Phase shift magnitude and direction determine whether Siberian hamsters reentrain to the photocycle

Body temperature (Tb) or activity rhythms were monitored in male Siberian hamsters (Phodopus sungorus) housed in an LD cycle of 16 h light/day from birth. At 3 months of age, rhythms were monitored for 14 days, and then the LD cycle was phase delayed by 1, 3, or 5 h or phase advanced by 5 h in four separate groups of animals. Phase delays were accomplished via a 1- or 3-h extension of the light phase or via a 5-h extension of the dark phase. The phase advance was accomplished via a 5-h shortening of the light phase. After 2 to 3 weeks, hamsters that were phase delayed by 1 or 3 h were then phase advanced by 1 or 3 h, respectively, via a shortening of the light phase. All of the animals reentrained to phase delays of 1 or 3 h and to a 1-h phase advance; 79% reentrained to a 3-h phase advance. In contrast, only 13% of the animals reentrained to the 5-h phase advance, 13% became arrhythmic, and 74% free ran for several weeks. After the 5-h phase delay, however, reentrainment was observed in 50% of the animals although half of them required more than 21 days to reentrain. The response to a phase shift could not be predicted by any parameter of circadian rhythm organization assessed prior to the phase shift. These data demonstrate that a phase shift of the LD cycle can permanently disrupt entrainment mechanisms and eliminate circadian Tb and activity rhythms. Magnitude and direction of a phase shift of the LD cycle determine not only the rate but also the probability of reentrainment. Furthermore, the phase of the LD cycle at which the phase shift is made has a marked effect on the proportion of animals that reentrain. Light exposure during mid-subjective night combined with daily light exposure during the active phase may explain these phenomena.     

Effect of jaw opening on the direction and magnitude of human incisal bite forces

The maximum bite force (MBF) appears to be different when measured at different jaw openings (e.g., Manns et al., 1979; Mackenna and Turker, 1983; Lindauer et al., 1993). However, the change could be related to a change in the bite direction. We have measured the MBF on incisors and its direction in three dimensions for different jaw openings in ten subjects. Surface electromyography (EMG) of anterior temporalis and masseter muscles on both sides was recorded simultaneously. The results showed that: (1) the average %MBF increased as the jaw was opened, reached a plateau between 14 and 28 mm of incisal separation, and then decreased at wider jaw openings; (2) the initial forward bite direction with respect to the mandibular occlusal plane shifted backwards during jaw opening; and (3) the activity of the masseter muscles declined and that of the temporalis muscles was largely unchanged, resulting in an increase of the ratio between the activity in temporalis and masseter muscles (T/M). There was a significant correlation between bite direction and jaw opening (r = 0.51, p < 0.001) and between T/M ratio and jaw opening (r = 0.56, p < 0.001). Based on comparative data, we have calculated sarcomere lengths while the jaw is opened and hypothesize that the average %MBF reaches its maximum when the sarcomeres in the masseter muscle achieve their optimum length. A plateau continues during further jaw opening, until those of temporalis reach their optimum length while those of masseter lengthen beyond their optimum length. The change in bite direction was attributed to either a change in the relation between upper and lower bite points as the jaw was opened or the gradual decline of masseter activity at larger openings.     

Measurement of magnitude and direction of velocity in high-temperature liquid metals. Part II: Experimental measurements

Experimental research work on the application of the sphere melting technique to measure magnitude as well as direction of velocity in liquid metals is the focus of Part II of this series of articles. The sphere melting time is detected by means of a sensing wire, which is connected to a specially designed electrical circuit. A novel apparatus is used whereby liquid metal is rotated with a specified tangential velocity. To measure the magnitude of velocity, the sensing wire of the sphere melting is located at the center of the sphere. To detect the direction of flow, three sensing wires are employed. These wires are placed at strategic locations inside the sphere and detect the melting times at three different locations. The ratio of the melting times of these locations identifies the direction of the flow. The experimental results are compared against model predictions. In addition, an error analysis is carried out to discover the possible sources of error in the detection of metal velocity. The liquid metals used in this research work are commercial purity aluminum and AZ91 magnesium alloy.     

