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The development of the microscope added an entirely new Two German scientists buy 50mg penegra with visa mens health yoga poses, Matthias Schleiden and Theodor dimension to anatomy and eventually led to explanations of Schwann discount 100 mg penegra visa androgen hormone effects, are credited with the biological principle referred to as basic body functions. Schleiden, a botanist, suggested in 1838 that each invaluable for understanding the etiologies of many diseases, and plant cell leads a double life—that is, in some respects it behaves thus for discovering cures for many of them. Although Leeuwen- as an independent organism, but at the same time it cooperates hoek improved the microscope, credit for its invention is usually with the other cells that form the whole plant. The first Schwann, a zoologist, concluded that all organisms are composed scientific investigation using a microscope was performed by of cells that are essentially alike. Nineteen years later, the addi- Francisco Stelluti in 1625 on the structure of a bee. In 1858, the German pathologist Rudolf Malpighi and Others Virchow wrote a book entitled Cell Pathology in which he pro- Marcello Malpighi (mal-pe′ge) (1628–94), an Italian anatomist, posed that cells can arise only from preexisting cells. He discovered nism of cellular replication, however, was not understood for the capillary blood vessels that Harvey had postulated and de- several more decades. In 1672, the Dutch teaching career, science was sufficiently undeveloped to allow anatomist Regnier de Graaf described the ovaries of the female him to handle numerous disciplines at once. By the time of his reproductive system, and in 1775 Lazzaro Spallanzani showed death, however, knowledge had grown so dramatically that sev- that both ovum and sperm cell were necessary for conception. Francis Glisson (1597–1677) described the liver, stomach, and intestines, and suggested that nerve impulses cause the emptying of the gallbladder. Thomas Wharton (1614–73) and Niels Twentieth Century Stensen (1638–86) separately contributed to knowledge of the Contributions to the science of anatomy during the twentieth century have not been as astounding as they were when little was homunculus: L. History of Anatomy © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 Chapter 1 History of Anatomy 17 (a) (b) (c) FIGURE 1. Because of the proliferation of scientific literature niques of such cognate disciplines as chemistry, physics, electron- toward the end of the nineteenth century, over 30,000 terms for ics, mathematics, and computer science have been incorporated structures in the human body were on record, many of which into research efforts. In 1895, in an attempt to reduce the confusion, There are several well-established divisions of human the German Anatomical Society compiled a list of approxi- anatomy. The oldest, of course, is gross anatomy, which is the mately 500 terms called the Basle Nomina Anatomica (BNA). Stringent courses in gross anatomy in professional classroom and in publications. Gross anatomy also forms the basis throughout the century, under the banner of the International for the other specialties within anatomy. At the Seventh International Congress (see chapter 10) deals with surface features of the body that held in New YorkCity in 1960, a resolution was passed to elimi- can be observed beneath the skin or palpated (examined by nate all eponyms (“tombstone names”) from anatomical terminol- touch). Structures like Stensen’s duct and Wharton’s duct, for example, are now properly referred to as the parotid duct and submandibular duct, respectively. Be- Microscopic Anatomy cause eponyms are so entrenched, however, it will be extremely Structures smaller than 0. The sciences of cytology (the But at least there is a trend toward descriptive simplification. The terminology used in this text is in accor- and histochemistry have aided electron microscopy by reveal- dance with the official anatomical nomenclature presented in ing the fine details of cells and tissues that are said to compose the reference publication, Nomina Anatomica, Sixth Edition. History of Anatomy © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 18 Unit 1 Historical Perspective (a) (b) (c) FIGURE 1. Radiographic Anatomy DSR can be used to observe movements of organs, detect defects, assess the extent of a disease such as cancer, or determine the ex- Radiographic anatomy, or radiology, provides a way of observing tent of trauma to tissues after a stroke or heart attack. Radiology is based on the prin- Magnetic resonance imaging (MRI), also called nuclear ciple that substances of different densities absorb different magnetic resonance (NMR), provides a new technique for diag- amounts of X rays, resulting in a differential exposure on film. An MRI image is created rapidly as lowed) or injected into the body to produce even greater con- hydrogen atoms in tissues, subjected to a strong magnetic field, trasts (fig. Angiography involves making a radiograph respond to a pulse of radio waves. In angiocardiography, being noninvasive—that is, no chemicals are introduced into the the heart and its associated vessels are x-rayed. It is better than a CT scan for distinguishing between soft permits the study of certain body systems through the use of mo- tissues, such as the gray and white matter of the nervous system. Traditional radiographs have had limi- A positron emission tomography (PET) scan is a radiolog- tations as diagnostic tools for understanding human anatomy ical technique used to observe the metabolic activity in organs because of the two-dimensional plane that is photographed. The radiograph image that is produced on film is Human anatomy will always be a relevant science. The recent development only does it enhance our personal understanding of body func- of the computerized axial tomography technique has been hailed as the greatest advancement in diagnostic medicine since the discov- tioning, it is also essential in the clinical diagnosis and treatment ery of X rays themselves. Human anatomy is no longer confined to the observa- tion and description of structures in isolation, but has expanded The computerized axial tomography technique (CT, or to include the complexities of how the body functions as an inte- CAT, scan) has greatly enhanced the versatility of X rays.
