Tooth microwear formation rate in Gasterosteus aculeatus.

Tooth microwear feature densities were significantly increased in a population of laboratory-reared three-spined stickleback Gasterosteus aculeatus in four days, after they were transferred from a limnetic feeding regime to a benthic feeding regime. These results show that even in aquatic vertebrates with non-occluding teeth, changes in feeding can cause changes in tooth microwear in just a few days, as in mammals.

Unusual anal fin in a Devonian jawless vertebrate reveals complex origins of paired appendages.

Jawed vertebrates (gnathostomes) have undergone radical anatomical and developmental changes in comparison with their jawless cousins (cyclostomes). Key among these is paired appendages (fins, legs and wings), which first evolved at some point on the gnathostome stem. The anatomy of fossil stem gnathostomes is, therefore, fundamental to our understanding of the nature and timing of the origin of this complex innovation. Here, we show that Euphanerops, a fossil jawless fish from the Devonian, possessed paired anal-fin radials, but no pectoral or pelvic fins. This unique condition occurs at an early stage on the stem-gnathostome lineage. This condition, and comparison with the varied condition of paired fins in other ostracoderms, indicates that there was a large amount of developmental plasticity during this episode-rather than a gradual evolution of this complex feature. Apparently, a number of different clades were exploring morphospace or undergoing multiple losses.

Within-guild dietary discrimination from 3-D textural analysis of tooth microwear in insectivorous mammals.

Resource exploitation and competition for food are important selective pressures in animal evolution. A number of recent investigations have focused on linkages between diversification, trophic morphology and diet in bats, partly because their roosting habits mean that for many bat species diet can be quantified relatively easily through faecal analysis. Dietary analysis in mammals is otherwise invasive, complicated, time consuming and expensive. Here we present evidence from insectivorous bats that analysis of three-dimensional (3-D) textures of tooth microwear using International Organization for Standardization (ISO) roughness parameters derived from sub-micron surface data provides an additional, powerful tool for investigation of trophic resource exploitation in mammals. Our approach, like scale-sensitive fractal analysis, offers considerable advantages over two-dimensional (2-D) methods of microwear analysis, including improvements in robustness, repeatability and comparability of studies. Our results constitute the first analysis of microwear textures in carnivorous mammals based on ISO roughness parameters. They demonstrate that the method is capable of dietary discrimination, even between cryptic species with subtly different diets within trophic guilds, and even when sample sizes are small. We find significant differences in microwear textures between insectivore species whose diet contains different proportions of 'hard' prey (such as beetles) and 'soft' prey (such as moths), and multivariate analyses are able to distinguish between species with different diets based solely on their tooth microwear textures. Our results show that, compared with previous 2-D analyses of microwear in bats, ISO roughness parameters provide a much more sophisticated characterization of the nature of microwear surfaces and can yield more robust and subtle dietary discrimination. ISO-based textural analysis of tooth microwear thus has a useful role to play, complementing existing approaches, in trophic analysis of mammals, both extant and extinct.

The impact of a nap opportunity during the night shift on the performance and alertness of 12-h shift workers.

The purpose of this workplace evaluation was to assess the effects on performance, alertness and subsequent sleep of strategic napping on 12-h overnight shifts. In a counterbalanced crossover design, 24 male aircraft maintenance engineers working in a forward rotating 12-h shift pattern volunteered to take part in the study for two work weeks. During the experimental week, each subject was given the opportunity to take a 20-min nap at work between 01:00 and 03:00 h on each of their two overnight shifts. On the control week no naps were taken on the night shifts. A computerized neurobehavioural test battery was employed to assess performance and subjective levels of fatigue at the beginning and end of each night shift, and pre- and postnap. Subjects were also asked to rate how near they had come to falling asleep while driving to and from work. The results revealed that taking a single 20-min nap during the first night shift significantly improved speed of response on a vigilance task measured at the end of the shift compared with the control condition. On the second night shift there was no effect of the nap on performance. Taking a short nap during either night shift had no significant effect on subjective ratings of fatigue, the level of sleepiness reported while driving to and from work, or subsequent sleep duration and sleep quality. Overall the results suggest some promise for a short duration nap taken in the workplace to counteract performance deficits associated with the first night shift.

