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PubMed2005

Soft tissue impact characterisation kit (STICK) for ex situ investigation of heart rhythm responses to acute mechanical stimulation.

Both mechanical induction and mechanical termination of arrhythmias have been reported in man. Examples include pre-cordial impacts by sports implements (baseballs, pucks) that can trigger arrhythmias, including ventricular fibrillation, or via the so-called pre-cordial thump, used as an emergency resuscitation measure to convert arrhythmias to normal sinus node rhythm. These interventions have been partially reproduced in experimental studies on whole animals. Relating observations at the system's level to underlying mechanisms has been difficult, however, largely because of: (i) a deficit in efficient and affordable pharmacological agents to selectively target (sub-)cellular responses in whole animal studies, and (ii) the lack of suitable experimental models to study the above responses at intermediate levels of functional and structural integration, such as the isolated heart or cardiac tissue. This paper presents a soft tissue impact characterisation kit (STICK), suitable for quantitative investigations into the effects of acute mechanical stimulation on cardiac electro-mechanical function in rodent isolated heart or tissue preparations. The STICK offers independent control over a range of relevant biophysical parameters, such as impact location and energy, pre-impact projectile speed and contact area, as well as over the timing of a mechanical stimulus relative to the cardiac cycle (monitored via electrocardiogram, ECG, here recorded directly from the cardiac surface). Projectile deceleration upon interaction with the tissue is monitored, contact-free, with a resolution of 175 microm, providing information on tissue deformation dynamics, force, pressure and work of the mechanical intervention. In order to study functional effects of cardiac mechanical stimulation in the absence of tissue damage, impacts must be limited (for juvenile Guinea pig heart) to 2-2.5 mJ in the slack left ventricle (diastolic impact) and 5-10 mJ in contracture (systolic impact), as confirmed by enzyme assay and histological investigation. Impacts, timed to coincide with the early T-wave of the ECG, are capable of triggering short runs of ventricular fibrillation. Thus, the STICK is a suitable tool for the study of acute cardiac mechano-electric feedback effects, caused by short impulse-like mechanical stimulation, at the level of the isolated organ or tissue.

Animals↗

PubMed2005

Successful resuscitation after sudden death in a one year old infant who sustained a blunt chest injury after a fall from 10 m.

Sudden cardiac arrest due to blunt anterior chest wall impact (Commotio Cordis) usually occurs in young athletes who are struck by a baseball or other projectile in the precordium. Survival is extremely rare if the induced ventricular fibrillation (VF) is not defibrillated immediately at the scene. We report here a rare case of a one-year-old infant survivor of cardiac arrest caused by blunt chest impact during an accidental fall from a fourth story window. Eye witnesses reported to have seen him land on the front of his chest directly onto the plastic rain cover on the ground floor. He was transferred to a nearby hospital within minutes, where ventricular fibrillation was recorded. Immediate cardiopulmonary resuscitation and defibrillation and was successful. He recovered without any subsequent sequelae. To the best of our knowledge, this rare incident represents the first time that an infant has survived such cardiac arrest in these circumstances that has been recorded in the literature. This has implications for the management of paediatric fall injuries.

Accidental Falls↗

PubMed2005

Determining whether a ball will land behind or in front of you: not just a combination of expansion and angular velocity.

We propose and evaluate a source of information that ball catchers may use to determine whether a ball will land behind or in front of them. It combines estimates for the ball's horizontal and vertical speed. These estimates are based, respectively, on the rate of angular expansion and vertical velocity. Our variable could account for ball catchers' data of Oudejans et al. [The effects of baseball experience on movement initiation in catching fly balls. Journal of Sports Sciences, 15, 587-595], but those data could also be explained by the use of angular expansion alone. We therefore conducted additional experiments in which we asked subjects where simulated balls would land under conditions in which both angular expansion and vertical velocity must be combined for obtaining a correct response. Subjects made systematic errors. We found evidence for the use of angular velocity but hardly any indication for the use of angular expansion. Thus, if catchers use a strategy that involves combining vertical and horizontal estimates of the ball's speed, they do not obtain their estimates of the horizontal component from the rate of expansion alone.

Attention↗

PubMed1993

Competitive athletes: preinjury and postinjury mood state and self-esteem.

