Correlation of effects of general anesthetics on somatosensory neurons in the primate thalamus and cortical EEG power

The effects of two types of general anesthetic on the neurophysiological properties of the primate somatosensory thalamus were correlated with effects on frontal cortex electroencephalographic (EEG) power and spectral properties. Graded doses of the intravenous agent methohexital sodium (METH) were studied in 12 cells in three monkeys on a halothane baseline anesthetic. Low doses of METH (0.2-1.0 mg/kg) produced a reduction of EEG power but had no effects on spontaneous or evoked thalamic activity. EEG power showed maximal attenuation after 2.0 mg/kg METH, whereas decreases in thalamic activity were first noted over a similar moderate dose range (2.0-5.0 mg/kg). The physiological parameter most sensitive to METH was the spontaneous activity, which showed initial changes in rate and moderate doses followed by marked inhibition at higher doses. Finally, the high dose of METH (10.0 mg/kg) produced marked reduction in all neurophysiological parameters with recovery over the following 30-45 min. The effects of the volatile anesthetic halothane were studied on 15 cells in four monkeys anesthetized with pentobarbital sodium. The low dose of halothane (0.25%) produced a facilitation of responses to cutaneous stimuli as well as decrease in the rate and burst patterns in the spontaneous activity. The power in the EEG was not affected at this concentration. The responses of the cells to the mechanical stimuli at moderate doses (0.5-1.0%) of halothane returned to the baseline magnitude, whereas spontaneous activity remained unaffected compared with initial effects. EEG power was reduced by 1% halothane. Finally, all neurophysiological parameters showed profound reduction at the highest halothane concentrations (2.0-3.0%) with recovery over the next 30-45 min. In conclusion, the two classes of anesthetics most commonly used for acute neurophysiological studies in the primate show well-defined thresholds at which changes in the response properties of thalamic neurons are produced. This threshold for the barbiturates and halothane can be predicted by monitoring of cortical EEG.     

The use of neuronal networks on multielectrode arrays as biosensors

Mammalian spinal neuronal networks growing on arrays of photoetched electrodes in culture provide a highly stable system for the long-term monitoring of multichannel, spontaneous or evoked electrophysiological activity. In the absence of the homeostatic control mechanisms of the central nervous system, these networks show remarkable sensitivities to minute chemical changes and mimic some of the properties of sensory tissue. These sensitivities could be enhanced by receptor up-regulation and altered by the expression of unique receptors. The fault-tolerant spontaneous network activity is used as a dynamic platform on which large changes in activity signify detection of chemical substances. We present strategies for the expression of novel supersensitivities to foreign molecules via genetic engineering that involves the grafting of ligand binding cDNA onto truncated native receptor DNA and the subsequent expression of such chimeric receptors.     

Control of jaundice in preterm newborns by an inhibitor of bilirubin production: studies with tin-mesoporphyrin

The development of mathematical models for determining antagonism, synergy or additivism for drug combinations is becoming increasingly important in medical research and medicine. This paper describes improvements in the Chou and Talalay method which provides for the first time confidence intervals for the combination index. The Monte Carlo technique was used to calculate the confidence intervals and to obtain the new parameters which are needed for the modified interaction diagnosis. This new method can be adapted to current as well as future formulae used to evaluate drug combinations. Programs written in Microsoft and Visual Basic were developed for use on commonly available personal computers which we call Combostat.     

Computerized hospitals: an attraction or deterrent to recruitment in nursing?

This article describes a survey of 202 nursing recruits at an 850 bed hospital newly computerized with an Integrated Hospital Information System (IHIS). The nurses answered questions concerning their demographic characteristics, their experience with computers, their attitudes to computers and whether the fact that the hospital was computerized affected their decision to apply for employment. Results of this study suggest that the nurses' decision to apply to this setting for employment did not depend upon the factor of computerization. The majority of recruits held positive attitudes towards computers and it appeared that nurse recruits might be part of an ever increasing computer-literate population. Those having less experience with computers indicated greater anxiety. Implications for recruitment strategies and education are that while no major deterrents may exist for recruitment, new nurses with no computer experience require special attention because they may have higher levels of anxiety about computers. In orientation they may need clarification of what computers can be expected to do in a nursing environment so that they do not form unrealistic expectations. They may need to be informed as to whether a hospital is using a more general Hospital Information System which serves the needs of all departments, or a Nursing Information System which is more closely directed to the nurses' own daily work, since it is the latter which will most affect their degree of contact with computers.     