As this lesion expands purchase penegra 100 mg online prostate cancer screening, due (D) Parietal to edema discount penegra 50 mg without a prescription prostate cancer you are not alone, and impinges on the immediately adjacent cortical ar- (E) Temporal eas, which of the following deﬁcits would most likely be seen? The examination reveals that the woman has a non- (D) Weakness of facial muscles ﬂuent (Broca) aphasia. A sagittal MRI shows a lesion in which of (E) Weakness of the upper extremity the following gyri? A 47-year-old woman presents with seizures and ill-deﬁned neu- (B) Inferior frontal rologic complaints. The examination reveals a bruit on the lateral (C) Lateral one-third of the precentral aspect of the head immediately rostral and superior to the ear. A (D) Middle frontal CT shows a large arteriovenous malformation in the area of the lat- (E) Supramarginal eral sulcus. Which of the following Brodmann areas represents the primary (A) Inferior sagittal sinus somatosensory cortex? The collection of posterior and anterior roots that occupy the lum- bar cistern are collectively known as which of the following? A 64-year-old man awakens with a profound weakness of his right (A) Cauda equina hand. The man is transported by ambulance to a major medical (B) Conus medullaris center, a distance of 240 miles and taking several hours. Which of the following gyri represents the most likely lo- (E) Filum terminale internum cation of this lesion? Which of the following Brodmann areas represents the primary (B) Medial one-third of precentral somatomotor cortex? The abducens nerve exits the brainstem at the pons-medulla junc- extremity. The history suggests that this deﬁcit has developed tion generally in line with the preolivary sulcus and passes rostrally slowly, perhaps over several years. MRI shows a meningioma im- just lateral to, and in the same cistern as, the basilar artery. Which of the following gyri is most of the following cisterns contains the abducens nerve and basilar likely involved in this patient? An 81-year-old woman is brought to the emergency department fecting her face and upper extremity. CT shows a hemorrhage that by her son with a complaint of weakness on the same side of her is conﬁned largely to the cortex and adjacent subcortical areas. CT shows a hemorrhage in the territory of the Which of the following vessels/segments are most likely involved? Which of the following represents the (A) A most likely origin of these vessels? A 22-year-old man is brought to the emergency department with a gunshot wound to the head. The MRI of a 27-year-old woman shows a meningioma impinging decerebrate. This lesion is located Which of the following most speciﬁcally describes the position of on which of the following lobes of the cerebral hemisphere? No other cranial nerve deﬁcits or motor or sensory deﬁcits are MRI shows a lesion in the optic tract that has spread into a struc- seen. Based on its following vessels/segments is most likely involved in this hemor- anatomical relationship, which of the following structures is most rhage? A 19-year-old man presents with significant paralysis of move- plexus, the glomus choroideum. No other deficits are sents the location of this part of the choroid plexus? Suspecting some type of lesion on the root or along the (A) Anterior horn of the lateral ventricle intracranial course of the oculomotor (III) nerve, the neurolo- (B) Atrium of the lateral ventricle gist orders an MRI. Which of the following describes the ap- (C) Body of the lateral ventricle pearance of the subarachnoid and ventricular spaces in a T2- (D) Caudal roof of the third ventricle weighted image? Which of the following represents the most common cause of (C) Light grey blood in the subarachnoid space (subarachnoid hemorrhage)? The MRI of an 11-year-old boy shows a tumor in the pontine por- that have persisted over several months. Which of the following describes lowing structures represents the border between the medullary the appearance of CSF in the ventricular spaces, and consequently and pontine parts of the fourth ventricle? A 71-year-old morbidly obese man is brought to the emergency problems are on the same side of his body. The son reports that the man complained lesion in the anterior lobe of the cerebellum. Which of the fol- of a sudden excruciating headache and then became stuporous.