In a prospective study, we determined whether preinjury and postinjury differences existed in the mood state and self-esteem of competitive athletes. The influence of severity of injury, gender, level of participation in sports, and type of sport on these dependent variables was also measured. Among 238 male and 38 female athletes from hockey, basketball, baseball, and volleyball teams, 36 sustained 43 injuries. Significant postinjury increases were noted for depression (P < 0.0001) and anger (P = 0.0012), whereas vigor (P < 0.0001) was significantly less after injury. When the 36 injuries were classified, 27 were minor or moderate (nonparticipation in sports for only one or two weekly assessments), and 9 were severe (nonparticipation for three or more weekly assessments). When a stepwise multiple regression equation was used to predict the scores for postinjury depression, the only significant predictor was the severity of injury (F = 8.48 [1, 34]; R2 = 0.30; P = 0.0063). Of the following physical and psychosocial variables--level of participation, type of sport, age, previous injury, preinjury stress, gender, mood state scales, and self-esteem--only level of participation (P < 0.0001) and type of sport (P = 0.0004) were predictors of injury. The significant preinjury and postinjury differences in mood state suggest that postinjury mood disturbances reported in previous studies are likely attributable to the occurrence of injury, are related to the severity of injury, and do not merely reflect a disturbed preinjury mood.

Affect↗

PubMed2002

Acute shoulder and elbow dislocations in the athlete.

Dislocations of the elbow are less common than shoulder dislocations. The primary treatment is conservative, with a conscious effort toward early mobilization. Recurrence is rare, and improvement in function and motion can be expected for up to 1 year. Operative treatment should be reserved for baseball pitchers and cases of complex instability.

Acute Disease↗

PubMed2002

Adolescent substance abuse. Assessment in the office.

There are no gold-standard tests for evaluating a teen suspected of abusing substances. Awareness of the high prevalence of substance abuse in youth, a high index of suspicion, and a firm desire to be a part of the solution are all that is required to address the problem of substance abuse in youth. In an age of "dotcoms" and societal complexity that fosters an emotionally "disconnected" atmosphere by uniting adolescents only by what they buy, plug into, click on, or blast away, teens need trusted medical homes where caring pediatricians are available to give youth accurate and authoritative facts and care to help them build inner resilience and connect them to the pain and hurt of the people in their lives. Until now, the "three strikes and you're out" maxim has been applied in medical care. This maxim may work for baseball, Clintonomics, and practical office management strategies but is not recommended for addressing the needs of substance using or abusing youth who are prey to advertising strategies. The size of the marketing and advertising budgets of the alcohol and cigarette industries is an indication of the relentless marketing directed toward vulnerable youth. Pediatricians would be doing teens a disservice if they fail to countermand this marketing effect by not using the "rule of seven"--the "seven 'S' screen," seven education attempts, seven different ways over 7 years, and persistence over seven attempts of chemically dependent adolescents to quit. It has been said by Osler that "These are our methods--to carefully observe the phenomena of life in all its stages, to cultivate the reasoning of the faculty so as to be able to know the true from the false. This is our work--to prevent disease, to relieve suffering, to heal the sick," and provide HOPE always.

Adolescent↗

PubMedDate not supplied

Eye injuries in athletics and recreation.

Sports-related eye injuries represent a significant eye health hazard worldwide. In the USA, it is estimated that eye injuries from sports account for more than 100,000 physician visits per year at the cost of greater than $175 million. The sports responsible for the greatest number of injuries are baseball, ice hockey, and racquet sports. In the USA there are over 189 million participants in these sports with a disproportionate number (one-third) of injuries involving the pediatric population. The most common injuries are abrasions and contusions, followed by more serious injuries, including hyphema. Substantial reduction in the incidence of eye injuries through prevention has been demonstrated in the sport of hockey which can serve as a model for other sports. Specific criteria for protective eyewear must be developed. Polycarbonate plastic lenses and frames which are sturdy and impact resistant provide optimal protection. Lensless goggles, street wear and spectacle correction glasses do not provide adequate eye protection. The ophthalmologist's role in preventing sports-related eye injuries includes addressing particular sports participants needs, identifying one-eyed athletes, and informing patients of the need for protective eyewear.

Athletic Injuries↗

PubMed1981

Sports eye injuries a preventable disease.

Each year, sports are responsible for over 100.000 preventable eye injuries. A face-protector standard was developed for hockey. Certified protectors effectively eliminated eye and face injuries to 1,200,000 players averting a projected 70,000 injuries and saving over $10,000,000 in medical expenses annually. The principle of absorbing energy in a protective device before the eye is injured is applied to other sports (racket sports, baseball, basketball). Recommendations are made on eye protection for athletes. Better data collection and standards for sports and children's eyewear are encouraged.

