Differential activation of the human costal and crural diaphragm during voluntary and involuntary breaths

Simultaneous electromyographic recordings from the human costal and crural diaphragm during voluntary augmented breathing and involuntary rebreathing show that the increase in inspiratory crural diaphragm activity was ~60% of the increase in costal diaphragm activity. However costal to crural diaphragm activation did not differ between the two tasks. The dissociation in the amplitude of activation of the costal and crural diaphragm becomes apparent only as the drive to breathe increases above tidal breathing.

The occupied electronic structure of ultrathin boron doped diamond

Using angle-resolved photoelectron spectroscopy, we compare the electronic band structure of an ultrathin (1.8 nm) δ-layer of boron-doped diamond with a bulk-like boron doped diamond film (3 μm). Surprisingly, the measurements indicate that except for a small change in the effective mass, there is no significant difference between the electronic structure of these samples, irrespective of their physical dimensionality, except for a small modification of the effective mass. While this suggests that, at the current time, it is not possible to fabricate boron-doped diamond structures with quantum properties, it also means that nanoscale boron doped diamond structures can be fabricated which retain the classical electronic properties of bulk-doped diamond, without a need to consider the influence of quantum confinement.

Abdominal Functional Electrical Stimulation to Augment Respiratory Function in Spinal Cord Injury

Background: Functional electrical stimulation (FES) is the application of electrical pulses to a nerve to achieve a functional muscle contraction. Surface electrical stimulation of the nerves that innervate the abdominal muscles, termed abdominal FES, can cause the abdominal muscles to contract, even when paralysed after spinal cord injury. As the abdominal muscles are the major expiratory muscles, and commonly partially or completely paralysed in tetraplegia, abdominal FES offers a promising method of improving respiratory function for this patient group. Objective: The aim of the article is to provide readers with a better understanding of how abdominal FES can be used to improve the health of the spinal cord-injured population. Methods: A narrative review of the abdominal FES literature was performed. Results: Abdominal FES can achieve an immediate effective cough in patients with tetraplegia, while the repeated application over 6 weeks of abdominal FES can improve unassisted respiratory function. Ventilator duration and tracheostomy cannulation time can also be reduced with repeated abdominal FES. Conclusion: Abdominal FES is a noninvasive method to achieve functional improvements in cough and respiratory function in acute and chronically injured people with tetraplegia. Potential practical outcomes of this include reduced ventilation duration, assisted tracheostomy decannulation, and a reduction in respiratory complications. All of these outcomes can contribute to reduced morbidity and mortality, improved quality of life, and significant potential cost savings for local health care providers.

Antibody Repertoire Development in Swine

We describe the domestication of the species, explore its value to agriculture and bioscience, and compare its immunoglobulin (Ig) genes to those of other vertebrates. For encyclopedic information, we cite earlier reviews and chapters. We provide current gene maps for the heavy and light chain loci and describe their polygeny and polymorphy. B-cell and antibody repertoire development is a major focus, and we present findings that challenge several mouse-centric paradigms. We focus special attention on the role of ileal Peyer's patches, the largest secondary lymphoid tissues in newborn piglets and a feature of all artiodactyls. We believe swine fetal development and early class switch evolved to provide natural secretory IgA antibodies able to prevent translocation of bacteria from the gut while the bacterial PAMPs drive development of adaptive immunity. We discuss the value of using the isolator piglet model to address these issues.

Single-crystal diamond refractive lens for focusing X-rays in two dimensions. Erratum

A correction is made to a citation in the article by Antipov et al. (2016) [J. Synchrotron Rad. 23, 163-168].

Single-crystal diamond refractive lens for focusing X-rays in two dimensions

The fabrication and performance evaluation of single-crystal diamond refractive X-ray lenses of which the surfaces are paraboloids of revolution for focusing X-rays in two dimensions simultaneously are reported. The lenses were manufactured using a femtosecond laser micromachining process and tested using X-ray synchrotron radiation. Such lenses were stacked together to form a standard compound refractive lens (CRL). Owing to the superior physical properties of the material, diamond CRLs could become indispensable wavefront-preserving primary focusing optics for X-ray free-electron lasers and the next-generation synchrotron storage rings. They can be used for highly efficient refocusing of the extremely bright X-ray sources for secondary optical schemes with limited aperture such as nanofocusing Fresnel zone plates and multilayer Laue lenses.

Cathodoluminescence of natural, plastically deformed pink diamonds

The 49 type I natural pink diamonds examined exhibit color restricted to lamellae or bands oriented along {111} that are created by plastic deformation. Pink diamonds fall into two groups: (1) diamonds from Argyle in Australia and Santa Elena in Venezuela are heavily strained throughout and exhibit pink bands alternating with colorless areas, and (2) diamonds from other localities have strain localized near the discrete pink lamellae. Growth zones are highlighted by a blue cathodoluminescence (CL) and crosscut by the pink lamellae that emit yellowish-green CL that originates from the H3 center. This center probably forms by the recombination of nitrogen-related centers (A-aggregates) and vacancies mobilized by natural annealing in the Earth's mantle. Twinning is the most likely mechanism through which plastic deformation is accommodated for the two groups of diamonds. The plastic deformation creates new centers visible through spectroscopic methods, including the one responsible for the pink color, which remains unidentified. The differences in the plastic deformation features, and resulting CL properties, for the two groups might correlate to the particular geologic conditions under which the diamonds formed; those from Argyle and Santa Elena are deposits located within Proterozoic cratons, whereas most diamonds originate from Archean cratons.

