Technology at what price?
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Decision Making, Organizational↗
Biomedical subjects
J Dye
Publications and source records attributed to J Dye.
Comparison of immunologic and physiologic effects of CO2 pneumoperitoneum at room and body temperatures.
BACKGROUND: Prolonged and complex laparoscopic procedures expose patients to large volumes of cool insufflation gas. The aim of this study was to compare the effects of a conventional room temperature carbon dioxide (CO2) pneumoperitoneum with those of a body temperature pneumoperitoneum. METHODS: Patients were randomized to undergo laparoscopic cholecystectomy with a CO2 pneumoperitoneum warmed to either body temperature (n = 15) or room temperature (n = 15). The physiologic and immunologic effects of warming the gas were examined by measuring peroperative core and intraperitoneal temperatures, peritoneal fluid cytokine concentrations, and postoperative pain. RESULTS: The mean duration of surgery was 32 min in both groups. Core temperature was reduced in the room temperature group (mean, 0.42 degrees C; p < 0.05). No reduction in temperature occurred when the gas was warmed. Greater levels of cytokines were detected in peritoneal fluid from the room temperature insufflation group tumor necrosis factor alpha (TNF-alpha): mean, 10.9 pg/ml vs. 0.42, p < 0.05; interleukin 1 beta (IL-1beta): mean, 44.8 pg/ml vs. 15.5, p < 0.05; and IL-6: mean, 60.4 ng/ml vs. 47.2. There was no difference in postoperative pain scores or analgesia consumption between the two groups. CONCLUSIONS: The authors conclude that intraoperative cooling can be prevented by warming the insufflation gas, even in short laparoscopic procedures. In addition, warming the insufflation gas leads to a reduced postoperative intraperitoneal cytokine response.
Ascitic Fluid↗
Does the ultrasonically activated scalpel release viable airborne cancer cells?
BACKGROUND: Viable cancer cells may implant at distant sites and cause tumor recurrence. One possible mechanism is the inadvertent exfoliation of viable tumor cells during dissection. The ultrasonically activated scalpel (UAS) uses ultrasonic energy to disrupt tissues by cavitation and produces a dense cloud of cellular debris that may contain viable cells. This study aimed to investigate the viability of airborne cells released during cancer dissection using the UAS and electrosurgery. METHODS: Flank tumors (n = 8) measuring 1 cm3 were induced in male WAG rats by subcutaneous injection of 2 x 10(6) CC531s colon cancer cells. Dissection was performed in cutting mode using the maximum power output of the respective devices. Electrosurgery was performed using a standard monopolar electrosurgical unit and a needle probe, and ultrasonic dissection was performed with the Harmonic Scalpel utilising the open surgical handset and the hooked spatula tip. The smoke plume was aspirated by a vacuum pump and bubbled under Hank's balanced salt solution to trap particulate matter. The viability of the cellular material was blindly assessed with the trypan blue test and by in vitro culture. The morphology of the cellular debris was studied by examination of cytospin preparations. RESULTS: Large quantities of cellular debris was trapped in the plume from both devices. However, no viable cells were isolated, nor did in vitro cell growth occur with either device. Examination of the debris from the UAS demonstrated a characteristic mixture of amorphous forms and very few morphologically intact cells. The cauterized tumor produced charred cells and tissue fragments. CONCLUSIONS: In conclusion, this study demonstrates that viable airborne cancer cells are not released after tumor ablation with the UAS or electrosurgery.
Animals↗
Human immunodeficiency virus infection abolishes CD4-dependent activation of ZAP-70 by inhibition of p56lck.
The effect of early human immunodeficiency virus-1 infection in vitro on proximal signal transduction events in primary peripheral blood lymphocytes was investigated with respect to CD4-mediated costimulation of CD3/T cell-receptor signalling. Tyrosine phosphorylation profiles induced by CD4 and CD3 + CD4 ligation were profoundly abrogated in virally infected cells, although CD4 receptor expression remained intact during early infection. Furthermore, the association of the tyrosine kinase p56lck with the CD4 receptor was reduced in virally infected cells. The downmodulation of CD4-mediated CD3 signalling coincided with the subsequent inhibition of the activity and tyrosine phosphorylation of the downstream kinase ZAP-70 in virally infected cells. The observed virally mediated cosignalling defects during early infection may account for the inhibition of distal signal events and thus contribute to HIV pathogenesis, such as reduced immune response to antigenic exposure, anergy, and apoptosis.
