By N. Hector. New Mexico State University.
As this example indicates levitra extra dosage 60 mg amex pomegranate juice impotence, more than one hormone may be capable of binding to a specific transport protein cheap levitra extra dosage 40 mg on-line impotence etymology. When several such hormones are present simultaneously, they com- pete for a limited number of binding sites on these transport proteins. Increases in plasma cortisol result in dis- placement of aldosterone from CBG, raising the unbound (active) concentration of aldosterone in the plasma. Simi- larly, prednisone, a widely used synthetic corticosteroid, can displace about 35% of the cortisol normally bound to CBG. As a result, with prednisone treatment, the free cortisol con- FIGURE 31. This relationship determines the amount of free concentrations of total cortisol and CBG. Peripheral Transformation, Degradation, and Excretion of Hormones, in Part, Determine Their Activity In addition to increasing the total amount of hormone that can be carried in plasma, transport proteins also pro- As a general rule, hormones are produced by their gland or vide a relatively large reservoir of hormone that buffers tissue of origin in an active form. As unbound table exceptions, the peripheral transformation of a hor- hormone leaves the circulation and enters cells, additional mone plays a very important role in its action. Specific hor- lowing a rapid increase in hormone secretion or the thera- mone transformations may be impaired because of a con- peutic administration of a large dose of hormone, the ma- genital enzyme deficiency or drug-induced inhibition of jority of newly appearing hormone is bound to transport enzyme activity, resulting in endocrine abnormalities. Other examples are the formation of the octapeptide mones into cells, slowing the rate of hormone degradation, angiotensin II from its precursor, angiotensinogen (see but also prevents loss by filtration in the kidneys. Chapter 34), and the formation of 1,25-dihydroxychole- From a diagnostic standpoint, it is important to recog- calciferol from cholecalciferol (see Chapter 36). The amount As in any regulatory control system, it is necessary for the of transport protein and the total plasma hormone content hormonal signal to dissipate or disappear once appropriate are known to change under certain physiological or patho- information has been transferred and the need for further logical conditions, while the free hormone concentration stimulus has ceased. For example, increased con- plasma concentrations of hormone are determined not only centrations of binding proteins are seen during pregnancy by the rate of secretion but also by the rate of degradation. Assays of total hormone content a hormone can potentially alter its circulating concentra- might be misleading, since free hormone concentrations tion. In such cases, it is helpful to compensate for altered degradation such that plasma hor- determine the extent of protein binding, so free hormone mone concentrations remain within the normal range. Processes of hormone degradation show little, if any, regu- The proportion of a hormone that is free, bound to a lation; alterations in the rates of hormone synthesis or se- specific transport protein, and bound to albumin varies de- cretion in most cases provide the primary mechanism for al- pending on its solubility, its relative affinity for the two tering circulating hormone concentrations. For example, the affinity of cortisol important site of degradation; for a few others, the kidneys for corticosteroid-binding globulin (CBG) is more than play a significant role as well. Diseases of the liver and kid- CHAPTER 31 Endocrine Control Mechanisms 575 neys may, therefore, indirectly influence endocrine status One approach to measuring MCR involves injecting a as a result of altering the rates at which hormones are re- small amount of radioactive hormone into the subject and moved from the circulation. Various drugs also alter normal then collecting a series of timed blood samples to deter- rates of hormone degradation; thus, the possibility of indi- mine the amount of radioactive hormone remaining. In on the rate of disappearance of hormone from the blood, its addition to the liver and kidneys, target tissues may take up half-life and MCR can be calculated. The MCR and half- and degrade quantitatively smaller amounts of hormone. In life are inversely related—the shorter the half-life, the the case of peptide and protein hormones, this occurs via greater the MCR. The half-lives of different hormones vary receptor-mediated endocytosis. The circulating concentration of hor- volved in hormone inactivation and degradation differs mones with short half-lives can vary dramatically over a for each hormone class. This is typical of hormones that regu- cific enzyme-catalyzed reactions are involved. Inactiva- late processes on an acute minute-to-minute basis, such as a tion and degradation may involve complete metabolism number of those involved in regulating blood glucose. Hor- of the hormone to entirely different products, or it may be mones for which rapid changes in concentration are not re- limited to a simpler process involving one or two steps, quired, such as those with seasonal variations and those such as a covalent modification to inactivate the hor- that regulate the menstrual cycle, typically have longer mone. In some cases, meas- The Measurement of Hormone Concentrations uring the urinary content of a hormone or hormone metabolite provides a useful, indirect, noninvasive means Is an Important Tool in Endocrinology of assessing endocrine function. The concentration of hormone present in a biological fluid The degradation of peptide and protein hormones has is often measured to make a clinical diagnosis of a suspected been studied only in a limited number of cases. These fragments are then metabolized by a variety acterized, they were quantitated in terms of biological re- of nonspecific peptidases to yield the constituent amino sponses they produced. The primary organ result, hormones came to be quantitated in terms of units, involved is the liver, although some metabolism also takes defined as an amount sufficient to produce a response of place in the kidneys. Complete steroid metabolism gener- specified magnitude under a defined set of conditions.