The nursing shortage revisioning the future.

A severe shortage of nurses is being experienced nationally and globally. In South Florida, one of the most severely impacted regions in the world, a group of healthcare organizations, educational institutions, and nursing organizations formed the Nursing Shortage Consortium to combat the nursing shortage. Strategic efforts to recruit and retain nurses are underway, with a focus on nurturing interest among young people and increasing opportunities to stimulate their interest, to increase the supply of appropriately prepared professional nurses.

The influence of endogenous dopamine levels on the density of [3H]SCH23390-binding sites in the brain of the honey bee, Apis mellifera L.

This paper examines the relationship between endogenous dopamine (DA) levels and the density of [3H]SCH23390-binding sites in the brain of the adult worker honey bee. DA levels were reduced pharmacologically using a single 10 microl injection of either alpha-methyl-DL-p-tyrosine (AMT; 250 microg or 500 microg) or alpha-methyl-DL-tryptophan (AMTP; 250 or 500 microg) into the haemolymph of the bee. In all cases, maximum depletion of DA was observed 3 h after treatment, but in bees treated with AMTP (250 or 500 microg) or with 250 microg AMT, DA levels returned to normal within 24 h of treatment. Neither AMT nor AMTP was selective for DA: both drugs also reduced serotonin (5-hydroxytryptamine, 5HT) levels in the brain. However, AMTP was more effective than AMT at depleting 5HT, whereas for DA, the reverse was true. Depletion of DA levels, using 250 microg AMT, led to a dramatic decline in the levels of specific binding of [3H]SCH23390, defined in this study as binding in the presence of 5x10(-6) M cis-(Z)-flupentixol (see Ref. [28] ). In contrast, naturally occurring diel fluctuations in DA levels, identified in the optic lobes of the brain, and changes in brain DA levels resulting from queenlessness, had no significant effect on the density of [3H]SCH23390-binding sites in the brain of the bee. Overall, these results indicate that under normal physiological conditions, there is no direct link in honey bees between changes in endogenous brain DA levels and the density of D(1)-like receptors labelled by [3H]SCH23390.

Who really makes the bed? Uncovering technologic dissonance in nursing.

Technologic dissonance in the practice arena is demonstrated in the use of nonnursing technologies that are present in but technically incongruent with a nursing environment. Technology in nursing is not necessarily nursing technology. The article traces the influences of technologic dissonance beyond the reductionist purview of the medical model to their source in design and engineering philosophies. The vision of technologic consonance in nursing may be realized in the influence and expression of the caring nurse in the design, engineering, ownership, and use of nursing technology.

Acute skier's thumb repaired with a proximal phalanx suture anchor.

The purpose of this study was to determine the functional outcome of a surgical technique for the repair of injuries of the ulnar collateral ligament of the thumb. A 14-point questionnaire was developed to determine functional outcome after surgical repair of acute ulnar collateral ligament rupture. Early ulnar collateral ligament repair was performed on 58 patients with grade III sprains (complete rupture) of the ligament using a new technique that employs a suture anchor for fixation. Forty-five patients were interviewed at a minimum postoperative interval of 12 months and were included in this study. Forty-four patients (98%) believed they had a stable repair, were satisfied with their surgery, and would have it again if necessary. Forty-four patients (98%) were not hindered in their day-to-day activities and had a functional range of motion. Mild discomfort was felt by eight of our patients (17%), but only three patients (7%) had pain with activities. The average time to return to skiing was 1.7 days. The use of a suture anchor provided a strong and stable repair if the surgery was performed early.

Hors d'oeuvre.

Basic Palaeontology by M. Benton and D. Harper Addison Wesley Longman, 1997. £22.99 pbk (xv+342 pages) ISBN 0 582 22857 3.

Cloning and characterisation of a glutamate dehydrogenase cDNA from tomato (Lycopersicon esculentum L.).