CD3 Complex↗
Actin cytoskeletal isoforms in human endothelial cells in vitro: alteration with cell passage.
The microfilamentous actin component of the cytoskeleton is crucial to endothelial angiogenesis and vascular permeability. Differences in actin cytoskeletal profiles in cultured human endothelial cells were explored: when first isolated, both primary human umbilical vein endothelial cells (HUVEC) and primary human placental microvascular endothelial cells (HPMEC) expressed F-actin, but not beta-actin or alpha-smooth muscle actin. A similar endothelial actin profile was observed in cryo-sections of freshly delivered term umbilical cord and placenta. In subsequent cell culture, although the actin cytoskeleton of HUVEC remained unchanged, the actin profiles of HPMEC altered after the second passage with the induction of alpha-smooth muscle actin expression, which was intercellularly heterogeneous and increased to 20% at P4. This behaviour occurred in HPMEC monolayers cultured on a variety of extracellular matrices. Comparisons with a spontaneously immortalized human microvascular cell-line, HGTEN 21, revealed that in prolonged passage, both alpha-smooth muscle actin and beta-actin were expressed, whereas HPMEC at P4 showed a lower level of beta-actin expression. Therefore, in comparison with large vessels, microvascular cells are more likely to dedifferentiate. This may reflect the ability of microvascular cells to remodel according to changing requirements for new vessel formation. In conclusion, passage of human microvascular endothelial cells, but not of larger vessel endothelial cells, alters the expression of actin isoforms. This may be important in relation to comparisons of in vitro and in vivo vascular permeability; higher passage microvascular endothelial cells should thus be used with caution in such studies.
Actins↗
Selective use of low-osmolality contrast agents for i.v. urography and CT: safety and effect on cost.
OBJECTIVE: The purpose of this study was to determine if the selective use of low-osmolality contrast material for excretory urography and CT is safe and if it saves money. MATERIALS AND METHODS: At the University Medical Center in Tucson, a questionnaire was developed to identify high-risk patients who would benefit from the use of a low-osmolality contrast agent. High-risk patients were defined as those with a history of a reaction to contrast material, severe allergies, asthma, severe cardiac disease, multiple myeloma, sickle cell disease, polycythemia, pheochromocytoma, or renal impairment. Beginning in March 1993, the questionnaire was given to all adult outpatients scheduled for daytime excretory urography and routine CT studies of the head and body. Only patients identified as high risk were given a low-osmolality (non-ionic) contrast agent. All other patients received high-osmolality (ionic) contrast material. The contrast agent chosen for a patient was determined by the person administering the questionnaire, usually a radiologic technologist. RESULTS: From March 1993 through December 1993, 1114 adult daytime outpatient excretory urographic and contrast-enhanced CT studies were examined at our institution. In 235 (21%) of the studies, a low-osmolality agent was used and in 879 (79%) studies, a high-osmolality agent was used. This represented a reduction in the use of low-osmolality agents from more than 90% of patients to 21%, an annual cost reduction from $288,000 to $60,480. We observed no untoward reactions to contrast material that could be specifically attributed to the increased use of high-osmolality agents. CONCLUSIONS: Selective use of low-osmolality contrast agents during excretory urography and CT can provide substantial cost savings and is not associated with a significant risk of major complications.
Arizona↗
Quality-of-life factors for parents of children with asthma.
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Adolescent↗
Ionic and synaptic mechanisms underlying a brainstem oscillator: an in vitro study of the pacemaker nucleus of Apteronotus.
1. In an in vitro preparation of the medullary pacemaker nucleus of Apteronotus, the consequences of a variety of ionic and pharmacological manipulations upon both ongoing activity and synaptic modulation of the nucleus were assessed. 2. Spontaneous rhythmicity in the pacemaker nucleus was found to be Na+-, K+-, and Ca(2+)-dependent. The extreme sensitivity to 4-aminopyridine (4-AP) relative to other treatments suggested that the K+ A-current is a critical element in the oscillations. 3. Elevated K+ or 4-AP were titrated to concentrations that suppressed spontaneous oscillations, but allowed modulatory, 'chirp' epsps to persist. The transition to elevated K+ revealed oscillatory properties in some neurons in the form of epsp-induced ringing 4. Threshold concentrations of 4-AP sufficient to halt oscillations, caused epsps to become larger and complex, increased input resistance, and enhanced the effects of current injection on epsp amplitude. A greater degree of voltage-sensitivity was also seen in later components of the complex epsp. 5. Several treatments presumed to increase Ca2+ caused desynchronization of firing and revealed diverging intrinsic frequencies among cells.
