Autotetraploid Induction of Three A-Genome Wild Peanut Species, Arachis cardenasii, A. correntina, and A. diogoi.

A-genome Arachis species (AA; 2n = 2x = 20) are commonly used as secondary germplasm sources in cultivated peanut breeding, Arachis hypogaea L. (AABB; 2n = 4x = 40), for the introgression of various biotic and abiotic stress resistance genes. Genome doubling is critical to overcoming the hybridization barrier of infertility that arises from ploidy-level differences between wild germplasm and cultivated peanuts. To develop improved genome doubling methods, four trials of various concentrations of the mitotic inhibitor treatments colchicine, oryzalin, and trifluralin were tested on the seedlings and seeds of three A-genome species, A. cardenasii, A. correntina, and A. diogoi. A total of 494 seeds/seedlings were treated in the present four trials, with trials 1 to 3 including different concentrations of the three chemical treatments on seedlings, and trial 4 focusing on the treatment period of 5 mM colchicine solution treatment of seeds. A small number of tetraploids were produced from the colchicine and oryzalin gel treatments of seedlings, but all these tetraploid seedlings reverted to diploid or mixoploid states within six months of treatment. In contrast, the 6-h colchicine solution treatment of seeds showed the highest tetraploid conversion rate (6-13% of total treated seeds or 25-40% of surviving seedlings), and the tetraploid plants were repeatedly tested as stable tetraploids. In addition, visibly and statistically larger leaves and flowers were produced by the tetraploid versions of these three species compared to their diploid versions. As a result, stable tetraploid plants of each A-genome species were produced, and a 5 mM colchicine seed treatment is recommended for A-genome and related wild Arachis species genome doubling.

The unseen epidemic: trauma and loneliness in urban midlife women.

BACKGROUND: Connectedness and attachment are vital parts of humanity. Loneliness, a state of distress in reaction to perceived detachment and isolation, is reported by over one-third of U.S. adults and is associated with numerous physical and mental health consequences. What contributes to loneliness, especially in women and minority populations, is poorly understood, but this population is also at greater risk for abuse and trauma. Our study aimed to further understand loneliness in urban midlife women and to explore the relationship that may exist with trauma(s). METHODS: To identify primacies for mental health care, female midlife participants (N=50) of a long-standing urban community-based cohort focused on health improvement completed a one-time audiotaped interview with both quantitative assessments and a qualitative interview. Loneliness was assessed by the UCLA 3-item Loneliness Scale. Using semi-structured interviews, open-ended questions facilitated a discussion regarding mental health needs and experiences. Interview transcripts were coded and analyzed following a grounded theory methodology. Themes around loneliness and trauma emerged. The transcripts were coded using the same methodology and coders as the individual interviews. Twenty women participated in two optional focus groups. RESULTS: Participants had a mean age of 50, with the majority identifying as Black/African American (N=37) and unemployed (N=33). Three themes emerged regarding perceived causes of loneliness: trauma, the burden of responsibilities for others, and secondary to unhealthy relationships. Loneliness associated with trauma will be explored here; other themes are beyond the scope of this paper and will be discussed in subsequent analyses. Quantitative results suggest that physical abuse (loneliness scores 5.4 vs. 4.0, p=0.003), as well as emotional abuse and neglect (loneliness scores 5.6 vs. 4.4, p=0.01), were associated with greater loneliness. CONCLUSION: In urban midlife low-income women, lifetime physical abuse and emotional abuse/neglect are associated with increased feelings of loneliness. Qualitative data provide insight into how participants viewed their traumatic histories, ways in which the trauma has ongoing influence, and how they experience loneliness. Though further investigation is needed, trauma-informed approaches should be considered in both primary care and mental health settings with a focus on mitigating loneliness and providing appropriate support and trauma treatment.

Transversely isotropic and isotropic material considerations in determining the mechanical response of geometrically accurate bovine tibia bone.

