Effects of magnesium sulfate and lidocaine in the treatment of ventricular arrhythmias in experimental amitriptyline poisoning in the rat

OBJECTIVES: Amitriptyline poisoning is associated with ventricular arrhythmias. Standard treatment is sodium bicarbonate but further intervention may be necessary. The present study compared the actions of lidocaine and magnesium sulfate on ventricular tachycardia induced by amitriptyline. DESIGN: Nonrandomized, controlled, intervention trial. SETTING: University laboratory. SUBJECTS: Thirty male Wistar rats anesthetized with pentobarbital and mechanically ventilated. INTERVENTIONS: After pretreatment with norepinephrine, the animals were subjected to a continuous infusion of amitriptyline. After the appearance of ventricular tachycardia, they were treated with magnesium sulfate (45 mg/kg + 15 mg/kg/min) or lidocaine (1 mg/kg + 0.5 mg/kg/min) or glucose infusion as a control. MEASUREMENTS AND MAIN RESULTS: In the group treated with magnesium sulfate, electrocardiogram tracings demonstrated that nine of ten animals converted from ventricular tachycardia to sinus rhythm compared with one of ten in both the lidocaine- and glucose-treated groups (p < .001). The animals treated with magnesium sulfate also had a significantly longer total time in sinus rhythm (10.0 +/- 1.6 mins) than those rats treated with lidocaine (1.7 +/- 1.5 mins) or glucose (1.5 +/- 1.5 mins). Magnesium sulfate significantly decreased blood pressure and heart rate, but no severe hemodynamic side effects were observed. CONCLUSIONS: Magnesium sulfate is effective in converting ventricular tachycardia in hyperadrenergic amitriptyline poisoning. In contrast, lidocaine had no effect on arrhythmias.     

Carnot comparison of multi-temperature level absorption heat cycles

Comparison of different absorption heat cycles is not always made on the correct manner. This also includes comparison of an ideal absorption cycle with a mechanical analogy. A new Carnot model operating with two heat engines and two mechanical heat pumps is defined to be the correct and logical way to describe the mechanical analogy for an absorption heat pump and an absorption heat transformer. General equations for the Carnot coefficient of performance, COP_r, are exemplified and simulated for an absorption heat pump and an absorption heat transformer, and an entropy flow fraction diagram is introduced. The important fact that the absorption heat cycles must operate under the same conditions when they are compared is discussed.     

Design and implementation of the Node Identity Internetworking Architecture

The Internet Protocol (IP) has been proven very flexible, being able to accommodate all kinds of link technologies and supporting a broad range of applications. The basic principles of the original Internet architecture include end-to-end addressing, global routeability and a single namespace of IP addresses that unintentionally serves both as locators and host identifiers. The commercial success and widespread use of the Internet have lead to new requirements, which include Internetworking over business boundaries, mobility and multi-homing in an untrusted environment. Our approach to satisfy these new requirements is to introduce a new Internetworking layer, the node identity layer. Such a layer runs on top of the different versions of IP, but could also run directly on top of other kinds of network technologies, such as MPLS and 2G/3G PDP contexts. This approach enables connectivity across different communication technologies, supports mobility, multi-homing, and security from ground up. This paper describes the Node Identity Architecture in detail and discusses the experiences from implementing and running a prototype.     

Steady-state bioavailability and day-to-day variability of a multiple-unit (CR/ZOK) and a single-unit (OROS) delivery system of metoprolol after once-daily dosing

Home blood pressure (BP) monitoring is useful in the clinical management of patients with hypertension and the identification of those with "white-coat" hypertension; i.e. high readings in the clinic but normal BP at home. In the process of evaluating this technique, we compared self-measured home BP with intra-arterial BP. Healthy white men (n = 40) of 20-40 years of age and body weight below 95 kg were recruited by advertising in the local newspaper. Following a standardized procedure, performed within 2-4 weeks of a response to the advertisement, BP was measured by a physician at a clinic screening, by the subject at home (14 readings in 7 days) and finally in the clinic concomitantly intra-arterially and oscillometrically. The correlation coefficient for mean (M) home BP (r = 0.73) and oscillometric BP (r = 0.74) against intra-arterial BP were slightly higher than for screening BP (r = 0.65). However, in plots of the differences for individual MBP between the methods against the average of the methods, it appears that at levels of average MBP above 100 mmHg, screening BP overestimates the BP level, while this was not the case for home BP or oscillometric BP. Thus, by using intra-arterial measurement as standard of comparison, subject self-measured home BP is a reliable method of estimating blood pressure level in young men. Home BP measured shortly after screening and recruitment provides useful information of resting BP in subjects who potentially may have initial anxiety about BP measurement.     

Commitment Nets in Software Process Improvement

Several studies have revealed the fact that nearly two-thirds of all software process improvement (SPI) efforts have failed or have at least fallen short of expectations. Literature and practice have shown that commitment to SPI at all organizational levels is essential for the success of any SPI endeavor. A research model for studying the existence, development and interplay of SPI-related commitment is introduced in this paper. This study suggests that software organizations operate through strategic, operational and personal commitment nets. These nets consist of actors, drivers, concerns, actions, commitment, and outcomes. The commitment nets model is applied in a study of four industrial SPI initiatives. The results from two of these cases are reported here. The results show that SPI is driven through the formation and reformation of commitment nets. The contents of strategic, operational and personal commitment nets are laid out and implications are discussed.     

