X. Ilja. Lesley University.
In hyperglycemia levitra professional 20mg lowest price erectile dysfunction treatment houston tx, increased amounts of glucose enter the urine discount levitra professional 20mg with amex erectile dysfunction premature ejaculation treatment, causing large amounts of water to be excreted. This “osmotic diuresis” is responsible for the increased volume of urine (polyuria) noted by the patient. Because of increased urinary water loss, the effective circulating blood volume is reduced. Therefore, less blood reaches volume-sensitive receptors in the central nervous system, which then trigger the sensation of thirst, causing increased drinking activity (polydipsia). A diabetic diet and the tapering of her steroid dose over a period of several weeks gradually returned Ms. Wheezer’s blood glucose level into the normal range. Chronically elevated levels of glucose in the blood may contribute to the development of the microvascular complications of diabetes mellitus, such as diabetic retinal damage, kidney damage, and nerve damage, as well as macrovascular complications such as cerebrovascular, peripheral vascular, and coronary vascular insufficiency. The precise mechanism by which long-term hyper- glycemia induces these vascular changes is not fully established. One postulated mechanism proposes that nonenzymatic glycation (glycosyla- tion) of proteins in vascular tissue alters the structure and functions of these pro- teins. A protein exposed to chronically increased levels of glucose will covalently bind glucose, a process called glycation or glycosylation. This process is not regu- lated by enzymes (see Chapter 9). These nonenzymatically glycated proteins slowly form cross-linked protein adducts (often called advanced glycosylation products) within the microvasculature and macrovasculature. By cross-linking vascular matrix proteins and plasma proteins, chronic hyper- glycemia may cause narrowing of the luminal diameter of the microvessels in the retina (causing diabetic retinopathy), the renal glomeruli (causing diabetic nephropathy), and the microvessels supplying peripheral and autonomic nerve fibers (causing diabetic neuropathy). The same process has been postulated to accelerate atherosclerotic change in the macrovasculature, particularly in the brain CHAPTER 31 / GLUCONEOGENESIS AND MAINTENANCE OF BLOOD GLUCOSE LEVELS 577 (causing strokes), the coronary arteries (causing heart attacks), and the peripheral A Glucose arteries (causing peripheral arterial insufficiency and gangrene). The abnormal lipid metabolism associated with poorly controlled diabetes mellitus also may contribute Plants Animals to the accelerated atherosclerosis associated with this metabolic disorder (see CO2 Chapters 33 and 34). Until recently, it was argued that meticulous control of blood glucose levels in a diabetic patient would not necessarily prevent or even slow these complications B Glucose of chronic hyperglycemia. The publication of the Diabetes Control and Compli- cations Trial, however, suggests that maintaining long-term euglycemia (normal blood glucose levels) in diabetic patients slows the progress of unregulated gly- Amino Lipids Other cation of proteins as well as corrects their dyslipidemia. In this way, careful con- acids sugars trol may favorably affect the course of the microvascular and macrovascular com- plications of diabetes mellitus in patients such as Di Abietes and Ann Sulin. C Glucose BIOCHEMICAL COMMENTS Glycogen Plants are the ultimate source of the earth’s supply of glucose. Plants pro- duce glucose from atmospheric CO2 by the process of photosynthesis D (Fig. In contrast to plants, humans cannot synthesize glucose by Glucose the fixation of CO2. Although we have a process called gluconeogenesis, the term Pyruvate may really be a misnomer. Glucose is not generated anew by gluconeogenesis; com- pounds produced from glucose are simply recycled to glucose. We obtain glucose Lactate from the plants, including bacteria, that we eat and, to some extent, from animals in our food supply. We use this glucose both as a fuel and as a source of carbon for the E synthesis of fatty acids, amino acids, and other sugars (see Fig. We store Glucose glucose as glycogen, which, along with gluconeogenesis, provides glucose when Pyruvate needed for energy (see Fig. Lactate, one of the carbon sources for gluconeogenesis, is actually produced Alanine from glucose by tissues that obtain energy by oxidizing glucose to pyruvate through glycolysis. The pyruvate is then reduced to lactate, released into the bloodstream, F and reconverted to glucose by the process of gluconeogenesis in the liver. This Glucose process is known as the Cori cycle (Fig. Dihydroxyacetone Carbons of alanine, another carbon source for gluconeogenesis, may be pro- Glycerol phosphate duced from glucose.
