Predicting the experience of dentinal caries or restorative dental treatment in adolescents using D1 and D3 visual caries assessments

Standardised epidemiological caries assessments used in oral health surveys have been shown to be poor at predicting whether a tooth surface will be treated restoratively when a patient visits a dentist. However, it has been argued that oral health surveys may be more relevant in determining needs at the level of an individual or groups of individuals. The objective of this study was to determine the discriminatory power of visual caries assessments at two thresholds (D₁ & D₃) in adolescents of average age 12.1 years to predict experience of dentinal caries 3 years later or the experience of restorative treatment (not re‐treatment) during the 3‐year period. The data was derived from a prospective 3‐year longitudinal study in which the dental care provided by 41 dentists for 403 adolescents was monitored. Dental caries experience was monitored by annual standardised assessments of caries undertaken by a single trained examiner. ROC analysis showed that caries assessed visually at the D₁ threshold in 12‐year‐olds was a better predictor (P < 0.001) of experiencing some dentinal caries after 3 years (Az = 0.781) than was caries assessed visually at D₃ threshold in 12‐year‐olds (Az = 0.670). Assessing caries visually at either the D₁ or the D₃ threshold had no discriminatory power for predicting whether an individual would experience some restorative treatment during the ensuing 3‐year period (Az for D₁ = 0.507; Az for D₃ = 0.518).     

健康人加压素释放和渴感的渗透压阈值

报道１２名受试者在静滴５％ＮａＣｌ２ｈ（每分钟０．０６ｍｌ／ｋｇ）的过程中血钠、血渗、血浆精氨酸加压素（ＡＶＰ）浓度和渴感等级的变化。结果显示，血浆ＡＶＰ浓度及渴感等级分别与血渗呈线性相关，回归方程分别为：血浆ＡＶＰ浓度（ｐＡＶＰ）－０．２４［血浆渗透压（ｐＯｓｍ）－２７４］（ｒ＝０．７２，Ｐ＜０．００１）；渴感等级（Ｔｈ）＝０．２３（ｐＯｓｍ－２７９）（ｒ＝０．６２，Ｐ＜０．００１）．两者灵敏度及阈值均较国外文献报道的结果低，认为加压素释放及渴感的渗透压阈值可能与遗传因素及生活习俗有关，ＡＶＰ分泌及渴感的渗透压调节可能存在种族差异。     

Effects of short-duration transients on cardiac rhythm

Cardiac stimulation thresholds of short-duration large-amplitude electrical transients were studied. An isolated rabbit heart model was used and transients were applied directly to the heart through electrodes of 1 mm² and 1 cm² surface area. A variety of oscillatory waveforms and pulse configurations were studied and indicated that, for transients shorter than 100 μs, stimulation thresholds approach a constant charge-transfer density of 3·4 μC cm⁻².     

Visual cortex ablation and thresholds for successively presented stimuli in rhesus monkeys: II. Hue

Summary Rhesus monkeys were trained to discriminate successively presented hues. The smallest difference they could reliably detect was determined before and after either inferotemporal ablation, or a lesion intended to remove as much as possible of prestriate area V4 (Zeki, 1973).As a group, the animals with lesions of V4 showed good but not perfect retention of their preoperative performance, and their thresholds were unaltered. The inferotemporal group showed no retention of the simplest successive task, red versus green, but after relearning their thresholds too were unaltered. It appears that animals without inferotemporal cortex can form precise internal representations of hues, and that the basis of the inferotemporal learning impairment may depend upon the nature of the stimuli to be discriminated.     

Prolyl-leucyl-glycinamide shares some effects with oxytocin but decreases oxytocin levels

Oxytocin treatment in rats induces long-lasting antistress and growth promoting effects. This study investigated whether prolyl-leucyl-glycinamide (PLG) (the c-terminal tripeptide of oxytocin) or tocinoic acid (the ring structure of oxytocin) could induce some of these effects in male rats. For this purpose, PLG (2 or 10 mg/kg, s.c.) or tocinoic acid (1 mg/kg, s.c.) was administered to rats once a day for 3 or 5 days. Blood pressure, heart rate, spontaneous motor activity, nociceptive thresholds, and the survival of ischaemic musculocutaneous flaps were measured. In addition, endogenous oxytocin levels and plasma levels of some hormones known to be influenced by oxytocin were determined. PLG (2 mg/kg, s.c., but not 10 mg/kg, s.c.) decreased diastolic blood pressure (p<0.05) and locomotor activity (p<0.05). PLG (10 mg/kg, s.c.) decreased gastrin (p<0.05) and endogenous oxytocin levels in plasma (p<0.01). Tocinoic acid decreased locomotor activity (p<0.05), but did not affect any of the other parameters measured. In conclusion, this study showed that both PLG and tocinoic acid decrease locomotor activity. In addition, PLG also induced some other effects similar to those induced by oxytocin treatment but when administered in high doses it decreased oxytocin levels.     