Molecular forms of serum prostate-specific antigen. The clinical value of percent free prostate-specific antigen

The concept of measuring the proportions of various forms of PSA in serum, particularly the proportion of free to total PSA, represents a new and exciting method of detecting early curable prostate cancers and avoiding unnecessary prostate biopsies in men who have BPH only. Compared with other methods of improving diagnostic specificity, it does not require transrectal ultrasound for determination of prostate volume, as does the use of PSA density, and it does not require multiple blood sampling over a sufficiently long period, as does PSA velocity. Recent findings suggest determination of the proportion of free to total PSA, rather than that of complexed to total PSA, to be the optimal discriminator between patients with prostate cancer and those with BPH in the PSA reflex range of 2.5 or 3 ng/mL to 10 ng/mL, and to improve the clinical accuracy of the PSA test substantially. If the total PSA value is normal, percent free PSA improves the sensitivity (increases cancer detection) of the PSA test; if the total PSA value is slightly elevated, percent free PSA enhances the specificity (eliminates unnecessary negative prostate biopsies) of the PSA test. Both of these outcomes are clinically desirable in attempting to diagnose early, curable prostate cancers in a cost-effective manner among men who also have varying degrees of BPH. Figure 5 contains a diagnostic algorithm for the detection of clinically significant prostate cancers at a curable stage, employing the concept of percent free PSA. As more is learned about percent free PSA, however, it may be necessary to make modifications in how this concept is used clinically.     

Constrained minimization of vibrational magnitudes using a modal reduction method

A numerically effective method is suggested and applied for evaluating objective and constraint functions when so-called vibrational magnitudes of a mechanical structure are minimized. General damped linear structures under external harmonic loading are considered. The magnitude functions studied can relate to displacements, velocities and accelerations and also to sectional and reactive forces. Both magnitudes at a specific frequency and peak magnitudes and averaged magnitudes over a frequency range are investigated. An arbitrary set of magnitude functions can be used in the constraints. Design variables are masses, dampings and stiffnesses of discrete and discretized continuous elements contained in the structure. The objective and constraint functions are expressed by use of the modal parameters (generally complex-valued) of the structural system. A reduced modal model is established and updated during the optimization process. Approximate derivatives (sensitivities) of the objective and constraint functions with respect to changes in design variables are calculated employing perturbed modal parameters. The optimization problem is solved by use of a primal method. Numerical examples demonstrate applications to the classical damped vibration absorber with two design variables and to a beam system used in a light-weight machine foundation with 14 design variables.     

Nocturnal antral pH rises are related to duodenal phase III retroperistalsis

The mechanisms behind nocturnal rises of gastric pH are unknown. We have analyzed the relation between interdigestive duodenal peristalsis and nocturnal pH in the gastric antrum. Simultaneous recording of antroduodenal pressures and intragastric pH was performed in 11 healthy subjects (six men, five women) overnight for 8 hr, using a catheter with seven pressure recording points and an antral glass pH electrode. Three pressure recording sites were closely spaced in the descending duodenum. Altogether 46 phase III activities were recorded. A retroperistaltic sequence in the last part of phase III was observed in 31 phase III activities (67.4%), while 15 phase III activities lacked retroperistalsis. All subjects had retroperistalsis in at least one phase III at night with a median of 60% (52-100%) (interquartile range). The duration of the whole phase III was 5.1 (3.1-7.0) min, whereas the duration of the retroperistaltic period was 2.0 (1.5-3.2) min, corresponding to 45% (23-64%) of the duration of phase III. The peak of antral pH occurred 7.4 (6.0-13.0) min from the start of the phase III in the duodenum and and the rise in pH lasted for 8.0 (4.8-12.0) min. Measurement of pH for a period of 10 min before and after phase III, demonstrated an increase in median pH from 1.2 (1.1-1.9) to 3.2 (1.6-4.7), respectively (P < 0.001). Phase III activities without duodenal retroperistalsis were not followed by a significant antral pH change (median 1.7 vs 1.8 before and after phase III, respectively). Increases of pH unrelated to phase III were uncommon, only 1.0 (1.0-2.2) events per night were observed and lasted for a short period of time, 2.1 (0.5-3.2) min. The results indicate that the cyclic rise in antral pH at night is due to a physiological duodenogastric reflux, caused by duodenal retroperistalsis in phase III. This reflux may play a role in protection of the antral mucosa.     

Scatter correction of transmission near-infrared spectra by photon migration data: quantitative analysis of solids

The scope of this work is a new methodology to correct conventional near-infrared (NIR) data for scattering effects. The technique aims at measuring the absorption coefficient of the samples rather than the total attenuation measured in conventional NIR spectroscopy. The main advantage of this is that the absorption coefficient is independent of the path length of the light inside the sample and therefore independent of the scattering effects. The method is based on time-resolved spectroscopy and modeling of light transport by diffusion theory. This provides an independent measure of the scattering properties of the samples and therefore of the path length of light. This yields a clear advantage over other preprocessing techniques, where scattering effects are estimated and corrected for by using the shape of the measured spectrum only. Partial least squares (PLS) calibration models show that, by using the proposed evaluation scheme, the predictive ability is improved by 50% as compared to a model based on conventional NIR data alone. The method also makes it possible to predict the concentration of active substance in samples with other physical properties than the samples included in the calibration model.