Adolescent↗

PubMed2003

Three-dimensional reconstruction of hepatic bridging fibrosis in chronic hepatitis C viral infection.

BACKGROUND/AIMS: Fibrosis in chronic hepatitis C infection begins in portal tracts, and can progress to 'bridging fibrosis' and eventually lead to cirrhosis. All current fibrosis staging systems are based on these three conceptual fibrosis stages (portal fibrosis, bridging fibrosis, cirrhosis) and vary only in how these stages are further subdivided. Despite the importance of bridging fibrosis, little is known about its three-dimensional characteristics. METHODS: Foci of bridging fibrosis were digitally reconstructed in three dimensions on two separate liver specimens with chronic hepatitis C viral infection. The amount of portal fibrosis was then correlated with bile duct diameter on trichrome-stained sections. RESULTS: After three-dimensional reconstruction, the bridges were seen to represent webs or membranes of fibrosis located at branch points of the portal tracts that extended between two portal branches, much like the webbing between the thumb and forefinger in a baseball-mitt. Direct measurements indicated that early portal fibrosis was associated with portal tracts containing bile ducts of approximately 18-19 mum diameter. CONCLUSIONS: Fibrosis bridges are located at branch points of portal tracts and are composed of three-dimensional webs or membranes that extend between portal tracts; when viewed as two dimensions on a glass slide, a 'bridge' of fibrosis is seen.

Aged↗

PubMed1991

Blunt trauma-induced pacemaker failure.

A 54-year-old man with an artificial pacemaker sustained blunt trauma to his chest when he was struck with a baseball bat. Within 15 minutes after the injury, the patient experienced cardiovascular collapse. His pacemaker failed, and he required insertion of a temporary transvenous pacemaker. At surgery, the defect was traced to failure of the pulse generator, a rare cause of pacemaker failure. Emergency department evaluation should include prompt and continuous ECG monitoring, an overpenetrated chest radiograph, and telemetry evaluation after discharge.

Cardiac Pacing, Artificial↗

PubMed1982

Acute central cervical spinal cord syndrome.

Two cases of the acute central cervical spinal cord syndrome are presented. A 63-year-old diabetic hypertensive man manifested the syndrome as a result of atraumatic ischemia of the cord. A 32-year-old health man developed it after sustaining a hyperextension injury in a baseball game. The pathogenesis and pathophysiology of this entity are reviewed. Knowledge of this entity is of major importance in the analysis and management of head and neck trauma, as well as in the recognition and management of atraumatic neurologic dysfunction due to ischemia, hemorrhage, or thrombosis.

Adult↗

PubMed2001

The effect of forearm rotation on laxity and stability of the elbow.

OBJECTIVE: The purpose of this study was to quantify the relationship between forearm rotation and valgus/varus laxity of the elbow joint over the range of elbow flexion. BACKGROUND: There is little known about the influence of forearm rotation on the laxity and stability of the elbow joint. The general opinion exists that forearm rotation does not significantly influence the laxity and stability of the elbow joint. METHODS: Nine fresh-frozen cadaver elbows were used. Passive elbow flexion with the forearm in neutral rotation and in 40 degrees and 80 degrees of pronation and supination was performed under valgus/varus loads: (1) in intact elbows; (2) after a lateral surgical approach (lateral epicondylar osteotomy of the distal humerus); (3) after release of the anterior bundle of the medial collateral ligament; and (4) after release of the anterior bundle of the medial collateral ligament plus radial head resection. Valgus/varus elbow laxity was quantified using an electromagnetic tracking device. RESULTS: There was a statistically significant effect (P < 0.05) of forearm rotation on valgus/varus laxity throughout the range of flexion. The laxity was always greater in pronation than in supination, regardless of the surgical approach or the integrity of the anterior bundle of the medial collateral ligament or radial head. CONCLUSIONS: Valgus/varus laxity of the elbow is forearm rotation-dependent. The potential role of this effect should be considered and controlled for in the design of studies examining laxity and stability of the elbow joint. RELEVANCE: The observation that forearm pronation increases valgus/varus laxity, particularly in medial collateral ligament deficient elbows, implies a possible additional factor in throwing kinematics that might put professional baseball pitchers at risk of medial collateral ligament injury due to chronic valgus overload. Our data indicate that forearm rotation should be considered during the clinical examination of elbow instability.

