Differences in intracortical responses following non-noxious and noxious stimulation in anaesthetized rats

Cortical responses have been proposed as a source for the extraction of unique and non-subjective sensory information. The present study aimed to investigate if it is possible to distinguish between non-noxious and noxious cortical responses with two different types of anesthesia. Sixteen rats were randomly allocated to receive either Hypnorm/Dormicum (HD) or isoflurane (ISO) anesthesia. Each animal had a custom-made microelectrode array implanted in the primary somatosensory cortex to record the local field potentials and a cuff electrode implanted around the sciatic nerve to deliver electrical stimulations. Three stimulation intensities were applied: 1x movement threshold (MT) (i.e., non-noxious activation), 5x MT (low intensity noxious activation), and 10x MT (high intensity noxious activation). The evoked potentials were assessed by extracting three features: 1) the negative peak (NP), 2) the positive peak (PP), and 3) the peak-to-peak (PtP) amplitudes. Our results showed that it was possible to distinguish between three levels of stimulation intensities based on the NP, PP, and PtP features for the HD group, whereas it was only possible to make the same differentiation with the use of PP and PtP when applying ISO. This work is believed to contribute to a basic understanding of how the cortical responses change in the hyperacute phase of pain and which cortical features may be suitable as objective measures of nociception.

Comprehensive assessments and related interventions to enhance the long-term outcomes of child, adolescent and young adult cancer survivors - presentation of the CARE for CAYA-Program study protocol and associated literature review

Background

Improved, multimodal treatment strategies have been shown to increase cure rates in cancer patients. Those who survive cancer as a child, adolescent or young adult (CAYA), are at a higher risk for therapy-, or disease-related, late or long-term effects. The CARE for CAYA-Program has been developed to comprehensively assess any potential future problems, to offer need-based preventative interventions and thus to improve long-term outcomes in this particularly vulnerable population.

Methods

The trial is designed as an adaptive trial with an annual comprehensive assessment followed by needs stratified, modular interventions, currently including physical activity, nutrition and psycho-oncology, all aimed at improving the lifestyle and/or the psychosocial situation of the patients. Patients, aged 15–39 years old, with a prior cancer diagnosis, who have completed tumour therapy and are in follow-up care, and who are tumour free, will be included. At baseline (and subsequently on an annual basis) the current medical and psychosocial situation and lifestyle of the participants will be assessed using a survey compiled of various validated questionnaires (e.g. EORTC QLQ C30, NCCN distress thermometer, PHQ-4, BSA, nutrition protocol) and objective parameters (e.g. BMI, WHR, co-morbidities like hyperlipidaemia, hypertension, diabetes), followed by basic care (psychological and lifestyle consultation). Depending on their needs, CAYAs will be allocated to preventative interventions in the above-mentioned modules over a 12-month period. After 1 year, the assessment will be repeated, and further interventions may be applied as needed. During the initial trial phase, the efficacy of this approach will be compared to standard care (waiting list with intervention in the following year) in a randomized study. During this phase, 530 CAYAs will be included and 320 eligible CAYAs who are willing to participate in the interventions will be randomly allocated to an intervention. Overall, 1500 CAYAs will be included and assessed. The programme is financed by the innovation fund of the German Federal Joint Committee and will be conducted at 14 German sites. Recruitment began in January 2018.

Discussion

CAYAs are at high risk for long-term sequelae. Providing structured interventions to improve lifestyle and psychological situation may counteract against these risk factors. The programme serves to establish uniform regular comprehensive assessments and need-based interventions to improve long-term outcome in CAYA survivors.

Trial registration

Registered at the German Clinical Trial Register (ID: DRKS00012504, registration date: 19th January 2018).

Causal Probabilistic Network and Power Spectral Estimation Used in Sleep Stage Classification

A new method for sleep-stage classification using a causal probabilistic network as automatic classifier has been implemented and validated. The system uses features from the primary sleep signals from the brain (EEG) and the eyes (AOG) as input. From the EEG, features are derived containing spectral information which is used to classify power in the classical spectral bands, sleep spindles and K-complexes. From AOG, information on rapid eye movements is derived. Features are extracted every 2 seconds. The CPN-based sleep classifier was implemented using the HUGIN system, an application tool to handle causal probabilistic networks. The results obtained using different training approaches show agreements ranging from 68.7 to 70.7% between the system and the two experts when a pooled agreement is computed over the six subjects. As a comparison, the interrater agreement between the two experts was found to be 71.4%, measured also over the six subjects.