Resolution of an immunodiagnostic dilemma: heavy chain chimeric antibodies for species in which plasmocytomas are unknown

The immunoglobulin (Ig) genes of many vertebrates have been characterized but IgG subclasses, IgD and IgE proteins are only available for three species in which plasmacytomas occur. This creates a major problem in the production and specificity verification of diagnostic anti-Ig reagents for the vast majority of mammals. We describe a novel solution using the swine system with its eleven different variants of IgG. It involves the in vitro synthesis of chimeric porcine-camelid heavy chain antibodies (HCAbs) that do not require light chains and therefore only a single transfection vector. The expressed chimeric HCAbs are comprised of the camelid VHH domain encoding specificity for lysozyme and the hinge, CH2 and CH3 domains of the various porcine IgGs. These HCAb retain their antigenic integrity and their ability to recognize lysozyme. The engineered specificity assures that these HCAb can be immobilized in native configuration when used for testing the specificity of anti-swine IgG antibodies. Comparative data to illustrate the importance of this point are provided. These are now available for use in hybridoma selection and as reference standards for evaluating the specificity of currently available anti-swine IgG antibodies.

Note: Laser ablation technique for electrically contacting a buried implant layer in single crystal diamond

The creation of thin, buried, and electrically conducting layers within an otherwise insulating diamond by annealed ion implantation damage is well known. Establishing facile electrical contact to the shallow buried layer has been an unmet challenge. We demonstrate a new method, based on laser micro-machining (laser ablation), to make reliable electrical contact to a buried implant layer in diamond. Comparison is made to focused ion beam milling.

Photoluminescence Spectroscopy of Diamond Films

Photoluminescence spectroscopy has been used to characterize polycrystalline diamond films prepared by filament assisted chemical deposition and by combustion (in an oxygenacetylene flame) techniques. The luminescence spectra of the chemical vapor deposited films are dominated by a defect band possibly associated with a neutral vacancy with a strong zero phonon line at 1.68 eV and weak phonon replicas at lower energies. The combustion films exhibit two additional luminescence bands with zero phonon lines at 1.95 and 2.16 eV. The 1.95 eV band has been tentatively assigned to a nitrogen-vacancy pair. We have also observed a strong dependence of the PL spectra radially across a given combustion film and associated this with details of the flame chemistry.

Movement of the human upper airway during inspiration with and without inspiratory resistive loading

The electromyographic (EMG) activity of human upper airway muscles, particularly the genioglossus, has been widely measured, but the relationship between EMG activity and physical movement of the airway muscles remains unclear. We aimed to measure the motion of the soft tissues surrounding the airway during normal and loaded inspiration on the basis of the hypothesis that this motion would be affected by the addition of resistance to breathing during inspiration. Tagged MR imaging of seven healthy subjects was performed in a 3-T scanner. Tagged 8.6-mm-spaced grids were used, and complementary spatial modulation of magnetization images were acquired beginning ∼200 ms before inspiratory airflow. Deformation of tag line intersections was measured. The genioglossus moved anteriorly during normal and loaded inspiration, with less movement during loaded inspiration. The motion of tissues at the anterior border of the upper airway was nonuniform, with larger motions inferiorly. At the level of the soft palate, the lateral dimension of the airway decreased significantly during loaded inspiration (-0.15 ± 0.09 and -0.48 ± 0.09 mm during unloaded and loaded inspiration, respectively, P < 0.05). When resistance to inspiratory flow was added, genioglossus motion and lateral dimensions of the airway at the level of the soft palate decreased. Our results suggest that genioglossus motion begins early to dilate the airway prior to airflow and that inspiratory loading reduces the anterior motion of the genioglossus and increases the collapse of the lateral airway walls at the level of the soft palate.

Voluntary and involuntary ventilation do not alter the human inspiratory muscle loading reflex

The reflex mechanism of the short-latency inhibitory reflex to transient loading of human inspiratory muscles is unresolved. Muscle afferents mediate this reflex, but they may act via pontomedullary inspiratory centers, other bulbar networks, or spinal circuits. We hypothesized that altered chemical drive to breathe would alter the initial inhibitory reflex if the neural pathways involve inspiratory medullary centers. Inspiration was transiently loaded in 11 subjects during spontaneous hypercapnic hyperpnea and matched voluntary hyperventilation. Electromyographic activity was recorded bilaterally from scalene muscles with surface electrodes. The latencies of the initial inhibitory response (IR) onset (32 ± 0.7 and 38 ± 1 ms for spontaneous and voluntary conditions respectively, P < 0.001) and subsequent excitatory response (ER) onset (80 ± 2.9 and 78 ± 2.6 ms, respectively, P = 0.46) and the normalized sizes of IR (65 ± 2 and 67 ± 3%, respectively, P = 0.50) and ER (51 ± 8 and 69 ± 6%, respectively, P = 0.005) were measured. Mean end-tidal Pco2 was 43 ± 1.5 Torr with dead space ventilation and was 14 ± 0.6 Torr with matched voluntary hyperventilation ( P < 0.001). A mean minute volume >30 liters was achieved in both conditions. The absence of significant difference in the size of the IR suggested that the IR reflex arc does not transit the brain stem inspiratory centers and that the reflex may be integrated at a spinal level. In voluntary hyperventilation, an initial excitation occurred more frequently and, consequently, the IR onset latency was significantly longer. The size of the later ER was also greater during voluntary hyperventilation, which is consistent with it being mediated via longer, presumably cortical, pathways, which are influenced by voluntary drive.