4-Aminopyridine↗
The distance to the stomach for feeding tube placement in children predicted from regression on height.
Nurses use several external measures referenced to the head and chest to gauge the insertion distance for orogastric and nasogastric (NG) tubes. Few of the measures have been tested. However, in previous studies height was the external measure most correlated with esophageal length both in children and adults. In this study, the ability of previously published regression equations on height to predict esophageal length for NG-tube insertion in 107 children was evaluated. The regression equations were examined for stability, predictive performance, and the likely positions of the tube. The data were heights and esophageal lengths obtained from esophageal manometry records and hospital charts. The predicted values for nasal insertions were biased and averaged 2.4 cm too long (R2prediction = .56, n = 30). Prediction errors greater than 5 cm in absolute value occurred in 25% of the nasally-referenced sample. The predicted values represented overestimates in 18 nasally referenced cases that were 11.5% longer on the average than the measured esophageal lengths. In contrast, the predicted values for the oral insertions were unbiased (R2prediction = .92, n = 77), and gave accurate predictions in the majority of cases. Eighty percent of the oral predictions were within +/- 1.5 cm of the measured esophageal length and represented percentage errors between 0 and 7% (M = 3%, n = 50).
Adolescent↗
Different classes of glutamate receptors mediate distinct behaviors in a single brainstem nucleus.
We have taken advantage of the increasing understanding of glutamate neuropharmacology to probe mechanisms of well-defined vertebrate behaviors. Here we report a set of experiments that suggests distinct roles for two major classes of glutamate receptors in a discrete premotor nucleus of the brainstem. The medullary pacemaker nucleus of weakly electric fish is an endogenous oscillator that controls the electric organ discharge (EOD). Its regular frequency of firing is modulated during several distinct behaviors. The pacemaker nucleus continues firing regularly when isolated in vitro, and modulatory behaviors can be reproduced by stimulating the descending input pathway. Glutamate agonists applied to the pacemaker in vitro produced increases in frequency, while glutamate antagonists selectively blocked stimulus-induced modulations. Experiments with glutamate antagonists in the intact animal resulted in specific effects on two well-characterized behaviors. Our data indicate that these behaviors are separately mediated in the pacemaker by receptors displaying characteristics of the kainate/quisqualate and N-methyl-D-aspartate subtypes of glutamate receptor, respectively.
2-Amino-5-phosphonovalerate↗
Effect of splenectomy on gram-negative bacterial clearance in the presence and absence of sepsis.
Severe sepsis leads to depression of the reticulo-endothelial system (RES) with delayed bloodstream clearance of particulate matter and bacteria. Splenectomy results in increased susceptibility to infection with encapsulated organisms but its effect on the resistance to postoperative Gram-negative infection has been little studied. We have investigated the effect of splenectomy on RES function by measurement of plasma fibronectin concentrations and bacterial clearance in the presence and absence of sepsis. In experiment 1, rabbits underwent splenectomy (n = 8) or laparotomy only (n = 8) 4 weeks before a second laparotomy. In experiment 2, animals had either splenectomy (n = 8) or laparotomy only (n = 8) followed 4 weeks later by devascularization of the appendix (sepsis). Plasma fibronectin concentrations and the blood clearance and organ distribution of an intravenous injection of 75Se-labelled viable Escherichia coli (2-3 X 10(8) colony forming units (c.f.u.] were measured 24 h after the second operation. Splenectomy resulted in: (1) a persistent reduction in plasma fibronectin concentration in the presence and absence of sepsis, and (2) a delay in the bloodstream clearance with reduced hepatic (Kupffer cell) uptake of E. coli which was exaggerated in the septic splenectomized animal. It is concluded that the spleen may be important for Gram-negative bacterial clearance, possibly related to its influence on plasma fibronectin concentration and Kupffer cell function.