The use of drugs in migraine

Drugs may be given either for treatment of the acute attack or as prophylaxis. Those most commonly used for the acute attack are analgesics, anti-emetics and ergotamine tartrate. A recent work (Volans, 1974) has shown that absorption may be impaired during a migraine attack. It is important therefore that not only is the analgesic given in an easily absorbed form but that a drug such as metaclopromide should be given to help restore the normal activity of the gastro-intestinal tract. Patients having one or more attacks of migraine a week may need prophylactic treatment. The drugs now used include: Methysergide, should only be used for severe cases when no other treatment has been found helpful. Dihydroergotamine, the vasoconstrictor activity is less than in ergotamine tartrate and can therefore be used prophylactically. Pizotifen, possesses powerful anti-serotonin properties. It also has marked antihistamine and antitryptamine properties as well as being a central sedative and anti-depressant. Clonidine, in doses of 1 mugm/Kg renders the blood vessels less sensitive to circulating amines and seems to be effective in about one third of patients with classical or common migraine. Sympathetic Blocking Agents: alpha-blockers: indoramine has recently given some good results; beta-blockers: such as propanolol and pindolol have also been used. Full trials of all the substances are now in progress. Tranquilisers and anti-depressants, two of those commonly used are diazepam and amitryptiline. In either cases a small dose only should be used. Anticonvulsants, phenytoin in doses of 50-100 mgs per day is sometimes helpful particularly in children or in those who have abnormal electroencephalograms.     

Finite‐Element Calculations on Alliant FX/80

The finite‐element method has proven to be an invaluable tool for analysis and design of complex, high‐performance systems, such as those typically encountered in the aerospace or automotive industries. However, as the size of the finite‐element models of such systems increases, analysis computation time using conventional computers can become prohibitively high. Parallel processing computers provide the means to overcome these computation‐time limits, provided the algorithms used in the analysis can take advantage of multiple processors. The writers have examined several algorithms for linear and nonlinear static analysis, as well as dynamic finite‐element analysis. The performance of these algorithms on an Alliant FX/80 parallel supercomputer has been investigated. For single load‐case linear static analysis, the optimal solution algorithm is strongly problem dependent. For multiple load cases or nonlinear static analysis through a modified Newton‐Raphson method, decomposition algorithms are shown to have a decided advantage over element‐by‐element preconditioned conjugate gradient algorithms. For eigenvalue/eigenvector analysis, the subspace iteration algorithm with a parallel decomposition is shown to achieve a relatively high parallel efficiency.     

Episodic gonadotropin-releasing hormone gene expression revealed by dynamic monitoring of luciferase reporter activity in single, living neurons

The existence of an intrinsic oscillator for pulsatile gonadotropin-releasing hormone (GnRH) secretion in normal and transformed GnRH neurons raises the question of whether the corresponding gene also is expressed in an episodic manner. To resolve this question, we used a modification of conventional luciferase technology, which enabled continuous monitoring of GnRH gene activity in single, living neurons. With this method, the relative rate of endogenous gene expression is estimated by quantification of photons emitted by individual neurons microinjected with a GnRH promoter-driven luciferase reporter construct. Immortalized GT1-1 neurons, which secrete the decapeptide GnRH in a pulsatile manner conceptually identical to that of their nontransformed counterparts in vivo, were chosen as the model for these studies. First, we injected individual cells with purified luciferase protein and established that the reporter half-life was sufficiently short (50 min) to enable detection of transient changes in gene expression. Next, we subjected transfected GT1-1 cells to continuous monitoring of reporter activity for 16 h and found that the majority of them exhibited spontaneous fluctuations of photonic activity over time. Finally, we established that photonic activity accurately reflected endogenous GnRH gene expression by treating transfected GT1-1 cells with phorbol 12-myristate 13 acetate (a consensus inhibitor of GnRH gene expression) and observing a dramatic suppression of photonic emissions from continuously monitored cells. Taken together, these results demonstrate the validity of our "real-time" strategy for dynamically monitoring GnRH gene activity in living neurons. Moreover, our findings indicate that GnRH gene expression as well as neuropeptide release can occur in an intermittent manner.     

Methods for the determination of pH value and redox potential in the rumen fluid of adult cattle

pH sticks and pH meters were tested to determine ruminal pH and mV meters in order to measure the redox potential in rumen contents. Rumen pH can be determined by reading pH sticks left in rumen liquor or immediately after removal. Differences between pH sticks and a reference method accounted for 0.01-0.48 pH units, depending on the pH stick used and the pH range of the ruminal contents (pH < 6, 6-7, > 7). Ruminal pH is accurately measured by the pH meters pHep and GPHR (y = -0.22 + 1.03x, or y = 0.15 + 0.97 x). By using a mV meter the redox potential in rumen liquor can be determined 10 min after start of measurement. Results determined with the mV meter GPHR showed a mean difference of 10-23 mV, those determined with ORP a mean difference of 131-202 mV in comparison with a reference method. There is no linear correlation between the data of the mV measurements and the data of the methylene blue reduction test in ruminal contents (y = -328.5 - 0.003 x; p = 0.652). Therefore these data may not be in used in the same manner for rumen liquor diagnosis.     