In finite element method (FEM) simulations of the mechanical response of bones, proper selection of stiffness versus density (E-ρ) formulae for bone constituents is necessary for obtaining accurate results. A considerable number of such formulae can be found in the biomechanics' literature covering both cortical and cancellous constituents. For determining the first and second modal frequencies (in both cranial-caudal and medial-lateral planes) of bovine tibia bone, this work assembled and numerically tested 22 isotropic and 21 orthotropic stiffness-density formulae combinations (cases). To accurately reproduce bone geometry, anatomical 3D models were generated from computed tomography (CT) scans. By matching the bone's digital mass to its actual mass, cortical and cancellous constituents were faithfully segmented by utilizing suitable values of three variables: (1) critical cutoff Hounsfield unit (HU) values, (2) cutoff density value, and (3) utilized number of sub-materials. Consequently, a balanced distribution of finite elements was generated with stiffness values congruent with their cancellous or cortical demarcations. Of the considered 22 isotropic formulae cases and 21 orthotropic (reduced to transversely isotropic) cases, only few yielded accurate frequency estimates. For verifying the accuracy of the solutions emanating from the various formulae, experimental vibration tests of corresponding mode frequencies and shapes (ProSig©) were conducted. When compared with the measured experimental frequency values, the most accurate isotropic formulae yielded numerical estimates of + 0.95% and + 10.65% for the first and second cranial-caudal (C-C) frequencies, respectively. The formulae yielding most accurate estimates also proved successful in estimating frequencies of a second tibia bone yielding numerical estimates within + 4.75% and + 1.88% of the said mode frequencies. For the transversely isotropic material assignment, the closest case scenario computed numerical estimates with a percentage difference of + 2.05% and + 9.36% for the first and second cranial-caudal (C-C) frequencies, respectively. Graphical abstract Mode shapes (left) 1 and (right) 2 for transversely isotropic case 15 T (Bone A): (a) cranial-caudal and (b) medial-lateral plane.

Double Versus Single Tendon Transfers to Improve Shoulder Function in Brachial Plexus Birth Palsy.

BACKGROUND: In children with brachial plexus birth palsy (BPBP) undergoing tendon transfers to augment shoulder external rotation, it is unclear whether transfer of the latissimus dorsi with its combined latissimus dorsi and teres major (cLT) versus isolated teres major (iTM) tendon transfer yield different outcomes. METHODS: Records of patients with BPBP who underwent shoulder tendon transfers to augment external rotation were retrospectively reviewed. Transfer type (cLT or iTM) was considered indiscriminate by virtue of surgeon preference. Modified Mallet Scale (mMS) and Active Movement Scale scores were recorded. Patients with <12 months' follow-up, C7 or lower palsy, humeral osteotomy, shoulder procedure(s) within 8 months, microsurgery within 1 year, or recurrent glenohumeral subluxation confirmed by postoperative imaging were excluded. Matched cohorts were identified within each tendon transfer group to yield similar preoperative shoulder function and glenohumeral alignment status. Outcomes for all tendon transfers as well as differences between cLT and iTM cohorts were analyzed. RESULTS: Among 121 cLT and 34 iTM transfers, 49 cLT and 14 iTM met the inclusion criteria. Subsequent matching of cohorts yielded 28 patients (14 cLT and 14 iTM). Average age at time of transfer was 3.0±1.4 years. Follow-up averaged 4.1±3.1 years. There were no statistically significant preoperative differences between cohorts, thus matching criteria were validated. Regardless of tendon(s) transferred, mMS external rotation improved (2.2 to 3.5, P<0.001), whereas mMS internal rotation decreased (3.8 to 3.2, P<0.001). When comparing matched cohorts, cLT transfer produced a greater mMS external rotation improvement than iTM (2.1 vs. 1.5, respectively; P=0.025). Loss of midline function (defined as mMS external rotation <3) occurred in 5 (35.7%) cLT and 2 (14.3%) iTM patients. CONCLUSIONS: Both cLT or iTM transfer are effective at augmenting shoulder external rotation in children with C5-C6 BPBP. Furthermore, cLT transfers may yield a larger improvement in external rotation in certain patients. However, both techniques slightly decrease shoulder internal rotation. Given that more total cLT patients lost midline function among matched cohorts, iTM transfer may still be considered when limited midline function is a concern. LEVEL OF EVIDENCE: Level III.