A full-length cDNA (legdh1) has been cloned encoding glutamate dehydrogenase (GDH) from tomato (Lycopersicon esculentum L.). legdh1 is 1568 bp long and contains an open reading frame encoding a 44.8 kDa polypeptide with a putative mitochondrial-matrix-targeting pre-sequence at its N-terminus. Southern analysis indicates the existence of one copy of legdh1 per haploid genome, and no closely related genes were detected by Southern analysis at low stringency. We hypothesise that in tomato, the two GDH subunits may arise from post-transcriptional modifications of a single gene. Northern analysis reveals high expression of legdh1 in roots, lower levels of expression in stems, flowers and leaves, and no detectable expression in fruits. In general, there was no correlation between steady-state mRNA level and protein activity in the tissues analysed, again suggesting the importance of post-transcriptional events in the regulation of GDH. Comparison of cloned plant GDH proteins reveals a high degree of homology throughout the sequence except for a very specific, highly divergent region.

Central quadriceps tendon for anterior cruciate ligament reconstruction. Part I: Morphometric and biomechanical evaluation.

We examined the anatomic and biomechanical adequacy of the central quadriceps tendon as an alternative graft source for anterior cruciate ligament reconstruction. Morphometry was performed on 15 preserved and 6 fresh-frozen specimens. Biomechanical testing was performed on the six fresh-frozen specimens. We initially used a triple suture through the tendon construction, and then clamping directly on the tendon. Morphometry yielded the following measurements: length, 6.1 +/- 1.0 cm; width, 2.7 cm (range, 2.1 to 3.7); and thickness, 7 mm (range, 6.4 to 7.8). The thickness was 1.8 times that of the patellar tendon. Biomechanical testing showed that suture failure occurred at 692 +/- 181 N, and tendon failure occurred at 1075 +/- 449 N. The load to tendon failure was 1.36 times that of a comparable-width patellar tendon graft, although the difference was not statistically significant. The failure mode was primarily through partial or complete tendinous avulsion, with only one specimen failing at midsubstance. These findings show the central quadriceps graft is of sufficient size and strength to be used for anterior cruciate ligament reconstruction.

The impact of surgical timing on postoperative motion and stability following anterior cruciate ligament reconstruction.

A prospective study was designed to determine the impact of surgical timing on postoperative motion and stability following anterior cruciate ligament (ACL) reconstructive surgery. The study population was limited to acute ACL ruptures from downhill skiing undergoing arthroscopic ACL surgery without arthrotomy or surgical intervention for other ligamentous structures; 185 patients were entered into four separate groups based on the time interval from injury to surgery. Motion and stability were tested at multiple time points from the index surgery and adverse events were recorded. We found no statistical difference in restoration of extension or flexion in any group at any time point. KT-1000 data at 12 months showed a side-to-side difference of < or = 3 mm in 94%, with 6% showing a side-to-side difference of > 3 and < or = 5 mm. We conclude that, in this population, by using modern arthroscopic surgical techniques and an aggressive postoperative physical therapy protocol, motion and stability can be restored in a high percentage of patients and that surgical success is independent of the timing of surgery.

Injured stable knee with acute effusion: MRI evaluation.

This study was done to evaluate the magnetic resonance imaging (MRI) findings in acute traumatic effusions of the knee without ligament instability or radiographic abnormality other than the effusion. On reviewing the charts of 927 patients who had MRI of the knee, we found 114 patients who met the following criteria for inclusion in this study: (1) acute effusion by examination or history, (2) ligament stability on examination, and (3) normal findings on radiographs (excluding effusion). The total of 144 pathologic diagnoses made by MRI included bone injury (53%), disruption of the anterior cruciate ligament (19%), sprain of the medial collateral ligament (12%), medial meniscus tear (11%), lateral meniscus tear (5%), and rupture of the posterior cruciate ligament ( < 1%). Eight studies (7%) were read as normal. These MRI data are significantly different from data of previous studies using arthroscopy to evaluate acute knee injuries without ligament instability. The findings more accurately reflect the injury pattern seen in this setting because MRI can show both bone and soft tissue injury. From this study, we conclude that bone injury is the most common cause of acute effusion in the patient with ligament stability and normal radiographs.

The conodont controversies.

The discovery of fossilized conodont soft tissues has led to suggestions that these enigmatic animals were among the earliest vertebrates and that they were macrophagous, using their oropharyngeal skeletal apparatus to capture and process prey. These conclusions have proved controversial. There is now a consensus that conodonts belong within the chordates, but their position within the clade is hotly debated. Resolution of these questions has major implications for our understanding of the origin of the vertebrates and the selective pressures that led to the development of the vertebrate skeleton.