The aquatic vertebrate embryo as a sentinel for toxins: zebrafish embryo dechorionation and perivitelline space microinjection

The spontaneous onset of autoantibodies against circulating factors, including factors II, V, VII, VIII, IX, XI, XII, and XIII, is a phenomenon of unclear causes. It may occur in patients with no underlying disease process or may be antedated by autoimmune diseases and malignancies. The antibodies are almost always IgG and are most commonly directed at F VIII. They generally present with a bleeding diathesis in patients with no history of prior bleeding events. The laboratory abnormalities vary depending on whether the inhibitor involves the intrinsic or extrinsic pathway of coagulation, and the laboratory studies may vary depending on the technique used. Supportive measures are used initially but are generally not completely effective. Supportive measures are followed by blood products, such as recombinant human F VIII, porcine F VIII, or PCC/aPCC. There are limitations to each of these, however. If bleeding is severe and high titers of inhibitors are present, plasma-pheresis may lead to a temporary decrease in the titer but is short-lived. Immunosuppressive therapy should ultimately be attempted to suppress further antibody production. Spontaneous remission may occur with some of the inhibitors, primarily postpartum or drug related, for reasons not fully understood.     

Numerical Evaluation of Uniform Beam Modes

The equation for calculating the normal modes of a uniform beam under transverse free vibration involves the hyperbolic sine and cosine functions. These functions are exponential growing without bound. Tables for the natural frequencies and the corresponding normal modes are available for the numerical evaluation up to the 16th mode. For modes higher than the 16th, the accuracy of the numerical evaluation will be lost due to the round-off errors in the floating-point math imposed by the digital computers. Also, it is found that the functions of beam modes commonly presented in the structural dynamics books are not suitable for numerical evaluation. In this paper, these functions are rearranged and expressed in a different form. With these new equations, one can calculate the normal modes accurately up to at least the 100th mode. Mike’s Arbitrary Precision Math, an arbitrary precision math library, is used in the paper to verify the accuracy.     

Monitoring intraoperative awareness. Vegetative signs, isolated forearm technique, electroencephalogram, and acute evoked potentials

Several methods have been developed to quantify central anaesthetic effects and monitor awareness during general anaesthesia. The most important of these are the PRST score, calculated from changes in blood pressure, heart rate, sweating, and tear production, the isolated forearm technique, where the patient is allowed to move during surgery, the processed electroencephalogram (EEG) and the derived parameters median frequency (MF) and spectral-edge frequency (SEF), and mid-latency auditory evoked potentials (MLAEP). In clinical practice, the application of individual doses of anaesthetics is generally guided by autonomic vegetative clinical signs such as changes in blood pressure, heart rate, sweating, and tear production, quantified as the PRST score. Unfortunately, these parameters are not very reliable with regard to predicting the suppression of consciousness and awareness, especially when high-dose opioids are used in patients with cardiovascular medications and a variety of accompanying diseases. The PRST score probably indicates mainly the autonomic responses to painful stimuli, and seems to be useful in guiding the individual use of analgesics. The isolated forearm technique is a useful test of the patient's responsiveness during general anaesthesia, and thus an instrument for investigating the incidence of awareness during different anaesthetic regimens and when muscle relaxants are employed. A disadvantage is that it can only be used for 20 to 30 min because of pressure-induced nerve blocks or lesions. It can not be employed when long-term relaxation is necessary and consciousness and awareness are to be monitored continuously. The processed EEG and the derived parameters MF and SEF are important scientific tools to quantify central effects of many anaesthetics and opioid analgesics that allow the development of pharmacodynamic-pharmacokinetic models of anaesthetic action. MF has proven to be useful in monitoring closed-loop feedback of intravenous drug administration. Unfortunately, until now there have been no clinical studies that document the usefulness of MF or SEF with regard to predicting intraoperative arousal or awareness. To the contrary, some experimental data failed to predict imminent arousal and response to surgical incision or verbal commands by MF or SEF. Therefore, the EEG seems to be of limited value for monitoring awareness, consciousness, or memory formation during anaesthesia. MLAEP are suppressed in a dose-dependent fashion by many general anaesthetics and correlate with wakefulness, awareness, and explicit and implicit memory during anaesthesia and seem to be a promising method of monitoring awareness during anaesthesia. Nevertheless, future studies will have to determine threshold values for the different MLAEP parameters for intraoperative awareness and explicit and implicit recall of intraoperatively presented information for the different commonly used anaesthetics. Only then will it be possible to determine the usefulness of the method in clinical practice.     

