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3.
Rev Med Chil ; 129(9): 1085-92, 2001 Sep.
Article in Spanish | MEDLINE | ID: mdl-11725475

ABSTRACT

During the last decade, there has been a significant increase in the use of computers in biomedical research. In particular, the use of these instruments in experimental control, as well as in the acquisition and storage of experimental data, has become universal. The current capacity of these machines enables the precise manipulation of many experimental variables and allows for very fast acquisition of data. In this article, we discuss the fundamentals of small personal computers and its use in experimental control and data acquisition. Further, we discuss technical aspects related to the management of measurement instrument's control and their technical limitations. Electrical recordings from the cerebral cortex are used as examples to illustrate the different aspect included in this article.


Subject(s)
Electronic Data Processing , Information Storage and Retrieval/methods , Research , Animals , Humans , Microcomputers , Models, Biological
4.
Rev Med Chil ; 129(8): 955-62, 2001 Aug.
Article in Spanish | MEDLINE | ID: mdl-11680971

ABSTRACT

A personal computer equipped with an analog-to-digital conversion card is able to input, store and display signals of biomedical interest. These signals can additionally be submitted to ad-hoc software for analysis and diagnosis. Data acquisition is based on the sampling of a signal at a given rate and amplitude resolution. The automation of signal processing conveys syntactic aspects (data transduction, conditioning and reduction); and semantic aspects (feature extraction to describe and characterize the signal and diagnostic classification). The analytical approach that is at the basis of computer programming allows for the successful resolution of apparently complex tasks. Two basic principles involved are the definition of simple fundamental functions that are then iterated and the modular subdivision of tasks. These two principles are illustrated, respectively, by presenting the algorithm that detects relevant elements for the analysis of a polysomnogram, and the task flow in systems that automate electrocardiographic reports.


Subject(s)
Medical Informatics Computing , Algorithms , Analog-Digital Conversion , Data Display , Diagnosis, Computer-Assisted , Electrocardiography , Microcomputers , Signal Processing, Computer-Assisted , Software Design , User-Computer Interface
5.
J Neurophysiol ; 84(5): 2699-702, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11068012

ABSTRACT

During specific rapid eye movement (REM) sleep deprivation its homeostatic regulation is expressed by progressively more frequent attempts to enter REM and by a compensatory rebound after the deprivation ends. The buildup of pressure to enter REM may be hypothesized to depend just on the time elapsed without REM or to be differentially related to non-REM (NREM) and wakefulness. This problem bears direct implications on the issue of the function of REM and its relation to NREM. We compared three protocols that combined REM-specific and total sleep deprivation so that animals underwent similar 3-h REM deprivations but different concomitant NREM deprivations for the first 2 (2T1R), 1 (1T2R), or 0 (3R) hours. Deprivation periods started at hour 6 after lights on. Twenty-two chronically implanted rats were recorded. The median amount of REM during all three protocols was approximately 1 min. The deficits of median amount of NREM in minutes within the 3-h deprivation periods as compared with their baselines were, respectively for 2T1R, 1T2R, and 3R, 35 (43%), 25 (25%), and 7 (7%). Medians of REM rebound in the three succeeding hours, in minutes above baseline, were, respectively, 8 (44%), 9 (53%), and 9 (50%), showing no significant differences among protocols. Attempted transitions to REM showed a rising trend during REM deprivations reaching a final value that did not differ significantly among the three protocols. These results support the hypothesis that the build up of REM pressure and its subsequent rebound is primarily related to REM absence independent of the presence of NREM.


