By O. Saturas. Dallas Baptist University.
Research on bacterial chromosome structure and func- Another chronic bacterial infection that affects the tion has tended to focus on Escherichia coli as the model lungs is tuberculosis generic 20mg forzest free shipping. This bacterium is an excellent system for such any other infectious disease 20 mg forzest overnight delivery. However purchase 20 mg forzest visa, as the diversity of bacterial life has become infected with the agent of tuberculosis quality forzest 20 mg, the bacterium more apparent in beginning in the 1970s purchase forzest 20mg with amex, the limitations of Mycobacterium tuberculosis. As with other chronic infec- extrapolating the findings from the Escherichia coli chromo- tions, the symptoms can be mild. But, for those with a weak- some to bacteria in general has also more apparent. See also Genetic identification of microorganisms; Genetic Beginning in the mid 1970s, there has been an increas- regulation of prokaryotic cells; Microbial genetics; Viral ing recognition that maladies that were previously thought to genetics; Yeast genetics be due to genetic or environmental factors in fact have their basis in chronic bacterial infections. A key discovery that prompted this shift in thinking concerning the origin of certain CHRONIC BACTERIAL DISEASE diseases was the demonstration by Barry Marshall that a bac- Chronic bacterial disease terium called Helicobacter pylori is the major cause of stom- Chronic bacterial infections persist for prolonged periods of ach ulcers. This lengthy persist- association with chronic Helicobacter pylori stomach and ence is due to a number of factors including masking of the intestinal infections and the development of certain types of bacteria from the immune system, invasion of host cells, and intestinal cancers. The spirochaete is able to terial infections have been shown to be associated with the establish a chronic infection in a host. The infection and the development of the adherent, exopolysaccharide-encased host’s response to the infection, causes arthritis and long-last- populations that are termed biofilms. This means that As a final recent example, Joseph Penninger has shown the immune system does not readily recognize the that the bacterium Chlamydia trachomatis is the agent that exopolysaccharide as foreign material that must be cleared causes a common form of heart disease. Within the blanket of polysaccharide the bac- ically infects a host and produces a protein that is very similar teria, which would otherwise be swiftly detected by the in three-dimensional structure to a protein that composed a immune system, are protected from immune recognition. The host’s immune response to the bacterial pro- a result, the infection that is established can persist for a tein results in the deterioration of the heart protein, leading to long time. An example of a chronic, biofilm-related bacterial infec- Evidence is accumulating that implicates chronic bacte- tion is prostatitis. Prostatitis is an inflammation of the prostate rial infection with other human ailments including schizo- 123 Cloning: Applications to biological problems WORLD OF MICROBIOLOGY AND IMMUNOLOGY phrenia and Alzheimer’s disease. While not yet conclusive, the experimental animals used as well as allows for specification involvement of chronic bacterial infections in maladies that of the sex of the progeny resulting in faster generation of have hitherto not been suspected of having a bacterial origin breeding stocks. Medical benefits from cloned transgenic animals Research efforts to prevent chronic bacterial infections expressing human proteins in their milk are numerous. For are focusing on the prevention of the surface adhesion that is example, human serum albumin is a protein used to treat a hallmark of many such infections. Molecules that can com- patients suffering from acute burns and over 600 tons are used petitively block the sites to which the disease-causing bacteria each year. By removing the gene that expresses bovine serum bind have shown promising results in preventing infections in albumin, cattle clones can be made to express human serum the laboratory setting. Another example is found at one biotech company that uses goats to produce human tissue plasminogen activa- See also Bacteria and bacterial infection; Biofilm formation tor, a human protein involved in blood clotting cascades. Cows can also be genet- CJD DISEASE • see BSE AND CJD DISEASE ically manipulated using nuclear gene transfer to produce milk that does not have lactose for lactose-intolerant people. There CLINICAL MICROBIOLOGY • see MICROBIOLOGY, are also certain proteins in milk that cause immunological reactions in certain individuals that can be removed and CLINICAL replaced with other important proteins. There is currently a significant shortage of organs for CLINICAL TRIALS, TYPES • see MICROBIOLOGY, patients needing transplants. Long waiting lists lead to pro- CLINICAL longed suffering and people often die before they find the nec- essary matches for transplantation. Transplantation technology in terms of hearts and kidneys is commonplace, CLONING: APPLICATIONS TO but very expensive. Xenotransplantation, or the transplanta- tion of organs from animals into humans, is being investi- BIOLOGICALCloning: Applications to biological problems PROBLEMS gated, yet graft versus host rejection remains problematic. As Human proteins are often used in the medical treatment of var- an alternative to xenotransplantation, stem cells can be used ious human diseases. The most common way to produce pro- therapeutically, such as in blood disorders where blood stem teins is through human cell culture, an expensive approach cells are used to deliver normal blood cell types. However, the that rarely results in adequate quantities of the desired protein.