If the ducts of sebaceous glands become blocked for some reason cheap 60mg levitra extra dosage free shipping erectile dysfunction pump for sale, the glands may become infected order levitra extra dosage 40 mg amex erectile dysfunction age 35, result- ing in acne. Sex hormones regulate the production and secretion of sebum, and hyperactivity of sebaceous glands can result in se- rious acne problems, particularly during teenage years. Sudoriferous Glands Eccrine Commonly called sweat glands, sudoriferous glands excrete per- Apocrine sweat gland spiration, or sweat, onto the surface of the skin. Perspiration is sweat gland composed of water, salts, urea, and uric acid. It serves not only for evaporative cooling, but also for the excretion of certain FIGURE 5. Sweat glands are most numerous on the palms, soles, axil- lary and pubic regions, and on the forehead. They are coiled and to as exocrine, because they are externally secreting glands that tubular (fig. These glands are formed before birth and function in evap- Sebaceous Glands orative cooling (figs. Apocrine sweat glands are much larger than the eccrine with hair follicles, because they develop from the follicular ep- glands. They are holocrine glands (see chapter 4) where they secrete into hair follicles. Integumentary System © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 Chapter 5 Integumentary System 119 Rib 13. List the three types of integumentary glands and describe the structure and function of each. A few of the many diseases and disorders of Lactiferous sinus the integumentary system are briefly discussed here. Ampulla Lobule Inflammatory Conditions (Dermatitis) Inflammatory skin disorders are caused by immunologic hyper- Lobe sensitivity, infectious agents, poor circulation, or exposure to en- vironmental assaults such as wind, sunlight, or chemicals. Some people are allergic to certain foreign proteins and, because of this inherited predisposition, experience such hypersensitive reac- FIGURE 5. Lesions, as applied to inflammatory conditions, are de- fined as more or less circumscribed pathologic changes in the tis- sue. Some of the more common inflammatory skin disorders and Mammary glands, found within the breasts, are specialized their usual sites are illustrated in fig. Washing away the dried residue of perspiration and infections (measles and chicken pox); bacteria, such as staphylo- sebum eliminates dirt. Excessive bathing, however, can wash off the coccus (impetigo); sexually transmitted diseases; leprosy; fungi natural sebum and dry the skin, causing it to itch or crack. Cerumen is a water and insect repellent, and also keeps type of benign neoplastic growth of melanocytes. These warts are usually treated effectively with Knowledge Check liquid nitrogen or acid. A different type of wart, called a venereal wart, occurs in the anogenital region of affected sexual partners. Indicate which portion is alive and Risk factors for cervical cancer may be linked to venereal warts, discuss what causes the cells in a hair to die. Integumentary System © The McGraw−Hill Anatomy, Sixth Edition Companies, 2001 Developmental Exposition system. The epidermis and the hair, glands, and nails of the skin The Integumentary System develop from the ectodermal germ layer (exhibits I, II, and III). EXPLANATION By 6 weeks, the ectodermal layer has differentiated into an Both the ectodermal and mesodermal germ layers (see chapter 4) outer flattened periderm and an inner cuboidal germinal (basal) function in the formation of the structures of the integumentary layer in contact with the mesenchyme. Basal cell carcinoma, the most central crater that erodes, crusts, and bleeds. Fortunately, there common skin cancer, accounts for about 70% of total cases. It is little danger that it will spread (metastasize) to other body usually occurs where exposure to sunlight is the greatest—on areas. These carcinomas are usually treated by excision (surgi- the face and arms. By 11 weeks, the mesenchymal cells below the germinal cells have differentiated into the distinct collagenous and elastic connective tissue fibers of the dermis. The tensile properties of these fibers cause a buckling of the epidermis and the formation of dermal papillae.