Subject(s)
Homeostasis/physiology , Sleep Deprivation/physiopathology , Sleep, REM/physiology , Animals , Electroencephalography , Rats , Rats, Sprague-Dawley , Sleep/physiology
6.
Shock ; 11(6): 403-10, 1999 Jun.
Article in English | MEDLINE | ID: mdl-10454829

ABSTRACT

Küpffer cells (KCs) have been implicated in leukocyte recruitment and microvascular dysfunction associated with liver inflammation. The overall objective of this study was to assess the role of KCs and polymorphonuclear (PMN) leukocytes on the oxidative stress elicited in the liver as a consequence of hind limb reperfusion in rats subjected to tourniquet shock, a shock model that differs from other models in that hepatic injury is a consequence of remote organ damage. Colloidal carbon clearance from blood and its incorporation into KCs demonstrate that these cells are activated after the 2 h hind limb reperfusion period and that they are responsible for the observed oxidative stress and for PMN leukocyte recruitment and activation. Liver oxidative stress in this model is evidenced by increased liver tissue GSSG/GSH ratio, thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation, myeloperoxidase (MPO) activity, an index of tissue-associated neutrophil accumulation, and a significant loss in total tissue superoxide dismutase (SOD) activity. Mean arterial blood pressure (MAP), as well as plasma levels of alanine aminotransferase (ALT), an index of hepatic tissue injury, total SOD activity, plasma levels of alpha-tocopherol and beta-carotene, and total plasma nitrite are also affected as a consequence of KC activation after the 2 h hind limb reperfusion period. Inhibition of KC activity by gadolinium chloride (GdCl3) reverted most of the above alterations to values that do no differ from those found in control animals. These results support the hypothesis that hepatic and systemic oxidative stress elicited by hind limb reperfusion in rats subjected to tourniquet shock is both KC and PMN leukocyte dependent.


Subject(s)
Kupffer Cells/metabolism , Liver/metabolism , Neutrophils/metabolism , Oxidative Stress , Shock/physiopathology , Alanine Transaminase/metabolism , Animals , Carbon/metabolism , Female , Gadolinium/pharmacology , Glutathione/metabolism , Malondialdehyde/metabolism , Neutrophil Activation , Nitrites/blood , Peroxidase/metabolism , Pressure , Rats , Rats, Sprague-Dawley , Reperfusion , Superoxide Dismutase/metabolism , Thiobarbituric Acid Reactive Substances/metabolism , Tourniquets , Vitamin E/blood , beta Carotene/blood
7.
Shock ; 9(5): 320-8, 1998 May.
Article in English | MEDLINE | ID: mdl-9617880

ABSTRACT

The role of nitric oxide (NO) on liver oxidative stress and tissue injury in rats subjected to tourniquet shock was investigated. This shock model differs from others in that injury is a consequence of remote organ damage. Liver oxidative stress becomes evident after hind limb reperfusion, as evidenced by the loss of total tissue thiols; by increases in tissue oxidized glutathione (GSSG), lipid peroxidation (LPO), plasma aminotransferases (alanine aminotransferase (ALT) and (aspartate aminotransferase (AST)), and plasma nitrites; and by a 36% loss in total superoxide dismutase (SOD) activity. Portal blood flow is reduced by 54.1% after 2 h of hind limb reperfusion. Inhibition of NO synthesis with Nomega-nitro-L-arginine methyl ester or L-arginine methyl ester increased mean arterial blood pressure; further reduced portal blood flow; and aggravated liver injury as assessed by further loss in total thiols, increased LPO and GSSG content, and further increases in plasma ALT and AST. Total plasma nitrites were lower than in control animals, and total tissue SOD activity decreased by more than 80%. Treatment with the NO donor sodium nitroprusside reverted the decrease in portal blood flow and also reverted tissue thiol loss, LPO, and GSSG increases, as well as the loss of ALT and AST to plasma and of SOD activity to levels comparable to untreated control shock animals. As expected, plasma nitrites were greater than in tourniquet control animals. These data support the hypothesis that endogenous NO formation protects the rat liver from the consequences of oxidative stress elicited by hind limb reperfusion in rats subjected to tourniquet shock.