Defects in the CFTR and found to have sickle trait discount levitra professional 20mg on-line erectile dysfunction emotional, and because of Will’s repeated sickle crises generic levitra professional 20mg without prescription erectile dysfunction kidney disease, Carrie chloride channel also affect sweat composi- wants to know whether she also has sickle trait (see Chapters 6 and 7 for Will tion, increasing the sodium and chloride Sichel’s history). A hemoglobin electrophoresis is performed that shows the com- contents of the sweat, thereby providing a position of her hemoglobin to be 58% HbA, 39% HbS, 1% HbF, and 2% HbA2,a diagnostic tool. The hematologist who saw her in the clinic on her first visit is studying the genetic mutations of sickle cell trait and asks Carrie for permission to draw additional blood for more sophisticated analysis of the genetic disturbance that causes her to produce HbS. Carrie informed her fiancé that she has sickle cell trait and that she wants to delay their marriage until he is tested. Victoria Tim (Vicky Tim) was a 21-year-old woman who was the victim of a rape and murder. She left her home and drove to the local convenience store. When she had not returned home an hour later, her father drove to the store, looking for Vicky. He found her car still parked in front of the store and called the police. They searched the area around the store, and found Vicky Tim’s body in a wooded area behind the building. Medical technologists from the police laboratory collected a semen sam- ple from vaginal fluid and took samples of dried blood from under the victim’s fin- gernails. Witnesses identified three men who spoke to Vicky Tim while she was at the convenience store. DNA samples were obtained from these suspects to deter- mine whether any of them was the perpetrator of the crime. Ivy Sharer’s cough is slightly improved on a multidrug regimen for pul- monary tuberculosis, but she continues to have night sweats. She is toler- ating her current AIDS therapy well but complains of weakness and fatigue. The man with whom she has shared “dirty” needles to inject drugs accom- panies Ivy to the clinic and requests that he be tested for the presence of HIV. RECOMBINANT DNA TECHNIQUES Techniques for joining DNA sequences into new combinations (recombinant DNA) were originally developed as research tools to explore and manipulate genes but are now also being used to identify defective genes associated with disease and to cor- rect genetic defects. Even a cursory survey of the current literature demonstrates that these techniques will soon replace many of the current clinical testing proce- dures. At least a basic appreciation of recombinant DNA techniques is required to understand the ways in which genetic variations among individuals are determined CHAPTER 17 / USE OF RECOMBINANT DNA TECHNIQUES IN MEDICINE 299 and how these differences can be used to diagnose disease. RESTRICTION FRAGMENTS EcoRI Enzymes called restriction endonucleases enable molecular biologists to cleave seg- ments of DNA from the genome of various types of cells or to fragment DNA obtained from other sources. A key feature of restriction enzymes is their specificity. Most of the DNA sequences recognized by restriction enzymes are "Sticky" ends palindromes, that is, both strands of DNA have the same base sequence when read in a 5 to 3 direction. The cuts made by these enzymes are usually “sticky” (that is, Fig. Note that the DNA sequence shown is a palindrome; the products are single-stranded at the ends, with one strand overhanging the other). Hundreds of restriction enzymes with different specificities of this sequence by EcoRI produces single- have been isolated (Table 17. Not shown Restriction fragments of DNA can be used to identify variations in base sequence is an example of an enzyme that generates in a gene. However, they also can be used to synthesize a recombinant DNA (also blunt ends (see Table 17. The sickle cell mutation causes the -globin gene to restriction enzyme recognition lose this MstII restriction site. Therefore, because Will Sichel is homozygous for the sickle sequence? Sequences Cleaved by Selected Restriction Enzymes* (B) (5’) T A C G A T (3’) A T G C T A Restriction Enzyme Source Cleavage Site (C) (5’) C T G A G (3’) AluI Arthrobacter luteus 5 - A G C T - 3 3 - T C G A - 5 G A C T C (D) (5’) A T C C T A (3’) BamHI Bacillus amyloliquefaciens H 5 - G G A T C C - 3 3 - C C T A G G - 5 T A G G A T EcoRI Escherichia coli RY13 5 - G A A T T C - 3 3 - C T T A A G - 5 HaeIII Haemophilus aegyptius 5 - G G C C - 3 3 - C C G G - 5 Restriction endonucleases were 5 - A A G C T T - 3 discovered in bacteria in the late HindIII Haemophilus influenzae Rd 3 - T T C G A A - 5 1960s and 1970s. These enzymes 5 - C C G G - 3 were named for the fact that bacteria use MspI Moraxella species 3 - G G C C - 5 them to “restrict” the growth of viruses (bac- MstII Microcoleus 5 - C C T N A G G - 3 teriophage) that infect the bacterial cells. However, they do not cleave PstI Providencia stuartii 164 5 - C T G C A G - 3 the bacterial DNA, because its bases are 3 - G A C G T C - 5 methylated at the restriction sites by DNA SmaI Serratia marcescens Sb 5 - C C C G G G - 3 methylases. Restriction enzymes also 3 - G G G C C C - 5 restrict uptake of DNA from the environ- *Restriction enzymes are named for the bacterium from which they were isolated (e.