When should induction protocols be used in the diagnostic evaluation of patients with paroxysmal events?

PURPOSE: To determine the timing of spontaneous psychogenic nonepileptic events (PNEE) during video-EEG telemetry (VEEG), and the need to use induction protocols (IP). METHODS: We studied 100 consecutive patients (75 females, 25 males) admitted to our inpatient VEEG unit from July 1994 to June 1996 for differential diagnosis of paroxysmal events. We recorded the time to the first diagnostic spontaneous event, identified by the patient or a family member as typical. Episodes were classified as PNEE, physiologic nonepileptic events (PhysNEE), and epileptic seizures (ES). RESULTS: The mean duration of VEEG was 74+/-SD 54.1 h. In 82 patients, a diagnostic event occurred spontaneously. The first event was an ES in 22 patients, a PNEE in 53, and a PhysNEE in 7. The time to first diagnostic event was significantly shorter for PNEE than for ES [15.0+/-SD 16.3 h (range 5 min to 58 h) vs. 28.6+/-SD 34.0 h (range 1-110 h) F=15.621, p < 0.0001]. In the first 24 h, 77.4% of the patients with PNEE had an event. By 48 h, all but 2 (96.2%) had had diagnostic events. After the first 58 h of monitoring, all patients with PNEE experienced a spontaneous diagnostic event. CONCLUSION: Spontaneous events can be expected to occur within 48 h in most patients with PNEE. Therefore, if IP are to be used as a diagnostic tool, we suggest that they be withheld during the initial 48 h of VEEG monitoring.     

自动加水系统在莱钢烧结厂的应用

莱钢型钢烧结厂混料采用自动加水系统,系统包括计算机、水分仪、皮带秤、流量计等设备,软件采用了Vijeo Citect画面编辑软件和Unity Pro编程软件,数据库采用SQL Serve2000。该自动加水系统应用后,混合料水分稳定率高达95%以上,操作人员从原先的4人减少到1人,加水误差从原来的25%降低到0.1%,烧结生产过程得到稳定和强化。     

An on-line computer graphics terminal for radiotherapy treatment planning

A programmed graphics terminal has been connected on-line to a large time-shared computer for calculating dose distributions in radiotherapy treatment planning and provides a viable alternative to dedicated systems and batch working. The terminal equipment is based on a mini-computer and includes a function-key devise for outline input, a large-screen refresh oscilloscope for viewing results and an X-Y plotter for hard-copy. Radiotherapy dose computation programs in standard Fortran are stored and run on a large remote computer with graphical interaction at the terminal. External beam programs can calculate dose distributions for most commonly used treatment situations and can compute in off-axis planes. Data input is fully interactive and easy to understnad. Dose distributions are displayed as isodose contours. Advantages of the system include accuracy, speed, ease of use and maintenance, and transferability of the programs between different host computers.     

Magnetic source imaging of abnormal low-frequency magnetic activity in presurgical evaluations of epilepsy

PURPOSE: Regional cortical dysfunction associated with epileptogenic activity was predicted from interictal localized abnormal low frequency neuromagnetic activity (ALFMA) using Magnetic Source Imaging (MSI). ALFMA can be detected in patients who show no interictal spikes. METHODS: A large array biomagnetometer was used in a blinded, rapid screening protocol. The MSI procedure required no alteration in epileptic medications. MSI results were compared with the presumed epileptogenic region as determined by a consensus of standard techniques, which included MR and electroclinical monitoring. RESULTS: One or more sites of localized abnormality were detected by MSI ALFMA in 29 of the 33 epileptic patients. ALFMA mapped with MSI showed a 48.5% specificity with respect to the presumed epileptogenic region. MSI ALFMA was in agreement with the final consensus as often as was ictal noninvasive video EEG monitoring, and was exceeded in specificity overall only by invasive ictal video EEG monitoring, which was required for conventional localization in 21 of the 33 patients tested with MSI. CONCLUSIONS: ALFMA measurements with MSI may augment the array of noninvasive methods used for reaching a consensus for epilepsy surgery.     

