Physiology of alpine skiing.

The extreme environment of cold, altitude and movement complexity makes alpine ski racing a difficult sport to study. This review comprises >30 years of research and includes 29 on-snow investigations of specific physiology relating to the various ski racing disciplines, nine off-snow investigations of the physiological capacities of ski racers of varying ability and four review articles. Alpine ski racing appears to involve a complex integration of many different physiological systems, none of which may be more important than the other to overall performance. While technical ability appears to be the greatest influencing factor on performance, the ability to continually exhibit technical competence through a long competitive season requires high capabilities within all physiological systems. Identifying the optimal approach and time to concurrently develop these systems is a challenge for sport scientists. Further research is required using modern portable investigative tools for determining aerobic and anaerobic demands and abilities, especially in the areas of muscle function and relative energy system contribution during both single and multiple runs on varying terrain.

Bilateral naevus of Ota: a rare manifestation in a Caucasian.

The naevus of Ota (naevus fusculocoeruleus ophthalmomaxillaris) was first described by the Japanese dermatologist M. T. Ota in 1939. It has a reported incidence of 0.2% to 1% in the Japanese population. It usually occurs in the skin innervated by the first or second branch of the trigeminal nerve. The naevus comprises dermal melanocytes and is congenital or acquired during adolescence. Commonly associated lesions include scleral melanocytosis and other ocular manifestations as well as lesions of the tympanic membrane, oral and intranasal mucosa and leptomeninges. Diseases associated with Ota's naevus in rare cases are open-angle glaucomas and melanoma. The naevus of Ota in Europeans is a rare manifestation. We report the very rare case of a bilateral naevus of Ota associated with enoral melanocytosis in a white European person.

Anterior versus posterior, and rim-rent rotator cuff tears: prevalence and MR sensitivity.

PURPOSE: To determine the relative distribution of the locations of rotator cuff tears, and the sensitivity of anterior versus posterior tears on MR images. PATIENTS AND METHODS: We identified 110 consecutive patients who had a shoulder MR and either a partial-thickness or a small full-thickness rotator cuff tear diagnosed at arthroscopy. From the arthroscopy videotapes, we classified the tears as centered in the anterior or posterior half of the cuff, and as either in the critical zone or adjacent to the bony insertion. The original MR interpretation was compared with the arthroscopic findings. MR sensitivity and patient age were compared between patients with tears in the anterior and posterior halves of the cuff. In addition, in patients with partial tears less than 2 cm in diameter, an age comparison between those with tears in the critical zone and those with articular surface tears adjacent to the bony insertion (rim-rent tear) was performed. RESULTS: The tear was centered in the anterior half of the rotator cuff in 79% of the patients younger than 36 years old, and in 89% of the patients 36 years old and over. The average age of the patients with tears in the anterior half (44 years) was not significantly different from the average age of those with posterior tears (40 years) (P = 0.23). The sensitivity of MR for anterior tears was 0.69, and for posterior tears it was 0.56 (P = 0.17). The average age of the 9 patients with rim-rent tears was 31 years, while that of the 28 patients with similarly-sized partial tears not involving the insertion was 40 years old (P = 0.048). Five of the nine rim-rent tears (0.56) were interpreted correctly on the original MR report; two of the other tears were misinterpreted as intratendinous fluid but were diagnosable in retrospect. CONCLUSION: Even in patients less than 36 years old, most partial and small full-thickness rotator cuff tears are centered in the anterior half of the supraspinatus. Although our figure for MR sensitivity for these tears is lower than in recent articles, we found no significant difference between the sensitivity of MR for diagnosing posterior tears versus tears in the anterior half of the supraspinatus tendon. Rim-rent tears can be mistaken for intratendinous signal, and should be carefully looked for in younger patients with shoulder pain.

Acromioclavicular joint disorders.

The acromioclavicular joint is commonly involved in athletic injuries. Most commonly, a sprain to the joint occurs with variability in the amount of ligamentous damage and displacement that occurs. In all but the most severe dislocations, treatment consists of initial sling immobilization and early functional rehabilitation. The outcome is usually excellent with full return of function following these injuries. The rarer types (IV, V, and VI) require operative reduction and fixation. Distal clavicle fractures are related injuries, which many times disrupt the stabilizing ligaments of the acromioclavicular joint. Many can be treated nonoperatively, but there are several subtypes that should be considered for early fixation to reduce complications of pain and shoulder dysfunction. An atraumatic, overuse condition, which is becoming more prevalent and seems related to weight training, is osteolysis of the distal clavicle. There is insidious onset of shoulder pain with symptoms and signs consistent with acromioclavicular pathology. Activity modification is the best method of controlling symptoms. Failure of the conservative approach necessitates operative excision of the distal clavicle.

Distributions of fluorescence decay times for parinaric acids in phospholipid membranes.

Analysis of fluorescence decay data for probes incorporated into model or biological membranes invariably requires fitting to more than one decay time even though the same probe exhibits nearly single-exponential decay in solution. The parinaric acids (cis and trans) are examples of this. Data are presented for both parinaric acid isomers in dimyristoylphosphatidylcholine membranes collected to higher precision than normally encountered, and the fluorescence decays are shown to be best described by a smooth distribution of decay times rather than by a few discrete lifetimes. The temperature dependence of the fluorescence decay reveals a clear shift in the distribution to longer lifetimes associated with the membrane phase transition at 23.5 degrees C. The physical significance is that fluorescence lifetime measurements appear to reflect a physical process with a distribution of lifetimes rather than several distinct physical processes.

The induction of giant ring traps and regulation of conidiogenesis in the predacious fungus Dactylella brochopaga.

The nematophagous fungus Dactylella brochopaga was grown and supplied with prey under different conditions of light and atmospheric stagnation. Poor ventilation induced the formation of functional giant traps, hitherto unreported. Darkness inhibited sporulation. The adaptive significance of these changes is discussed.

The influence of percussion, occlusion and mastication on the occurrence of silent periods in masseter muscle activity.

The occurrence of silent periods in masseter muscle activity was investigated during percussion of the bony structures of the head and neck, during occlusion of the teeth on surfaces of varying hardness, and during chewing of different food-stuffs. Silent periods were demonstrated on percussion during isometric and isotonic contraction of the masseter muscles and the occurrence of silent periods was influenced by the force of occlusion and by the nature of the surface contacted. Mandibular velocity was investigated during tapping and chewing sequences by ultra-high-speed cinematography, but it was not found possible to identify a critical change in mandibular velocity associated with the occurrence of silent periods. More silent periods were observed during the chewing of hard foods than of soft foods and there were more silent periods near the beginning of chewing sequences than towards the end. Differences in latency and duration of silent periods were observed in relation to artificial changes in the occlusion.