By I. Ur-Gosh. Saint Louis Christian College.
A sample of top athletes prazosin 1 mg without prescription, for example purchase 2 mg prazosin visa, is probably not representative of the general population in smoking, alcohol and dietary habits. A study of patients attending a sports injury clinic will only be representative of that group of patients. This may be distorted by demographic or geographical factors so that, for example, the pattern of injuries presenting to an urban sports injury clinic will be different to that in a district general hospital. Researchers must always be aware of potential bias, and readers should always look out for bias affecting results. Papers describing a case or case series are, by definition, a selected sample, but bias can easily occur in populations studies too. Case control studies are common and convenient in sport medicine research. The criteria used to select both the cases and the control must be explicit. Cases and controls should be matched as closely as possible so that, ideally, the only feature separating them is the feature to be studied. An injury study that compares a population of athletes with a population, similar in age and sex, but who are sedentary or attending hospital for a different condition, can draw few conclusions about the factors causing injury. There are many other potential 7 Evidence-based Sports Medicine sources of bias in the case control study. One of the most prevalent is recall bias, where those who suffer a particular injury or illness are more likely to recall events around that time and make inappropriate associations. The randomised controlled trial is an attempt to avoid as many of these sources of bias as possible. The sample is selected before an intervention and allocated to an intervention or control group using random methods.
Cholera is self-limiting cheap 2mg prazosin with mastercard, possibly because the bacteria remain in the intestine buy discount prazosin 1mg line, where they are washed out of the system by the diffuse watery diarrhea. Over the past three years, Percy Veere has persevered through the death of his wife and the subsequent calamities of his grandson Dennis “the Menace” Veere, including salicylate poisoning, suspected malathion poisoning, and now cholera. Veere decided to send his grandson home for the remainder of the summer. The cytokine TNF (tumor necrosis fac- tor) uses a type of receptor called the death domain receptor (Fig. These receptors function as a trimer when they bind TNF (which is also a trimer). On TNF binding, an inhibitory protein called the “silencer of death” is released from the receptor. The receptor then binds and activates several adaptor proteins. One adaptor protein, FADD (fas-associated death domain), recruits and activates the zymogen form of a proteolytic enzyme called caspase. Caspases 202 SECTION TWO / CHEMICAL AND BIOLOGICAL FOUNDATIONS OF BIOCHEMISTRY TNF Death domains Procaspases Ser-T kinase NF-κB Death Fig. The portion of the receptor shown in blue is called the death domain because it binds adaptor proteins that initiate different signaling pathways lead- ing to cell death. The adaptor protein FADD forms a scaffold on which proteolytic procas- pases cleave each other, thereby initiating a death pathway. The adaptor protein TRADD binds a protein that binds a serine-threonine kinase (Ser-T kinase) that initiates another signaling pathway leading to activation of the transcription factor NF- B. Caspases are proteolytic enzymes initiate a signal transduction pathway leading to apoptosis (programmed cell death) that have a critical role in pro- (see Chapter 18). Another adaptor protein, TRADD (TNF receptor-associated grammed cell death (also called death domain), initiates signaling pathways that lead to activation of the gene-spe- apoptosis) (see Chapter 16). Caspases are cific transcription factors Jun and NF- B (nuclear factor- B). Through these path- present as latent zymogens until their auto- ways, TNF mediates cell-specific responses, such as cell growth and death, the proteolysis (self-cleavage) is activated by inflammatory response, and immune function.
Upper respiratory infections buy cheap prazosin 1 mg on-line, infectious mononucleosis order 2 mg prazosin amex, myocarditis and hepatitis are some of the specific entities that will be addressed in this chapter. Emphasis will be placed on what recommendations to make to athletes concerning exercising while acutely ill and when to return to practice and/or competition. Methods Computerised bibliographic database (Medline) was searched from the earliest date until July 2001 using a combination of the following key words along with Medline subject headings (MeSH). Relevant articles were also retrieved from reference lists of pertinent review articles. Key words: • exercise • physical training • fever, infection • metabolism 83 Evidence-based Sports Medicine • acute phase response • viral myocarditis • infectious mononucleosis • hepatitis • gastroenteritis • respiratory infections • sudden death. Fever and/or acute infectious disease – general considerations Fever is defined as 38° Celsius or higher oral or rectal temperature. It is associated with acute and chronic infections, muscle trauma, neoplasms, heat related illness, prolonged exercise and some medications. It is difficult to different some of the effects of fever from the effects of the condition causing it; however, in general, it is recognised that fever impairs muscle strength,1 mental cognition and pulmonary perfusion. Additionally fever increases insensible fluid loss and increases overall systemic metabolism. Additionally, decreased muscle strength could be seen as a potential factor for increased risk of injury although there are no studies to support this theory. The aerobic exercise capacity, as determined from submaximal exercise studies, is decreased during fever. On the other hand, the observed maximal oxygen uptake has been shown to be unaffected during short lasting, experimental pyrogen induced fever as well as in conditions of thermal dehydration. There do not appear to be any studies where maximal oxygen uptake has been measured during ongoing infection and fever (most likely for ethical reasons).