He reminded Leonard not to make any assumptions and to keep an open mind generic forzest 20 mg with amex. Leonard did what he was told and immediately realized he was lean- ing both his arms on the support bars of the treadmill while running buy discount forzest 20 mg line. By using his shoulders to support his weight generic forzest 20 mg amex, Leonard was probably causing progressive microtrauma to both shoulder joints purchase forzest 20mg otc. As the pain from the trauma intensiﬁed quality forzest 20mg, Leonard began guarding against the pain by not using them. First he was immobilizing them as he Are Your Ways of Staying Healthy Making You Sick? Then he was immobilizing them further by refusing to use them because of the pain, giving himself a double whammy. Conclusion Attempting to stay healthy through diet and exercise is certainly recom- mended. However, as with Maria, Jennifer, and Leonard, exercise and diet- ing can be hazardous to your health if not done properly and with supervision. And don’t forget to analyze your own so-called healthy habits when searching for clues to your mystery malady. Ask yourself these questions: • Have you begun any new routine or regimen in an attempt to get or stay healthy? Neck, back, and joint pain affects a whopping 60 to 85 percent of the population at any given time. Musculoskeletal and joint pain often starts without warning and for no obvi- ous or easily explainable reason. In other cases, it becomes recurrent and we don’t know why we are hurting or how to ﬁx it. Most of the time, with this kind of pain, people just assume they have injured themselves, and the injury was the precipitating cause of their pain. In this chapter, we share several interesting cases of seemingly unex- plainable muscle or joint pain. Once these frustrated patients used the Eight Steps, they ﬁnally found the correct diagnosis and obtained relief from their pain. Being an active young man and having injured various parts of his body at one time or another, he knew the drill. When he got home, he iced the most painful area of his back, laid down, and later applied moist heat. He felt reasonably certain the pain would diminish before he went back to work on Monday. In fact, the pain remained fairly intense and persisted the entire week. He was x-rayed and when it was determined his pain was probably a soft tissue injury, he was treated with nonsteroidal anti-inﬂammatory drugs and given a prescription for physical therapy, which he pursued twice a week for several weeks. The drugs and physical therapy helped somewhat, but they didn’t com- pletely resolve his problem. He ﬁgured out that if he kept moving around—walking, riding a bike, or doing any other activity (including sex), he had less back pain. Lying down or sitting in a chair or car for some reason caused his back to become stiff and hurt even more. Even though he would get up and stretch periodically, by the end of each work- day, he was close to tears from the pain. He was ready to give up his job to become a construction worker or anything that was less sedentary and more physical. Every morning, he awoke with increased back stiffness, and the pain in the lower left quadrant of his back was excruciating. Massage therapy felt great but did not afford him any long- lasting relief. Acupuncture lessened the sensation of pain, but the relief only lasted for a few hours. His doctor examined Brad again and discovered that his patient was, indeed, “tight. They helped until Brad Do You Have Unexplained Back, Neck, or Joint Pain? Brad tried a number of other things in an effort to help himself, includ- ing wearing magnets. He dropped a few pounds because he was afraid he was getting sciatica like his uncle whose condition had improved with weight loss.
If not generic 20 mg forzest with mastercard, you may need to re-establish your priori ties and organise your time accordingly discount forzest 20mg on-line. External constraints – there is no point in having your heart set on a particular date if this is unsuitable for the publisher’s schedule or if a jour nal needs to have your article six months ahead of publication discount forzest 20 mg. Personal goals – do you want your work published within a certain year or in a particular quarterly journal? This will give you a very firm tar get to work towards purchase 20mg forzest overnight delivery, but you must make sure that it is a realistic goal 20mg forzest with visa. Writing style – you will need to estimate how long you personally need to complete the task. This might be in short, inten sive bursts or at a slow, steady pace over a longer period of time. Do you need to research background information, or do you have most of your data ready? You may need to allow for a longer period of time for researching your material. A manuscript of 120,000 words requires a very different timescale to a smaller project of 60,000 words. Prob lems can arise if different writing styles have not been addressed in the planning stage. The timetable should meet the needs of each individual, and this often means going with the lowest common denominator. There is no point one person racing ahead if the other author is still methodically 238 WRITING SKILLS IN PRACTICE but slowly working through his or her own work. Remember to include additional slots for meetings, sharing work, joint planning and editing sessions. Other considerations – major events, whether personal, social or work, need to be taken into account. Allow for time out for such things as major business trips, family weddings or planned hospital treatment. You are now ready to make an estimate of how much time you will need to complete each stage. Work backwards from your finish date and mark in completion dates for each stage on your plan. Remember that it is commonplace for articles for peer-reviewed journals to be returned for re drafting, and editors may return your chapter or book with queries or cor rections requiring your attention. These factors need to be taken into consideration when planning your schedule. Setting up a timetable Use your planner to draw up a timetable that includes weekly or monthly schedules covering your intended timeframe. Block out time committed to non-writing activities like work, shopping, a hobby or family activities like taking the children swimming. Remember to include one-off events like weddings, holidays or work situations such as attending a major con ference. Draw your timetable large enough so that there is space to write in daily goals. Use your planning sheet to mark the completion dates for your subgoals, main goals and stages on the timetable. If you find that one of your completion dates coincides with a major event, then reschedule it. Planning individual sessions You are now ready to start drawing up plans for your writing slots. It might be to complete a database search, or to find out what books are available on a specific subject. However, without any specific goals about what you do when you get there, you will be un able to gauge how much further on you are in your work schedule. MANAGING YOUR TIME EFFECTIVELY 239 You may want to break tasks down into different categories.