Development of an implantable transverse intrafascicular multichannel electrode (TIME) system for relieving phantom limb pain

Phantom limb pain frequently follows amputation. Currently there is no fully effective treatment available. Our aim is to develop an innovative Human Machine Interface (HMI) where we apply multi-channel microstimulation to the nerve stump of an amputee subject to manipulate the phantom limb sensations and explore the possibility of using microstimulation as a treatment for phantom limb pain.

Encoding of self-paced, repetitive forelimb movements in rat primary motor cortex

Multi-unit, intra-cortical recordings from the primary motor cortex have been shown to provide information about functional movement of the body, and thus, have been used as command signals for control of an external robotic arm in rat and monkey. However, study of the M1 responses has shown that movement encoding may be dependent on both the functional and behavioral context of the intended motion. The main objective of the present work was to determine if self-paced, repetitive forelimb movements are effectively encoded in multiple-unit recordings from the primary motor cortex (M1) in freely moving, non-constrained rats. Four rats were chronically implanted with 7-channel, 50 microm tungsten micro-wire arrays. Standard psychophysical techniques were first used to train the rats to depress a response paddle in return for a food reward. We computed peri-event time histograms and found both statistically significant excitatory (24/49) and inhibitory (9/49) pre-paddle activity up to 200 ms before a paddle hit. On average, responses from 161+/-37 individual paddle hits were necessary in order to detect statistically significant (> 95%), excitatory pre-paddle action. Thus, while it is possible to detect self-paced, forelimb movements in multi-unit recordings of M1, the high number of repetitions required would limit the efficacy of a real-time cortical neuroprosthesis.

Acute peripheral nerve recording characteristics of polymer-based longitudinal intrafascicular electrodes

We examined the recording characteristics of two different types of polymer-based longitudinal intrafascicular electrodes (LIFEs) in peripheral nerve: single-stranded (s-polyLIFEs) and multistranded (m-polyLIFEs). Recordings were also made from Pt-Ir wire-based electrodes (PtIrLIFEs) as a control. The electrodes were implanted in either tibial or medial gastrocnemius branches of the rabbit sciatic nerve, and in the sciatic nerve of rats. Recorded neural activity induced by manually elicited afferent neural activity showed that both polyLIFE versions performed comparably to PtIrLIFEs.

The effect of moderate levels of simulated altitude on sustained cognitive performance

Previous work has documented cognitive deficits at high altitudes (15,000-25,000 ft), but there is controversy for lower altitudes. This study looked at the effects of moderate altitudes--12,500 ft and 15,000 ft--on short-term memory in comparison to 2,000 ft. Seventy-two student pilots and instructors were first administered the Vocabulary, Digit Span, and Digit Symbol subtests from the Wechsler Adult Intelligence Scale-Revised, the Vandenberg Mental Rotation Test, and the near-contrast sensitivity portion of the Vistech VCTS 6000 chart. Participants then spent 1 1/2 hr at their designated altitude for cognitive testing. Participants performed a 30 min vigilance task while listening to an audiotape with instructions to recall radio calls prefaced by their assigned call sign. Half of the radio calls were high memory loads (at least 4 pieces of information), and half were low memory loads (no more than 2 pieces of information). No effects of altitude were found in performance on the Vigilance task. However, for readbacks of high memory load, significant deficits in recall were observed at 12,500 ft and 15,000 ft, whereas no effect of altitude was observed on recall of readbacks with low memory loads. These results indicate that, at altitude, short-term memory was exceeded for the readbacks requiring a larger amount of information to be recalled, and that cognitive deficits are found at lower altitudes than previously observed.

