Temperature affects phenological synchrony in a tree-killing bark beetle.

Phenological synchrony can promote population growth in species with positive density dependence. Variation among life stages in the thermal thresholds for development can foster phenological synchrony under thermal regimes that include frequent occurrence of temperatures between developmental thresholds. The southern pine beetle is an insect with positive density dependence that has recently undergone important shifts in population abundance at the northern extremes of their distribution. We evaluated the hypothesis that cooler winter temperatures in their northern range cause a convergence of the population life stage structure that leads to synchrony in spring flight phenology. We used a combination of approaches. First, in situ laboratory experiments demonstrated a threshold temperature for pupation that was greater than was required for larval development; rearing larvae at lower temperatures increased the pooling of individuals at the end stage of larval development and synchrony in adult emergence. Second, a development rate model showed a similar convergence of the majority of the population at the end stage of larval development when brood experienced the cooler temperatures of the northern region, but not with temperatures from the southern region, or as a null model. Finally, field trapping of wild beetles showed greater synchrony in the pine forests of New Jersey than in the warmer, historically occupied forests of Georgia and Mississippi. Given these results, pine-dominated forests in the northern edge of the southern pine beetle's range may experience more frequent occurrence of outbreaks, due to the positive feedbacks associated with a synchronous spring emergence of this insect.

Regeneration of pigeon fast and slow muscle fiber types after partial excision and mincing.

The pigeon's metapatagialis muscles, containing fast fibers in two slips and slow fibers in another slip, were excised for a third of their length, minced, and replaced into their previous sites. After regeneration, the pattern of fiber types and their ATPase and oxidative enzymes were examined histochemically. Ultrastructural examination was carried out on the fast fibers. After 4-17 wk the muscles had regenerated into patterns histochemically similar to the controls only within the slip containing fast fibers. The slow slip was much less regenerated, and had a histochemically embryonic composition. Fiber types were characterized and their cross-sectional areas measured, and the degree of atrophy was greatest in the large fast fibers and the slow fibers. Ultrastructural studies revealed a number of alterations of the mitochondria, including dense and light areas in the matrix and an altered pattern of the cristae into parallel tubular or vesicular aggregations. Other changes included dilated sarcoplasmic reticulum, myofibril disorganization, and a compaction of filaments. The slow fibers were thought to be slower in their regeneration rates because of the pattern of multiple innervation's producing a more complex regenerative pattern.

Lobar pulmonary hemorrhage. An unusual complication of Swan-Ganz catheterization.

Massive lobar pulmonary hemorrhage related to Swan-Ganz catheterization represents a catastrophic complication that, to our knowledge, has received little attention in the literature. Our experience with two recent cases emphasizes the life-threatening nature of such bleeding as well as the potential for patient salvage after urgent resectional therapy. A spectrum of pulmonary vascular injuries is incurred after the insertion of a balloon-tipped catheter, and there are therapeutic approaches for each. The anticoagulation associated with cardiac surgical procedures prompts us to suggest that the technique of insertion and the use of the Swan-Ganz catheter in these patients be modified to avoid this complication.

Mild brain trauma in sports. Diagnosis and treatment guidelines.

Much has been written about the evaluation and management of mild brain trauma in sports. No less than 10 different 'guidelines' have been proposed and published to aid the clinician in the diagnosis of the condition. Too often, these guidelines have creating confusion instead of promoting an understanding of the spectrum of brain injury. As the understanding of the basic science of mild brain injury evolves, so must the approach to the concussed athlete. This article presents an up-to-date and clinically useful approach to the management of the athlete with a mild brain injury. The definition of 'concussion' is discussed and clarified and pertinent epidemiological data which highlight the importance of management skills as applied to athletes in a wide variety of sports are also reviewed. There is really no such thing as a 'mild concussion' if one considers the rare but catastrophic outcome of the second impact syndrome. For this reason, we review and expand upon the mechanisms of injury and pathophysiology. The accurate diagnosis of mild brain injury requires considerable experience, a high index of suspicion, a careful history and a series of examinations of the athlete, and a working knowledge of the athlete's personality and the likelihood of minimising their symptoms. The value of orientation questions pertinent to the athlete is now well established. Any focal neurological deficit or the deterioration of an athlete's condition warrants immediate hospitalisation, brain imaging and neurosurgical consultation. More commonly, athletes present with a brief alteration of consciousness, headache and amnesia and require careful examination and observation before returning to competition. The astute clinician will always err on the side of conservative management. The complete resolution of all symptoms before a return to play is imperative. Computerised tomography is very sensitive in the imaging of mild brain injuries. Neuropsychological testing is also very sensitive in the evaluation of brain injuries in athletes, and may become more clinically useful in the future.