Animals↗
An in vitro physiological preparation of a vertebrate communicatory behavior: chirping in the weakly electric fish, Apteronotus.
1. An in vitro preparation of the medullary pacemaker nucleus of the weakly electric fish Apteronotus leptorhynchus was studied which fires regularly and synchronously at the fish's characteristic frequency of electric organ discharge (EOD). Upon bipolar stimulation of tissue regions through which pass prepacemaker nucleus afferents to the pacemaker, a brief, transient increase in discharge frequency ensued at short-latency (Fig. 1A). 2. Intracellular recordings revealed that the acceleration was accompanied by a depolarization and decline in action potential amplitude. The magnitude of these changes was both phase- (Fig. 5) and amplitude-dependent, with the latter showing an evident threshold effect (Figs. 4 and 12). The response was reversibly blocked by high Mg2+ saline (Fig. 1B), and the magnitude of the accelerations showed marked facilitation during repeated stimulation (Fig. 6). 3. Optical and histological identification allowed characteristically different responses in the intracellular recordings to be attributed to the two cell types of the pacemaker nucleus: pacemaker and relay cells (Figs. 2 and 3). Similar responses have been observed at these respective recording locations in the intact animal during chirping (Dye and Heiligenberg 1987). 4. Simultaneous recordings of pairs of cells revealed a transient change in the phase relationship of firing during the accelerations which was most marked between relay and pacemaker cells (Fig. 7). These dual recordings also revealed that the relay cells depolarize and accelerate more than pacemaker cells (Fig. 10), suggesting that they are the principal effectors of this behavioral modulation. 5. Trains of pulses additionally elicited a long-lasting frequency elevation which occurred at a slightly higher threshold than the brief accelerations. This slow frequency change relaxed back to baseline following a biexponential time course which closely resembled that of a distinct behavior seen in intact fish, termed 'yodeling' (Dye 1987).
Action Potentials↗
Suture materials in contaminated wounds: a detailed comparison of a new suture with those currently in use.
The relationship between five different suture materials (expanded polytetrafluoroethylene (PTFE), polypropylene, polyglycolic acid, polydioxanone and polyglactin 910) and infection has been studied in 540 guinea-pig wounds contaminated with synergistic enteric organisms. The recently introduced expanded PTFE suture has been studied because, unlike the others, it has not previously been studied under these contaminated conditions. The incidence of wound infection in the control series was 26 per cent and all suture materials increased this figure significantly. The infection rate using expanded PTFE of 51 per cent was similar to all other sutures except polyglycolic acid, which produced an infection rate of 41 per cent. This difference was not statistically significant at the 5 per cent level. This confirms other studies including our own which show that the presence of most suture materials in contaminated wounds increases the incidence of infection. It further demonstrates that expanded PTFE is no different from other materials in this regard.
Animals↗
Dynamics and stimulus-dependence of pacemaker control during behavioral modulations in the weakly electric fish, Apteronotus.
1. Weakly electric fish generate around their bodies low-amplitude, AC electric fields which are used both for the detection of objects and intraspecific communication. The types of modulation in this signal of which the high-frequency wave-type gymnotiform, Apteronotus, is capable are relatively few and stereotyped. Chief among these is the chirp, a signal used in courtship and agonistic displays. Chirps are brief and rapid accelerations in the normally highly regular electric organ discharge (EOD) frequency. 2. Chirping can be elicited artificially in these animals by the use of a stimulus regime identical to that typically used to elicit another behavior, the jamming avoidance response (JAR). The neuronal basis for the JAR, a much slower and lesser alteration in EOD frequency, is well understood. Examination of the stimulus features which induce chirping show that, like the JAR, there is a region of frequency differences between the fish's EOD and the interfering signal that maximally elicits the response. Moreover, the response is sex-specific with regard to the sign of the frequency difference, with females chirping preferentially on the positive and most males on the negative Df. These features imply that the sensory mechanisms involved in the triggering of these communicatory behaviors are fundamentally similar to those explicated for the JAR. 3. Additionally, two other modulatory behaviors of unknown significance are described. The first is a non-selective rise in EOD frequency associated with a JAR stimulus, occurring regardless of the sign of the Df. This modulation shares many characteristics with the JAR. The second behavior, which we have termed a 'yodel', is distinct from and kinetically intermediate to chirping and the JAR. Moreover, unlike the other studied electromotor behaviors it is generally produced only after the termination of the eliciting stimulus.