Subject(s)
Glutathione/metabolism , Liver/physiopathology , NG-Nitroarginine Methyl Ester/pharmacology , Nitric Oxide Synthase/antagonists & inhibitors , Oxidative Stress , Shock, Traumatic/physiopathology , Superoxide Dismutase/metabolism , Alanine Transaminase/blood , Animals , Aspartate Aminotransferases/blood , Blood Pressure , Cysteine/metabolism , Female , Glutathione Disulfide/metabolism , Lipid Peroxidation , Liver/drug effects , Liver/metabolism , Malondialdehyde/analysis , Nitroprusside/pharmacology , Rats , Rats, Sprague-Dawley , Reperfusion , Shock, Traumatic/metabolism , Superoxide Dismutase/antagonists & inhibitors , Tourniquets
8.
Free Radic Res ; 22(6): 561-9, 1995 Jun.
Article in English | MEDLINE | ID: mdl-7633577

ABSTRACT

Rats subjected to tourniquet shock suffer a severe form of circulatory shock, tissue and organ oxidative stress, and final multiple system organ failure (MSOF) and death of the animals within 24 h of tourniquet release. The oxidative damage observed in hind-limb muscle tissue after reperfusion does not by itself account for the final systemic and lethal MSOF. We have postulated that organ failure has its genesis in a primary perfusion abnormality, e.g. the hind limbs, which is followed by secondary hypoperfusion of other organs, such as the liver, as has been shown to be the case in several septic shock models. It has also been shown that injured or necrotic tissue can activate neutrophils, Küpffer cells, platelets, and both the complement and coagulation cascades. In turn, complement activation also leads to neutrophil and Küpffer cell activation as assessed by their capacity to generate oxyradicals. Herein we have evaluated the potential protective effect of ibuprofen on hepatic oxygen-derived free radical production, as well as its effects on both polymorphonuclear leucocyte (PMN) activation and liver infiltration. The protective effect of ibuprofen on hepatic oxidative injury was assessed by determining total thiol groups (SH), thiobarbituric acid-reactive substances (TBARS), and by the release of aspartic acid (AsT) and alanine (AIT) aminotransferases in control animals, in animals subjected to 5 h of tourniquets, and in animals after 2 h of hind-limb reperfusion. Liver infiltration by PMNs was determined by histology after staining with eosin-hematoxylin, and PMN activation by their capacity to reduce nitro blue tetrazolium (NBT).(ABSTRACT TRUNCATED AT 250 WORDS)


Subject(s)
Ibuprofen/therapeutic use , Liver Diseases/prevention & control , Reactive Oxygen Species/metabolism , Reperfusion Injury/prevention & control , Shock, Traumatic/metabolism , Alanine Transaminase/blood , Animals , Chemical and Drug Induced Liver Injury , Evaluation Studies as Topic , Free Radicals , Liver Diseases/metabolism , Male , Neutrophil Activation/drug effects , Rats , Rats, Sprague-Dawley , Reperfusion Injury/complications , Reperfusion Injury/metabolism , Shock, Traumatic/complications , Sulfhydryl Compounds/metabolism , Thiobarbituric Acid Reactive Substances/metabolism , Tourniquets
9.
J Neurophysiol ; 72(4): 1745-55, 1994 Oct.
Article in English | MEDLINE | ID: mdl-7823099

ABSTRACT

1. Sixteen rats were recorded continuously for 3 days using an automated system that detected, quantified, and stored the incidence of cortical delta waves, cortical sigma spindles, hippocampal theta rhythm, and electromyographic activity. A time series then was constructed wherein 15-s epochs were ascribed to one behavioral state: wakefulness (W), quiet sleep (QS), or active sleep (AS, a state also referred to as REM sleep). From those series, AS episodes and non-AS intervals could be determined. Episodes and intervals were defined as lasting at least two epochs and the one-epoch episodes and intervals were incorporated to the ongoing state. 2. Having established the length of each AS episode and non-AS interval, pairings were made, on the one hand between episodes and their preceding intervals, and on the other, between episodes and the intervals that followed. 3. Highly significant correlations were found between the length of AS episodes and the length of the non-AS intervals that followed. Correlations were also significant when calculated separately versus the amount of QS and of W within the following interval. Correlations improved when they were performed against the log of the interval and when only intervals with a predominance of QS were selected. 4. No significant correlation was found between the length of AS episodes and the length of the preceding non-AS intervals, except for a negative one that was present only when the statistical analysis was performed in the unsmoothed array where the one-epoch episodes and intervals were preserved. 5. These results suggest that there is a short-term homeostasis operating within the spontaneous architecture of sleep in rats. This homeostatic mechanism is not manifested by the regulation of the length of AS episodes. Instead, there is a forward regulatory mechanism that, given the duration of an AS episode, permissively controls the interval that the animal may abstain from AS, and hence the timing of the triggering of a new AS episode.