Probing the corticospinal link between the motor cortex and motoneurones: some neglected aspects of human motor cortical function

This review considers the operation of the corticospinal system in primates. There is a relatively widespread cortical area containing corticospinal outputs to a single muscle and thus a motoneurone pool receives corticospinal input from a wide region of the cortex. In addition, corticospinal cells themselves have divergent intraspinal branches which innervate more than one motoneuronal pool but the synergistic couplings involving the many hand muscles are likely to be more diverse than can be accommodated simply by fixed patterns of corticospinal divergence. Many studies using transcranial magnetic stimulation of the human motor cortex have highlighted the capacity of the cortex to modify its apparent excitability in response to altered afferent inputs, training and various pathologies. Studies using cortical stimulation at 'very low' intensities which elicit only short-latency suppression of the discharge of motor units have revealed that the rapidly conducting corticospinal axons (stimulated at higher intensities) drive motoneurones in normal voluntary contractions. There are also major non-linearities generated at a spinal level in the relation between corticospinal output and the output from the motoneurone pool. For example, recent studies have revealed that the efficacy of the human corticospinal connection with motoneurones undergoes activity-dependent changes which influence the size of voluntary contractions. Hence, corticospinal drives must be sculpted continuously to compensate for the changing functional efficacy of the descending systems which activate the motoneurones. This highlights the need for proprioceptive monitoring of movements to ensure their accurate execution.

Reflection anisotropy spectroscopy of the oxidized diamond (001) surface

We report reflection anisotropy spectroscopy (RAS) measurements of the oxidized (001) surface of a type IIb natural diamond. These measurements were made possible due to recent developments in diamond surface preparation. We compare RAS results from the hydrogenated, clean and oxidized C(001) surface and demonstrate that RAS is sensitive to the structural transition of the surface from the 2 × 1 reconstruction of the clean surface to the 1 × 1 reconstruction of the oxidized surface.

Understanding the chemical vapor deposition of diamond: recent progress

In this paper we review and provide an overview to the understanding of the chemical vapor deposition (CVD) of diamond materials with a particular focus on the commonly used microwave plasma-activated chemical vapor deposition (MPCVD). The major topics covered are experimental measurements in situ to diamond CVD reactors, and MPCVD in particular, coupled with models of the gas phase chemical and plasma kinetics to provide insight into the distribution of critical chemical species throughout the reactor, followed by a discussion of the surface chemical process involved in diamond growth.

The piglet as a model for B cell and immune system development

The ability to identify factors responsible for disease in all species depends on the ability to separate those factors which are environmental from those that are intrinsic. This is particularly important for studies on the development of the adaptive immune response of neonates. Studies on laboratory rodents or primates have been ambiguous because neither the effect of environmental nor maternal factors on the newborn can be controlled in mammals that: (i) transmit potential maternal immunoregulatory factors in utero and (ii) are altricial and cannot be reared after birth without their mothers. Employing the newborn piglet model can address each of these concerns. However, it comes at the price of having first to characterize the immune system of swine and its development. This review focuses on the porcine B cell system, especially on the methods used for its characterization in fetal studies and neonatal piglets. Understanding these procedures is important in the interpretation of the data obtained. Studies on neonatal piglets have (a) provided valuable information on the development of the adaptive immune system, (b) lead to important advances in evolutionary biology, (c) aided our understanding of passive immunity and (d) provided opportunities to use swine to address specific issues in veterinary and biomedical research and immunotherapy. This review summarizes the history of the development of the piglet as a model for antibody repertoire development, thus providing a framework to guide future investigators.

Immunoglobulins, antibody repertoire and B cell development

Swine share with most placental mammals the same five antibody isotypes and same two light chain types. Loci encoding lambda, kappa and Ig heavy chains appear to be organized as they are in other mammals. Swine differ from rodents and primates, but are similar to rabbits in using a single VH family (VH3) to encode their variable heavy chain domain, but not the family used by cattle, another artiodactyl. Distinct from other hoofed mammals and rodents, Ckappa:Clambda usage resembles the 1:1 ratio seen in primates. Since IgG subclasses diversified after speciation, same name subclass homologs do not exist among swine and other mammals unless very closely related. Swine possess six putative IgG subclasses that appear to have diversified by gene duplication and exon shuffle while retaining motifs that can bind to FcgammaRs, FcRn, C1q, protein A and protein G. The epithelial chorial placenta of swine and the precosial nature of their offspring have made piglets excellent models for studies on fetal antibody repertoire development and on the postnatal role of gut colonization, maternal colostrum and neonatal infection on the development of adaptive immunity during the "critical window" of immunological development. This chapter traces the study of the humoral immune system of this species through its various eras of discovery and compiles the results in tables and figures that should be a useful reference for educators and investigators.

Noninvasive Stimulation of Human Corticospinal Axons Innervating Leg Muscles

These studies investigated whether a single electrical stimulus over the thoracic spine activates corticospinal axons projecting to human leg muscles. Transcranial magnetic stimulation of the motor cortex and electrical stimulation over the thoracic spine were paired at seven interstimulus intervals, and surface electromyographic responses were recorded from rectus femoris, tibialis anterior, and soleus. The interstimulus intervals (ISIs) were set so that the first descending volley evoked by cortical stimulation had not arrived at (positive ISIs), was at the same level as (0 ISI) or had passed (negative ISIs) the site of activation of descending axons by the thoracic stimulation at the moment of its delivery. Compared with the responses to motor cortical stimulation alone, responses to paired stimuli were larger at negative ISIs but reduced at positive ISIs in all three leg muscles. This depression of responses at positive ISIs is consistent with an occlusive interaction in which an antidromic volley evoked by the thoracic stimulation collides with descending volleys evoked by cortical stimulation. The cortical and spinal stimuli activate some of the same corticospinal axons. Thus it is possible to examine the excitability of lower limb motoneuron pools to corticospinal inputs without the confounding effects of changes occurring within the motor cortex.

