Defining myocardial fibrosis in haemodialysis patients with non-contrast cardiac magnetic resonance.

BACKGROUND: Extent of myocardial fibrosis (MF) determined using late gadolinium enhanced (LGE) predicts outcomes, but gadolinium is contraindicated in advanced renal disease. We assessed the ability of native T1-mapping to identify and quantify MF in aortic stenosis patients (AS) as a model for use in haemodialysis patients. METHODS: We compared the ability to identify areas of replacement-MF using native T1-mapping to LGE in 25 AS patients at 3 T. We assessed agreement between extent of MF defined by LGE full-width-half-maximum (FWHM) and the LGE 3-standard-deviations (3SD) in AS patients and nine T1 thresholding-techniques, with thresholds set 2-to-9 standard-deviations above normal-range (1083 ± 33 ms). A further technique was tested that set an individual T1-threshold for each patient (T11SD). The technique that agreed most strongly with FWHM or 3SD in AS patients was used to compare extent of MF between AS (n = 25) and haemodialysis patients (n = 25). RESULTS: Twenty-six areas of enhancement were identified on LGE images, with 25 corresponding areas of discretely increased native T1 signal identified on T1 maps. Global T1 was higher in haemodialysis than AS patients (1279 ms ± 5.8 vs 1143 ms ± 12.49, P < 0.01). No signal-threshold technique derived from standard-deviations above normal-range associated with FWHM or 3SD. T11SD correlated with FWHM in AS patients (r = 0.55) with moderate agreement (ICC = 0.64), (but not with 3SD). Extent of MF defined by T11SD was higher in haemodialysis vs AS patients (21.92% ± 1 vs 18.24% ± 1.4, P = 0.038), as was T1 in regions-of-interest defined as scar (1390 ± 8.7 vs 1276 ms ± 20.5, P < 0.01). There was no difference in the relative difference between remote myocardium and regions defined as scar, between groups (111.4 ms ± 7.6 vs 133.2 ms ± 17.5, P = 0.26). CONCLUSIONS: Areas of MF are identifiable on native T1 maps, but absolute thresholds to define extent of MF could not be determined. Histological studies are needed to assess the ability of native-T1 signal-thresholding techniques to define extent of MF in haemodialysis patients. Data is taken from the PRIMID-AS (NCT01658345) and CYCLE-HD studies (ISRCTN11299707).

Protein synthesis in pulmonary alveolar macrophages. Source of amino acids for leucyl-tRNA.

Extracellular, intracellular and tRNA-bound leucine pools of the adherent pulmonary alveolar macrophage were examined to determine the relationships between them and the precursor for protein synthesis. When cells were cultured in media of various leucine concentrations, the patterns of isotope distribution in intracellular and extracellular leucine did not correlate with the patterns seen in protein-bound leucine. hence, the free leucine pools cannot be used reliably as precursors for calculating rates of protein synthesis. tRNA-bound leucine, however, behaved isotopically as if it were the precursor. Constant synthetic rates were calculated using the tRNA specific activity over a wide range of leucine concentrations. In addition, by measuring the tRNA-bound specific activities of three different amino acids, leucine, valine and phenylalanine, and their respective specific activities in protein, we were able to calculate independently three separate but identical synthetic rates. At physiological amino acid concentrations, the macrophage intracellular leucine pool and the tRNA-bound leucine pool received less than half of their amino acids from extracellular sources. At 5 mM external leucine, the intracellular specific activity was indistinguishable from that of the medium leucine, but the specific activity of the tRNA-bound leucine pool remained only about 50% that of the extracellular value. The most straightforward interpretation of why the tRNA-bound leucine did not flood with external label under conditions where the intracellular pool has reached equilibrium is to propose that some portion of the leucine for protein synthesis is derived directly from protein turnover before the degradation products have mixed with the common amino acid pool.

Event-related potentials as indices of display-monitoring performance.

We evaluated event-related potentials (ERP) as indices of performance in three visual display-monitoring tasks: (a) signal detection, (b) running memory and (c) computation. Using factor analysis, we developed a global measure of performance (PFI) for each task. Task-relevant and irrelevant-probe stimuli elicited ERPs, which included components P1, N1, P2, P300, slow waves, and fronto-central negativities. In tasks (a) and (b), P300 amplitude in the task-relevant ERPs increased when the task was engaged, and was greater for accurate-than for inaccurate-response trials. In tasks (a) and (c), the irrelevant-probe ERPs also differed among task and performance conditions. To relate ERP measures to PF1, we developed linear regression models distinguished by three factors: general versus individual-subject, stimulus relevance, and signal-to-noise ratio (SNR). Model accuracy and reliability were highest for individual-subject, relevant-stimulus and high-SNR models, where average R2 values for the three tasks were 0.44, 0.46, and 0.38, respectively. We discuss implications of the models for performance monitoring and implications of the ERP effects for human information processing.