Aged↗

PubMed2000

'In the safety of your own home': results from a national survey on gun use at home.

In the US, guns, particularly handguns, are typically brought into the home for protection. The wisdom of having a firearm in the home, however, is disputed. While guns appear to be a risk factor for family homicide, suicide and unintentional firearm fatality, no evidence has been available about gun use at home to intimidate family members and little about gun use to thwart crimes by intruders, or about the use of other weapons in home self-defense. Over the past decade, various private surveys have asked questions about the respondent's use of guns in self-defense. None, however, has asked detailed questions about the use of guns to threaten or intimidate the respondent. This study presents results from a national random digit dial telephone survey of 1906 US adults conducted in the spring of 1996. Respondents were asked about hostile gun displays and use of guns and other weapons in self-defense at home in the past five years. The objective of the survey was to assess the relative frequency and characteristics of weapons-related events at home. Thirteen respondents reported that a gun was displayed against them at home, two reported using a gun in self-defense at home, and 24 reported using another weapon (e.g. knife, baseball bat) in home self-defense. While we do not always know whose weapon was used in these incidents, most gun brandishings were by male intimates against women. A gun in the home can be used against family members or intruders and can be used not only to kill and wound, but to intimidate and frighten. This small study provides some evidence that guns may be used at least as often by family members to frighten intimates as to thwart crime, and that other weapons are far more commonly used against intruders than are guns.

Adolescent↗

PubMed1998

Epilepsy and athletics.

This article reviews the debate regarding epileptic patients and their participation in sports, particularly contact (i.e., basketball, soccer, baseball) and collision (i.e., football, rugby, hockey) sports. Epilepsy is defined and described, as well as the dangers and benefits of exercise to the epileptic patient, including participation in athletic competition.

Adolescent↗

PubMed1999

Nutrition and exercise in individuals with diabetes.

Individuals with type 1 (insulin-dependent diabetes mellitus [IDDM]) and type 2 (non-insulin-dependent diabetes mellitus [NIDDM]) diabetes should be encouraged to exercise. Although there is an absence of consistent evidence that adaptations to routine exercise improve glucose control in type 1 diabetes, there is evidence that shows improved glucose control in individuals with type 2 diabetes. Although both groups benefit from exercise, the merit and suitability of routine exercise is measured by the extent to which the advantageous adaptive effects of regular exercise surpass the risks of a sole bout of exercise. In addition, when considering acute versus routine exercise, special considerations must be given to children with diabetes and older adults at risk for insulin resistance. Finally, a greater research focus is needed on engaging in competitive and recreational sports so that children and adults with diabetes may participate safely in activities such as baseball, swimming, basketball, soccer, and hockey.

Aged↗

PubMed2001

Osteochondritis dissecans of the humeral capitellum. Diagnosis and treatment.

Elbow pain seen in the at-risk athlete, such as a baseball player (in particular, a pitcher) or gymnast, should raise suspicion for OCD. OCD of the humeral capitellum remains a difficult problem to treat. Once radiographic changes are obvious, long-term studies suggest that half of affected individuals will be symptomatic. Currently, the key to successful treatment is early detection. Gymnasts, in general, fare worse in returning to sport. The reason is not entirely clear but is likely related to the amount of force directed across the elbow and the nature of the sport. Pitchers sometimes can be returned, but to another position. Radiographs remain the screening test of choice but can give the surgeon a false sense of security, because changes early in the disease process may not be obvious radiographically. Views at 45 degrees flexion and contralateral elbow views are helpful. The advent of MR imaging now allows the practicing orthopaedic surgeon to assess very early lesions effectively that might otherwise be underappreciated on radiographs. With more advanced lesions, radiographic findings are more obvious and demonstrate the more classic capitellar fragment with a surrounding zone of lucency. MR imaging is this setting is helpful in assessing the overlying articular cartilage and, hence, the stability of the fragment. In the absence of obvious loose bodies or mechanical symptoms, rest is the first step in treatment. If symptoms persist, then operative intervention is indicated. About half of these patients heal with nonoperative treatment. Pretreatment assessment of fragment viability has not traditionally been incorporated into the treatment algorithm. Recent anecdotal evidence suggests that stability and viability of a fragment can be assessed using intravenous contrast. Knowledge of the fragment viability could allow those lesions likely to heal without surgical intervention to be distinguished from those requiring surgical intervention. The procedure should be chosen based on the size of the lesion and the integrity of the subchondral bone. Subchondral drilling and microfracture can only resurface defects and cannot reconstitute subchondral bone. Autologous chondrocyte implantation has limited ability to address subchondral bone loss, whereas autograft and allograft osteochondral transplantation can restore subchondral bone. Most authors would agree that there is no role currently for reduction and fixation of long-standing, free loose bodies. No consensus exists regarding acute dislodging of an in situ loose fragment. Long-term results after radiographic changes are present suggest a degenerative course in about half the patients. Whether the newer techniques of cartilage resurfacing will significantly impact the natural history of this process remains to be seen.