Movement of the tongue during normal breathing in awake healthy humans

Electromyographic (EMG) activity of the airway muscles suggest that genioglossus is the primary upper airway dilator muscle. However, EMG data do not necessarily translate into tissue motion and most imaging modalities are limited to assessment of the surfaces of the upper airway. In this study, we hypothesized that genioglossus moves rhythmically during the respiratory cycle and that the motion within is inhomogeneous. A 'tagged' magnetic resonance imaging technique was used to characterize respiratory-related tissue motions around the human upper airway in quiet breathing. Motion of airway tissues at different segments of the eupnoeic respiratory cycle was imaged in six adult subjects by triggering the scanner at the end of inspiration. Displacements of the 'tags' were analysed using the harmonic phase method (HARP). Respiratory timing was monitored by a band around the upper abdomen. The genioglossus moved during the respiratory cycle. During expiration, the genioglossus moved posteriorly and during inspiration, it moved anteriorly. The degree of motion varied between subjects. The maximal anteroposterior movement of a point tracked on the genioglossus was 1.02 +/- 0.54 mm (mean +/- s.d.). The genioglossus moved over the geniohyoid muscle, with minimal movement in other muscles surrounding the airway at the level of the soft palate. Local deformation of the tongue was analysed using two-dimensional strain maps. Across the respiratory cycle, positive strains within genioglossus reached peaks of 17.5 +/- 9.3% and negative strains reached peaks of -16.3 +/- 9.3% relative to end inspiration. The patterns of strains were consistent with elongation and compression within a constant volume structure. Hence, these data suggest that even during respiration, the tongue behaves as a muscular hydrostat.

The isolator piglet: a model for studying the development of adaptive immunity

The period from late gestation to weaning in neonatal mammals is a critical window when the adaptive immune system develops and replaces the protection temporarily provided by passive immunity and pre-adaptive antibodies. It is also when oral tolerance to dietary antigen and the distinction between commensal and pathogenic gut bacteria becomes established resulting in immune homeostasis. The reproductive biology of swine provides a unique model for distinguishing the effects of different factors on immune development during this critical period because all extrinsic factors are controlled by the experimenter. This chapter reviews this early stage of development and the usefulness of the piglet model for understanding events during this transitional stage. The review also describes the major features of the porcine immune system and the immune stimulatory and dysregulatory factors that act during this period. The value of the model to medical science in such areas as food allergy, organ transplantation, cystic fibrosis and the production of humanized antibodies for immuno-therapy is discussed.

Characterization of metabolism in the Fe(III)-reducing organism Geobacter sulfurreducens by constraint-based modeling

Geobacter sulfurreducens is a well-studied representative of the Geobacteraceae, which play a critical role in organic matter oxidation coupled to Fe(III) reduction, bioremediation of groundwater contaminated with organics or metals, and electricity production from waste organic matter. In order to investigate G. sulfurreducens central metabolism and electron transport, a metabolic model which integrated genome-based predictions with available genetic and physiological data was developed via the constraint-based modeling approach. Evaluation of the rates of proton production and consumption in the extracellular and cytoplasmic compartments revealed that energy conservation with extracellular electron acceptors, such as Fe(III), was limited relative to that associated with intracellular acceptors. This limitation was attributed to lack of cytoplasmic proton consumption during reduction of extracellular electron acceptors. Model-based analysis of the metabolic cost of producing an extracellular electron shuttle to promote electron transfer to insoluble Fe(III) oxides demonstrated why Geobacter species, which do not produce shuttles, have an energetic advantage over shuttle-producing Fe(III) reducers in subsurface environments. In silico analysis also revealed that the metabolic network of G. sulfurreducens could synthesize amino acids more efficiently than that of Escherichia coli due to the presence of a pyruvate-ferredoxin oxidoreductase, which catalyzes synthesis of pyruvate from acetate and carbon dioxide in a single step. In silico phenotypic analysis of deletion mutants demonstrated the capability of the model to explore the flexibility of G. sulfurreducens central metabolism and correctly predict mutant phenotypes. These results demonstrate that iterative modeling coupled with experimentation can accelerate the understanding of the physiology of poorly studied but environmentally relevant organisms and may help optimize their practical applications.

Length-dependent changes in voluntary activation, maximum voluntary torque and twitch responses after eccentric damage in humans

To assess the contribution of central and peripheral factors to changes in maximum voluntary force and its length dependence after eccentric muscle damage, voluntary and twitch torque were measured across a wide angular range, along with voluntary activation using twitch interpolation. Isometric torque from both maximum voluntary contractions (MVCs) and paired twitches to motor nerve stimulation were measured from 60 to 150 deg elbow flexion in 10 deg increments in eight subjects. Optimal angles were determined by curve fitting. Each subject then performed eccentric contractions until voluntary torque had decreased by approximately 40%. Measurements were repeated at 2 h, 1 day and 8 days post-exercise to follow acute and longer-term changes. Before exercise, the optimal angle was in the mid-range (93+/-10 deg; mean+/-s.d.) for MVCs, and at a more extended elbow angle for the twitch (106+/-6 deg, P < 0.05). Voluntary activation was generally high (> 94%) but depended on elbow angle, with activation being approximately 4% lower at the most flexed compared to the most extended angle. Two hours after exercise, MVCs decreased 40%, while twitch torque declined 70%. All subjects showed a shift in optimal angle to longer muscle lengths for MVCs (17+/-16 deg at 2 h, 14+/-7 deg at day 1, P < 0.05). This shift contributed minimally (approximately 3%) to the reduction in torque at 90 deg, as the torque-angle relation was relatively flat around the optimum. The twitch showed a smaller shift (approximately 4 deg) to longer lengths which was not statistically significant. Voluntary activation was significantly impaired in the early stages after exercise (2 h and day 1, P < 0.05), particularly at short muscle lengths. By 8 days after exercise, the optimal angle had returned to pre-exercise values, but MVC, twitch torque and voluntary activation had not fully recovered. Eccentric exercise causes a short-term shift in the optimal angle for MVCs and produces a length-dependent impairment in voluntary activation. Therefore, it appears that both central and peripheral factors limit muscle performance following eccentric damage, with limits to voluntary drive being especially important at short lengths.

