously had been merely residential and custodial institutions. Second, public policy decisions at the state and federal level conferred enforceable legal rights on long-term care patients similar to those already in place for hospital patients.
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