Animal Communication↗
Intracellular recording in the medullary pacemaker nucleus of the weakly electric fish, Apteronotus, during modulatory behaviors.
1. The weakly electric gymnotiform fish, Apteronotus leptorhynchus, can be induced to perform a variety of modulations of its quasi-sinusoidal, electric organ discharge (EOD) in acute physiological preparations. These modulations, many of which are communicatory in function, include the jamming avoidance response (JAR). We have recorded intracellularly from neurons of the medullary pacemaker nucleus which is responsible for maintaining the ongoing EOD frequency during these modulatory behaviors. 2. We have used dye-filled microelectrodes to characterize single cell morphology of the two types of cells in the pacemaker nucleus (relay and pacemaker cells) and to localize anatomically the site of the differing responses we see during frequency modulations. We have also recorded with KCl-filled electrodes and attributed these data to cell type and location on the basis of characteristic behavior during these modulations. 3. Much of our data deals with chirps, brief accelerations of the EOD frequency lasting 10 to 14 ms. We see distinct patterns of activity in the pacemaker nucleus corresponding to different anatomical locations: the relay cell soma and axon, and the pacemaker cell soma and axon. Most of these loci show a marked rise in baseline voltage during the acceleration in spike frequency. The most unusual of these is the pacemaker cell axon which displays an often extreme decline in spike amplitude concurrent with the chirp (Fig. 7A). 4. 'Yodeling' (Dye 1987) appears to involve similar, characteristic changes in the pattern of firing as those seen during chirping. Similar quantitative analyses suggest that the JAR involves a different mechanism, however.
Animals↗
Clinical assessment of the neonatal Dinamap 847 during anesthesia in neonates and infants.
Direct measurements of systolic, diastolic, and mean arterial blood pressure and electrocardiogram-derived heart rates were compared with indirect arterial blood pressure measurements using the Dinamap 847XT noninvasive monitor. A total of 260 paired comparisons from 16 patients were analyzed. A regression analysis of paired data over a wide range of blood pressure values gave the following results: for heart rate r = 0.97, for systolic arterial pressure r = 0.84, for mean arterial pressure r = 0.73, and for diastolic arterial pressure r = 0.52. The 95% confidence limits for systolic, mean, and diastolic arterial pressure were +/- 16 mm Hg, +/- 18 mm Hg, and +/- 21 mm Hg, respectively. The Dinamap monitor was found to be an accurate trend recorder of heart rate and blood pressure during anesthesia in neonates and small infants.
Anesthesia, General↗
Effect of propofol anesthesia on baroreflex activity in humans.
Previous studies have shown that infusions of propofol, a new intravenous anesthetic, were associated with decreased arterial pressure and slow heart rates. To evaluate the role of baroreflex mechanisms in sustaining these conditions, the effects of two infusion rates of propofol (54 and 108 micrograms.kg-1.min-1) to supplement 66% nitrous oxide in oxygen anesthesia were studied in twelve ASA class I patients having a mean age of 34 years. Baroreflex control of heart rate was studied by perturbing the patients' arterial pressure with phenylephrine or sodium nitroprusside. Valsalva maneuvers were used to assess the response of the systemic arterial system. Steady state anesthesia at both infusion rates was not associated with decreased sensitivity of the baroreflex control of heart rate, but resetting of the reflex occurred to allow lower arterial pressures for a given heart rate than in the awake state. During propofol infusions at either rate, the diastolic pressure overshoot normally associated with the relief of raised airway pressure in the Valsalva maneuver was significantly reduced. It is concluded that propofol/nitrous oxide anesthesia is not associated with impairment of baroreflex sensitivity, but that central sympatholytic and/or vagotonic mechanisms enable low heart rates to be sustained despite decreased arterial pressures.
Adult↗
An assessment of the Dinamap 845.
The accuracy of the Dinamap 845 automatic blood pressure recorder was assessed by comparing its own indirect determinations of blood pressure with direct intra-arterial recordings. It was found that in the majority of cases it was capable of producing reliable trend information during anaesthesia. The instrument may not be able to interpret pressure signals from a patient with a severe dysrhythmia. It is probably an unsuitable monitor for use with very rapidly acting drugs such as sodium nitroprusside.
Anesthesia↗