Electrocardiograph monitor artifacts in a neonatal intensive care unit

A wide variety of artifacts may be found when monitoring the ECG in a neonatal intensive care unit. Many of the artifacts resemble arrhythmias, and unless they are recognized as artifacts they may lead to serious errors of diagnosis and therapy. Many of the artifacts are caused by patient movement such as seizures, tremulousness, or hiccups. Others may be introduced by the monitor itself or be caused by electrical equipment in the vicinity. A group of ECG tracings is presented to illustrate the various artifacts encountered. Features that distinguish the artifacts from the arrhythmias they mimic are described, as are suggestions for elimination of the artifacts.     

Ventricular pressure slope and bileaflet mechanical heart valve closure

The maximum left ventricular pressure slope (dP/dt) value has been used by several investigators as the criterion for studying mitral valve closure. In this article, the relationship between the ventricular pressure slope (dP/dt) and the leaflet closing behavior of bileaflet mechanical heart valves (BMV) is investigated. Two current BMVs, the St. Jude Medical 29 mm and CarboMedics 29 mm, installed in the mitral position of a mock circulatory pulsatile flow loop were used as the study model. Under simulated physiologic pressures and flow conditions, the experiment was conducted at 70, 90, and 120 beats/min with corresponding flow rates of 5.0, 6.0, and 7.5 liters/min, respectively. A laser sweeping technique was used to monitor the leaflet closing motion within the last 3 degrees excursion at valve closure. A modified dual beam laser sweeping technique system was used to register the difference of leaflet/housing impact time between the two BMV closing leaflets in asynchronous closure. Common BMV asynchronous closures were found in both BMVs at all three heart rates tested. The second closing leaflet was found to always close at higher velocity than the first. Simultaneous measurements of the ventricular pressure (Pv) and the leaflet closing time showed that Pv exhibited three stage characteristics. In the first stage, Pv gradually increased as the ventricle was filled. A sudden rise of Pv occurred immediately after closing of the first leaflet. The maximum dp/dt occurred in the third stage after closure of both BMV leaflets. The BMV closing behavior and the corresponding Pv pattern were found to depend strongly upon valve type and heart rate. The time averaged ventricular pressure slope (dp/dt) values at 70, 90, and 120 beats/min were about 40, 70, and 150 mmHg/sec for the St. Jude Medical valve and 40, 105, and 205 for the CarboMedics valve during the first closing stage. The maximum dp/dt values were 2670, 4350, and 5000 mmHg/sec for the St. Jude Medical valve and 1210, 2530, and 3210 mmHg/sec for the CarboMedics valve at the three heart rates tested, respectively. The study showed that the left ventricular pressure patterns (dP/dt) at valve closure were the result of valve operation under given driving conditions. The dp/dtmax cannot be used as the criterion for studying BMV closure.     

Prolonged studies of perfluorocarbon associated gas exchange and of the resumption of conventional mechanical ventilation

We applied functional magnetic resonance imaging (FMRI) to map the somatotopic organization of the primary motor cortex using voluntary movements of the hand, arm, and foot. Eight right-handed healthy subjects performed self-paced, repetitive, flexion/extension movements of the limbs while undergoing echo-planar imaging. Four subjects performed movements of the right fingers and toes, while the remaining subjects performed movements of the right fingers and elbow joint. There was statistically significant functional activity in the left primary motor cortex in all subjects. The pattern of functional activity followed a topographic representation: finger movements resulted in signal intensity changes over the convexity of the left motor cortex, whereas toe movements produced changes either at the interhemispheric fissure or on the dorsolateral surface adjacent to the interhemispheric fissure. Elbow movements overlapped the more medial signal intensity changes observed with finger movements. Functionally active regions were confined to the cortical ribbon and followed the gyral anatomy closely. These findings indicate that FMRI is capable of generating somatotopic maps of the primary motor cortex in individual subjects.     

Platelet aggregability in vivo is attenuated by verapamil but not by metoprolol in patients with stable angina pectoris

One of the most widely studied simple sequences in the mammalian genome is the (TG)n dinucleotide sequence. Because these microsatellites are highly polymorphic, we chose to study microsatellites from cosmids to provide genetic markers for the porcine genome. After screening a porcine cosmid library with a (CA)10 probe, 20 cosmids containing microsatellites were subcloned and 17 microsatellites identified by sequencing. Oligonucleotide primers flanking the repeat were designed for seven (TG)n microsatellites with n > 14. These seven microsatellites revealed polymorphism and were regionally assigned to chromosomes by fluorescent in situ hybridization of initial cosmids. These seven loci will be useful for both the construction of the genetic map and as landmark loci on the physical map of the porcine genome.     

