Origin of the hungry caterpillar: Evolution of fasting in slug moths (Insecta: Lepidoptera: Limacodidae).

Studies of caterpillar defense strategy evolution typically focus on aposematic coloration, gregarious behavior, and/or chemical defense. In the slug moth family Limacodidae, the evolution of chemical defense is coupled to the life history trait of first instar feeding behaviors. In nettle caterpillars, the first instars fast and molt into a second instar that feeds. In contrast, gelatines and monkey slug larval forms feed in the first instar. This study focused on whether the evolution of fasting associated with the nettle morphology was a derived trait of single or multiple origins. Twenty-nine species of Limacodidae (including one Chrysopolominae) representing 27 genera and four outgroup species with known first and final instar morphologies and behaviors were included. Four out-group species representing Megalopygidae (1 sp), Dalceridae (1 sp) and Aididae (2 sp) were included. These were sequenced for three molecular markers for a total of 4073 bp, mitochondrial COI (∼1500 bp), 18S (∼1900 bp) and the D2 region of 28S (approximately 670 bp). Maximum likelihood and Bayesian analyses were conducted. The resulting phylogeny and comparative analysis of feeding strategy revealed that the nettle caterpillar morphology and behavior of larval fasting may have a single origin.

A molecular phylogenetic analysis of the vampire moths and their fruit-piercing relatives (Lepidoptera: Erebidae: Calpinae).

Within butterflies and moths, adult hematophagy is limited to species within the vampire moth genus Calyptra. These moths are placed within the subfamily Calpinae, whose other members are known to exhibit a broad range of feeding behaviors including those that can be considered 'piercers' of fruits or other hosts and 'tear feeders'. Here, we reconstruct a phylogenetic hypothesis of Calpinae using molecular data to test whether hematophagy in Calyptra arose from plant or animal-related behaviors. We use a Bayesian method of ancestral state reconstruction to determine the most likely feeding behaviors for the subtribes and genera within this lineage.

Utility and evolution of cytochrome b in insects.

Cytochrome b (cyt-b) is widely used in molecular phylogenetic studies of vertebrate, but not invertebrate, taxa. To determine whether this situation is an historical accident or reflects the utility of cyt-b, we compared the abilities of cyt-b, COI, and one nuclear ribosomal gene region (D1 of 28S) to recover intergeneric relationships within the tiger moth tribes Ctenuchini and Euchromiini. Additionally, we compared the rate of sequence and amino acid evolution of cyt-b across insects. Cytochrome b had the same level of sequence variation and A/T bias as COI, but was less useful for recovering intergeneric relationships. The total evidence tree casts doubt on the traditional taxonomy of the group. For the class Insecta, we found that functional conservation of amino acids occurs for the same regions as those found in vertebrates with the exception of Mallophaga (lice). Lice have an accelerated rate of nonsynonymous substitutions. Accelerated rate of cyt-b nucleotide and amino acid evolution in Apidae (bees) may be correlated with increased metabolic rates associated with facultative endothermy (= heterothermy).

Cervical facet dislocation: techniques for ventral reduction and stabilization.