After 4 weeks generic levitra professional 20mg on-line erectile dysfunction due to medication, she was With the wrist held passively at 30° of dorsiflexion buy discount levitra professional 20 mg on line erectile dysfunction treatment charlotte nc, she removed from the cast and therapy was started three could extend her fingers fully at the proximal interpha- times a week to focus on joint range of motion, with the langeal and distal interphalangeal joints, but lacked 40° only limitation being that there was no passive wrist flex- of extension at the metacarpal phalangeal joints. She was to wear a wrist extension splint she was observed standing, her elbow was flexed 60°, the that held her wrist in 20° to 30° of extension full time, forearm was pronated, the wrist flexed, the thumb was except during bathing, for 6 more weeks to protect the adducted, and the fingers were midpoint between flexion transferred tendon. After 6 weeks, the splint was removed and extension. She had a myofascial lengthening of the except for nighttime wear, which was to be used for 6 biceps at the elbow, distal release of the pronator teres, months. Functional activities in therapy focused on ac- and a transfer around the ulnar border of the flexor carpi tivities of daily living, and teaching her how to tie her ulnaris to the extensor carpi radialis brevis. After 1 year, Cam- stance myotomy of the adductor pollicis was performed bria and her mother were again evaluated and she was in the palm. Thumb abduction was augmented with a very happy with the outcome because she felt her arm transfer of the palmaris longus. Her mother, however, was un- procedure the hand remains in the ideal positon with 20° happy because she said Cambria, in spite of the surgery of wrist dorsiflexion (Figure C8. The fingers are in a and extensive therapy, still did not use her hand any more postion of comfort and the thumb rests in mild abduction than before. She notes that although she had learned to (Figure C8. She was placed in a long arm cast in 80° tie her shoes, she only used one hand. She was also having some difficulty getting her transferred flexor carpi ulnaris was performed on the arm into shirt sleeves, especially if the sleeves were a lit- dorsolateral side of the wrist. The transfered tendon had become prominent wrist flexion stretching exercises immediately, and by the (Figure C8. She had graduated from high school and time she went to college, the rest wrist position was at 30° wanted to have something done before she started college to 40° extension, and maximum passive wrist flexion in 2 months. On physical examination she had 50° of was to 10° wrist flexion. On follow-up 1 year later, there dorsiflexion at rest and with maximum active wrist flex- was no significant change from the 3-month postopera- ion, could only get to −30° of wrist flexion. On passive tive visit and she was happy with the result. If finger flexors or flexor carpi radialis are lengthened, the flexor carpi ulnaris is transferred into the extensor carpi radialis brevis if there is minimal residual ulnar deviation. Transfer of the flexor carpi ul- naris to the extensor carpi radialis longus allows for wrist extension in a more radial direction. If there is a significant ulnar deviation deformity, lengthening of the extensor carpi ulnaris should also be performed. For severe wrist deformity with minimal finger flexor contractures but no active finger extension, transfer of the flexor carpi ulnaris should be into the extensor digitorum communis. Wrist flexion is then augmented by plication of the radial wrist extensors or by adding a transfer of the pronator teres to the extensor carpi radialis brevis. This procedure is only indicated for indi- viduals with active finger flexion when the wrist and fingers are passively held in an extended position. The same postoperative routine is used as for the flexor carpi ulnaris transfer alone. Fingers are always included in the cast with 30° to 40° of flexion of the interphalangeal and metacarpal phalangeal joints. Upper Extremity 413 For individuals with very severe wrist deformities, the indications for treatment are usually due to problems with custodial care, such as having problems getting arms in shirt sleeves and problems keeping the wrist flex- ion crease clean. The primary treatment for these deformities is wrist fusion by shortening the wrist. The shortening is provided by excision of the carpal bones, usually the proximal row, but in some severe cases all the carpal bones are removed, and the distal metacarpals are fused to the radius.