Evaluation of blocking and conditioned inhibition to a CS signaling a decrease in US intensity

Two experiments employing a conditioned emotional response procedure with rats evaluated the associative tendencies acquired by a target CS when a compound of that stimulus and another CS was reinforced by a low-intensity US whereas the latter CS alone was reinforced by a higher intensity US. Experiment 1 involved a blocking sequence in which the element and compound trials occurred in successive phases, followed by eventual testing of the responding to the target CS alone. Less evidence of excitatory conditioning was observed than in a comparison group which had the element and compound paired with the same low-intensity US. Experiment 2 included contemporaneous differential reinforcement of the element and compound CSs and periodic summation tests in which the target CS was compounded with another independently trained CS. Clear evidence was obtained of the development of inhibitory tendencies by the target CS. The results are consistent with the predictions of the Rescorla-Wagner model and are discussed in relation to the several determining assumptions of the model.     

Cell kinetic analysis of intact rat colonic crypts by confocal microscopy and immunofluorescence

BACKGROUND & AIMS: Precise quantitative and spatial analysis of cell cycle-related biomarkers in colonic crypts is often vital for studies of colon carcinogenesis and cancer prevention. To overcome the limitations of histology, confocal laser microscopy of microdissected whole crypts was used to quantitate S phase and mitotic cells. METHODS: Microdissected distal colonic crypts were studied in a modified rat starvation refeeding model. S phase cells were labeled in vivo with 5-bromodeoxyuridine. Mitotic cells were labeled with MPM2 (antibody to mitosis-specific epitope) and also assessed for chromatin morphology with propidium iodide. Sequential optical crypt sections, produced by confocal microscopy, were digitally imaged. S phase labeling indices per whole crypt were also compared with those derived by conventional immunohistochemistry. RESULTS: S phase and mitotic cells were clearly discriminated without background staining. The labeled S phase cell number and fraction per whole crypt were significantly decreased with starvation and increased with refeeding. Variability in the labeling index between whole crypts analyzed by confocal microscopy was significantly smaller than between histological crypt sections. Consequently, the intervention contributed to 92.2% of the total variability of the labeling index in whole crypts but only to 59% of the variability in histological sections. CONCLUSIONS: Major limitations of histology are overcome by crypt microdissection and confocal microscopic analysis. The total crypt cell population as well as labeled M phase and S phase cells can be imaged, localized, and quantitated with improved precision.     

Combined cis-platinum and alpha interferon therapy of advanced hepatocellular carcinoma

To evaluate the clinical efficacy of alpha-interferon(IFN-alpha) plus cis-platinum in hepatocellular carcinoma(HCC). 56 inoperable patients with HCC were divided into IFN-alpha plus cis-platinum treated group (n = 30) and no antitumor therapy group (n = 26). The survival of IFN-alpha plus cis-platinum treated patients was significantly better than that of patients who received no antitumor therapy (p = 0.001). Median survival time was 33 weeks and 14.0 weeks, respectively. The cumulative estimated survival rates of our IFN-alpha plus cis-platinum treated group (93.5% at 3mo, 75.0% at 6mo) were for longer than that of the no antitumor therapy group (84.6% at 3mo, 57.7% at 6mo). Objective tumor regression, greater than 50% was observed in 13.3% (4 of 30) of patients receiving IFN-alpha plus cis-platinum. By the univariate analysis, the absence of portal vein thrombus (p < 0.05), alkaline phosphatase lesser than 280 U/L (p = 0.001), total bilirubin less than 2.0 mg% (p < 0.05), serum triglyceride less than 155 mg/dl (p < 0.05) were shown to be the factors most significantly favoring a better survival. By the multivariate analysis, using Cox proportional hazards model, IFN-alpha plus cis-platinum treated group (p = 0.0001), alkaline phosphatase less than 280 mg/dl (p = 0.005), the absence of portal vein thrombus (p = 0.020) were independent favorable prognostic factors. We conclude that IFN-alpha plus cis-platinum is useful in patients with inoperable HCC and the above favorable prognostic factors may also be useful in the design and analysis of future clinical trials of systemic chemotherapy for HCC.     

Pair-rule expression patterns of even-skipped are found in both short- and long-germ beetles

Now that the genes controlling embryonic patterning have been identified in several model organisms, long-standing questions concerning the evolution of developmental systems are open to investigation. Examination of the expression of even-skipped in a variety of insects reveals that Insect germ-type designations apparently do not reflect the variations in the mechanisms of segmentation evident throughout insect phylogeny.