Intracortical stiffness of mid-diaphysis femur bovine bone: lacunar-canalicular based homogenization numerical solutions and microhardness measurements.

Microscale lacunar-canalicular (L-C) porosity is a major contributor to intracortical bone stiffness variability. In this work, such variability is investigated experimentally using micro hardness indentation tests and numerically using a homogenization scheme. Cross sectional rings of cortical bones are cut from the middle tubular part of bovine femur long bone at mid-diaphysis. A series of light microscopy images are taken along a line emanating from the cross-section center starting from the ring's interior (endosteum) ring surface toward the ring's exterior (periosteum) ring surface. For each image in the line, computer vision analysis of porosity is conducted employing an image segmentation methodology based on pulse coupled neural networks (PCNN) recently developed by the authors. Determined are size and shape of each of the lacunar-canalicular (L-C) cortical micro constituents: lacunae, canaliculi, and Haversian canals. Consequently, it was possible to segment and quantify the geometrical attributes of all individual segmented pores leading to accurate determination of derived geometrical measures such as L-C cortical pores' total porosity (pore volume fraction), (elliptical) aspect ratio, orientation, location, and number of pores in secondary and primary osteons. Porosity was found to be unevenly (but linearly) distributed along the interior and exterior regions of the intracortical bone. The segmented L-C porosity data is passed to a numerical microscale-based homogenization scheme, also recently developed by the authors, that analyses a composite made up of lamella matrix punctuated by multi-inclusions and returns corresponding values for longitudinal and transverse Young's modulus (matrix stiffness) for these micro-sized spatial locations. Hence, intracortical stiffness variability is numerically quantified using a combination of computer vision program and numerical homogenization code. These numerically found stiffness values of the homogenization solution are corroborated experimentally using microhardness indentation measurements taken at the same points that the digital images were taken along a radial distance emanating from the interior (endosteum) surface toward the bone's exterior (periosteum) surface. Good agreement was found between numerically calculated and indentation measured stiffness of Intracortical lamellae. Both indentation measurements and numerical solutions of matrix stiffness showed increasing linear trend of compressive longitudinal modulus (E11) values vs. radial position for both interior and exterior regions. In the interior (exterior) region of cortical bone, stiffness modulus values were found to range from 18.5 to 23.4 GPa (23 to 26.0 GPa) with the aggregate stiffness of the cortical lamella in the exterior region being 12% stiffer than that in the interior region. In order to further validate these findings, experimental and FEM simulation of a mid-diaphysis bone ring under compression is employed. The FEM numerical deflections employed nine concentric regions across the thickness with graded stiffness values based on the digital segmentation and homogenization scheme. Bone ring deflections are found to agree well with measured deformations of the compression bone ring.

Does weight-bearing assignment after intramedullary nail placement alter healing of tibial shaft fractures?

INTRODUCTION: There is no consensus regarding postoperative weight-bearing (WB) assignment after treatment of tibial shaft fractures with an intramedullary nail. This study aims to determine if the postoperative WB assignment after tibia intramedullary nail placement alters healing. METHODS: Closed AO type 42A fractures treated with a reamed statically-locked intramedullary nail over a 10-year period were retrospectively reviewed from injury at 2, 3, 6, 9 and 12 month intervals until union or revision. Patients were categorized according to postoperative weight-bearing assignment: weight-bearing-as-tolerated (WBAT) or non-weight-bearing (NWB). Patients with additional diagnoses that confound routine fracture healing were excluded. Postoperative radiographic union scores for tibial fractures (RUST), coronal/sagittal angulations, and length were compared between different weight-bearing groups. Union was defined as a RUST≥10 at a painless fracture site. RESULTS: A total of 83 patients achieved union (32 WBAT, 51 NWB). Both WB groups had similar preoperative demographics. Average age was 37±13 years and follow-up averaged 1.3±0.2 years. There were no significant differences in average time to radiographic union between NWB versus WBAT groups (5.5 vs. 6.1 months, respectively; P=0.208) nor radiographic healing at 2, 3, and 6-month intervals (P=0.631). There were two nonunions and one fracture shortened in the NWB group. There were no reoperations for symptomatic or broken hardware in either cohort. CONCLUSION: Immediate WBAT after statically-locked intramedullary nail placement in simple tibial shaft fractures does not alter the time until or course of radiographic union. LEVEL OF EVIDENCE: IV.