Resistance training-induced increases in muscle mass and performance in ponies.

The purpose of this study was to determine whether 8 wk of progressive resistance exercise training would produce increases in strength and changes in foreleg muscle characteristics indicative of hypertrophy in ponies. Two mature 3- to 6-yr-old, male ponies (188 +/- 16 kg) were taught to carry sheets of lead over their saddle region (wither) while walking on a level treadmill at 1.9 m.s-1. This initial familiarization period was followed by 8 wk of training (3 d per wk), in which the ponies performed a series of progressive sets of weight carrying to fatigue. Each workout started with a 2-min walk at 1.9 m.s-1 followed by sets of weight carrying. The ponies carried 44.5 kg for the first set with increases of 22.3 kg per set until fatigue. Weights were applied and then removed for 60-90 s between sets using a chain hoist and sling apparatus. Measurements of forelimb girth, body weight, and total weight carried were recorded at each workout session. Ultrasound measurement of the diameters of the superdigital flexor muscles and muscle biopsies were performed before and after the 8-wk training period. Eight weeks of resistance training resulted in significant increases in peak weight carried (260%, P < 0.05) and total weight carried (1525%, P < 0.05) during each workout. Forelimb girth increased 12 +/- 1% (P < 0.05) with a corresponding 19 +/- 3% (P < 0.05) increase in muscle cross-sectional diameter. There were no changes (P > 0.05) in Type I muscle fiber area; however, there was a nonsignificant 26% increase in Type IIA+IIB fiber area. These data suggest that 8 wk of progressive resistance exercise training increase strength and cause changes in muscle size and characteristics consistent with hypertrophy.

The effects of anabolic steroids and strength training on the human immune response.

The immune response was assessed in 13 competitive bodybuilders self-administering anabolic-androgenic steroids and ten competitive bodybuilders not administering these drugs. Laboratory assessment included the number and relative distribution of T-cells, T-helper/inducer cells, T-cytotoxic/suppressor cells, activated T-cells, lymphocyte transformation to the mitogens, pokeweed mitogen (PWM), phytohemagglutinin (PHA), Concanavalin-A (CON-A), Staphylococcus aureus Cowan strain I (SAC), serum immunoglobulins, and natural killer (NK) activity. There were no significant differences in T-cell subsets among steroid users and non-users, but lymphocyte transformation studies revealed that the anabolic-androgenic steroid-using group had enhanced proliferative ability to the B-cell mitogen, SAC, in comparison to non-bodybuilding controls. NK activity was significantly (P less than 0.05) augmented in the anabolic-androgenic steroid users but not in the non-using bodybuilders. Serum immunoglobulin levels, in particular IgA, were significantly (P less than 0.017) lower in the steroid-using group. Four of 13 steroid users and three of eight non-steroid-using bodybuilders had detectable antinuclear antibodies. These studies indicate that 1) anabolic-androgenic steroid use as practiced by contemporary athletes is a potent modulator of immune responsiveness and 2) autoantibodies are prevalent in strength-trained men even in the absence of anabolic steroid use.

Suprascapular nerve injuries with isolated paralysis of the infraspinatus.

Nerve lesions are frequently overlooked in the differential diagnosis of shoulder pain, and there have been few reports in the literature of injuries of the supracapsular nerve that involve only the infraspinatus. We report four cases of suprascapular nerve injuries which involve solely the infraspinatus in which each patient presented with shoulder pain and weakness. The diagnosis can be suspected by careful history and physical examination, but must be confirmed by the appropriate electrical studies. Our patients required 6 months to 1 year to regain full function, and isokinetic testing revealed near normal return of strength. Further diagnostic work-up and surgery may be necessary for those cases which fail to demonstrate satisfactory improvement in the expected time period.