Optical bleaching, TSL and OSL features of CVD diamond

Luminescence and optical features of chemical vapour deposition (CVD) diamond have been studied in view of the potential application of this material in ionising radiation dosimetry field. For this purpose, thermally stimulated luminescence (TSL) and optically stimulated luminescence (OSL) techniques have been used. A large amount of work has emphasised the excellent dosimetric properties of CVD diamond. Nevertheless, TSL measurements showed that after irradiation, this material is extremely sensitive to ambient light and the stored dose information is drastically affected by optical bleaching. From OSL analysis, it follows that both types of processes (TSL and OSL) were characterised by the same excitation and emission spectra and that optical bleaching originated from a broad stimulation band lying from visible to near infrared with a continuous character.

Thermoluminescence properties of CVD diamond for clinical dosimetry use

The application of diamond to dosimetry is desirable because of its tissue equivalence, chemical inertness and small size, but this has not been commercially viable owing to the non-reproducible response of natural diamond. The chemical vapour deposition (CVD) of diamond permits controlled, reproducible and large-scale production of this material at potentially low cost. An investigation of some clinically relevant features like the depth-dose distribution as well as the absorbed dose profile, obtained using thermoluminescence (TL), is reported for several CVD diamond films. The TL characterisation presented here shows that CVD diamond films should be excellent TL-mode detectors in instances of radiotherapy and in vivo radiation dosimetry.

The pre-immune variable kappa repertoire of swine is selectively generated from certain subfamilies of Vkappa2 and one Jkappa gene

Combinatorial diversity is highly restricted during formation of the pre-immune heavy chain repertoire of swine, raising the question of whether the same is true for the pre-immune light chain repertoire. Before addressing this question, we first used competitive PCR to show that kappa and lambda light chains in swine are equally expressed in mature B cells similar to the situation in humans but alike that in other studied Ungulates. This justified efforts to examine the repertoire of both light chain types. These studies also revealed that lambda is preferentially expressed at sites of B cells lymphogenesis, perhaps because of the use of a surrogate light chain containing lambda5. Data are presented here on >100 VkappaJkappa-containing transcripts and approximately 180 genomic Vkappa genes to show that >90% of the pre-immune repertoire is generated from three subfamilies of IGKV2 genes and one of five Jkappa segments. The kappa locus contains >or=50 IGKV2 genes belonging to at least five subfamilies and an undetermined but perhaps equal number of IGKV1 genes. The porcine IGKV1 and IGKV2 genes share 87% sequence similarity with their human counterparts and Jkappa1 through Jkappa5 share sequence and organizational homology with those in sheep, horse, human and mouse. Swine have a single Ckappa gene. These findings contrast with those from rodents and primates but are reminiscent of those on the pre-immune heavy chain repertoire of swine in that it is generated using a relatively restricted number of gene segments. These restricted pre-immune repertoires may reflect the minimal exposure of the fetus to maternal factors and environmental antigens. The significance for swine immunology of characterizing the pre-immune repertoire is discussed.

Reflectance anisotropy spectra of the diamond (100)-(2x1) surface: evidence of strongly bound surface state excitons

We compare the results of ab initio calculations with measured reflection anisotropy spectra and show that strongly bound surface-state excitons occur on the clean diamond (100) surface. These excitons are found to have a binding energy close to 1 eV, the strongest ever observed at a semiconductor surface. Important electron-hole interaction effects on the line shape of the optical transitions above the surface-state gap are also found.

Characterization of porcine CD19 and anti-CD19 monoclonal antibodies

CD19 is an important pan B cell marker and co-stimulatory protein in humans and mice. Efforts to further characterize B cell ontogeny in swine have been hampered by the lack of monoclonal antibodies (mAb) to valuable surface markers like Vpre-B, CD19, CD34 and CD43. We report here on the complete nucleotide and deduced amino acid sequence of porcine CD19, the cross-reactivity of anti-human CD19 monoclonals and efforts to prepare anti-porcine CD19 mAb to bacterially-expressed products. Porcine CD19 is highly homologous to those in the few other species studied, i.e. human, mouse and guinea pig, but only in certain domains. Among the 14 CD19 exons, homology approaches 90% to human CD19 in exons 6, 9, 11 and 12 and is approximately 80% with other species in this region. The highly homologous C-terminal cytoplasmic region contains nine tyrosines including the YEND/E motif that binds the SH2 domain of Fyn. Two different porcine CD19 isoforms that differ in their 3' UTRs were identified just as in human CD19. Thus, the signaling properties of CD19 may be similar to those in humans. On the other hand, only 60% sequence similarity was seen in exons 1-5 that encode the N-terminal extracellullar region that is involved in ligand binding and is the target of CD19-specific mAb. This probably explains why only 1 of the 17 anti-human CD19 mAb tested recognized swine B cells. Furthermore, when the extracellular domains of CD19 were expressed in E. coli, mAbs to the bacterially-expressed product did not recognize CD19 on porcine B cells suggesting that carbohydrate-dependent conformation may determine antigenicity.

Nomenclature of the Proteins of Cows’ Milk—Sixth Revision

This report of the American Dairy Science Association Committee on the Nomenclature, Classification, and Methodology of Milk Proteins reviews changes in the nomenclature of milk proteins necessitated by recent advances of our knowledge of milk proteins. Identification of major caseins and whey proteins continues to be based upon their primary structures. Nomenclature of the immunoglobulins consistent with new international standards has been developed, and all bovine immunoglobulins have been characterized at the molecular level. Other significant findings related to nomenclature and protein methodology are elucidation of several new genetic variants of the major milk proteins, establishment by sequencing techniques and sequence alignment of the bovine caseins and whey proteins as the reference point for the nomenclature of all homologous milk proteins, completion of crystallographic studies for major whey proteins, and advances in the study of lactoferrin, allowing it to be added to the list of fully characterized milk proteins.

