Electrode Positioning for Reliable Telemetry ECG Recordings During Social Stress in Unrestrained Rats

We describe a surgical procedure for optimizing the location of telemetry ECG leads in rats. The new location was aimed at obtaining an accurate representation of ECG features throughout the cardiac cycle by limiting the voltage instability usually observed during intense somatomotor activity and improving the signal-to-noise ratio. The two electrodes (wire loops) were fixed on the dorsal surface of the xiphoid process and in the anterior mediastinum close to the right atrium. The implantation procedure was fast, little invasive, and allowed animals to completely recover from intervention. The performance of the “improved” location (IL, n = 10) with respect to two subcutaneous (SC) positionings (“conventional positioning,” CSP, n = 5; “updated location,” USL, n = 5) was evaluated by comparing ECGs obtained in baseline, stress and recovery conditions and during different behavioral activities (immobility and grooming). The resident-intruder test (emotional/physical challenge) was chosen as experimental stress paradigm. The noise level of ECGs obtained from IL rats was lower than in CSP and USL animals, in all recording conditions. Percentages of correctly recognized beats (CRBs) over the total number of beats (TBs) were significantly higher in IL rats than in CSP and USL animals, both in baseline conditions (99% vs. 11% and 40%) and situations involving high somatomotor activity (stress: 97%, 5% and 16%; recovery: 97%, 7%, and 15%) (p < 0.01). The performance of IL as compared to CSP and USL was also better when percentages during grooming and immobility were considered (grooming: 93% vs. 4% and 23%; immobility: 97%, 6%, and 33%; p < 0.01).     

大鼠肝再生过程中碱性磷酸酶活性变化及其超微细胞化学研究

目的 研究2／3肝切除后大鼠肝再生过程中碱性磷酸酶(AKP)活性的变化及其细胞定位。方法 利用比色法对AKP活性进行定量分析；用酶的原位复性电泳技术分析再生肝中AKP的种类和活性变化；用电镜细胞化学方法研究酶定位。结果 在肝部分切除后的肝再生期间，AKP出现两个活性高峰(16h和19h)，在每个活性高峰后，AKP均有显著下降；获得3种肝型AKP同工酶(140、160和180kD)，其中180kD的AKP只在肝再生过程中出现；随着肝再生的进展，AKP活性出现在细胞的不同部位。结论 AKP在肝再生过程中起重要作用，可能参与细胞代谢、物质转运、DNA合成和细胞分化。     

The relationship between the electromyogram-amplitude and isometric extension torques of neck muscles at different positions of the cervical spine

A group of 12 healthy men volunteered for the experiment. Electromyograms (EMG) were obtained from semispinalis capitis, splenius capitis, levator scapulae, and trapezius muscles. The flexion angle of the cervical spine was precisely adjusted to 0°, 10°, 20°, and 30° relative to the horizontal, with a constant angle of the atlanto-occipital joint. The subjects made eight short (about 2 s) vertical extension forces (6%, 12%,18%, 24%, 30%, 36%, 42%, and 48% of maximal voluntary peak contraction force). For each position, the centre of pressure under the head was determine as the basis for the calculation of the external lever arm. The presence of motor endplate regions was ascertained by multiple surface electrodes. The slopes of individual linear regression lines for the root mean square (rms)-values were dependent on the existence of endplates in the area of the electrodes — endplates caused smaller rms values per Newton metres of external torque. Significant intersubject differences between regression equations could not be eliminated by the normalization of EMG-parameters and/or torques. The elimination of gravity, the continuous monitoring of positions, and the consideration of localization of motor endplate regions were essential prerequisites for the acquisition of reliable relationships between EMG of different neck muscles and external torques. Two important conclusions were derived for the prediction of torques from EMG measurements: firstly, individual regression equations which take into account the position of the head and neck should be used; secondly, normalization procedures do not justify the application of average regressions to a group of subjects.     