OBJECT: To demonstrate the safety and utility of one surgical approach, the authors reviewed their experience with the ventral surgical approach for decompression, reduction, and stabilization in 10 patients with either unilateral or bilateral cervical facet dislocation. METHODS: Six patients presented with unilateral cervical facet dislocation and four patients with bilateral cervical facet dislocation. There were six male and four female patients who ranged in age from 17 to 72 years (average 37.1 years). The level of facet dislocation was C4-5 in one, C5-6 in four, and C6-7 in five patients. Three patients presented with a complete spinal cord injury (SCI), three patients with an incomplete SCI, three with radicular symptoms or myeloradiculopathy, and one patient was neurologically intact. All patients underwent plain radiography, magnetic resonance imaging, and computerized tomography evaluation of the cervical spine. All patients had sustained significant ligamentous injury with minimum or no bone disruption. All patients underwent ventral decompressive surgery, reduction of the dislocation, and stabilization of the cervical spine. Techniques for performing ventral reduction of unilateral or bilateral cervical facet dislocation are described. Decompression, reduction, and stabilization of the cervical spine via the ventral approach was accomplished in all but one patient. This patient underwent a ventral decompressive procedure and an attempt at ventral reduction and subsequent dorsal reduction and fusion in which a lateral mass screw plate fixation system was used; this was followed by ventral placement of instrumentation and fusion. There were no surgery-related complications. Postoperative neurological status was unchanged in four patients and improved in six patients. No patient experienced neurological deterioration after undergoing this surgical approach. CONCLUSIONS: The authors conclude that a ventral surgical decompression, reduction, and stabilization procedure provides a safe and effective alternative for the treatment of patients with unilateral or bilateral cervical facet dislocation without significant bone disruption.

Detection of vertebral artery injury after cervical spine trauma using magnetic resonance angiography.

BACKGROUND: We prospectively describe the incidence, magnetic resonance-based diagnosis, and treatment of vertebral artery (VA) injury resulting from closed cervical spine trauma. METHODS: Patients with fracture or dislocation on plain radiographic studies underwent computed tomography. Among these patients, the subset with computed tomographic evidence of foramen transversarium (FT) fracture underwent magnetic resonance angiography as early as possible. RESULTS: During a 16-month period, 38 patients with closed cervical trauma were treated. Twelve patients demonstrated fracture extension through at least one FT by computed tomography. Among these patients, four showed unilateral VA injury by magnetic resonance angiography, all ipsilateral to the fractured FT. Three cases of VA occlusion and one of focal narrowing were demonstrated. All four patients were initially treated with aspirin, and two were systemically anticoagulated. None developed irreversible neurologic deficits from the VA compromise. CONCLUSION: Our data suggest that the incidence of VA injury in closed cervical spine trauma is significant and that FT fractures warrant flow-sensitive magnetic resonance imaging.

Phylogenetic placement of rickettsiae from the ticks Amblyomma americanum and Ixodes scapularis.

A rickettsial isolate (isolate MOAa) belonging to the spotted fever group (SFG) was obtained from the lone star tick Amblyomma americanum. We used PCR to characterize the genes for the rickettsial outer membrane proteins rOmpA and rOmpB. We sequenced the PCR products (domains I of both the rompA gene and the rompB gene) of MOAa and WB-8-2, another rickettsial isolate from A. americanum. To place MOAa and WB-8-2 and two other nonpathogenic isolates (Rickettsia rickettsii Hip2 and Rickettsia montana M5/6) with respect to their putative sister species, we included them in a phylogenetic analysis of 9 Rickettsia species and 10 Rickettsia strains. Our phylogenetic results implied three evolutionary lineages of SFG rickettsiae and that WB-8-2 and MOAa were most closely related to R. montana. New World isolates were not the most closely related to each other (they did not form a clade). Rather, our results supported four independent origins (introductions) of rickettsiae into North America from different Old World regions. The results of our phylogenetic analysis did not support the hypothesis of a stable coevolution of rickettsiae and their tick hosts. Finally, we examined the rompA gene of a nonpathogenic rickettsial symbiont isolated from the tick Ixodes scapularis. In a phylogenetic analysis, the symbiont was placed as the sister to R. montana and its isolates. The relationship of this symbiont to R. montana raised questions as to the potential origin of pathogenic SFG rickettsiae from nonpathogenic tick symbionts, or vice versa.

Molecular phylogenetics of the avian genus Pipilo and a biogeographic argument for taxonomic uncertainty.