Subject(s)
Cerebral Cortex/physiology , Hippocampus/physiology , Homeostasis/physiology , Sleep, REM/physiology , Animals , Delta Rhythm , Male , Polysomnography , Rats , Rats, Sprague-Dawley , Sleep Deprivation/physiology , Sleep Stages/physiology , Theta Rhythm
10.
Sleep ; 17(3): 208-19, 1994 Apr.
Article in English | MEDLINE | ID: mdl-7939119

ABSTRACT

Distributions within a 12:12 light:dark schedule of wakefulness (W), active sleep (AS), quiet sleep (QS) and of QS rich in delta (QSD) and in spindle (QSS) activities were evaluated for 52 days from 15 rats. Angular statistics were applied for each state by equating their hourly incidence to data distributed around a circle. Measures of location (mean angle, median angle, mode angle, maximum semicircle), dispersion (mean vector, standard deviation, quartile deviation), skewness and kurtosis were computed and their intra- and interindividual variabilities were compared. Mean angles (in hours and after lights-on) averaged 5.5 for QS, 8.6 for AS, 18.4 for W, 1.9 for QSD and 10.6 for QSS. Length of vectors, representing concentration around the mean angle, averaged 0.22 for QS, 0.36 for AS, 0.22 for W, 0.38 for QSD and 0.23 for QSS. Distributions of QS and W were closely related to the light-dark step function. QSD had a leptokurtic distribution, sharply rising at the beginning of the sleep-predominant phase, whereas AS and QSS had smoother distributions reaching maxima in its second half. In rodents as in humans, QSS and AS have opposite distributions to QSD. QSS may contribute to maintain sleep through the resting phase of the light-dark schedule after restorative function associated with delta activity has been fulfilled.


Subject(s)
Circadian Rhythm/physiology , Light , Rats, Sprague-Dawley/physiology , Sleep , Animals , Delta Rhythm , Electronic Data Processing , Male , Rats , Wakefulness
12.
Free Radic Res Commun ; 17(5): 313-25, 1992.
Article in English | MEDLINE | ID: mdl-1483582

ABSTRACT

The placement of rubber band tourniquets upon rat hind-limbs for 5 h followed by reperfusion of the extremities results in a severe form of circulatory shock characterized by hypotension and death within 24 h of tourniquet release. Oxidative damage to muscle tissue is an early consequence of hind-limb reperfusion on tourniquet release, yet this local damage does not explain the lethal hypotensive shock state which evolves within the next 24 h. Multiple system organ failure (MSOF), of as of yet unknown causes, is usually described in relation to several shock states. It has been suggested that injured or necrotic tissue may activate neutrophils, platelets, and the coagulation system leading to embolization in remote tissues. Effective decreases in hepatic blood flow have been observed in several forms of sepsis which precedes the biochemical evidence consistent with an ischemic insult of the liver. In support of our original hypothesis, that organ failure has its genesis in a primary perfusion abnormality with secondary ischemic organ injury, herein we have assessed the possibility that oxygen-derived free radicals are generated in the liver of rats after reperfusion of their hind-limbs on release of the tourniquets. We report on the protective effects of allopurinol (ALLO) and a mixture of superoxide dismutase (SOD) catalase (CAT) and dimethylsulfoxide (DMSO) on liver free sulfhydryl content (SH), thiobarbituric acid-reactive substances (TBARS), and on the release of aspartic acid (AsT) and alanine aminotransferase (AlT) activities, and of alkaline phosphatase during a 5 h tourniquet period and after 2 h of reperfusion of the hind-limbs. During the hind-limb ischemic period hepatis tissue SH levels remained essentially constant during the first hour (6.02 +/- 0.36 to 5.65 +/- 0.20 mumoles/g wet tissue), and decreased significantly, over and above the normal circadian decrease of liver glutathione levels, to 4.02 +/- 0.69 mumoles/g wet tissue after the third hour and remained lowered until tourniquet release. A further significant decrease (3.11 +/- 0.49 mumoles/g wet tissue) was observed after 2h of reperfusion. TBARS production remained constant during the 5 h hind-limb ischemic period (168.4 +/- 37.3 mumoles/g wet tissue) and rose by 55% to 261.7 +/- 55.8 mumoles/g wet tissue after 2 h of tourniquet release. ALLO, but not the SOD-CAT-DMSO combination, protected hepatic SH loss during the hind-limb ischemic insult, yet both offered protection after 2 h of tourniquet release.(ABSTRACT TRUNCATED AT 400 WORDS)