Midlatency auditory evoked potentials as indicators of perceptual processing during general anaesthesia

We tested the hypothesis that midlatency auditory evoked potentials (MLAEP) can predict the occurrence of long latency AEP components (LLAEP), which are taken as evidence for perceptual processing. Forty-one patients undergoing cardiac surgery were anaesthetized with propofol and alfentanil. During several periods of surgery we recorded LLAEP. Peak-to-peak amplitude measures were used to determine if a particular LLAEP recording trace contained a recognizable waveform. Both before and after each LLAEP recording epoch, MLAEP and the spontaneous electroencephalogram (EEG) were recorded. Peak latencies and amplitudes of brainstem peak V and midlatency peaks Na, Pa, Nb, Pb and Nc, characteristic frequencies from the spontaneous EEG, mean arterial pressure (MAP) and nasopharyngeal temperature (7) were compared between recording epochs with and without clear LLAEP waveforms. These variables were also used in a discriminant analysis to predict the occurrence of an LLAEP waveform. Pa and Nb latencies were significantly shorter both before and after recording epochs in which an LLAEP waveform occurred, compared with epochs in which no LLAEP waveform occurred. Using a combination of up to six EEG, MLAEP, MAP and T measures, it was possible to predict the occurrence or absence of an LLAEP waveform with a sensitivity of 89% and specificity of 86%. We conclude that MLAEP components provide information on the possibility of perceptual processing during general anaesthesia, and thus may be relevant for monitoring depth of anaesthesia.     

How peer education changed peer sexuality educators'' self-esteem, personal development, and sexual behavior

Series of well-documented case reports strongly suggest a causal association between tiaprofenic acid and a form of aseptic cystitis, which can cause serious and long-term morbidity if the drug is not withdrawn promptly. These findings are supported in the Australian and UK spontaneous reporting data-bases. Using sales data as the denominator, a comparison of NSAIDs in the WHO drug monitoring data-base indicates that the reaction is specific to tiaprofenic acid and cannot be accounted for by changes in reporting patterns in certain countries or years. Delayed recognition is an important feature of this reaction and possible reasons for this are discussed. Comparison of the risk profiles of seven NSAIDs indicated that tiaprofenic acid had the poorest risk profile, compared with NSAIDs of similar efficacy, when cystitis reports were included. The results suggest that combining spontaneous reports, classified according to severity, with sales data may enhance the ability of drug monitoring data-bases to contribute to risk benefit appraisals.     

Neurons of the rat suprachiasmatic nucleus show a circadian rhythm in membrane properties that is lost during prolonged whole-cell recording

The suprachiasmatic nucleus is commonly considered to contain the main pacemaker of behavioral and hormonal circadian rhythms. Using whole-cell patch-clamp recordings, the membrane properties of suprachiasmatic nucleus neurons were investigated in order to get more insight in membrane physiological mechanisms underlying the circadian rhythm in firing activity. Circadian rhythmicity could not be detected either in spontaneous firing rate or in other membrane properties when whole-cell measurements were made following an initial phase shortly after membrane rupture. However, this apparent lack of rhythmicity was not due to an unhealthy slice preparation or to seal formation, as a clear day/night difference in firing rate was found in cell-attached recordings. Furthermore, in a subsequent series of whole-cell recordings, membrane properties were assessed directly after membrane rupture, and in this series we did find a significant day/night difference in spontaneous firing rate, input resistance and frequency adaptation. As concerns the participation of different subpopulations of suprachiasmatic nucleus neurons expressing circadian rhythmicity, cluster I neurons exhibited strong rhythmicity, whereas no day/night differences were found in cluster II neurons. Vasopressin-containing cells form a subpopulation of cluster I neurons and showed a more pronounced circadian rhythmicity than the total population of cluster I neurons. In addition to their strong rhythm in spontaneous firing rate they also displayed a day/night difference in membrane potential.     

Measuring Irrigation Well Discharges

Irrigation wells frequently discharge directly into canals. Upstream elbows, the pump head, or other pipe fittings may produce a distorted flow profile that is detrimental to the proper installation and operation of commonly available pipe meters. Before attempts to condition the flow with longer discharge piping or straightening vanes, it is desirable to know how distorted the flow profile really is. If this information can be provided, the meter technician can determine whether a correction in the meter coefficient will suffice, or if flow conditioning equipment is needed, or whether flow conditioning equipment, if already installed, is working effectively. An economical method of field evaluating the result of an installed meter in this compromised situation is described. The method uses a conveniently fashioned pitot-tube system that can be clamped to the pump discharge pipe. It is used to quickly detect the velocity at several points across the pipe diameter. Distorted profiles can be detected and measured. Pitot-tube systems have long been used in pipe flows. Most require that special taps be drilled in the outflow pipe of the well. Some use special double-tube constructions that are difficult to build using simple machine-shop procedures. This pitot impact tube, with its static pressure companion tube, can be constructed using common shop techniques and standard small pipe fittings.