The preparticipation physical examination.

For decades the preparticipation physical examination (PPE) has been used to screen athletes prior to sports participation to prevent injury or illness. Evolution of the PPE, it is theorized, originated from the need to identify individuals with conditions that may predispose them to injuries or life-threatening situations. However, the effectiveness, practicality, and worthiness of the examination are a matter of debate. As members of a medical team, physicians are responsible for the health and safety of the athlete. The PPE is the first step in satisfying this responsibility. This article discusses the components of the PPE and presents the evidence-based model of knowledge behind the PPE.

Pre-participation physical evaluation.

The pre-participation physical evaluation is an integral part of any sports or activity program. There are many alternative methods for completing this evaluation, using varying degrees of frequency and thoroughness. A practical approach to the pre-participation physical evaluation is presented for use in an office as well as in a mass-screening situation.

Performance-enhancing supplements.

Supplements that are marketed as ergogenic aids have achieved widespread use in the United States. In image-conscious society, these agents are not only being consumed by athletes, but also by those looking for a quick fix to enhance their appearance. Many assume that the performance claims made by the manufacturers are based on actual data, and that these agents must be safe because they are sold to the general public. Unfortunately, in most cases these assumptions are false. Creatine has become very popular, particularly among college and high school athletes. Studies within the last 5 years have shown that creatine does seem to have certain ergogenic benefits in a laboratory setting. It is not currently known whether these benefits actually can be transferred to the playing field. Although creatine has not consistently been shown to cause any major side effects, there is some question regarding creatine's effect on the kidneys, particularly with long-term use. Also, the safety of supplementation in children and adolescents has not been examined at all; its use in this population should be discouraged until there are more data. Androstenedione is an agent that has received a large amount of popular press in the last year, and this has led to an surge in its usage. It is believed to exert its ergogenic effects through conversion to testosterone. But what limited data are available suggest that at the recommended dosage, it does not cause any measurable change in testosterone levels, or provide any ergogenic benefit in inexperienced weight lifters. Also, it has yet to be determined whether androstenedione causes any of the side effects often attributed to use of the illegal anabolic steroids. Its mechanism of action suggests it has the potential to cause many of these negative effects. Studies are just beginning to appear in the literature, and certainly more data need to be gathered before androstenedione supplementation can be recommended for use as an ergogenic aid.

The preparticipation evaluation.

The preparticipation evaluation (PPE) is the first step toward meeting the responsibility of maintaining the health and safety of the athlete. The ideal timing for the PPE is 6 weeks prior to the competitive season to allow adequate time for treatment and rehabilitation of problems. It is suggested that a complete screening evaluation be performed prior to entrance into a new level of school with annual limited reevaluations thereafter. The annual reevaluation should focus on the medical history with the physical examination emphasizing the cardiovascular system and interim injuries and medical problems. Currently, there are no data to support routine screening laboratory, radiographic, or cardiovascular testing in the asymptomatic athlete with an unremarkable history and normal examination. Two different methods for performing the PPE can be used (station-type mass screening and office setting), with each having its own distinct advantages and disadvantages. The most important and difficult decision for the physician screening young athletes is determining clearance for activity. Guidelines based on the demands of the sport and specific medical problems have been established; however, the physician's clinical judgement should be used in interpreting these recommendations for each individual athlete. The PPE is an excellent opportunity for the physician to positively influence the health care and safety of a local sports program. Through genuine interest, thorough evaluation, and knowledgeable counseling, the athlete will develop confidence in the evaluating physician. This confidence can translate into a good relationship and hopefully this interaction will encourage the athlete to trust the physician's judgement and seek early evaluation and treatment for problems that arise.

Drug programs.

Drug programs can be a positive method to assist athletes in the decision-making process concerning drug use. The keys to a successful drug program include the following: (1) inclusion of all involved parties in the development and administration of the program, (2) a reliable testing program that is sensitive for the drugs banned, (3) a disciplinary program that is consistent, (4) an evaluation and treatment program to prevent recurrence of the behavior or one that will treat the disease, and (5) the maintenance of confidentiality that will foster the confidence and support of all involved parties in the program.