Effect of initial joint position on nerve-cuff recordings of muscle afferents in rabbits

The objective was to characterize nerve-cuff recordings of muscle afferents to joint rotation over a large part of the physiological joint range. This information is needed to develop control strategies for functional electrical stimulation (FES) systems using muscle afferent signals for sensory feedback. Five acute rabbit experiments were performed. Tripolar cuff electrodes were implanted around the tibial and peroneal divisions of the sciatic nerve in the rabbit's left leg. The electroneurograms (ENG) were recorded during passive ankle rotation, using a ramp-and-hold profile starting at seven different joint positions (excursion = 5 degrees, velocity = 10 degrees/s, initial positions 60 degrees, 70 degrees, 80 degrees, 90 degrees, 100%, 110 , and 120 ). The amplitude of the afferent activity was dependent on the initial joint position. The steady-state sensitivity of both nerve responses increased with increasing joint flexion, whereas the dynamic sensitivity increased initially but then decreased. The results indicate that recordings of the muscle afferents may provide reliable information over only a part of the physiological joint range. Despite this limitation, muscle afferent activity may be useful for motion feedback if the movement to be controlled is within a narrow joint range such as postural sway.

Effect of agonist-antagonist electrical stimulation on muscle afferent recordings in anesthetized rabbits

Objective. Sensory feedback extracted from muscle afferents is an approach to achieve closed-loop control of paralyzed muscles using functional electrical stimulation (FES). The objective of the present study was to characterize the effect of agonist-antagonist electrical stimulation on nerve cuff recordings of muscle afferent activity. Methods. Cuff electrodes were implanted around the tibial and peroneal nerve branches in five acute rabbit experiments. Two wires were implanted in each of the tibialis anterior (TA) and the lateral gastrocnemius (LG) muscles to obtain bipolar, intramuscular stimulation. Electroneurograms (ENG) were recorded during trapezoidal rotations of the ankle joint and compared during periods (25%, 50% and 100% of maximal force) with and without electrical stimulation of the muscle. Results. The activity from a stretched and electrically stimulated muscle showed the same pattern as the recordings from a matched nonstimulated muscle. The background afferent activity increased with increasing level of muscle stimulation. The static and dynamic sensitivities were not found to be different, except in one case (peroneal nerve at 100% TA recruitment). Discussion. The main contribution to the tibial activity was believed to originate from muscle afferents in nonstimulated, synergist muscles. The main contribution to the peroneal activity was believed to be from muscle afferents within the muscle being stimulated. It was suggested that the increased background activity could be attributed to the increased activity of the Golgi tendon organs. Conclusions. Sensory information about joint flexion and joint extension are preserved in muscle afferent recordings from electrically activated muscles at low and intermediate stimulation levels, but it still has to be shown whether muscle afferent information can be useful as sensory feedback in FES control.

Neuro-fuzzy extraction of angular information from muscle afferents for ankle control during standing in paraplegic subjects: an animal model

This paper is part of a project whose aim is the implementation of closed-loop control of ankle angular position during functional electrical stimulation (FES) assisted standing in paraplegic subjects using natural sensory information. In this paper, a neural fuzzy (NF) model is implemented to extract angular position information from the electroneurographic signals recorded from muscle afferents using cuff electrodes in an animal model. The NF model, named dynamic nonsingleton fuzzy logic system is a Mamdani-like fuzzy system, implemented in the framework of recurrent neural networks. The fuzzification procedure implemented was the nonsingleton technique which has been shown in previous works to be able to take into account the uncertainty in the data. The proposed algorithm was tested in different situations and was able to predict reasonably well the ankle angular trajectories especially for small excursions (as during standing) and when the stimulation sites are far from the registration sites. This suggests it may be possible to use activity from muscle afferents recorded with cuff electrodes for FES closed-loop control of ankle position during quite standing.

Nerve cuff recordings of muscle afferent activity from tibial and peroneal nerves in rabbit during passive ankle motion