Innovative use of chemodenervation in the treatment of postoperative genital hyperhidrosis-like symptoms.

Postoperative complications present in many forms and can cause great morbidity and even mortality in patients who experience them. Frey syndrome is an example of a postoperative complication in which aberrant nerve regeneration following parotidectomy leads to hyperhidrosis induced by gustatory stimuli. We present a unique but similar case of aberrant nerve regeneration and resulting hypersecretion that emerged 6-7 months following perineoplasty and labial reduction for lichen sclerosus in a 53-year-old woman. An exhaustive investigation ruled out genitourinary causes of her symptoms. Pads, tampons, and surgical procedures provided no relief. We propose that the mechanism of her excessive watery secretions is similar to that which causes Frey syndrome: iatrogenic damage to nerves that aberrantly regenerate to innervate local structures involved in secretory control. The parallels between our patient's condition and Frey syndrome are evident in the duration between surgery and onset of symptoms and the response to treatment with onabotulinum toxin, highlighting a shared cholinergic pathway. Onabotulinum injections are well tolerated by patients with localized hyperhidrosis and symptom control typically lasts several months. In this manuscript we present a novel mode of delivery of onabotulinum toxin topically to a mucosal region. With these treatments, the patient's hyperhidrosis-like symptoms remain well controlled for 3-4 months, at which point she returns to clinic for treatment. The patient did not experience symptomatic relief until this unique treatment plan was initiated. Her case illustrates the need for further understanding of recalcitrant postoperative complications involving local structures controlling liquid secretion, such as sweat glands and vascular plexuses.

Geometric-attributes-based segmentation of cortical bone slides using optimized neural networks.

In cortical bone, solid (lamellar and interstitial) matrix occupies space left over by porous microfeatures such as Haversian canals, lacunae, and canaliculi-containing clusters. In this work, pulse-coupled neural networks (PCNN) were used to automatically distinguish the microfeatures present in histology slides of cortical bone. The networks' parameters were optimized using particle swarm optimization (PSO). When forming the fitness functions for the PSO, we considered the microfeatures' geometric attributes-namely, their size (based on measures of elliptical perimeter or area), shape (based on measures of compactness or the ratio of minor axis length to major axis length), and a two-way combination of these two geometric attributes. This hybrid PCNN-PSO method was further enhanced for pulse evaluation by combination with yet another method, adaptive threshold (AT), where the PCNN algorithm is repeated until the best threshold is found corresponding to the maximum variance between two segmented regions. Together, this framework of using PCNN-PSO-AT constitutes, we believe, a novel framework in biomedical imaging. Using this framework and extracting microfeatures from only one training image, we successfully extracted microfeatures from other test images. The high fidelity of all resultant segments was established using quantitative metrics such as precision, specificity, and Dice indices.

Laser skin treatment in non-Caucasian patients.

The demand for facial rejuvenation and cosmetic procedures is rising among all ethnicities and skin types. The authors present a review of lasers and how to select a laser based on skin type and the treatment goals of laser resurfacing: skin laxity, dyschromia, hair removal, keloid, and hypertrophic scarring. In addition, they discuss preprocedural and postprocedural considerations, potential complications, and their management to maximize patient outcomes and minimize risk.