We sequenced 1709 base pairs (bp) of mitochondrial DNA including parts of cytochrome b, ND 2, and the control region (CR I, II) for seven members of the avian genus Pipilo (towhees), Melozone kieneri (rusty-crowned ground-sparrow), and Arremonops rufivirgatus (olive sparrow). A total of 457 bp was variable and 257 bp were potentially phylogenetically informative. All gene regions were similarly variable (20.2 to 28.4%) except for CR II (38.4%); third position transitions were as common as substitutions in the CR. Tree topology was sensitive to choice of outgroup(s) and individual sequences used as exemplars. Six trees were considered viable phylogenetic hypotheses based on maximum parsimony and maximum likelihood analyses. These trees generally supported two groups of towhees (rufous-sided group, brown towhee group), a sister taxon relationship for P. aberti and P. crissalis, and a sister taxon relationship for P. ocai and P. maculatus. The occurrence of M. kiernei within Pipilo in three trees challenges the monophyly of the latter; the other species of Melozone and other outgroups require study to resolve Pipilo monophyly. The relationships of P. albicollis and P. fuscus were ambiguous, as they were with previous data sets (allozymes, mtDNA restriction sites); they could be sister species or either one could be the basal species in the brown towhee group. We suggest that this taxonomic uncertainty obtains from the contemporaneous origin of P. fuscus, P. albicollis, and the ancestor of P. aberti/P. crissalis. We favor a "star" phylogeny because species in unrelated lineages found in the same region as P. albicollis are similarly difficult to resolve phylogenetically. Synapomorphies from coding genes and the CR did not preferentially support basal and terminal nodes, and hence did not provide different windows of taxonomic resolution, which might be expected from the apparent rapid rate of CR evolution. Phylogenetic trees inferred from allozymes, restriction sites, and mtDNA sequences were congruent, suggesting that each is a useful source of phylogenetic information.

Biomechanics of the thoracolumbar spine.

The thoracolumbar spine is the principal load-bearing structure of the body. As such, it is subject to a wide variety of forces that can be described by biomechanical principles. Forces act through vectors, depending on the direction of force and the relative location of the instantaneous axis of rotation. Patterns of failure due to supraphysiologic loading or through the loss of structural integrity may be predicted based on the applied force vectors and the stabilization components lost. An understanding of these forces and their effects on the spine is crucial for the safe and efficacious treatment of spinal deformities.

Hydrocephalus requiring urgent external ventricular drainage in a patient with diabetic ketoacidosis and cerebral edema: case report.

OBJECTIVE AND IMPORTANCE: Neurological deterioration, typically attributed to cerebral edema, is a rare but life-threatening complication in the treatment of diabetic ketoacidosis (DKA). We report the case of a child with DKA who became comatose but demonstrated acute obstructive hydrocephalus, instead of cerebral edema. CLINICAL PRESENTATION: An 11-year-old male patient presented with new-onset insulin-dependent diabetes mellitus and DKA. He was initially responsive but, after several hours of treatment, became unresponsive, with dilated pupils and decerebrate posturing. Cranial computed tomographic scanning demonstrated obstructive hydrocephalus resulting from focal cerebellar and brain stem edema. INTERVENTION: The patient was initially managed with medical treatment but ultimately required urgent ventricular drainage to arrest a progressive herniation syndrome. To our knowledge, this report describes only the second such case reported and the first requiring urgent ventriculostomy. CONCLUSIONS: These observations emphasize the importance of recognizing hydrocephalus as a potentially reversible cause of coma in DKA and of initiating prompt neurosurgical intervention, if warranted.

Solitary fibrous tumor presenting as a symptomatic intraspinal mass: case report.