Athletic Injuries↗

PubMed2001

The role of arthroscopic thermal capsulorrhaphy in the hip.

Arthroscopic thermal modification of collagen in the hip capsular tissue appears to be a treatment option for patients with hip instability. Traumatic hip instability is associated with frank dislocation or a subluxation, and labral tears. Atraumatic hip instability is associated with evidence of generalized ligament laxity. It can be associated with bone-collagen type disorders, including Ehlers-Danlos syndrome, Down syndrome, arthrochalasis multiplex congenita, developmental dysplastic hip, and idiopathic type. As previously discussed by Bellabarba et al, capsular laxity may be the underlying cause of dynamic hip instability. The capsule is a fibrous, thick, and strong structure that encircles the proximal femur and the acetabulum. The capsule is thicker anteriorly than posteriorly, and consists of two sets of fibers, circular and longitudinal. The capsule ligaments play a very important role in hip stability. The hip joint capsule is reinforced by the iliofemoral, pubofemoral, and ischiofemoral ligaments. It remains sensitive to stretch and serves as a mechanism for muscular feedback and pain. The iliofemoral ligament limits hyperextension and lateral rotation of the hip joint and is taut in full extension. Full extension of the hip exposes the capsule and ligaments to a twisting and shortening effect that forces the head onto the acetabulum. We are currently studying the effect of iliofemoral ligament deficiency and its relationship to instability. Many of the properties of synovial lubrication depend on contact with articular surfaces, and incongruency due to instability may have some functional role in distribution of synovial fluid, leading to stresses from weightbearing and eventually to rapid deterioration of the articular surfaces. The high-level athletes in this series include two professional baseball players, three professional golfers (PGA), one professional football player (NFL), one figure skater (Olympic gold medalist), one gymnast (Olympic level, bilateral hips), and one ballet dancer; they returned to their pre-injury level of activity. The other patients returned to their pre-injury functional lifestyle. Hip instability appears to present consistently with stable gait abnormalities and painful sensation of instability. Recognizing the various patterns of hip instability is complicated, and therefore management and outcome of these disorders are quite variable. Bellabarba et al concluded that physical therapy alone had been unsuccessful and that temporary success of a posterior capsular "plication" in one patient showed promise. Arthroscopic thermal modification of collagen in the hip capsular tissue appears to be a treatment option for patients with hip instability. The hip joint capsule is predominantly type 1 collagen, and the mechanism of tissue shrinkage through type 1 collagen alteration is well documented in the literature. Short-term results appear promising, however, more studies are required to determine the long-term efficacy of this procedure in the treatment of this challenging disorder.

Arthroscopy↗

PubMed1996

Advances in the molecular understanding of gonadotropins-receptors interactions.

The extracellular domain (ECD) of gonadotropin receptors belong to the leucine-rich repeat (LRR) protein superfamily and their transmembrane domain (TMD) is characteristic of the seven alpha-helices G-protein-coupled receptors (GPCR). The availability of the X-ray structures of porcine ribonuclease inhibitor (RI), a LRR protein, and bacteriorhodopsin (bR) allows the construction of 3D models of the ECD and the TMD of gonadotropin receptors, respectively. The predicted models are to a large extent consistent with currently available biochemical and mutational data. The models provide a reliable basis for understanding how the hormone binds and activates its receptor. The ECD, in particular the LRR region, serves as a baseball glove which efficiently catches the large hormone and optimally orient the appropriate parts of it for interaction with the seven-transmembrane-helix domain of the receptor. This in turn is expected to lead to a conformational change to be sensed by the appropriate G-protein complex leading to the stimulation of cAMP synthesis and steroids production.

Binding Sites↗