Steroids and steroid-like compounds.

Athletes have been searching for an "edge" in competition as long as there has been a reward for success. Anabolic-androgenic steroids have been the most popular of these ergogenic aids when winning is the only goal. The authors present a concise review of these substances, their prevalence, efficacy, adverse effects, and legality. This article also presents a steroid user profile and discusses physician perception and management of a patient who uses these drugs. The popular precursors of testosterone, dehydroepiandrosterone, and androstenedione are discussed with a review of the limited available data on these substances.

The adolescent basketball player.

Adolescent basketball players can be viewed in two ways, as a unique population requiring special attention for their unique problems or as a similar group sharing the same problems as their adult counterparts. Attention should be paid to issues related to adolescence in general including changes in body size, growth of the musculoskeletal system, and hormonal changes that contribute to changes in behavior, emotions, and maturity. Attention to the particular needs of the adolescent basketball player may help prevent problems or lead to early recognition and intervention.

Substance abuse.

The three types of drugs commonly used in sports--therapeutic drugs, performance-enhancing drugs, and recreational drugs--have been discussed and presented in a way that should be helpful to health care providers dealing with athletes. The goal of this article has been not only to present information concerning drugs but also to raise the awareness level so that abuse of all types of drugs will be considered by athletic trainers, physicians, and health care providers when they deal with athletes. The role of the physician in the area of drug abuse is no different than the physician's role in dealing with any health problem, diagnosis, and management. The responsibility of the physician who deals with athletes always has been, is, and always will be the health and safety of the athlete.

Sports Medicine: A Team Effort.

In brief: The subspecialty of sports medicine is not reserved for the physician, who is just one member of the team. Sports scientists, psychologists, dentists, optometrists, athletic trainers, physical therapists, orthotists and prosthetists, podiatrists, nutritionists, and others play an integral part on the sports medicine team. However, the primary care physician can be the key to optimal performance of the sports medicine team-by being familiar with the talent and capability of specialists, communicating effectively, and knowing his or her own limitations.

Practice guidelines: which ones to follow?

Three levels of recommendations have been amalgamated under the "practice guidelines" label: consensus papers of large groups such as the Bethesda Conference(1), guidelines and criteria prepared by groups or individuals based on opinions about and interpretation of the literature, and algorithms developed by managed care organizations. If these various documents were religious worshippers, they would not only sit in different churches, but would worship a different Supreme Being. However, the two authors have used the terms interchangeably, resulting in a quagmire in which physicians and their patients can only sink and attorneys and insurers can flourish.

Stimulants and Athletic Performance (Part 1 of 2): Amphetamines and Caffeine.

In brief: Some athletes use amphetamines and caffeine to fight fatigue, but the effects of these substances on athletic performance are unclear. Both can be harmful. Amphetamines affect the central nervous system (CNS) and can cause tremulousness, anxiety, insomnia, and fever. Caffeine can increase free fatty acid utilization, mask fatigue through CNS stimulation, and increase the force of skeletal muscle contraction. The International Olympic Committee has banned the use of amphetamines altogether, and has banned caffeine when its values are greater than 15 µ g· ml(-1) in a urine test.

Stimulants and Athletic Performance (Part 2): Cocaine and Nicotine.

In brief: Cocaine and nicotine are among the stimulants that some athletes use in their quest for better performance or simple escape (amphetamines and caffeine were discussed in part 1 of this series [November, page 128]). Cocaine can cause paranoia and insomnia, and an overdose can lead to arrhythmias, coma, seizures, hyperthermia, and death. Nicotine affects several body systems and processes, and the impact of smoking on performance is negative in most cases. So far, little is known about how chewing tobacco influences performance.

Preparticipation Screening of College Athletes: Value of the Complete Blood Cell Count.

In brief: A retrospective study of 1,067 college athletes was done to determine the prevalence of certain abnormalities in their preseason complete blood cell count. The authors analyzed the values for white blood cell count, hemoglobin, mean corpuscular volume, and platelet count. In addition, they reviewed the literature to determine if an abnormality in any of these parameters alters athletic performance. Their conclusion: Only a hemoglobin level is useful in preseason evaluations.