Measurement of magnitude and direction of velocity in high-temperature liquid metals. Part I: Mathematical modeling

This article describes the development of a mathematical model that predicts the time required for a metal sphere to melt in a metal bath under different fluid flow conditions. The sphere is made from the same metal as the bath. The model solves numerically the pertinent momentum and energy equations in three dimensions, employing the SIMPLER algorithm. For the case of a pure metal, the model uses the heat integration algorithm to account for the latent heat of fusion. For the situation of a metal alloy with long freezing range, it incorporates the enthalpy method to account for the latent heat of fusion. The model is validated extensively: first, by using Paterson’s analytical solution; second, by using the experimental results of Gallium melting in a rectangular enclosure; and third, by using experimental results involving ice spheres melting in water. The practical use of this model is to study the influence of various parameters in the sphere melting system. This study facilitates the detection of liquid metal velocity using the sphere melting technique.     

Expectancy?×?value effects: Regulatory focus as determinant of magnitude and direction.

The authors propose that a promotion focus involves construal of achievement goals as aspirations whose attainment brings accomplishment. Commitment to these accomplishment goals is characterized by attempts to attain the highest expected utility. In contrast, a prevention focus involves construal of achievement goals as responsibilities whose attainment brings security. Commitment to these security goals is characterized by doing what is necessary. The different nature of commitment to accomplishment goals versus security goals is predicted to influence the interactive effect of goal expectancy and goal value on goal commitment, as evident in both task performance and decision making. Four studies found that the classic positive interactive effect of expectancy and value on goal commitment increases with a promotion focus and decreases with a prevention focus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The formation of cognitive maps of adjacent environments: Evidence from the head direction cell system.

In 2 experiments the authors tested whether the head direction (HD) cell system underlies a sense of direction maintained across environments. In Experiment 1, HD neurons failed to maintain their firing directions across T mazes in adjacent environments but rather reoriented to the T maze within each environment. Such reorientation suggests that familiar landmarks override an internal directional sense, so in Experiment 2 the authors recorded HD neurons as rats walked between novel and familiar "rooms" of a 4-chamber apparatus. In novel rooms, HD neurons maintained the firing direction of the preceding environment. However, in familiar rooms, HD neuron firing directions shifted to agree with the landmarks therein. With repeated experience, a homogeneous representation of all rooms developed in a subset of the rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cardiac outcome in patients with subarachnoid hemorrhage and electrocardiographic abnormalities

OBJECTIVE: Approximately 25% of patients with subarachnoid hemorrhage (SAH) have electrocardiographic (ECG) abnormalities consistent with myocardial ischemia or myocardial infarction (MI), and their cardiac prognosis remains unclear. The objective of this study was to determine the cardiac and all-cause mortality rate of a series of patients with SAH with ECG changes consistent with ischemia or MI. METHODS: Using an existing database of patients with SAH and predetermined ECG criteria for ischemia or MI, a study group of patients with abnormal ECG results within 3 days of presentation and before aneurysm surgery was identified. Database patients without abnormal ECG results served as a control group. Cardiac mortality, defined as death resulting from arrhythmia, congestive heart failure, or cardiogenic shock, was assessed by chart review. RESULTS: Of 439 patients with SAH in the database, 58 met the criteria for the study group. Forty-one of these patients were treated neurosurgically. No deaths resulting from cardiac causes occurred, and 20 patients died as a result of noncardiac causes. In a multivariable analysis, age older than 65 years and Hunt and Hess grade of at least 3 were predictive of all-cause mortality. ECG abnormalities, however, were not a statistically significant predictor. CONCLUSION: In patients with SAH and ECG readings consistent with ischemia or MI, the risk of death resulting from cardiac causes is low, with or without aneurysm surgery. The ECG abnormalities are associated with more severe neurological injury but are not independently predictive of all-cause mortality.     