Activity from muscle afferents regarding ankle kinesthesia was recorded using cuff electrodes in a rabbit preparation in which tactile input from the foot was eliminated. The purpose was to determine if such activity can provide information useful in controlling functional electrical stimulation (FES) systems that restore mobility in spinal injured man. The rabbit's ankle was passively flexed and extended while the activity of the tibial and peroneal nerves was recorded. Responses to trapezoidal stimulus profiles were investigated for excursions from 10 degrees to 60 degrees using velocities from 5 degrees/s to 30 degrees/s and different initial ankle positions. The recorded signals mainly reflect activity from primary and secondary muscle afferents. Dorsiflexion stretched the ankle extensors and produced velocity dependent activity in the tibial nerve, and this diminished to a tonic level during the stimulus plateau. The peroneal nerve was silent during dorsiflexion, but was activated by stretch of the peroneal muscles during ankle extension. The responses of the two nerves behaved in a reciprocal manner, but exhibited considerable hysteresis, since motion that relaxed the stretch to the driving muscle produced an immediate cessation of the prior stretch induced activity. A noted difference between the tibial and peroneal nerve responses is that the range of joint position change that activated the flexor afferents was greater then for the extensor afferents. Ankle rotation at higher velocities increased the dynamic stretch evoked responses during the stimulus ramp but showed no effect on the tonic activity during the stimulus plateau. Prestretching the muscles by altering the initial position increased the response to the ramp movement, however, for the peroneal nerve, when the prestretch brought the flexor muscles near to their maximal lengths, the response to additional stretch provided by the ramp movement was diminished. The results indicate that the whole nerve recorded muscle afferent activity may be useful for control of FES assisted standing, because it can indicate the direction of rotation of the passively moved ankle joint, along with coarse information regarding the rate of movement and static joint position.

Causal probabilistic network and power spectral estimation used in sleep stage classification

A new method for sleep-stage classification using a causal probabilistic network as automatic classifier has been implemented and validated. The system uses features from the primary sleep signals from the brain (EEG) and the eyes (AOG) as input. From the EEG, features are derived containing spectral information which is used to classify power in the classical spectral bands, sleep spindles and K-complexes. From AOG, information on rapid eye movements is derived. Features are extracted every 2 seconds. The CPN-based sleep classifier was implemented using the HUGIN system, an application tool to handle causal probabilistic networks. The results obtained using different training approaches show agreements ranging from 68.7 to 70.7% between the system and the two experts when a pooled agreement is computed over the six subjects. As a comparison, the interrater agreement between the two experts was found to be 71.4%, measured also over the six subjects.

Expression of CD43 epitopes on NK and T cells

CD43 epitope expression was studied with a panel of monoclonal antibodies (MoAbs) by immunohistochemistry on freeze sections of lymphoid tissues. The MoAb WEN3 stained most cells weakly in the T areas and scattered splenic red pulp cells strongly, whereas the other MoAbs strongly stained the majority of the cells in the T areas but gave variable staining patterns of cells in the non-T areas. Flow cytometry on CD4+ and CD8+ T cells (T4 and T8 cells), freshly isolated NK cells and LAK cells showed distinct staining profiles for each cell type, with epitope expression patterns of T8 cells lying between those of T4 cells and NK/LAK cells. T8 cells were split by one of the MoAbs, the NK cells, but not LAK cells, were split by two other MoAbs.

Hemodynamic measurements in a sheep model with a hollow fiber artificial kidney containing modified cellulose

HFAK-RC caused pronounced leukopenia, increase in TXB2 levels in plasma and hemodynamic pressure changes as a reflection of complement activation during EC in sheep. In contrast no increase in TXB2 levels and no changes in hemodynamics are observed with HFAK-MC. The leukopenia and granulocytopenia in the latter is much less pronounced and probably reflects the phenomenon "frustrated phagocytosis".

Perforation of the terminal ileum with cytomegalovirus vasculitis and Kaposi's sarcoma in a patient with acquired immunodeficiency syndrome

This case report documents a perforation of the terminal ileum in a 40-year-old white male homosexual with the acquired immunodeficiency syndrome. The perforation occurred at a site that had severe cytomegalovirus infection and was in close proximity to multiple nodules of Kaposi's sarcoma. The ileum showed multiple deep ulcers with large numbers of cytomegalovirus inclusions and vasculitis with infected endothelial cells, small-vessel thrombosis, focal disruption, and hemorrhage. We review the evidence that cytomegalovirus infection--and not Kaposi's sarcoma--was responsible for this perforation and, in light of the new medical therapy for such infections, should be regarded as an important cause of gastrointestinal perforation in patients with the acquired immunodeficiency syndrome.