Using templated agarose scaffolds to promote axon regeneration through sites of spinal cord injury.

The past 30 years of research in spinal cord injury (SCI) have revealed that, under certain conditions, some types of axons are able to regenerate. To aid these axons in bridging the lesion site, many experimenters place cellular grafts at the lesion. However, to increase the potential for functional recovery, it is likely advantageous to maximize the number of axons that reach the intact spinal cord on the other side of the lesion. Implanting linear-channeled scaffolds at the lesion site provides growing axons with linear growth paths, which minimizes the distance they must travel to reach healthy tissue. Moreover, the linear channels help the regenerating axons maintain the correct mediolateral and dorsoventral position in the spinal cord, which may also improve functional recovery by keeping the axons nearer to their correct targets. Here, we provide a protocol to perform a full spinal cord transection in rats that accommodates an implanted scaffold.

Segmentation of histology slides of cortical bone using pulse coupled neural networks optimized by particle-swarm optimization.

The aim of this study is to automatically discern the micro-features in histology slides of cortical bone using pulse coupled neural networks (PCNN). To the best knowledge of the authors, utilizing PCNN in such an application has not been reported in the literature and, as such, constitutes a novel application. The network parameters are optimized using particle swarm optimization (PSO) where the PSO fitness function was introduced as the entropy and energy of the bone micro-constituents extracted from a training image. Another novel contribution is combining the above with the method of adaptive threshold (T) where the PCNN algorithm is repeated until the best threshold T is found corresponding to the maximum variance between two segmented regions. To illustrate the quality of resulting segmentation according to this methodology, a comparison of the entropy/energy obtained of each pulse is reported. Suitable quality metrics (precision rate, sensitivity, specificity, accuracy, and dice) were used to benchmark the resulting segments against those found by a more traditional method namely K-means. The quality of the segments revealed by this methodology was found to be of much superior quality. Another testament to the quality of this methodology was that the images resulting from testing pulses were found to be of similarly good quality to those of the training images.

On the relevance of uniaxial tensile testing of urogynecological prostheses: the effect of displacement rate.

INTRODUCTION AND HYPOTHESIS: Uniaxial tensile testing is commonly used to calculate values of mechanical properties of urogynecological prostheses used in stress urinary incontinence and pelvic organ prolapse surgery in women. Clinical behavior of these products has been linked to their mechanical properties, hence influencing the clinician's preference for one brand or another. The objective of this study is to assess the effect of displacement rate used in uniaxial tensile testing on peak load, extension at peak load, and initial stiffness of Prolene® mesh, used as a proxy for urogynecological prostheses. METHODS: Strips of Prolene® mesh measuring 10 × 30 mm were submitted to uniaxial tensile testing at the following rates: 1, 10, 50, 100, and 500 mm/min. Peak load, elongation at peak load, and initial stiffness were computed from load vs displacement curves at all displacement rates. The effect of displacement rate on these parameters was estimated by fitting linear trend lines through the data. RESULTS: The displacement rate at which uniaxial tensile testing is performed has significant effects on the values of extension at peak load and initial stiffness, but not on the peak load. CONCLUSIONS: When urogynecological prostheses are submitted to uniaxial tensile testing, studies at more than one displacement rate should be performed. More importantly, these displacement rates should be within the range of applicability.

Vaccinia virus A35R inhibits MHC class II antigen presentation.

The Vaccinia virus gene A35R (Copenhagen designation) is highly conserved in mammalian-tropic poxviruses and is an important virulence factor, but its function was unknown. We show herein that A35 does not affect viral infectivity, apoptosis induction, or replication; however, we found that A35 significantly inhibited MHC class II-restricted antigen presentation, immune priming of T lymphocytes, and subsequent chemokine and cytokine synthesis. A35 localized to endosomes and reduced the amount of a model antigenic peptide displayed in the cleft of class II MHC. In addition, A35 decreased VV specific T cell responses in vivo. Thus, this is the first report identifying a function for the A35 protein in virulence as well as the first report identifying a VV gene that inhibits peptide antigen presentation.