Analysis of human CD4 T lymphocyte proliferation induced by porcine lymphoblastoid B cell lines

BACKGROUND

This study was undertaken to characterize the two porcine lymphoblastoid cell lines L23 and L35, derived from a pig inoculated by the retrovirus Tsukuba-1, and to determine how they induce a strong human lymphocyte proliferation.

METHODS

Phenotypic characterization was performed by flow cytometry and reverse transcriptase-polymerase chain reaction analyses. Xenogeneic mixed lymphocyte reactions (XMLR) were performed using unfractionated human peripheral blood mononuclear cells (huPBMC) and purified CD4+ T lymphocytes as responding cells, in the presence of blocking antibodies and fusion proteins.

RESULTS

The immunoglobulin genes were demonstrated to be rearranged in L23 and L35 cell lines, in agreement with the expression of a B cell phenotype. Both induced a similar proliferation of huPBMCs and purified human CD4+ lymphocytes from adult or cord blood (naïve cells). Proliferation of CD4+ T lymphocytes was completely blocked by anti-SLA-DR plus anti-SLA-DQ mAbs, excluding human lymphocyte transformation by porcine viruses. The frequency of proliferative precursors was inconsistent with that induced by a retroviral superantigen but similar to classical direct xenoantigen presentation as observed with other porcine antigen-presenting cells. Extensive analysis of costimulatory signals led to the identification of the CD28 pathway, in agreement with membrane expression of B7 molecules on L23 and L35 cells, and of the CD2 pathway in L35 cells.

CONCLUSION

These two porcine lymphoblastoid cell lines have been further characterized and clearly identified as belonging to the B cell lineage. By expressing major histocompatibility complex class II antigens and costimulatory molecules, they induce a vigorous proliferative response of human CD4+ lymphocytes through a direct presentation pathway.

Switch recombination in fetal porcine thymus is uncoupled from somatic mutation

Since fetal serum Ig isotype profiles suggested that IgG and IgA could be of de novo origin, we studied their transcription and secretion. IgM transcripts were present at 50 days of gestation in major fetal lymphoid tissues, IgG and IgA transcription was pronounced at 60 days in fetal thymus and both transcription and secretion in this organ increased in late fetal life. The CDR3 spectratype of thymic IgG and IgA transcripts was as polyclonal as that of IgM already at 70 days in utero indicating a broad repertoire of switched B-cells. However, VDJs transcribed with the switched isotypes were not hypermutated as were those from immunized fetuses, indicating that switch recombination and somatic mutation are not coupled in utero in piglets. This finding and the fact that the oligoclonal IgA and IgM repertoires in a non-inductive site of the mucosal immune system (parotid gland) becomes polyclonal in piglets reared germ-free, suggest that initial expansion of switched B-cells in fetal and neonatal piglets is not driven by environmental antigen. Our findings collectively suggest that all IgA and IgM may result from de novo synthesis while some IgG probably results from selective transport. The latter is consistent with the gradual decline in serum IgG concentration in germ-free isolator piglets and the expression of FcRn in the porcine placenta.

Change in length of relaxed muscle fascicles and tendons with knee and ankle movement in humans

Ultrasonography was used to measure changes in length of muscle fascicles in relaxed human tibialis anterior and gastrocnemius during passively imposed changes in joint angle. Changes in the length of muscle fascicles were compared to changes in the length of the whole muscle-tendon units calculated from joint angles and anthropometric data. Relaxed muscle fascicles underwent much smaller changes in length than their muscle-tendon units. On average, muscle fascicles in tibialis anterior 'saw' 55 +/- 13 % (mean +/- S.D.) of the total change in muscle-tendon length. This indicates nearly half of the total change in muscle-tendon length was taken up by stretch of tendon. In gastrocnemius, which has relatively long tendons, only 27 +/- 9 % of the total change in muscle-tendon length was transmitted to muscle fascicles. Thus, the tendency for passive movement to be taken up by the tendon was greater for gastrocnemius than tibialis anterior (P = 0.002). For these muscles, the relatively large changes in tendon length across much of the physiological range of muscle-tendon lengths could not wholly be explained by tendon slackness, changes in fibre pennation, or stretch or contraction history of the muscle. Our data confirm that when joints are moved passively, length changes 'seen' by muscle fascicles can be much less than changes in the distance between muscle origin and insertion. This occurs because tendons undergo significant changes in length, even at very low forces.

Balancing acts: respiratory sensations, motor control and human posture

1. The present brief review covers some novel aspects of integration between respiration and movement of the body. 2. There are potent viscerosomatic reflexes in animals involving small-diameter pulmonary afferents that, when excited, would limit exercise. However, recent studies using lobeline injections to excite pulmonary afferents in awake humans suggest that there is no evoked reflex motoneuronal inhibition. Instead, the noxious respiratory sensations generated by the vagal afferents may be crucial in the decision to stop exercise. 3. While respiratory movements may affect limb movements, the control of the trunk and limbs can involve interaction (and even interference) with key respiratory muscles, such as the diaphragm. Recent studies have revealed that not only does the diaphragm receive feed-forward drive prior to some limb movements, but that it also contracts both phasically and tonically during repetitive limb movements. 4. Thus, challenges to posture can indirectly challenge ventilation, while coordinated diaphragm contraction may contribute to control of the trunk.