OBJECTIVE AND IMPORTANCE: Mesenchymal, nonmeningeal tumors of the central and peripheral nervous systems are rare. Specifically, the solitary fibrous tumor, which occurs in both benign and malignant forms, was first described in the pleura and more recently in a number of sites, including the mediastinum, abdomen, upper respiratory tract, nasopharynx, and orbit. It has not, however, previously been known to involve the spine or to induce cord compression. CLINICAL PRESENTATION: We describe the case of a 33-year-old man who presented with back pain, progressive myelopathy, and lower extremity dysesthesias. Imaging studies demonstrated an intradural extramedullary mass at T7-T8. INTERVENTION: At surgery, the lesion was found to be firm, fibrous, intimately apposed to the T8 sensory nerve root but emanating from neither root nor dura. Histologically, the tumor was composed of spindle cells in a storiform pattern with extensive collagen deposition in the intercellular matrix. Immunohistochemistry showed diffuse positive staining of tumor cells for CD34 antigen but negative staining for S100 and EMA, a profile that is consistent with a histopathological diagnosis of solitary fibrous tumor and that effectively rules out meningioma and nerve sheath tumor. CONCLUSION: This is the first report of an intraspinal solitary fibrous tumor, a rare entity that should be included in the differential diagnosis of intradural extramedullary spinal neoplasms.

Cervical spine fractures in the elderly.

BACKGROUND: Cervical spine fractures in the elderly are relatively common. The management of such injuries may be complicated by underlying medical debility and osteopenia as well as reduced tolerance to halo immobilization. METHODS: Over a 1-year period, 43 cervical spine fractures were treated at our institution. Ten (23%) were in persons 70 years of age or older. This retrospective analysis describe the clinical features, treatment, and outcome of these 10 elderly patients. All fractures in this patient population involved the atlantoaxial complex, including five combination C1-C2 fractures. Six patients were treated with early halo immobilization and three were initially managed with a rigid cervical collar. Three patients required posterior cervical fusion. RESULTS: Of the six patients undergoing halo immobilization, five progressed to osseous union. Three patients were immobilized in a Philadelphia collar resulting in one osseous union, one nonunion, and one death. Three patients underwent posterior cervical fusion with subsequent osseous union in all three. CONCLUSIONS: Although external immobilization with a halo device is our treatment of choice for most C1 and C2 fractures in elderly patients, a Philadelphia collar is useful in select cases when halo immobilization or early surgical fusion is contraindicated. Posterior cervical fusion can be safely and effectively performed in elderly patients and should be strongly considered for initial therapy in the elderly with fracture types unlikely to progress to osseous union with external immobilization alone.

In search of butterfly origins.

To determine the sister taxon to butterflies, the relationships among the macrolepidopteran superfamilies were investigated using sequence data from the ND1 gene of mitochondrial DNA. Both sequence data and translated amino acids were used. We examined how different models of amino acid evolution (nonadditive) affected the inference of tree topology. We then added previously published sequence data from the 18S and 28S subunits of ribosomal RNA. In most analyses, regardless of data type and treatment, the Hedyloidea is either the sister taxon to butterflies or derived within the butterfly clade. These molecular results are compared to a reanalysis of morphological characteristics. The reanalysis of morphology agrees with Minet's 1991 hypothesis of hedyloid relationships. Analysis of combined molecular and morphology data supports the hypothesis that hedylids are the sister group to butterflies. Scott's hypothesis that hawk moths (Sphingidae) are the sister taxon to butterflies is discounted.

Unilateral posterolateral decompression without stabilization for neurological palliation of symptomatic spinal metastasis in debilitated patients.

Patients with symptomatic spinal metastases and limited life expectancy are often too debilitated to withstand anterior or posterolateral spinal cord decompression and segmental stabilization. More limited surgery aiming solely at preservation or restoration of neurological function and relief from pain offers the potential for significant improvement in the quality of remaining life without incurring undue perioperative morbidity and mortality. Eight patients with spinal metastases and limited life expectancy underwent a unilateral transpedicular decompression procedure on their most symptomatic side and/or the side of maximum tumor involvement. All patients were neurologically improved within the 1st postoperative week; all were ambulatory and continent postoperatively. Postoperatively, all five patients with preoperative motor deficits demonstrated increased motor strength, and the three patients with predominant radicular pain reported marked improvement. There were no perioperative deaths and two transient perioperative complications. The average length of hospitalization was 6 days for patients without complications and 10 days for the entire group. Unilateral transpedicular decompression without stabilization is an effective and safe method for palliating symptomatic spinal metastases in debilitated patients with widespread malignancy and limited life expectancy. This therapeutic option should be considered in select cases as an alternative to either nonoperative management or anterior or posterolateral decompression and segmental stabilization.