Prevalence and magnitude of osteopenia associated with insulin-dependent diabetes mellitus

Effects of bilateral chemical inactivation of the nucleus tractus solitarius (NTS) by microinjection of kainic acid (KA) on fluid and NaCl absorption across the jejunum were examined in anesthetized Sprague-Dawley rats. Jejunal fluid and NaCl absorption was measured in a jejunal loop before and after the microinjection of artificial cerebrospinal fluid (aCSF) or KA into the NTS. Net fluid and NaCl absorption was not altered by a microinjection of aCSF. However, net fluid (from 1.12 +/- 0.07 to 1.66 +/- 0.06 ml/30 min) and NaCl (Na+ from 164.5 +/- 10.1 to 243.3 +/- 7.1 muEq/30 min; and Cl- from 175.9 +/- 7.5 to 260.8 +/- 6.5 muEq/30 min) absorption was significantly increased by the chemical inactivation of the NTS. To examine the efferent mechanism of the increased net absorption induced by the NTS inactivation, mesenteric nerve activity (MNA) was measured before and after the inactivation of the NTS. MNA was significantly increased by 165.9 +/- 74.2% after the bilateral inactivation of the NTS. Furthermore, absorption experiments were conducted in rats with pretreatment of atropine (acetylcholine-antagonist) or yohimbine (specific alpha 2-antagonist). In atropine treated rats, net jejunal absorption was significantly increased by the inactivation of the NTS. However, the increase in net absorption induced by the inactivation of the NTS was completely abolished by pretreatment with yohimbine. These results suggest that the NTS has a tonic suppression on jejunal absorption through alpha 2-adrenergic mechanism.     

Factors affecting epirubicin pharmacokinetics and toxicity: evidence against using body-surface area for dose calculation

PURPOSE: An exploratory study to test whether body-surface area (BSA) should be used for the calculation of epirubicin dose. PATIENTS AND METHODS: The relationship between pretreatment characteristics and the effects of epirubicin were investigated in 20 chemotherapy-naive patients. Measurements of body size, renal and hepatic function, and other factors were correlated with epirubicin pharmacokinetics (PK) and epirubicin-induced neutropenia. All patients received 150 mg of epirubicin infused continuously over 120 hours, regardless of body size. Factors were analyzed by univariate and multivariate linear regression. RESULTS: There were no correlations between BSA or weight with any PK parameter or with the degree of neutropenia. In multivariate analysis, indicators of liver function were the only factors that correlated with neutropenia and epirubicin PK. Thus, correlations for neutropenia were seen with antipyrine clearance (P = .003), activated partial thromboplastin time (APTT) (P = .005) and serum transferrin (P = .01). Further, the area under the concentration-time curve (AUC) for epirubicin correlated with prothrombin index (P < .01), antipyrine clearance (P < .01), and serum bile salt concentration (P = .03), and there were similar correlations for epirubicin steady-state concentration (CpSS). Epirubicin clearance correlated with antipyrine clearance (P = .02). PK parameters for dihydroepirubicin correlated with prothombin index, serum transferrin, and bile salt concentrations (P < .001 for all correlations). Because of the number of statistical examinations performed, some of these correlations may be spurious. However, some are likely to be real, since the same variables repeatedly correlated with different epirubicin-associated outcomes. There were no correlations between epirubicin PK indices or neutropenia and serum aminotransferase levels or other biochemical liver function tests, creatinine, or any of the clinical factors examined. CONCLUSION: These results led us to question the use of BSA for epirubicin dose calculation. In contrast, quantitative liver function tests may give a better indication of drug handling and toxicity and may be useful to determine more accurate methods for dose calculation of epirubicin.     

Value of T-wave direction with lead III ST-segment depression in acute anterior wall myocardial infarction: electrocardiographic prediction of a "wrapped" left anterior descending artery