Mosses in the Malheur National Forest in Oregon has been growing reproduce by forming runners that grow horizontally cheap 20 mg forzest mastercard, produce for some 2400 years generic forzest 20 mg without a prescription. The growth now covers 2200 acres discount 20mg forzest free shipping, an new stalks cheap 20mg forzest visa, then decompose cheap forzest 20mg mastercard, leaving a new plant that is a clone area equivalent to 1665 football fields. Analysis of the genetic material obtained from differ- Bacteria reproducing asexually double their numbers ent regions of the fungal growth has shown the DNA to be rapidly, approximately every 20 minutes. This reproduction identical, demonstrating that the growth is indeed from the rate is offset by a high death rate that may be the result of the same fungus. The fungus than Yeasts reproduce asexually by budding; they can also draws off nutrients, suffocating the tree. In the budding process a bulge forms on can extend as deep as 10 feet into the soil, and can invade the the outer edge of the yeast cell as nuclear division takes place. When viewed from the air, the pattern of dead One of these nuclei moves into the bud, which eventually trees looks remarkably like a mushroom. Understanding more of the nature Bees, ants, wasps, and other insects can reproduce sex- of this effect could lead to the use of the fungus to control ually or asexually. In some 35 Asilomar conference WORLD OF MICROBIOLOGY AND IMMUNOLOGY designed to minimize the chance of vectors (carriers) contain- ing recombinant DNA molecules from escaping into the envi- ronment, where they could potentially harm humans or other parts of the ecosystem. Because these projected experiments had never been done, assignment to a risk category was, of course, somewhat speculative and subjective. At all risk levels, the guidelines called for the use of bio- logical barriers. Bacterial host cells should be from strains unable to survive in natural environments (outside the test tube). Vectors carrying recombinant DNA, including plas- mids, bacteriophages, and other viruses, were to be nontrans- missible and unable to survive in natural environments. For experiments having minimal risk, the guidelines recommended that scientists follow general microbiology safety procedures. These included not eating, drinking, or smoking in the lab; wearing laboratory coats in the work area; Budding yeast cells undergoing asexual reproduction; yeast are single-celled fungi. For example, procedures producing aerosols, such as using a species the eggs may or may not be fertilized; fertilized eggs blender, were to be performed under an enclosed ventilation produce females, while unfertilized eggs produce males. The advantage of asexual propagation to farmers is Moderate-risk experiments required the use of a laminar that the crops will be more uniform than those produced from flow hood, the wearing of gloves, and the maintenance of neg- seed. Some plants are difficult to cultivate from seed and asex- ative air pressure in the laboratory. This would ensure that air ual reproduction in these plants makes it possible to produce currents did not carry recombinant DNA out of the laboratory. These included isolation of the laboratory vegetative propagation and is used for such crops as potatoes, from other areas by air locks, having researchers shower and bananas, raspberries, pineapples, and some flowering plants change their clothing upon leaving the work area, and the used as ornamentals. Farmers plant the so-called “eyes” of incineration of exhaust air from the hoods. With raspberry bushes, cloning of recombinant DNA from highly pathogenic organ- branches are bent and covered with soil. Also forbidden were a separate plant with their own root system and can eventually experiments involving the production of more than 10 liters of be detached from the parent plant. See also Cell cycle and cell division The scientists at the Asilomar conference also resolved to meet annually to re-evaluate the guidelines. As new proce- dures were developed and safer vectors and bacterial cells Asilomar conferenceASILOMAR CONFERENCE became available, it became possible to re-evaluate and relax some of the initially stringent and restrictive safety standards. Soon after American microbiologist Hamilton Smith’s 1970 discovery of the first restriction enzyme, it became possible to See also Recombination; Viral genetics; Viral vectors in gene combine DNA from different sources into one molecule, pro- therapy ducing recombinant DNA. Concern by scientists and lay peo- ple that some of this recombinant-technology DNA might be harmful to humans prompted the research to stop until scien- ATOMIC FORCE MICROSCOPE Atomic force microscope tists could evaluate its risks. In February 1975 over 100 internationally respected In 1985, the development of the atomic force microscope molecular biologists met at the Asilomar conference center in (AFM) allowed scientists to visualize the surface of cellular California. There they decided upon a set of guidelines to be structures during some physiological processes.
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