Suppression of EMG activity by transcranial magnetic stimulation in human subjects during walking

1. The involvement of the motor cortex during human walking was evaluated using transcranial magnetic stimulation (TMS) of the motor cortex at a variety of intensities. Recordings of EMG activity in tibialis anterior (TA) and soleus muscles during walking were rectified and averaged. 2. TMS of low intensity (below threshold for a motor-evoked potential, MEP) produced a suppression of ongoing EMG activity during walking. The average latency for this suppression was 40.0 +/- 1.0 ms. At slightly higher intensities of stimulation there was a facilitation of the EMG activity with an average latency of 29.5 +/- 1.0 ms. As the intensity of the stimulation was increased the facilitation increased in size and eventually a MEP was clear in individual sweeps. 3. In three subjects TMS was replaced by electrical stimulation over the motor cortex. Just below MEP threshold there was a clear facilitation at short latency (approximately 28 ms). As the intensity of the electrical stimulation was reduced the size of the facilitation decreased until it eventually disappeared. We did not observe a suppression of the EMG activity similar to that produced by TMS in any of the subjects. 4. The present study demonstrates that motoneuronal activity during walking can be suppressed by activation of intracortical inhibitory circuits. This illustrates for the first time that activity in the motor cortex is directly involved in the control of the muscles during human walking.

Enhancer-promoter specificity mediated by DPE or TATA core promoter motifs

To investigate the basis for enhancer-promoter specificity, we compared the ability of enhancers to activate transcription in vivo from core promoters containing either downstream promoter element (DPE) or TATA box motifs. To eliminate position effects, we generated and analyzed pairs of sister Drosophila lines that contain a DPE- or TATA-dependent reporter gene at precisely the same genomic position relative to each enhancer. These studies revealed transcriptional enhancers that are specific for promoters that contain either DPE or TATA box elements. Thus, the core promoter not only mediates the initiation of transcription, but also functions as a regulatory element.

Unexpected reflex response to transmastoid stimulation in human subjects during near-maximal effort

1. In human subjects, a high-voltage electrical pulse between electrodes fixed over the mastoid processes activates descending tract axons at the level of the cervico-medullary junction to produce motor responses (cevicomedullary evoked responses; CMEPs) in the biceps brachii and brachioradialis muscles. 2. During isometric maximal voluntary contractions (MVCs) of the elbow flexors, CMEPs in the biceps brachii and brachioradialis muscles are sometimes followed by a second compound muscle action potential. This response can be observed in single trials (amplitude of up to 60 % of the maximal M wave) and follows the CMEP by about 16 ms in both muscles. The response only occurs during very strong voluntary contractions. 3. The second response following transmastoid stimulation appears with stimulation intensities that are at the threshold for evoking a CMEP in the contracting muscles. The response grows with increasing stimulus intensity, but then decreases in amplitude and finally disappears at high stimulation intensities. 4. A single stimulus to the brachial plexus during MVCs can also elicit a second response (following the M wave) in the biceps brachii and brachioradialis muscles. The latency of this response is 3-4 ms longer than that of the second response observed following transmastoid stimulation. This difference in latency is consistent with a reflex response to stimulation of large-diameter afferents. 5. The amplitude of the second response to transmastoid stimulation can be reduced by appropriately timed subthreshold transcranial magnetic stimuli. This result is consistent with intracortical inhibition of the response. 6. We suggest that transmastoid stimulation can elicit a large transcortical reflex response in the biceps brachii and brachioradialis muscles. The response travels via the motor cortex but is only apparent during near-maximal voluntary efforts.

Antibody repertoire development in fetal and neonatal piglets. IV. Switch recombination, primarily in fetal thymus, occurs independent of environmental antigen and is only weakly associated with repertoire diversification

The epitheliochorial placenta of swine is considered a barrier to Ag and selective transport of IgG, so this species should be an excellent model with which to determine whether switch recombination is Ag dependent. Analysis of Ig levels and Ig isotype profiles in >150 normal and virus-infected fetuses from 38-110 days of gestation (DG) suggested that IgG, IgA, and IgM were most likely the result of de novo fetal synthesis. Although transcripts for IgM could be recovered at DG 50 (114 DG is full gestation) in all major fetal lymphoid tissues, those for IgG and IgA first became prominent at 60 DG in thymus, and transcription and spontaneous secretion became especially pronounced in this organ in older fetuses. Data on transcription, secretion, and serum isotype profiles suggest that although all fetal IgA and IgM may result from de novo synthesis, some IgG may result from low-level selective transport. The complementarity-determining region 3 spectratypes of thymic IgA and IgG transcripts at 70 and 90 days, respectively, were as polyclonal as that of IgM, indicating a broad repertoire of switched B cells although the VDJs transcribed with these switched isotypes in normal fetuses were not diversified in comparison to those from animals exposed to environmental Ags such as age-matched, virus-infected fetuses, colonized isolator piglets, and conventional adults. However, VDJs expressed with switched isotypes were more diversified than those expressed with IgM. Thus, switch recombination in fetal life does not appear to be driven by environmental Ag and is only weakly coupled to VDJ diversification. These findings, and the fact that the oligoclonal IgA and IgM repertoires in a noninductive site of the mucosal immune system (parotid gland) become polyclonal in piglets reared germfree, suggest that initial expansion of the switched cells in the B cell compartment of fetal and neonatal piglets is not driven by environmental Ag.