BACKGROUND: Lead III ST-segment depression during acute anterior wall myocardial infarction (AMI) has been attributed to reciprocal changes. However, the value of the T-wave direction (positive or negative) in predicting the site of obstruction and type of the left anterior descending (LAD) artery is not clear and has not been studied before. HYPOTHESIS: The aim of the study was to assess retrospectively the correlation between two patterns of lead III ST-segment depression, and type of LAD artery and its level of obstruction during first AMI. METHODS: The study group consisted of 48 consecutive patients, admitted to the coronary care unit for first AMI, who showed ST-segment elevation in lead a VL and ST-segment depression in lead III on admission 12-lead electrocardiogram. The patients were divided by T-wave direction into Group 1 (n = 31), negative T wave, and Group 2 (n = 17), positive T wave. The coronary angiogram was evaluated for type of LAD ("wrapped", i.e., surrounding the apex or not), site of obstruction (pre- or postdiagonal branch), and other significant coronary artery obstructions. RESULTS: Mean lead III ST-segment depression was 1.99 +/- 1.32 mm in Group 1 and 1.13 +/- 0.74 mm in Group 2 (p = 0.004); mean ST-segment elevation in a VL was 1.35 +/- 0.84 mm and 1.23 +/- 0.5 mm, respectively (p = 0.5). A wrapped LAD was found in 12 patients (38.7%) in Group 1 and in 13 in Group 2 (76.4%) (p = 0.02). The sensitivity of lead III ST-segment depression with positive T wave to predict a wrapped LAD was 52%, and the specificity was 82% with a positive predictive value of 76%. On angiography, 25 patients (80%) in Group 1 and 13 (76%) in Group 2 had prediagonal occlusion of the LAD (p = 0.77). No significant difference between groups was found for right and circumflex coronary artery involvement or incidence of multivessel disease. CONCLUSIONS: The presence of lead III ST-segment depression with positive T wave associated with ST-segment elevation in a VL in the early course of AMI can serve as an early electrocardiographic marker of prediagonal occlusion of a "wrapped" LAD.     

Apical hypertrophy with massive myocardial fibrosis: comparison with electrocardiographic changes

RESEARCH QUESTION: Although gait patterns of children are well described in gait analysis studies for barefoot gait, loading patterns in gait with shoes have not been analysed compared to barefoot gait. METHODS: 30 children (age 1.8 to 4.8 years) were examined. Ground reaction forces were recorded using two series connected Kistler plates, taking the 3D coordinates and the time coordinate. The gait aspect was recorded using a video system. Three shoe types were tested against each other and against barefoot gait. RESULTS: 1399 gait cycles, 739 barefoot, 660 with shoes were usable for calculation. Statistic analyses comparing barefoot gait to gait with shoes showed: A significant increase in ground contact duration, a shifting of maximal load from the rear towards the midfoot area, a significant increased maximal load, a cushioning of the initial impact at primary ground contact. A comparison between the shoes showed no significant influence of a medial subtalar orthotic support. CONCLUSION: Shoes cause a significant change of loading patterns. But there are also significant differences between different shoe types. CLINICAL RELEVANCE: Shoes for children must provide a stabilisation for the hindfoot, and must not restrict motion in the areas of the ankle and the metatatrsophalangeal joints. The amount of load in the different gait phases must be considered for the construction of a dynamic shoe for children.     

Incidence and magnitude of hypoxaemia with ketamine in a rural African hospital

The excretion of sevoflurane metabolites in the urine collected every 12 h after sevoflurane anaesthesia was measured by ion exchange chromatography. A metabolite, which was converted on incubation with glucuronidase to hexafluoroisopropanol was detected in the urine. The maximum excretion was found in the first 12 h after anaesthesia, none was found in the last collection 3 days after anaesthesia. The excretion half-life for the metabolite was calculated to be 55 h. A significant increase in the urinary excretion of organic and inorganic fluoride was also observed during the first 12 h after anaesthesia. The cumulative organic and inorganic fluoride excretion in the 3 days after sevoflurane anaesthesia was 1588 and 856 mumol, respectively (ratio = 1.85). The excreted half-lives for organic and inorganic fluoride were calculated to be 4028 and 2069 min, respectively. Our study showed that a hexafluoroisopropanol glucuronide is excreted in the urine, and the major part of urinary metabolites of sevoflurane, organic and inorganic fluoride, are excreted within 2 days of sevoflurane inhalation in man.     

Prognostic value of electrocardiographic monitoring of patients with severe diphtheria

The clinical, the 12-lead, and the 24-hour electrocardiographic findings in 15 consecutively studied Vietnamese children (aged 7 months to 16 years) with severe diphtheria were documented. Five patients died, three from respiratory arrest and two from cardiogenic shock; one of these two patients had complete heart block that necessitated insertion of a pacemaker. Electrocardiographic abnormalities were detected by 24-hour monitoring in all 15 cases, even though most patients had no clinical signs of myocarditis. Rates of supraventricular and ventricular ectopy were elevated and remained high long after other clinical manifestations were no longer noted. The degree of ventricular ectopy at the time of presentation was significantly associated with fatal outcome. In this series, more than two ventricular ectopic beats on a recording upon admission to the hospital predicted fatal outcome with 100% sensitivity and 100% specificity. A variety of nonsustained bradyarrhythmias and tachyarrhythmias were also observed up until discharge from the hospital. The time course of recovery from diphtheritic myocarditis is longer than has been appreciated previously.     