Drug and alcohol use by disabled and nondisabled persons: a comparative study

The study is an initial attempt to provide comparative alcohol and drug use data on disabled and nondisabled persons. The lack of useful information on disabled persons is described in the literature review. Sixty-six disabled students and 115 nondisabled students returned questionnaires which examined their alcohol and drug use. The two groups were compared using tests of significance. The data provided in this report tend to confirm the notion that the disabled and nondisabled students use alcohol and drugs in similar ways. Caution is urged against generalization, and the need for additional studies is emphasized.

Response of protein C and protein C inhibitor to warfarin therapy in patient with combined deficiency of Factors V and VIII

The role of Protein C in combined factor V/VIII deficiency was examined by reducing the Protein C concentration using warfarin therapy in a patient with the combined deficiency. The factor VIII deficiency was like Hemophilia-A, with deficiency of VIII:C and VIII:C(Ag), but normal VIIIR:Ag and VIIIR:cof. The factor V deficiency was due to loss of the V antigen. During warfarin therapy the Protein C level was reduced, but concentrations of factors V and VIII did not change. Protein C Inhibitor was normal throughout. Thus combined factor V/VIII deficiency is not related to Protein C levels.

Lactose malabsorption in children and adolescents with inflammatory bowel disease

Lactose breath hydrogen tests were given to 70 children and adolescents with chronic ulcerative colitis and Crohn's disease in order to determine the prevalence of lactose malabsorption in childhood inflammatory bowel disease. Twenty-nine percent of these patients demonstrated lactose malabsorption; the majority of these children (70%) experienced gastro-intestinal symptoms during the test. The prevalence was not significantly different whether the diagnosis was ulcerative colitis or Crohn's disease. With the exception of those with diffuse small bowel disease, the location of intestinal involvement with Crohn's disease and the severity of clinical symptoms did not affect lactose malabsorption. Lactose malabsorption was not more frequent in patients with inflammatory bowel disease than in a group of children with recurrent abdominal pain and normal gastrointestinal x-rays, although significant differences in the prevalence of lactose malabsorption were observed in relation to ethnic background. Milk incubated with commercially available yeast lactase (lactAid, Surgarlo Co., Atlantic City, N.J.) for greater than 24 h prevented an increase in breath hydrogen when administered to 6 patients previously shown to have lactose malabsorption.

[Videoprocessing pupillographic perimetry in hemianopsia (author's transl)]

In cases of homonymous hemianopsia, with the aid of pupillographic perimetry it is possible to differentiate between infra- or suprageniculate lesions. Principally the validity of Wernicke's theory remains unchanged. However in processes in the central visual pathways a hemihypokinesia of varying degree may be found. In the blind visual fields so far in our cases a congruence between pupillographic and perimetric thresholds has not been confirmed. The phenomenon of hemihypokinesia of the pupil is discussed.

Structural difference at the active site of dibucaine resistant variant of human plasma cholinesterase

Human plasma cholinesterase from five different genotypes -- E1U E1U, E1U E1A, E1A E1A, E1U E1S, E1A E1S, and E1U E1U C5+ -- was purified 8,000 fold from serum by a two-step procedure involving chromatography on DEAE-cellulose and preparative disc electrophoresis. The esterases were labeled with diisopropyl-1, 3-C14-fluorophosphate (DFP) aminoethylated, and digested by trypsin. The trytic digests were subjected to high voltage electrophoresis, and the radioactive peptides were detected by radioautography. Comparison of the peptides revealed different electrophoretic mobilities of the usual and atypical (dibucaine resistant) plasma cholinesterase peptides. The results are consistent with a structural abnormality of the active center in the variant enzyme. No difference was observed an the esteratic site of the enzyme with C5 component.

[A description of a method for objective perimetry (author's transl)]

An infrared-sensitive TV Camera has been fitted into a projection perimeter, which allows to control fixation independent of the particular background illumination. The consensual pupil light reflex, triggered by the test light of the perimeter, is measured and registered with a special TV processor designed for this purpose. The method was tested for its efficiency on four healthy volunteers. The course of sensory and pupillomotor thresholds were measured on the 135 degree meridian of the visual field. Determinations were conducted in the photopic range of 10 asb background illumination with two test points of 27' and 7'. A difference of 10 dB was found between the sensory and pupillomotor thresholds.