Meniscal injuries associated with acute anterior cruciate ligament tears in alpine skiers.

We reviewed the records of 315 patients receiving an arthroscopically assisted stabilizing procedure for an acute anterior cruciate ligament injury incurred while alpine skiing to evaluate associated meniscal injuries. Meniscal injuries were classified by type, location, and treatment of the tear. Of the 317 knees operated on, all demonstrated an anterior cruciate ligament tear at arthroscopy. Ninety-eight percent of the injuries (310) were diagnosed within 3 days of injury, and 97% (307) were reconstructed within 28 days of injury. All tears occurred in the intrasubstance of the ligament; 32% were isolated injuries and 68% were combined with other injuries. In 159 patients with 170 meniscal tears 141 of the tears (83%) were lateral and 29 (17%) were medial. The injury triad of anterior cruciate ligament-medial collateral ligament-lateral meniscus was seen nine times as often as the anterior cruciate ligament-medial collateral ligament-medial mensicus combination.

Treatment of comminuted distal radial fractures with preliminary horizontal finger trap traction and a Roger-Anderson external fixation device.

Over a five-year period, 43 patients with comminuted distal radial fractures were treated with a Roger-Anderson external fixation device after the fracture was aligned in Strong's horizontal finger trap traction. Nineteen patients (21 wrists) were available for personal interview and radiographic follow-up. A 0.5-mm loss of radial height and an average loss of 2.4 degrees of palmar angulation presented. Range of motion (ROM) was excellent, stiffness was nonexistent or minimal in 81%, pain was nonexistent or minimal in 86%, and weakness of grasp was nonexistent or minimal in 81%. Complications were minimal; they included three pin tract infections, two of which required pin removal before they resolved. One patient fractured a pin that also required removal. Strong's horizontal finger trap traction and the Roger-Anderson external fixation device simplified the sometimes difficult treatment of this fracture. It seems to be most effective in young athletic individuals who have good bone stock and very comminuted fractures.

Biomechanical and histological evaluation of the Herbert screw.

The Herbert screw has been demonstrated to have widespread clinical applicability. A biomechanical and histological evaluation of the Herbert screw was conducted to better define its applications. When subjected to pull-out, toggle, and compression testing, in a cancellous bone calf model, it was demonstrated to be biomechanically inferior to the 4.0 mm ASIF cancellous screw. The use of two Herbert screws minimized but did not eliminate this difference. Articular cartilage healing in a rabbit model was consistently demonstrated if the Herbert screw was buried deep to the osteochondral junction. However, toluidine blue histochemical staining showed that the hyaline-like repair cartilage differed qualitatively from normal cartilage. Utilization of the Herbert screw should include an understanding of the limitations of its fixation potential and a recognition of the repair response after intraarticular applications.

Arthroscopy update #5. Rehabilitation after arthroscopic lateral retinacular release.

This study compares postoperative quadriceps strength with functional results in a homogeneous population with isolated anterior knee pain and patellofemoral instability. Although several factors may interfere with the success of lateral retinacular release, this study suggests that poor quadriceps rehabilitation is the single factor preventing total return to athletic participation in patients with lateral subluxation. Many patients seem to adopt changes in life-style in order to accommodate weakened quadriceps and remain symptom free.

Peroneal nerve entrapment in runners.

In a practice involving large groups of athletes, seven runners and one soccer player with peroneal nerve compression neuropathy secondary to exercise have been found. Running incited pain, numbness and tingling to varying degrees in all patients, and examination after running revealed muscle weakness and a positive percussion test as the nerve winds around the fibular neck. Nerve conduction velocity studies confirmed the diagnosis in the five patients on whom the test was performed; other studies served primarily to exclude other causes of pain. All patients were treated surgically by neurolysis of the peroneal nerve as it travels under the sharp fibrous edge of the peroneus longus origin. Seven of eight had excellent results and returned to their previous level of physical exertion without further symptoms. We think entrapment of the peroneal nerve at the fibular neck is a more common entity than previously recognized, and it should be considered in the differential diagnosis of exertional lateral leg pain.