Bone in-growth fixation of the femoral stem can be performed if necessary discount levitra extra dosage 60 mg mastercard impotence vacuum pumps. Acetabular fixation is generally by This is the most commonly used device in patients with bone in-growth order levitra extra dosage 40mg with visa erectile dysfunction drugs compared. Ultra-High-Molecular-Weight Polyethylene Hybrid total hip replacement: The acetabular compo- nent is fixed by bone in-growth while the femoral com- This hard, high-density material provides a low-friction ponent is cemented. Furthermore, it allows Customised: Following tumor resection or difficult revi- plastic deformity increasing congruity. The Radiology of Hip and Knee Joint Prostheses 107 Knee The joint-line height is drawn from the tibial tubercle to the superior surface of the tibial component (the infe- Unicompartmental: Used when only one compartment rior edge of the femoral component) on the lateral radi- needs replacement; both the femoral and tibial sides of ograph. A joint line 8 mm higher than in the preoperative ex- amination is associated with a poorer clinical outcome. Total knee replacement: Posterior-cruciate-sparing or A low joint line causes a low patella and may result cruciate-substituting designs may be inserted. Unicompartmental arthroplasty: The femoral and tibial Mobile tibial polyethylene bearings: Rotating platform components should parallel each other, with no rotatory allows rotation, meniscal bearings allow rotation and an- element, and lie parallel to floor. Constrained: Reserved for revision surgery, severe bone loss or after tumor resection. These devices do not permit knee rotation and are subject to failure (loosening) in pa- Bone In-growth and Porous Coating tients whose activity level is high. Porous coating, while significantly adding to the cost of Patellofemoral: Either as part of a total knee replacement, joint replacement, may significantly improve implant when a polyethylene “button” is cemented into the articu- longevity. Beads of a similar alloy are sintered onto the lar surface of the patella, or as a specific patellofemoral metallic components, permitting bony in-growth to occur joint replacement when the major knee compartments are without the need for intervening cement. Clearly, this requires stability to allow in-growth to occur, with implications for the postoperative period. Normal Appearances Anticipated normal plain-film appearances include re- sorption of medial femoral cortex at the calcar femoris Hip Replacements (98%), reduced bone density where it is unloaded, the ab- sence of a thin lucent rim around the implant, although The following features on plain film suggest an ideal po- such a lucency with a sclerotic margin is common (79%) sition for a total hip replacement. A lucent line of more than 2 mm implies unacceptable tion angle should be about 40±10° on an AP view. It is also normal to see endosteal sclerosis at the Acetabular anteversion should measure 0–30° on a true tip of a prosthesis (36%), localized periosteal new bone lateral view. The femoral component should be coaxial and cortical thickening, representing altered stress loading with the femoral shaft. Acetabular screws, if used, should (12%) and a degree of prosthetic subsidence (7%). The lucent line has Complications of Joint Replacement a sclerotic margin and develops during the first 2 years after insertion. A metal- joints, including pain and other symptoms, for which no bone lucency may be present immediately after surgery cause may be found. In addition, not all abnormal joint replace- quential radiographs for cemented devices whereas slight ments are associated with symptoms. Overall, complica- subsidence is acceptable, and part of the design in unce- tions occur in 1-5% of total hip replacements annually. The major complications are described in the follow- ing: Knee Replacements Loosening With or Without Coexisting Infection Alignment: Obtain standing views to check alignment and compare with earlier radiographs. The infection rate is approximately 1% of total hip replacements, 2% of Total knee: The tibial articular surface should be par- total knee replacements and 3% of revision joints per an- allel to the floor in a weight-bearing position. Obviously, figures vary but at 10 years after inser- femoral component should lie in 5-7° of valgus. The tion as many as 50% of hips may appear radiographical- patellar button should be central and well embedded in ly loose, 30% requiring revision. Weissman The major plain-film findings of loosening include the 18[F]-fluorodeoxyglucose (FDG) positron emission to- presence of cement-bone lucencies and/or cement-metal mography is relatively untried, but appears to perform lucency of more than 2 mm in width. The progressive similarly to 3-phase bone scan but less well than conven- widening of an interface, especially if associated with bone tional radiographs. The presence of a joint effusion (shown on plain X-ray or ultrasound) implies a Arthrography joint that is abnormal, although a small joint effusion is usual in total knee replacements. Additional signs include The major objective of arthrography is to obtain fluid for excessive component migration or subsidence of unce- culture and sensitivity and to document intra-articular mented components, subsidence of cemented components, needle position. It is important to remember to aspirate cement or fatigue fractures of metallic components, dis- material for both aerobic and anaerobic cultures. A periosteal reaction should always be re- riostatic, aspiration prior to local anesthetic or saline in- garded as suspicious of infection, as opposed to local cor- jection is preferred.