Control of single-joint movements in deafferented patients: evidence for amplitude coding rather than position control

Two deafferented patients and several control subjects participated in a series of experiments to investigate how accurate single-joint movements are programed, spatially calibrated, and updated in the absence of proprioceptive information. The deafferented patients suffered from a permanent and severe loss of large sensory myelinated fibers below the neck. Subjects performed, with and without vision, sequences of forearm supinations and pronations with two temporal delays between each movement (0 s and 8 s). Overall, the lack of proprioception did not yield any significant decrease in movement accuracy when vision was available. Without vision, the absence of proprioceptive afferents yielded (1) significantly larger spatial errors, (2) amplitude errors similar to those of control subjects, and (3) a significant drift when an 8-s delay was introduced between two successive movements. Subjects also performed, without vision, a 20 supination followed by a 20 pronation that brought back the wrist to the starting position. On some trials, the supination was blocked unexpectedly by way of a magnetic brake. When the supination was blocked, subjects were already on the second target and no pronation was required when the brake was released. The defferented patients, unaware of the procedure, always produced a 20 pronation. These data confirm that deafferented patients were not coding a final position. It rather suggests that they coded an amplitude and translated the spatial distance between the two targets in a corresponding force pulse. Overall, the results highlight the powerful and key role of proprioceptive afferents for calibrating the spatial motor frame of reference.     

Eye position signals in human saccadic processing

Summary 1. We studied saccades to briefly flashed targets in 8 human subjects. The target flash occurred (i) during smooth pursuit (ramp-flash), (ii) just before a saccade to another target (step-flash), or (iii) during steady fixation (flash only). All lights were extinguished after the target flash so that smooth pursuit or saccadic eye movements occurred during the interval of complete darkness between the target flash and the saccade to it. We compared these saccades to those made without intervening eye movement (flash only), and quantified the extent to which the saccadic system compensated for the change in eye position that occurred during the dark interval. 2. Saccades to control flashes were reasonably accurate (mean gain 0.87) and consistent. Compensation for the intervening eye movement in the ramp-flash and step-flash paradigms was highly variable from trial to trial. On average, subjects compensated for 27% of the intervening pursuit eye movement on ramp-flash trials and for 58% of intervening saccadic movement on step-flash trials. 3. Multiple regression analysis showed that the variability did not depend on factors such as variations in underlying saccadic gain, response latency, timing of stimuli or size of the required response. We conclude that this variability is intrinsic to saccadic responses that require the use of an eye position signal. 4. These results show that an eye position signal is available to the saccadic system but that this signal has low fidelity. The high variability and low fidelity of the eye position signal suggest that the saccadic system does not normally operate in spatial coordinates, which require the use of an accurate eye position signal, but rather in retinal coordinates.     

The reproducibility of test contractions for calibration of electromyographic measurements

Summary The main purpose of this study was to evaluate the reproducibility of electromyographic (EMG) measurements and specifically to test a calibration procedure with submaximal test contractions. Bipolar surface electrodes (20 mm fixed distance) were repositioned by a tracing sheet on both trapezius muscles, halfway between acromion and processus prominens. Submaximal test contractions were performed by keeping both arms straight abducted 90° and forward flexed 10° for 15-s periods. The arm position could be precisely reproduced in the frontal plane, but deviated forwards by 4° in the horizontal plane, where the sensitivity of the EMG response to arm position was lowest. The electrodes were repositioned within a radius of 3 mm with a probability of 90%. Large deviations in the EMG response were found within this radius and a significant depression of the EMG response was recorded over the middle part of the muscle (the innervation zone?). This change in sensitivity of the EMG response with electrode position occurred in parallel for the test and maximal contractions. The total coefficient of variation was estimated to be 23% for recurrent EMG measurements using the calibration procedure described.     

Konsekutive Serie von 100 Colonresektionen mit einer modifizierten fortlaufenden Nahttechnik

Zusammenfassung Es wird anhand einer konsekutiven Serie über eine modifizierte fortlaufende Nahttechnik am Colon berichtet, die gerade bei älteren Patienten eine sichere und rasche Methode der Anastomosierung darstellt. Die klinisch relevante Insuffizienzrate sowie auch die Letalitätsrate betrugen in dieser Serie je 2%, wobei die Ursachen für die Letalität aber keine Folge der Insuffizienz waren. Die Komplikationsrate betrug 11%, die urologischen Komplikationen mit 6% standen hierbei im Vordergrund.