Subject(s)
Liver Diseases/etiology , Oxygen/metabolism , Reperfusion Injury/complications , Shock/complications , Alanine Transaminase/blood , Alkaline Phosphatase/blood , Animals , Aspartate Aminotransferases/blood , Female , Free Radicals , Hindlimb/blood supply , Ischemia , Liver/metabolism , Male , Rats , Rats, Sprague-Dawley , Sulfhydryl Compounds/metabolism , Thiobarbiturates , Tourniquets
13.
Brain Res Bull ; 27(5): 573-80, 1991 Nov.
Article in English | MEDLINE | ID: mdl-1756375

ABSTRACT

A microcomputer-based system is described that detects, counts and stores cortical delta and sigma waves, hippocampal theta waves and electromyographic activities in the rat by building matrices with the incidence of those four variables (columns) in 15-second bins (rows). Data tables are submitted to statistical, graphics and spread-sheet software to assess internal organization of sleep episodes and 24-hour distribution of sleep variables. Within sleep episodes, cross-correlograms reveal a delta-sigma-theta sequence, while autocorrelograms quantify clustering and periodicity of variables. Sleep accumulates in the lights-on phase, with high concentration of delta at the beginning of this sleep-predominant phase and of sigma and theta in its second half. These are notable similarities with human sleep architecture. Simple procedures for data reduction into standard behavioral state diagnosis are demonstrated. The low cost of personal computers and data acquisition interfaces facilitates the automation of complex paradigms by ad hoc on-line programs that produce as output a data base that can be processed by standard software, providing a fluid pathway of automated acquisition, analysis and presentation of data.


Subject(s)
Hippocampus/physiology , Sleep/physiology , Animals , Databases, Bibliographic , Delta Rhythm , Electroencephalography , Electromyography , Male , Microcomputers , Rats , Rats, Inbred Strains , Theta Rhythm
14.
Rev Med Chil ; 119(10): 1207-8, 1991 Oct.
Article in Spanish | MEDLINE | ID: mdl-1845216
15.
Rev Med Chil ; 118(12): 1387-92, 1990 Dec.
Article in Spanish | MEDLINE | ID: mdl-2152674

ABSTRACT

Projects on informatics at the School of Medicine of the University of Chile are being brought about in accordance with both its institutional goals and present trends in technology. Prominent among the latter are the widespread distribution of autonomous processing power represented by low-cost computers and the ease of communication at local and worldwide levels. Our main project has been the design and start of a computer network that integrates the School's Departments and the geographically dispersed teaching hospitals. The principal services provided by the network are local and international electronic mail, access to data bases, and emulation of mainframe terminals (eg, to run remotely a mainframe's statistics software). Automated bibliographic search has been made available both through remote access to Medline data base and through local usage of compact disc (CD-ROM) versions. Since our network is open, it should become a forceful mean of assisting and integrating the biomedical community throughout the country.