Conclusion—preventing bone loss and vertebral fractures can be attained to some degree with any of the currently approved medications quality 60mg levitra extra dosage erectile dysfunction pump how to use, exercise levitra extra dosage 60mg on line erectile dysfunction medication cialis, and possibly diet. A person who has sustained a fracture is certainly a candidate for pharmacologic therapy. Pulmonary dysfunction secondary to MS is a leading cause of morbidity and mortality in MS. Assessment should include history of pneumonia, aspiration, dypnea, weak cough, hypophonia, and fatigue. Treatment is predicated on noninvasive interventions whose goals are to: 1. Avoid upper respiratory infections, particularly during the influenza season ADDITIONAL READING Halper J. This page intentionally left blank Chapter 19 The Nurse’s Role in MS Research Objectives: Upon completion of this chapter, the learner will: Describe the roles and responsibilities of the nurse in MS research Identify key concepts in the research processResponsibilities of the research coordinator A. Investigator’s brochure—a detailed, confidential description of the structure and formulation of the drug, and a summary of the studies and adverse events. Source documents—documents that contain all the clinical information gathered during a visit. Case report forms—concise information reflective of the source documents entered into duplicate forms that are collected and returned to the sponsor for data entry. Open label—the investigators and patients are aware of what drug or treatment is being tested. Single-blinded study—the patient is blinded to the treatment but the investigator is aware of what is being tested. Double-blinded study—neither the investigator nor the patient knows who has been randomly assigned to what treatment (active therapy or placebo). Cross-over study—participants receive either placebo or tested therapy over a specific time, then investigational drug for the remainder of the study. Informed consent is obtained from the subjects or from a legal representative. The research plan makes adequate provision for monitoring the data to ensure the safety of subjects. The consent must be easily understood by a lay person and must contain the following: A. An explanation of the purpose of the research, the design or the study, and procedures that are experimental C. A description of any foreseeable risks or discomforts including, for women who are able to have children, risks to childbearing or to the fetus. A disclosure of appropriate alternative procedures or course of treatment, if any, that may be advantageous to the subject F. A statement describing the extent to which confidentiality of records will be maintained, including the fact that the FDA might inspect the records G. For research involving more than a minimal risk, an explanation as to whether compensation and medical treatments are available H. An explanation of who should be contacted for answers to pertinent questions about the research and the research subject’s rights I. A statement that participation is voluntary, refusal to partici- pate will not result in any penalty or loss of service to which the subject is otherwise entitled, and that the subject may withdraw at any time without penaltyAdverse events A. Adverse drug experience—any unfavorable and unintended sign, symptom, or disease temporally associated with the use of investigational product B. Serious adverse drug experience—any experience that results in death, a life-threatening adverse event, inpatient hospitalization 98 NURSING PRACTICE IN MULTIPLE SCLEROSIS: A CORE CURRICULUM or prolongation of hospitalization, a persistent or significant disability or incapacity related to the research C. Unexpected adverse drug experience—any adverse experience, the specificity or severity of which is not consistent with the current investigator’s brochureNursing assessment A. How realistic are the patient’s expectations of what the drug under study will and will not do for MS?
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