Supracondylar fractures of the humerus: the role of dynamic factors in prevention of deformity.

In a retrospective survey of eighty-two children with supracondylar fractures of the humerus, forty were found to have sufficient clinical and roentgenographic data to classify the fractures as varus or valgus, and to determine the carrying angles at end result. The initial displacement (varus or valgus) of the distal fragment correlated with the final carrying angle, but the use of internal fixation, the adequacy of reduction achieved and the duration of traction or immobilization did not. The sixteen varus supracondylar fractures immobilized with the forearm in supination had a mean varus deformity of about 16 degrees, whereas the eight immobilized in pronation had a varus deformity of only 3 degrees. The findings in the few valgus fractures suggested that the valgus angulation was less at follow-up if they had been immobilized in supination. Dissection of eight cadaver limbs and electromyographic studies of one normal limb suggested that the position of the forearm affects the result by altering muscle tension.

Traumatic lesions of the metatarsophalangeal joint of the great toe in athletes.

In the 1972, 1973, and 1974 football seasons at the University of Arkansas, 74 players sustained sprains of the ankle, producing a total of 152 missed practices and 6 missed games. Although only 18 injuries of the first metatarsophalangeal joint complex were seen, these later resulted in 92 missed practices and 7 missed games. This injury has been a significant problem for both the university and for most other major institutions, judging from a 70% response to 94 questionnaires sent to trainers of 94 large colleges and universities throughout the United States. It is the researchers opinion that the artificial turf surface, particularly as it ages, the shoes, and shoe fitting are all possible contributors to the incidence of the problem. Nonoperative treatment, whose hallmark is rest, is the treatment of first choice. Taping and splinting with a 0.51-mm spring steel splint with reinforcement, both pre- and postinjury, are beneficial. Injections of steroids or any other attempt to return the still painful athlete to activity are contraindicated. Late surgery, particularly in the event of capsular ruptures, as well as early repair, can be of benefit. The need to re-evaluate the shoes and playing surfaces in the light of this and other injuries is emphasized.

Repairs by trephination and suturing of longitudinal injuries in the avascular area of the meniscus in goats.

Trephination may encourage healing of a tear in the avascular area of the meniscus, but healing may not be complete in unstable tears. We studied trephination with suture of longitudinal injuries in the avascular area of the medial meniscus in 20 goats; samples were studied at 3, 8, and 25 weeks. All 20 tears treated by trephination and suture were completely (4 samples) or partly (16 samples) healed. The average tensile strength of the healed repair was 40.4 kg/cm2 at 25 weeks. The level of DNA synthesis and tissue ingrowth decreased with time; DNA synthetic activity was also found in the chondrocytes of the menisci treated by suture alone. Only three of the menisci treated by suture alone were partly healed, and the remainder showed no gross evidence of healing. The addition of trephination to the sutured meniscus appears to promote healing of longitudinal injuries in the avascular area and is recommended rather than suturing or trephination alone. Meniscal suture alone may stabilize the tear and stimulate cell proliferation for healing, but it appears to be significantly restricted without an adequate blood supply.

Anatomical and physiologic characteristics to predict football ability. Report of study methods and correlations, University of Arkansas, 1976.

In a prospective study of 56 scholarship players at the University of Arkansas in 1976, 14 anatomical and physiologic measurements were carried out on each of the 56 players, to include certain orthopaedic strength, power, and balance tests, and compared to the coaches' subjective ratings of football ability in an effort to determine which characteristics best correlate to the athlete's true performance. The correlation matrix for the criterion measure and the predictor variables of selected anatomical strength, balance, and power measures are presented, and the results of the study indicate that genu varum (0.445) and tibial torsion (-0.33) had the highest correlation with the coaching criterion variable. The average tibial torsion was 42.6 for these scholarship athletes, while normal average tibial torsion among a nonscholarship group was 27.40 degrees. Other anatomical characteristics measured, as well as strength and power measure, could not reach the critical level of +/- 0.263 to be significant at the 0.05 level, although horsepower was close (0.255). The Margaria-Kalamen power test was significantly related to the 40-yard dash, and a moderately good measure of football ability.

Natural history of anterior cruciate tears.