A paradigm for facial skin rejuvenation.

There is a significant desire by patients to reverse the signs of aging caused by photodamage. Numerous procedures for facial skin rejuvenation have been developed in an attempt to minimize the erythema, dyspigmentation, and rhytides associated with photoaging. The initial procedures developed for facial rejuvenation involve skin resurfacing via complete ablation of layers of skin. Of these procedures, ablative laser resurfacing is the most precise technique and is considered the gold standard for facial skin rejuvenation. Although ablative procedures are quite efficacious, they carry significant patient downtime and risks of adverse effects such as scarring and dyspigmentation. Concerns regarding patient morbidity have led to the development of nonablative procedures that target dermal collagen without damaging the epidermis. Of these technologies, intense pulsed light is the most commonly used because it effectively targets both the erythema and dyspigmentation seen in photoaging. Nonablative techniques minimize side effects and patient downtime; however, they do not match the results seen in fully ablative procedures. Fractional laser technologies-first nonablative and more recently ablative-represent the most recent attempt to match the results seen in fully ablative procedures with less patient downtime. Their results are promising but require further study.

Vaccinia virus decreases major histocompatibility complex (MHC) class II antigen presentation, T-cell priming, and peptide association with MHC class II.

Vaccinia virus (VACV) is the current live virus vaccine used to protect humans against smallpox and monkeypox, but its use is contraindicated in several populations because of its virulence. It is therefore important to elucidate the immune evasion mechanisms of VACV. We found that VACV infection of antigen-presenting cells (APCs) significantly decreased major histocompatibility complex (MHC) II antigen presentation and decreased synthesis of 13 chemokines and cytokines, suggesting a potent viral mechanism for immune evasion. In these model systems, responding T cells were not directly affected by virus, indicating that VACV directly affects the APC. VACV significantly decreased nitric oxide production by peritoneal exudate cells and the RAW macrophage cell line in response to lipopolysaccharide (LPS) and interferon (IFN)-gamma, decreased class II MHC expression on APCs, and induced apoptosis in macrophages and dendritic cells. However, VACV decreased antigen presentation by 1153 B cells without apparent apoptosis induction, indicating that VACV differentially affects B lymphocytes and other APCs. We show that the key mechanism of VACV inhibition of antigen presentation may be its reduction of antigenic peptide loaded into the cleft of MHC class II molecules. These data indicate that VACV evades the host immune response by impairing critical functions of the APC.

Electrically evoked locomotor activity in the turtle spinal cord hemi-enlargement preparation.

We assessed the locomotor capacity of the left half of the spinal cord hindlimb enlargement in low-spinal turtles. Forward swimming was evoked in the left hindlimb by electrical stimulation of the right dorsolateral funiculus (DLF) at the anterior end of the third postcervical spinal segment (D3). Animals were held by a band-clamp in a water-filled tank so that hindlimb movements could be recorded from below with a digital video camera. Left hindlimb hip and knee movements were tracked while electromyograms (EMGs) were recorded from left hip and knee muscles. In turtles with intact spinal cords, electrical stimulation of the right D3 DLF evoked robust forward swimming movements of the left hindlimb, characterized by rhythmic alternation between hip flexor (HF) and hip extensor (HE) EMG discharge, with knee extensor (KE) bursts occurring during the latter part of each HE-off phase. After removing the right spinal hemi-enlargement (D8-S2), DLF stimulation still evoked rhythmic locomotor movements and EMG bursts in the left hindlimb that included HF-HE alternation and KE discharge. However, post-surgical movements and EMG bursts had longer cycle periods, and movements showed lower amplitudes compared to controls. These results show that (1) sufficient locomotor CPG circuitry resides within the turtle spinal hemi-enlargement to drive major components of the forward swim motor pattern, (2) contralateral circuitry contributes to the excitation of the locomotor CPG for a given limb, and (3) a sufficient portion of the descending DLF pathway crosses over to the contralateral cord anterior to the hindlimb enlargement to activate swimming.