These arterial changes result in decreased ◗ The Heart in the Elderly blood flow and poor supply of oxygen and nutrients to There is much individual variation in the way the heart heart muscle purchase levitra professional 20mg online erectile dysfunction doctor chicago. Lack of exercise weakens the heart eases purchase levitra professional 20mg without a prescription erectile dysfunction doctors in maine, and personal habits. However, some of the changes muscle and decreases the efficiency of the heart. The heart be- decreases the efficiency of the skeletal muscles, which further taxes the heart. The valves become less flexible, ◗ Saturated fat in the diet. Elevated fat levels in the blood and incomplete closure may produce an audible murmur. Damage within the conduction system can ◗ High blood pressure (hypertension) damages heart produce abnormal rhythms, including extra beats, rapid muscle. Both diseases cause damage to small failure of the conduction system (heart block) can cause blood vessels. Because of the decrease in the reserve strength of the heart, elderly people are often Efforts to prevent heart disease should include having limited in their ability to respond to physical or emotional regular physical examinations and minimizing the con- stress. Box 14-2 Clinical Perspectives Lipoproteins: What’s the Big DL? HDLs remove found in bile salts needed for digestion of fats, in hormones, cholesterol from the tissues, such as the walls of the arteries, and and in the plasma membrane of the cell. However, high levels carry it back to the liver for reuse or disposal. Thus, high levels of cholesterol in the blood have been associated with athero- of HDLs indicate efficient removal of arterial plaques, whereas sclerosis and heart disease. It now appears that the total amount of blood cholesterol is Diet is an important factor in regulating lipoprotein levels. Cholesterol is Saturated fatty acids (found primarily in animal fats) raise transported in the blood in combination with other lipids and LDL levels, while unsaturated fatty acids (found in most veg- with protein, forming compounds called lipoproteins. These etable oils) lower LDL levels and stimulate cholesterol excre- compounds are distinguished by their relative density. Thus, a diet lower in saturated fat and higher in unsatu- density lipoprotein (HDL) is about one-half protein, whereas rated fat may reduce the risk of atherosclerosis and heart low-density lipoprotein (LDL) has a higher proportion of cho- disease. Other factors that affect lipoprotein levels include cig- lesterol and less protein. VLDLs, or very-low-density lipopro- arette smoking, coffee drinking, and stress, which raise LDL teins, are substances that are converted to LDLs. THE HEART AND HEART DISEASE 299 ◗ Heart Studies Ultrasound consists of sound waves generated at a frequency above the range of sensitivity of the human ear. Experienced listeners can gain much information about In echocardiography (ek-o-kar-de-OG-rah-fe), also the heart using a stethoscope (STETH-o-skope). This rel- known as ultrasound cardiography, high-frequency sound atively simple instrument is used to convey sounds from waves are sent to the heart from a small instrument on the within the patient’s body to an examiner’s ear. The ultrasound waves bounce off the The electrocardiograph (ECG or EKG) is used to heart and are recorded as they return, showing the heart record electrical changes produced as the heart muscle in action. Movement of the echoes is traced on an elec- contracts. It provides information on the size and tracing, or electrocardiogram, represents this activity as shape of heart structures, on cardiac function, and on waves. The P wave represents the activity of the atria; possible heart defects. Changes in the waves and the in- Checkpoint 14-14 What do ECG and EKG stand for? In right heart catheteri- Heart specialists employ medical and surgical approaches zation, an extremely thin tube (catheter) is passed to the treatment of heart disease, often in combination.
10 of 10 - Review by X. Ilja
Votes: 303 votes
Total customer reviews: 303