Characterization of monoclonal antibodies recognizing immunoglobulin kappa and lambda chains in pigs by flow cytometry

The existence of two types of the immunoglobulin (Ig) light chain in pigs was documented>30 years ago and has been confirmed by the cloning of porcine light chain genes homologous to human and murine Ig kappa (Igkappa) and Ig lambda (Iglambda). However, immunochemical reagents defining these two light chain isotypes have not been characterized. Here, we show that rabbit antisera specific for human Igkappa and Iglambda and certain anti-porcine light chain monoclonal antibodies (mAb) are useful in distinguishing light chain isotypes by flow cytometry (FCM). Porcine B cell lines L23 and L35 stained positive only with anti-human Iglambda antiserum and were negative when tested using anti-human Igkappa antiserum. While mAbs K139.3E1, 1G6 and 27.7.1 also tested positive on these cell lines, mAb 27.2.1 did not. Therefore, FCM was used to examine the hypothesis that K139.3E1, 1G6 and 27.7.1 are Iglambda-specific whereas mAb 27.2.1 recognizes the Igkappa chain in pigs. Double staining of peripheral blood mononuclear cells (PBMC) with pairs of anti-light chain mAbs and using cocktails of anti-light chain mAbs and anti-human polyclonal antiserum, confirmed this hypothesis with the exception that mAb K139.3E1 appears to recognize only a subset of Iglambda(+) B cells in most pigs. In summary, we identified two pan-specific anti-pig Iglambda mAbs, one anti-lambda mAb that recognizes a lambda-light chain subset and one anti-pig Igkappa mAb.

Changes in respiratory sensations induced by lobeline after human bilateral lung transplantation

1. The sensations evoked by the injection of lobeline into the right antecubital vein were studied in 8 subjects after bilateral lung transplantation and 10 control subjects. In control subjects, two distinct sensations were experienced. There was an early noxious sensation (onset approximately 10 s) followed by a late sensation of breathlessness (onset approximately 26 s) associated with involuntary hyperventilation. The early sensation was accompanied by respiratory and cardiovascular changes. 2. In contrast to control subjects, the early respiratory events and the noxious sensations evoked by injections of lobeline (18-60 microg kg(-1)) did not occur in subjects with recent bilateral lung transplantation. This suggests that the early respiratory sensations are mediated by the discharge of receptors in the lungs. 3. The late hyperventilation and the accompanying sensation of breathlessness occurred in both transplant and control subjects and are therefore likely to be mediated by receptors elsewhere in the body, presumably systemic arterial chemoreceptors stimulated by lobeline. 4. In control subjects, but not transplant subjects, there was a consistent decrease in mean arterial pressure associated with the lobeline injection. This suggests that pulmonary afferents mediate the hypotension. 5. For transplant subjects studied more than a year after transplantation, there was some evidence that the noxious respiratory sensations evoked by lobeline had returned. This suggests that some functional reinnervation of pulmonary afferents may occur.

Sacroiliac joint dysfunction: a long-term follow-up study

Sixty-nine patients with sacroiliac joint dysfunction were prospectively evaluated and treated with a structured physical therapy program. Follow-up clinical outcome was obtained from a patient questionnaire administered by an independent reviewer a minimum of 2 years after treatment. Average patient age was 40 years, and 80% were women. Ninety-five percent rated their result as good or excellent, while 5% believed their outcome was fair or poor. A structured physical therapy program can produce good long-term results in most patients; however, 5% continue to be symptomatic. This small subset may be candidates for more invasive evaluation.

Gender-Related Differences of Hyaluronic Acid Distribution in the Human Vocal Fold

OBJECTIVE

To quantify the distribution of hyaluronic acid (HA) within the normal human vocal fold and evaluate gender- and age-related differences.

STUDY DESIGN

Prospective, cross-sectional study by age and gender groups using cadaveric vocal folds to study hyaluronic acid differences.

METHODS

Twenty-five vocal fold halves obtained at autopsy were evaluated from nine adult male (age range, 34-52 y), seven adult female (age range, 21-41 y), four geriatric male (age range, 65-77 y), and five geriatric female (age range 65-82 y) subjects. Midmembranous vocal fold sections were stained for HA using the Muller-Mowry colloidal iron (acid mucopolysaccharide) stain with and without hyaluronidase. Digital imaging software was used to quantify the distribution of HA across the lamina propria at the vocal fold edge from superficial (subepithelial) to deep (vocalis muscle).

RESULTS

A significant gender difference (P =.03) was noted in distribution when controlled for age. Combined, male subjects had a relatively constant distribution pattern throughout the depth of lamina propria. Female subjects showed relatively less HA in the first 15% of depth (most superficial) but showed more HA in the deeper 40% to 100% (toward vocalis muscle) than in male subjects.

CONCLUSIONS

Important clinical implications may be extrapolated from our findings. First, relatively less HA in the most superficial area implies less protection from vibratory trauma and overuse and may explain in part why more female than male patients have phonotrauma to phonotraumatic lesions. Second, evaluating the distribution of HA in the normal human vocal fold allows more direction in our application of HA as a therapeutic lamina propria substitute in patients with voice disorders.

Diamond optically transparent electrodes: demonstration of concept with ferri/ferrocyanide and methyl viologen

A new type of optically transparent electrode is reported on--an electrically conductive diamond thin film. The electrode was free-standing (0.38 mm thick and 8 mm in diameter), mechanically polished to a 7-nm rms roughness over a 10-microm linear distance, boron-doped (0.05% B/C in the reactant gas mixture), and mounted in a thinlayer transmission cell. The electrode has a short-wavelength cutoff of approximately 225 nm, which is the indirect band gap of the material, and transmits light out to at least 1,000 nm. In theory, the electrode has an optical window from 225 nm well out into the far-infrared, except for the boron acceptor band and the intrinsic multiphonon absorptions. The electrode was used to electrooxidize ferrocyanide to ferricyanide, and the absorbance change associated with the formation of the oxidized product (lambdamax = 420 nm) was spectroscopically monitored. The electrode was also used to electroreduce methyl viologen (MV2+) to the cation radical (MV+*) and the neutral (MV0). The depletion of MV2+ (lambdamax = 257 nm) and formation of MV+* (lambdama = 398 and 605 nm) were spectroscopically monitored.