Location of spinal cord pathways that control hindlimb movement amplitude and interlimb coordination during voluntary swimming in turtles.

We performed mechanical lesions of the midbody (D2-D3; second to third postcervical spinal segments) spinal cord in otherwise intact turtles to locate spinal cord pathways that 1) activate and control the amplitude of voluntary hindlimb swimming movements and 2) coordinate hindlimb swimming with the movement of other limbs. Pre- and postlesion turtles were held by a band clamp around the carapace just beneath the water surface in a clear Plexiglas tank and videotaped from below so that kinematic measurements could be made of voluntary forward swimming with motion analysis software. Movements of the forelimbs (wrists) and hindlimbs (knees and ankles) were tracked relative to stationary reference points on the plastron to obtain bilateral measurements of hip and forelimb angles as functions of time along with foot trajectories. We measured changes in limb movement amplitude, cycle period, and interlimb phase before and after spinal lesions. Our results indicate that locomotor command signals that activate and regulate the amplitude of voluntary hindlimb swimming travel primarily in the dorsolateral funiculus (DLF) at the D2-D3 level and cross over to drive contralateral hindlimb movements. This suggests that electrical stimulation of the D3 DLF, which was previously shown to evoke swimming movements in the contralateral hindlimb of low-spinal turtles, activated the same locomotor command pathways that the animal uses during voluntary behavior. We also show that forelimb-hindlimb coordination is maintained by longitudinal spinal pathways that are largely confined to the ventrolateral funiculus (VLF) and mediate phase coupling of ipsilateral limbs, presumably by interenlargement propriospinal fibers.

Crossed commissural pathways in the spinal hindlimb enlargement are not necessary for right left hindlimb alternation during turtle swimming.

We examined the coordination between right and left hindlimbs during voluntary forward swimming in adult red-eared turtles, before and after midsagittal section of the spinal cord hindlimb enlargement (segments D8-S2) or the enlargement plus the first preenlargement segment (D7-S2). Our purpose was to assess the role of crossed commissural axons in these segments for right-left hindlimb alternation during voluntary locomotion. Midsagittal splitting severed commissural fibers and separated the right and left halves of the posterior spinal cord. Adult turtles (n = 9) were held by a band clamp around the shell in a water-filled tank while digital video of forward swimming was recorded from below and computer analyzed with motion analysis software. In a subset of these animals (n = 5), we also recorded electromyograms from hip extensor and/or hip flexor muscles on both sides. Surprisingly, splitting spinal segments D8-S2 or D7-S2 did not affect the strength of out-of-phase coordination between right and left hindlimbs, although hindlimb movement amplitudes were reduced compared with presurgical controls. These results show that commissural axons in the hindlimb enlargement and preenlargement cord are not necessary for right-left hindlimb alternation during voluntary swimming. We suggest that alternating propriospinal drive from the right and left sides of the forelimb enlargement maintains the out-of-phase coordination of right and left hindlimbs in the bisected-cord preparation. Our data support the hypothesis that descending propriospinal (forelimb-hindlimb) and crossed commissural (hindlimb-hindlimb) spinal cord pathways function together as redundant mechanisms to sustain right-left hindlimb alternation during turtle locomotion.

Unique SARS-CoV protein nsp1: bioinformatics, biochemistry and potential effects on virulence.

Viruses have evolved a myriad of strategies for promoting viral replication, survival and spread. Sequence analysis of the Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) genome predicts several proteins that are unique to SARS-CoV. The search to understand the high virulence of SARS-CoV compared with related coronaviruses, which cause lesser respiratory illnesses, has recently focused on the unique nsp1 protein of SARS-CoV and suggests evolution of a possible new virulence mechanism in coronaviruses. The SARS-CoV nsp1 protein increases cellular RNA degradation and thus might facilitate SARS-CoV replication or block immune responses.