Subject(s)
Computer Communication Networks/organization & administration , Databases, Bibliographic , Medical Informatics/organization & administration , Schools, Medical/organization & administration , Universities/organization & administration , CD-ROM , Chile , Computer Systems , MEDLINE
16.
Rev Med Chil ; 118(8): 909-12, 1990 Aug.
Article in Spanish | MEDLINE | ID: mdl-2152234

ABSTRACT

In the sixties and seventies, the School of Medicine of the University of Chile was the first Chilean institution to incorporate computers into academic endeavors through its own Computer Center. Later, professors were marginated from policy making, which became oriented to administrative goals, but they compensated that situation with the easy access to personal computers brought about by present technology. In 1986, when School authorities were again elected by the faculty staff, professors were able to participate again in a committee designing projects in this area. Current development at the School of Medicine include a proliferation of personal computers, the implementation of a computer network with access to medical data bases, and a growing number of applications in the fields of research and teaching. In the near future, due to the accessibility of telecommunications and computers, these advancements should have an impact on the whole biomedical community, a situation that would restore, after many years, the traditional role of the University of Chile in the life of the country.


Subject(s)
Medical Informatics/history , Schools, Medical/history , Chile , History, 20th Century , Information Systems/history , Libraries, Medical , Medical Informatics/organization & administration
17.
J Infect Dis ; 161(5): 1020-2, 1990 May.
Article in English | MEDLINE | ID: mdl-2182724

ABSTRACT

To assess the possible role of oxygen-derived free radical in the pathogenesis of cutaneous necrotizing vasculitis (Thomas reaction) induced by epinephrine in endotoxin-primed rabbits, animals were treated with superoxide dismutase (intraperitoneal or local), catalase, allopurinol, or ibuprofen 2 h before inducing the reaction. This is done by an earlobe intravenous injection (10 micrograms) of endotoxin followed by an intradermal injection (100 micrograms) of epinephrine in the shaved abdomen; 18-24 h later, a hemorrhagic-necrotic lesion can be observed at the site of the epinephrine injection. The reaction was completely inhibited by superoxide dismutase, catalase, and ibuprofen, while allopurinol afforded only partial protection. Thus, oxyradicals seem to participate in the pathogenesis of this reaction.


Subject(s)
Endotoxins/toxicity , Epinephrine/toxicity , Escherichia coli , Oxygen/metabolism , Vasculitis/etiology , Animals , Catalase/pharmacology , Female , Free Radicals , Lipopolysaccharides/toxicity , Male , Necrosis , Rabbits , Skin/pathology , Superoxide Dismutase/pharmacology
18.
Med Microbiol Immunol ; 178(4): 211-6, 1989.
Article in English | MEDLINE | ID: mdl-2664439

ABSTRACT

Isogenic Escherichia coli strains, differing in their expression of K1 antigen and ColV plasmid, were studied for their ability to produce disease. Newborn rats were used to test the ability of these strains to colonize the intestine and to produce bacteremia and meningitis; adult rats were used to test their ability to produce urinary tract infection. Colonization of intestine and bladder by K1+ ColV+ E. coli was associated with rapid induction of bacteremia and higher mortalities compared with colonization with K1+ ColV- strains. These findings suggest that the ColV plasmid could play a role in the pathogenesis of human infections.


Subject(s)
Antigens, Bacterial , Bacteriocin Plasmids , Escherichia coli/pathogenicity , Meningitis/microbiology , Plasmids , Urinary Tract Infections/microbiology , Animals , Animals, Newborn , Antigens, Surface , Escherichia coli/genetics , Escherichia coli/immunology , Rats , Rats, Inbred Strains , Sepsis/microbiology , Sepsis/mortality , Virulence
20.
Brain Res Bull ; 20(1): 133-8, 1988 Jan.
Article in English | MEDLINE | ID: mdl-3342339

ABSTRACT

A data acquisition program is described for the Apple II series of microcomputers that allows for continuous, direct monitoring of electrographic elements from cortical, hippocampal and muscle leads from rats. The program detects cortical delta waves and sigma activity, hippocampal theta activity and electromyographic activity. The detected elements are counted and stored in memory at 15 second intervals (bins). Every three hours, the data are transferred to disks for permanent storage and off-line analysis.


Subject(s)
Signal Processing, Computer-Assisted , Sleep/physiology , Software , Animals , Calibration , Cerebral Cortex/physiology , Electroencephalography , Electromyography , Hippocampus/physiology , Microcomputers , Monitoring, Physiologic , Muscles/physiology , Rats
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