Highest genetic diversity at the northern range limit of the rare orchid Isotria medeoloides

Populations in previously glaciated regions are often genetically depauperate in comparison with populations at lower latitudes, due either to bottlenecks experienced in post-glacial colonization or to contemporary genetic drift in small, peripheral populations. Populations of the rare self-fertilizing North American orchid Isotria medeoloides are largest in the previously glaciated region near the northern range limit, allowing us to examine the role of historical versus contemporary processes in determining population genetic diversity and structure. If contemporary processes predominate, genetic diversity should increase with increasing census size. In contrast, if sequential bottlenecks associated with colonization are paramount, diversity should decrease with latitude and be relatively insensitive to census size. We genotyped 299 individuals from 20 populations at four variable microsatellite loci to contrast genetic diversity and structure for populations in previously glaciated regions versus previously unglaciated regions. Populations were highly inbred (F=0.95) and highly differentiated (R(ST)=0.485). Across all sampled populations, genetic diversity decreased and genetic differentiation increased with declining population size. Small southern populations were especially differentiated and genetically depauperate. In the glaciated part of the range, genetic diversity increased as populations approached the northern range limit, demonstrating the centrality of contemporary processes for this post-glacial colonist.

Engaging recreational fishers in management and conservation: global case studies

Globally, the number of recreational fishers is sizeable and increasing in many countries. Associated with this trend is the potential for negative impacts on fish stocks through exploitation or management measures such as stocking and introduction of non-native fishes. Nevertheless, recreational fishers can be instrumental in successful fisheries conservation through active involvement in, or initiation of, conservation projects to reduce both direct and external stressors contributing to fishery declines. Understanding fishers' concerns for sustained access to the resource and developing methods for their meaningful participation can have positive impacts on conservation efforts. We examined a suite of case studies that demonstrate successful involvement of recreational fishers in conservation and management activities that span developed and developing countries, temperate and tropical regions, marine and freshwater systems, and open- and closed-access fisheries. To illustrate potential benefits and challenges of involving recreational fishers in fisheries management and conservation, we examined the socioeconomic and ecological contexts of each case study. We devised a conceptual framework for the engagement of recreational fishers that targets particular types of involvement (enforcement, advocacy, conservation, management design [type and location], research, and monitoring) on the basis of degree of stakeholder stewardship, scale of the fishery, and source of impacts (internal or external). These activities can be enhanced by incorporating local knowledge and traditions, taking advantage of leadership and regional networks, and creating collaborations among various stakeholder groups, scientists, and agencies to maximize the probability of recreational fisher involvement and project success.

Unusual presentation of blunt laryngeal injury with cricotracheal disruption by attempted hanging: a case report

The management of a patient with traumatic disruption of the cricotracheal junction in an attempted suicide by hanging is described. Such injury is uncommon, and many patients die at the scene; detailed radiologic imaging is rare because of the urgency of airway management. The delayed complete disruption of the major airway in this patient allowed adequate imaging and corrective management. Associated soft-tissue injuries of the great vessels of the neck are also described.

Persistent foreign body sensation and pharyngeal pain due to retention of staples: an interesting sequelae of endoscopic stapling procedure

The surgical treatment of a pharyngeal pouch with endoscopic stapling diverticulotomy is a relatively new concept. Long-term results and complications are yet to be fully studied. We describe a patient who developed persistent pharyngeal pain and foreign body sensation due to retention of a clump of staples at the cricopharyngeal sphincter. This complication has not been reported before. This case highlights the need for repeat endoscopy rather than a barium swallow X-ray if the patients are symptomatic after stapling procedures.

The tracheostomy tube change: a review of techniques

Tracheostomy tube changing is a routine procedure. However, occasional problems can arise and result in fatalities. This article reviews the various measures and techniques used to optimize the safeguarding of the airway during a tracheostomy tube change, including the 'railroad' technique. The management of accidental decannulations is also reviewed.

Coronal computed tomography of the normal vestibular aqueduct in children and young adults

OBJECTIVE

To characterize the appearance of the normal vestibular aqueduct on coronal computed tomography (CT).

DESIGN

Retrospective evaluation of routine CT images of the temporal bones.

SETTING

Private tertiary care center.

PATIENTS

Twenty-four children and young adults (14 females and 10 males), aged 2 to 24 years (average age, 10 years).

MAIN OUTCOMES MEASURES

Axial CT images were evaluated for the size of the vestibular aqueduct as previously described. On coronal CT images the vestibular aqueduct was evaluated for shape, dimensions, and angle. These measurements were made posteriorly, at the first point of vestibular aqueduct definition, and anteriorly, where the vestibular aqueduct abuts the posterior semicircular canal.