Phylogenetic studies of ribosomal RNA variation in higher moths and butterflies (Lepidoptera: Ditrysia).

The selection of exemplars has been shown both theoretically and empirically to affect tree topology, but the importance of the number and nature of taxa used to represent higher taxonomic lineages in molecular studies is rarely stressed. In our rRNA study of higher moths and butterflies (Lepidoptera: Ditrysia), the selection of different exemplars and outgroups caused major tree rearrangements. We also examined the effectiveness with which conserved rRNA regions track the diversification of Lepidoptera. Homoplasy is as prevalent at the few variable sites of conserved regions (18E, 18J, 28F) as at the many variable sites of a more rapidly evolving region (28B). Finally, 28B sequence variation differs qualitatively among lepidopteran superfamilies of presumed comparable age, the Papilionoidea (true butterflies) and Noctuoidea (cutworm moths and relatives).

EVOLUTIONARY CHARACTER ANALYSIS: TRACING CHARACTER CHANGE ON A CLADOGRAM.

Abstract- There has been little formal discussion concerning character analysis in cladistics, even though characters and their character state trees are central to phylogenetic analyses. We refer to this field as Evolutionary Character Analysis. This paper defines the components of evolutionary character analysis: character state trees, transmodal characters, cladogram characters, attribute and character phylogenies; and the use of these components in phylogenetic inference and evolutionary studies. Character state trees and their effect on cladogram construction are discussed. A new method for numerically coding complex character state trees is described that further reduces the number of variables required to describe them. This method, ordinal coding, reduces the size of data matrices, and facilitates retrieval of state codes. This paper advocates the use of both biological evidence and evidence internal to the cladogram itself to construct character state trees (CSTs). We discuss general models of character evolution (morphocline analysis, Fitch minimum mutation model, etc.) and their role in forming CSTs. Character state trees formed with theories of character evolution are referred to as transmodal characters. These transmodal characters are contrasted with cladogram characters (Mickevich, 1982), and the place of each in a phylogenetic analysis is discussed. The method for determining cladogram characters is detailed with more complicated examples than found in previous publications. We advocate testing transmodal characters by comparing them with the resultant cladogram characters. This comparison involves transformation series analysis (TSA; Mickevich, 1982) which is viewed as an extension of reciprocal illumination. The TSA procedure and its place in hypothesis testing are reviewed. Tracing the evolution of characters interests both systematists and non-systematists alike. When character state trees (transmodal characters) are optimized on pre-existing phylogenies, character phylogenies and attribute phylogenies result. Attributes are defined as a feature that may or may not be homologous (i.e., ecological categories, plant hosts, etc.). We provide two illustrations of this approach, one involving the evolution of the anuran ear and another involving the coevolution of the butterfly Heliconius and its hostplants. Finally, the components of phylogenetic character analysis can be used to test more general evolutionary theories such as the biogenetic law and vicariance biogeography.

An automated interferometer for the analysis of anaesthetic gas mixtures.

A microprocessor-controlled interferometer is described. The eyepiece of a conventional Jamin type interferometer has been replaced by an array of photocells which records the intensity across the interference pattern. Mathematical correlation procedures are used to locate the principal interference pattern maximum and, by sequential analysis of a fresh gas mixture followed by fresh gas plus vapour, it is possible to determine both oxygen and vapour concentrations. The instrument was used to analyse mixtures of oxygen and nitrous oxide and also oxygen, nitrous oxide plus halothane. It was found that the oxygen concentration could be determined to an accuracy of +/- 1% v/v and the vapour concentration to +/- 0.1% v/v. The instrument is suitable for monitoring concentrations delivered by an anaesthetic machine and may be included in a microprocessor-controlled anaesthetic machine.