This is not unexpected in a system so subject to the effects of outlier verdicts purchase penegra 100 mg overnight delivery androgen hormone use in livestock. A review of the files of a national medical malpractice insurer indi- cates that less than 1% of its physician-policyholders have two paid claims over a 10-year period of time (16) cheap 100 mg penegra overnight delivery prostate news. The likelihood that a physi- cian who has one paid claim will have a second in the succeeding decade is only one in five (16). Therefore, even paid claims do not reliably identify a group of physicians practicing substandard medicine. Finally, the Harvard Medical Practice Study (25) looked at the actual litigation that arose from the more than 32,000 medical records they reviewed and concluded that there was no relationship whatever between the presence or absence of medical negligence and the out- come of malpractice litigation (26). The only variable correlated with the outcome of litigation was the degree of injury. Plaintiffs with the most serious injury were more likely to be successful in court, irre- spective of whether the injury was caused by negligence. Chapter 15 / The Case for Legal Reform 211 Because the majority of malpractice claims are found to be without merit and the extent of injury is more strongly correlated with litigation outcome than with medical negligence, insurance companies cannot predict with any certainty the likelihood that an individual physician will incur malpractice liability in the future. This means premium rates must be predicated primarily on group, rather than individual, experience. In this context, medical specialty and geography (location of the practice) are more important determinants of rates than a physician’s personal experience. Using the extremes as an example, it is easy to see the limits of experience rating in the context of medical malpractice insurance. A physician with no claims could argue that his or her premium should be close to zero. On the other hand, following a single million-dollar claim, the physician’s rate the following year could be many hundreds of thou- sands of dollars. Given the facts above, this would be illogical as well as unfair and would undermine the very notion of insurance. Therefore, in most cases the premium burden is evenly divided among physician groups with only modest experience-based discounts or surcharges actuarially creditable. The Settlement Issue Personal injury attorneys sometimes argue that outlier jury verdicts could be avoided if insurance companies settled claims more readily (27). First, physician defen- dants win approx 80% of malpractice trials (5), making it difficult to argue that those claims should have been settled. Second, the physician, not the insurance company, is the defendant and usually retains the right to make any decision on settlement. In our legal system, the defendant is entitled both to the presumption of innocence and the right to a day in court. It is disingenuous for plaintiff attorneys to suggest that the court- room has become too dangerous a venue for the exercise of one’s legal rights. The alternative to a forced settlement should not be an unreason- able jury verdict. Finally, so-called “nuisance settlements” only encour- age more litigation. Insurance Companies and Markets The plaintiff bar argues that the sharp rise in the cost of malpractice insurance is principally caused by exploitation of physicians and man- agement incompetence by the companies that provide coverage. Sixty percent of physicians are 212 Anderson insured in mutual companies owned by the policyholders themselves (5). The remainder find coverage with commercial carriers, many of which insure other risks unrelated to professional liability. The physi- cian-owned companies are dedicated to providing malpractice coverage for their policyholder-owners. These companies tend to be state-based, although several have expanded regionally and a few nationally. Several hundred companies write medical malpractice insurance in the United States, but that figure may be misleading because only a fraction of these are actively writing and the 20 largest medical liability insurers accounted for 56% of malpractice premium in 2002 (28). The 60% of physicians insured in physician-owned mutuals are spread among approx 40 companies. When insurers perceive the medical-legal environment as poor, they will be forced to reduce insurance writings or leave the state entirely. A poor environment is basically defined as one where premium rates fail to cover the risk of liability and a reasonable return on investment. Forty-six companies, primarily commercial car- riers but some mutuals as well, ceased writing this business between 2000 and 2002 (28), typically for one of the following three reasons: 1. The company felt the business to be unprofitable, or more generally, that the practice of medicine had become uninsurable. State regulators prohibited additional writing because of the precari- ous financial position of the company or regulatory violations. The exodus of such a large percentage of insurers from the market has substantial costs for doctors, injured plaintiffs, and all health care consumers. When a given market will not support enough insurers to cover all doctors, the physicians will be unable to practice in that venue and patients will be forced to travel long and potentially hazardous distances to receive medical care.