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A consecutive series of 100 resections of the colon using a modified technique of continuous (running away) suture

Summary Based on a consecutive series it is reported about a modified type of continuous suture on the colon, used especially in elderly patients for being a secure and prompt method of anastomosing. The rate of insufficiency and mortality, as far as the clinical relevance is concerned, turns out to be 2% each and there was no relation between mortality and insufficient anastomosis. The complication rate was 11%, whereby the urological complications predominated with 6% of the total.

     

Contrasting effects of vasopressin,desglycinamide-vasopressin and amphetamine on a delayed matching to position task in rats

The effects of peripherally injected arginine vasopressin (AVP: 0–25 g/kg), its desglycinamide analogue (DGAVP: 0–25 g/kg), which is practically devoid of pressor activity, and d-amphetamine (AMP: 0–1.25 mg/kg) were studied using a delayed (0–32 s) matching to position task (Dunnett 1985). A limited hold for responding (20 s) was in operation. This task enables an accurate assessment of forgetting in rats. AVP reliably improved per cent correct performance, and this effect was substantiated by accuracy indices derived from signal detection theory (TSD). DGAVP, however, was inactive, suggesting that the parent peptide's pressor properties were responsible for its beneficial effects. AMP disrupted performance in a dose-related manner, and was the only substance to alter a TSD bias index (responsivity index, RI), indicating a degree of response repetition at the highest dose. These results are consistent with some earlier reports, and suggest that AVP may enhance memory by peripheral action, while AMP disrupts performance. Closer inspection of the data, however, suggested that the peptide reduced general responsiveness. A new index to measure bias (Sahgal 1987) suggested that AVP-treated subjects restricted their sample and choice responses to one side of the operant chamber, thereby achieving a spuriously high detection rate with few errors of commission (incorrect responses). It is concluded that AVP does not, after all, improve performance: on the contrary it has detrimental effects, and produces errors of omission (failure to respond).     

自由体位分娩对自然分娩率和剖宫产率影响的临床观察

目的:观察自由体位分娩对不同分娩方式的影响。方法:选取94例来我院分娩的孕产妇为研究对象,按入院顺序将其分为两组,采取常规卧位分娩的为对照组,应用自由体位分娩的则为观察组。对比两组产妇的产程时间及分娩方式。结果:①产程时间方面,两组产妇第二、第三产程时间差异不明显(P>0.05),但观察组第一及总产程时间显著低于对照组(P<0.05)。②分娩方式方面,观察组自然分娩率要显著高于对照组,剖宫产率明显低于对照组,P<0.05。结论:通过采取自由体位的方式进行分娩,可缩短产程,降低剖宫产率。     

Social Inequalities in Changes in Diet in Adolescents during Confinement Due to COVID-19 in Spain: The DESKcohort Project

Adolescence is a critical period in the consolidation of healthy lifestyles that can last into adulthood. To analyze changes in food consumption and eating behaviors in high-school adolescents during the first confinement, a cross-sectional study was conducted at the end of confinement in Spain. Changes in the frequency or quantity of consumption of different types of food and food-related behaviors were analyzed. Socioeconomic and health-related variables were also considered. To determine whether dietary changes were related to socioeconomic position (SEP), Poisson regression models with robust variance were estimated. Overall, there were some changes towards a healthier diet such as an increase in fruit consumption (38.9%) and a decrease in the consumption of soft drinks (49.8%), sweets and pastries (39.3%), and convenience foods (49.2%). Some changes, however, were related to less healthy behaviors, such as a more irregular pattern of meal distribution (39.9%) or an increase in snacking between meals (56.4%). Changes towards less healthy eating were also related to students’ SEP. The risk of worsening the diet was found to be 21% higher in adolescents from a more disadvantaged SEP. Future public policies could be adapted to avoid increasing nutritional and health inequalities.