Reduced nocturnal morphine analgesia in mice following a geomagnetic disturbance

Latency to respond to an aversive thermal stimulus and the degree of analgesia induced by morphine were examined in mice injected with either isotonic saline or morphine sulfate (10 mg/kg) during midscotophase of a 12:12 h LD cycle. When mean response latencies were compared to the degree of geomagnetic disturbance (Ap index) present on test days, it was found that during the geomagnetic storm on December 17th, 1982, a significant reduction (P<0.01) in response latency was evident in both saline- and morphine-treated mice. The reduction in response latencies was greater, and lasted longer in the morphine-treated animals. It is suggested that the pineal gland may mediate this biomagnetic effect.     

The Effects of Stages of the Estrous Cycle on Pain Thresholds in Female White Rats

The effects of stages in the estrous cycle on electrical pain thresholds were studied in white rats in conditions of chronic measurement. On recording day 3, females in the diestrus and estrus stages showed sharp increases in shudder and paw-shuffling thresholds. Females in proestrus and metestrus showed no change in thresholds as compared with those in the first days of recording. Starting from day 7, there were progressive decreases in electrical pain thresholds regardless of the stage of the estrous cycle. Data for all animals showed that regular measurement of pain thresholds induces a smooth two-fold increase in body resistance from day 1 to day 7. This was followed by a sharp drop on day 8, with parallel decreases in body resistance and electrical pain thresholds. Thus, chronic measurement of electrical pain thresholds and body resistance changed in a complex fashion, and threshold values depended on the stage of the estrous cycle.     

Corticospinal excitability and sleep: a motor threshold assessment by transcranial magnetic stimulation after awakenings from REM and NREM sleep

Transcranial magnetic stimulation (TMS) is a recently established technique in the neurosciences that allows the non-invasive assessment, among other parameters, of the excitability of motor cortex. Up to now, its application to sleep research has been very scarce and because of technical problems it provided contrasting results. In fact delivering one single suprathreshold magnetic stimulus easily awakes subjects, or lightens their sleep. For this reason, in the present study we assessed motor thresholds (MTs) upon rapid eye movement (REM) and non-rapid eye movement (NREM) sleep awakenings, both in the first and in the last part of the night. Taking into account that a full re-establishment of wake regional brain activity patterns upon awakening from sleep needs up to 20-30 min, it is possible to make inferences about the neurophysiological characteristics of the different sleep stages by analyzing the variables of interest immediately after provoked awakenings. Ten female volunteers slept in the lab for four consecutive nights. During the first night the MTs were collected, following a standardized procedure: 5 min before lights off, upon stage 2 awakening (second NREM period), upon REM sleep awakening (second REM period), upon the final morning awakening (always from stage 2). Results showed that MTs increased linearly from presleep wakefulness to REM sleep awakenings, and from the latter to stage 2 awakenings. There was also a time-of-night effect on MTs upon awakening from stage 2, indicating that MTs decreased from the first to the second part of the night. The increase in corticospinal excitability across the night, which parallels the fulfillment of sleep need, is consistent with the linear decrease of auditory arousal thresholds during the night. The maximal reduction of corticospinal excitability during early NREM sleep can be related to the hyperpolarization of thalamocortical neurons, and is in line with the decreased metabolic activity of motor cortices during this sleep stage. On the contrary, the increase of MTs upon REM sleep awakenings should reflect peripheral factors. We conclude that our findings legitimate the introduction of the TMS technique as a new proper tool in sleep research.     

基于coif5小波的多普勒胎心音信号提取算法的研究

胎心率监护是围产期胎儿监护的关键技术指标，超声多普勒测量胎心率是最常用的无创方法。由于胎心多普勒信号具有信噪比低、非平稳的随机性特点，提出基于coif5小波，结合双重阈值方法的胎心音信号提取算法。实验表明，该算法有效地解决了由于胎心率加倍、减半所引起的胎心率曲线翻转问题，提高了多普勒胎心音信号提取的准确性。