Simplified Finite-Element Model for Tissue Regeneration with Angiogenesis

A simplified finite-element model for tissue regeneration is proposed. The model takes into account the sequential steps of angiogenesis (neo-vascularization) and wound closure (the actual healing of a wound). An innovation in the present study is the combination of both partially overlapping processes, yielding novel insights into the process of wound healing, such as geometry related influences, and could be used to investigate the influence of local injection of hormones that stimulate partial processes occurring during wound healing. These insights can be used to improve wound healing treatments. The models consist of nonlinearly coupled diffusion-reaction equations, in which transport of oxygen, growth factors, and epidermal cells and mitosis are taken into account.     

Correlation coefficients for electrocardiographic and constitutional variables

The influence of noncardiac factors such as constitutional variables, sex, and age upon the orthogonal electrocardiogram (ECG) and vectorcardiogram was investigated in 300 normal Japanese subjects. Constitutional variables included body height (HT), body weight (WT), deviation from ideal body weight (DIW), chest transverse diameter (TD), chest sagittal diameter (SD), SD/TD ratio, and chest circumference (CC). Among these constitutional variables, HT was found to be the most important determinant of ECG, followed by WT, TD, CC, SD, SD/TD ratio, and DIW, in that order. An increase in HT resulted in the augmentation of magnitudes of a large number of the QRS and ST-T parameters. WT showed almost the same trends as HT. Of the four measurements of the chest configuration under study, TD proved to be the most powerful determinant. An increase in TD led to a significant increase in QRS duration and to a superior and anterior shift of the maximal T vector. The remaining constitutional variables revealed far less significant correlation with ECG measurements than did HT and WT. Besides the constitutional variables, sex and age were also proved to be important ECG determinants. Advancing age had the effect of reducing the magnitude of many of the QRS and ST-T measurements. It is also of interest that a majority of the QRS and ST-T parameters were larger in male than in female patients. It should be emphasized from the results of this study that normal ECG criteria must be established for each ECG determinant.     

Velocity encoding using both phase and magnitude

Imaging time constitutes a major limitation of phase-contrast (PC) angiography. It is possibly the main disadvantage of PC methods over the time-of-flight (TOF) methods that actually are used clinically. This relatively long imaging time comes from the fact that conventional PC methods require the acquisition of at least four images with different velocity sensitization to reconstruct a single angiogram (1, 2). However, more than one-half of the information gathered through the acquisition of these four images is either redundant or simply discarded. We propose a faster approach to making PC angiograms in which the quantity of data acquired is diminished by as much as a factor 2. This is made possible by encoding velocity information in both the phase and magnitude of the image. Due to the use of extra radiofrequency (RF) and gradient waveforms, decreases in data requirements do not translate in a direct manner into decreases in imaging time. Nevertheless, significant reductions in imaging time are achieved with the present approach.     

Value, magnitude, and accentuation.

Studies relating estimation of size and value appeared to find that the greater the need the greater the overestimation of size of the object. However, the present authors observed that the stimuli used in these experiments (e.g., money and candy) tend to increase in size with increased value. A cross-validation of the findings was made by selecting objects (cars and typewriters) wherein the physical attributes could be made to covary negatively with value. Ss (college students) tended to underestimate the more valued object (e.g., Volkswagen vs. Chevrolet) suggesting that judgments from memory tend to accentuate the relationship between size estimation and value; and that the findings of previous research emphasizing overestimation of size with increased value were a function of the stimuli used. From Psyc Abstracts 36:01:3HJ45S. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

激光垂准仪竖井定向的测量实践

介绍了通过高精度激光垂准仪投点,利用瞄直法进行矿山竖井定向测量实践。表述了瞄直法在矿山竖井定向的测量过程及实际操作过程中应该注意的事项。应用实践表明,激光垂准仪竖井定向是一种快捷、高效,并能完全满足矿山生产精度要求的测量方法。