RESULTS

We were able to measure the vestibular aqueduct on 100% of the anterior coronal views, 77% of the midisthmus axial CT images, and 53% of posterior coronal CT images, (P<.001). The shape of the vestibular aqueduct on coronal CT scans varied posteriorly to anteriorly from being a slit to being an oval or round. The dimensions (mean + SD) of the isthmus on the anterior coronal views were 3.1 + 1.8 mm long by 1.6 + 0.8 mm wide. The upper limits of normal, as defined by the mean + 2 SDs, are 6.8 x 3.3 mm.

CONCLUSIONS

We have easily and consistently identified the vestibular aqueduct on coronal CT images; in fact, we found the vestibular aqueducts more consistently measurable on coronal CT scans than on axial CT scans. The addition of these views may improve the sensitivity of the CT scan in the evaluation of sensorineural hearing loss in children.

Pharmacological characterization of dopamine systems in the nucleus accumbens core and shell

Recent anatomical data suggest that the nucleus accumbens can be parcellated into a core region, related to the caudate-putamen, and a shell region, associated with the limbic system. We have used pharmacological methods to characterize the dopamine innervations of the nucleus accumbens core and shell in the rat. Concentrations of both dopamine and serotonin were significantly greater in the nucleus accumbens shell than the nucleus accumbens core. Metabolite: amine ratios suggested that both dopamine and serotonin utilization are greater in the core. However, dopamine turnover (as determined by measuring the rate of decline of dopamine after alpha-methyl-p-tyrosine treatment) was not significantly different in the two accumbal sectors. Dopamine concentrations in the two nucleus accumbens sectors were decreased to an equivalent degree at both 4 and 18 h after reserpine administration. In contrast, serotonin concentrations were decreased to a significantly greater degree in the nucleus accumbens core than nucleus accumbens shell at 4 h, but not 18 h, after reserpine administration. Administration of haloperidol increased dopamine utilization in both nucleus accumbens sectors, but augmented utilization to a significantly greater degree in the nucleus accumbens core. Clozapine increased dopamine utilization to an equivalent degree in both nucleus accumbens regions. Short duration immobilization stress selectively increased dopamine utilization in the nucleus accumbens shell. These data indicate that there are significant differences between the nucleus accumbens core and nucleus accumbens shell in basal dopamine metabolism, and indicate that the core and shell dopamine innervations can be distinguished on the basis of response to both pharmacological and environmental challenges.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative microanalysis of cell walls of Saprolegnia diclina Humphrey and Tremella mesenterica Fries

Cell walls of the fungi Saprolegnia declina Humphrey and Tremella mesenterica Fries were analyzed quantitatively. Particular attention was paid to the hydrolysis and analysis of neutral sugars, amino sugars and amino acids. These components, together with total lipids, total uronic acids and the ashed residue, accounted for more than 90% by weight of the original dry cell wall preparation. There were substantial losses of amino acids during hydrolysis; however, analytical recovery approached 100% when total protein was calculated from the total nitrogen analysis. The analytical procedures were reproducible (+/- 3% for amino acids and amino sugars, and +/- 5-10% for other components) when applied to individual cell wall preparations. However, even under carefully standardized conditions, different cell wall preparations from the same species showed variable composition. Glucose was the predominant neutral sugar in the cell wall polymers of both species. The amino acid compositions were remarkable in that neither species contained detectable levels of cyst(e)ine. Hydroxyproline was detected in both species. The report from Tremella mesenterica is the first for this amino acid from the cell wall of a Basidiomycete.

Studies of intermediary metabolism in germinating pea cotyledons. The pathway of ethanol metabolism and the role of the tricarboxylic acid cycle

1. The pathway of ethanol metabolism in cotyledons of 3-day-old pea seedlings has been examined by incubating tissue slices with [1-(14)C]ethanol and [2-(14)C]ethanol for periods up to 1hr. 2. Ethanol was rapidly incorporated into citrate and glutamate but relatively small amounts of (14)C were present in the evolved carbon dioxide even after 1hr. of ethanol metabolism. 3. Similar data were obtained from experiments in which [1,2-(14)C(2)]acetaldehyde and [(14)C]acetate were supplied. 4. The results are interpreted as indicating that ethanol is metabolized essentially via the reactions of the tricarboxylic acid cycle with a substantial drain of alpha-oxoglutarate to support the biosynthesis of glutamate. 5. It is concluded that oxaloacetate, required for the incorporation of ethanol into citrate, arises mainly from the transamination of aspartate and the fixation of carbon dioxide.