In some situations the use of sealed opaque envelopes discount penegra 100mg free shipping prostate cancer 185, with monitoring of the concealment process penegra 50mg fast delivery androgen hormone killing, may be more feasible. Blinding of the clinician or patient to the allocation is more difficult. For example, an obstetrician might be more reassured with the results of magnetic resonance pelvimetry in a breech presentation at term, than with manual pelvimetry, which will influence subsequent decisions to perform an emergency section. Alternatively, one could try to mask the clinician by only presenting standardised test results, without any reference to the type of test. The a priori calculation of the necessary sample size for a randomised diagnostic study is not straightforward. In trials in which patients are randomised to one of two test strategies (Figure 4. Let us explain this with another randomised diagnostic trial from the literature, in which ultrasonography was compared with clinical assessment for the diagnosis of appendicitis. A large group of patients with abnormal results in the ultrasound group, indicating operation, would also have been detected at clinical examination. The same argument stands for a subgroup of patients with a normal ultrasound. The sum of these two groups forms the total with concordant test results. As patients with concordant test results will receive the same management, their event rates will be identical except for chance differences. The rate difference, 9%, results solely from the events in the discordant group. By 77 THE EVIDENCE BASE OF CLINICAL DIAGNOSIS Ultrasound group Control group n=151 n=151 % discordant x events y events Abnormal in ultrasound n events n events and control group % concordant Normal in ultrasound and control group o events o events Figure 4. This could result from a rate of non-therapeutic operations of 55% in patients with a positive clinical assessment and otherwise negative ultrasound, and a rate of 10% in patients with a positive ultrasound and otherwise negative clinical examination. It would be very strange to expect such a high discordance rate in advance. This example shows that it is important to incorporate the discordance rate in sample size calculations of randomised trials of diagnostic tests. Conclusions In this chapter we discuss the evaluation of the prognostic impact of tests. From a patient perspective one could argue that it is not so much the correspondence with the “truth” that should be the focus of a diagnostic test evaluation, but the likelihood that such a test detects events of clinical interest, and the possibilities that exist to let test results guide subsequent clinical decision making to reduce the likelihood of such events occurring. The latter can be evaluated by evaluating a test–treatment combination in a clinical trial, for which several possible designs are discussed. The examples of published randomised diagnostic trials in this chapter show that it is feasible to perform such a thorough evaluation of a 78 DIAGNOSTIC TESTING AND PROGNOSIS diagnostic test. Several additional examples can be found in the literature, such as trials of mediastinoscopy, cardiotocography and MRI,11,18,19 and of a number of screening tests. This makes it impossible to differentiate between the treatment effect and the prognostic value of the test. Power analyses of any diagnostic trial should incorporate an estimation of the discordance rate, as differences in outcome can only be expected for patients who have discordant test results. In this chapter we have shown that a design incorporating randomisation of discordant test results is more efficient, provides more information, and is less prone to bias. Most importantly, all of these designs require a prespecified test–treatment link. This is to allow for the application of the study results in other settings, and to guard the internal validity of the study. Critical appraisal of the design and reporting of studies of imaging and measurement of carotid stenosis. Predictive power of duplex ultrasonography in asymptomatic carotid disease. Antithrombotic treatment of ischemic stroke among patients with occlusion or severe stenosis of the internal carotid artery: a report of the Trial of Org 10172 in Acute Stroke Treatment (TOAST). Low molecular weight heparinoid, ORG 10172 (danaparoid), and outcome after acute ischemic stroke: a randomized controlled trial. The Publications Committee for the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) Investigators [see comments]. Lack of effect of aspirin in asymptomatic patients with carotid bruits and substantial carotid narrowing. Doppler ultrasonography in suspected intrauterine growth retardation: a randomized clinical trial. Likelihood ratios with confidence: sample size estimation for diagnostic test studies. Prospective, randomized outcome study of endoscopy versus modified barium swallow in patients with dysphagia. Helicobacter pylori test-and- eradicate versus prompt endoscopy for management of dyspeptic patients: a randomised trial. Investigation for mediastinal disease in patients with apparently operable lung cancer.
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