An evaluation of 361 patients with documented anterior cruciate tears was carried out with analysis of mechanisms, symptomatology, physical findings, and limitations. At the time of injury, patients generally heard a loud pop and felt their knee "slide apart" with a subsequent hemarthrosis. Internal tibial rotation was described as the principal mechanism of iniury in 81.6% of the patients. Less than 20% had a triad type injury. A "crossover" test enabled reproduction of the mechanism. On a 100 point scale, those with "no repair" scored a mean of 55.4, direct repairs 56.7, pes transfers 59.6, and modified MacIntosh 88.9 points. The natural course of a patient can often be projected. A Continuing comparative study of results from treatment regimens and procedures is indicated.

Treatment of acromioclavicular separations. A retrospective study.

A retrospective study of 134 patients with Types I, II, and III acromioclavicular separations was carried out. The average followup was 6.3 years, with the longest being 19 years, and the shortest being 1 year. The mechanism of injury was a direct blow in 92% of the patients. The average age of the patients was 30.1 years, with a range from 13 to 68 years. All patients were evaluated using a standard rating system for the shoulder and humerus, the total for perfect recovery being 100. Twenty-four patients with Type I separations were immobilized 19.5 days, with a disability period of 6 weeks, and rated 94 points. Twenty-five patients with Type II separations were immobilized 27 days for the conservative groups, had a disability period of 6 weeks, and rated 90 points. Eighty-five patients with Type III acromioclavicular separations were followed. Seven patients had conservative treatment, were immobilized an average of 22 days, with a disability period of 13 weeks, and rated 82. Of those patients who underwent surgical repair, excluding Dacron graft substitution, the immobilization period was 6 weeks, with a disability period of 12 weeks, and a rating of 80. Fifty-eight patients underwent repair with double velour Dacron prosthetic substitution for the coracoclavicular ligaments, combined with distal clavicular resection in all but two patients. The average immobilization period was 1 week, with the average disability period being 3 weeks. The average rating was 96, with 24 patients rating 100. The major cause for a rating less than 100 was light to moderate pain that persisted in a few cases, which was only occasional and associated with a particular activity. One infection occurred requiring graft removal 5 months after surgery. Calcification in the area of the coracoclavicular ligaments did not affect the final rating and recurrence of deformity was not noted.

A lateral extra-articular tenodesis for anterior cruciate ligament deficiency of the knee.

This article reviews patients with documented anterior cruciate ligament-deficient knees. Historical features are emphasized, and a rating system is provided. A lateral tenodesis is described, with timing of the repair and proper rehabilitation stressed.

Surgical management of congenital saccular cysts of the larynx.

Congenital saccular cysts of the larynx are unusual lesions that commonly present with respiratory obstruction in infants and children. The saccular cyst may result from an atresia of the laryngeal saccule orifice or may represent the retention of mucus in the collecting ducts of submucosal glands located around the ventricle. Traditionally, the treatment of the lesions has been endoscopic unroofing or marsupialization. Frequently, this modality requires multiple procedures as well as concomitant tracheotomy. There also have been reports of acquired subglottic stenosis. We have found that removal of the recurrent saccular cyst can be achieved relatively safely and effectively via a lateral cervical approach to the thyrohyoid membrane. We review our experience with four patients with congenital saccular cysts and detail the evaluation and surgical management of these lesions.

An extremely luminous panchromatic outburst from the nucleus of a distant galaxy.

Variable x-ray and γ-ray emission is characteristic of the most extreme physical processes in the universe. We present multiwavelength observations of a unique γ-ray-selected transient detected by the Swift satellite, accompanied by bright emission across the electromagnetic spectrum, and whose properties are unlike any previously observed source. We pinpoint the event to the center of a small, star-forming galaxy at redshift z = 0.3534. Its high-energy emission has lasted much longer than any γ-ray burst, whereas its peak luminosity was ∼100 times higher than bright active galactic nuclei. The association of the outburst with the center of its host galaxy suggests that this phenomenon has its origin in a rare mechanism involving the massive black hole in the nucleus of that galaxy.

Trephination and suturing of avascular meniscal tears: a clinical study of the trephination procedure.

On the basis of animal studies, an arthroscopic surgical system and procedure of trephination plus suturing were designed for clinical practice. The system consists of a trephine with a tooth-like tip, a guide, and an ordinary arthroscopic power handle. The guide introduces the trephine to the tear without abrading articular cartilage and controls the depth of the trephination. The power handle connected to a suction system provides an inside-out cut core of meniscal tissue. Thirty-six patients with meniscal tears underwent arthroscopic trephination plus suturing (group TS) and 28 patients had suturing alone (group S). The follow-up was 25 to 78 months. Two symptomatic retears have occurred in group TS and 7 symptomatic retears in group S. The symptomatic retear rate of group TS was significantly smaller than group S (P < .01). It is indicated that the patients treated with trephination have fewer symptoms and lower clinical failure rate. Arthroscopic trephination is a safe and easy procedure.