Healthy individuals seropositive for rheumatoid factor.
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False Positive Reactions↗
Biomedical subjects
R Ruiz
Publications and source records attributed to R Ruiz.
[Hypercoagulability and exanthematous Mediterranean fever].
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Acute Disease↗
Quantitative automated latex nephelometric immunoassay for determination of myoglobin in human serum.
We have evaluated a new latex nephelometric test for the quantitation of myoglobin in human serum. The assay consists of incubating the diluted serum sample (20-fold) for 12 min at room temperature with latex particles covalently coated with anti-myoglobin antibodies and then quantifying the change of light-scatter produced. The assay is fully automated on the Behring nephelometer analyzer with a sampling rate of 150 samples/hour. There is no interference from bilirubin (up to 340 mumol/l), haemoglobin (up to 7,000 mg/l), or rheumatoid factor (up to 1,100 int. units/ml). Myoglobin standard curve extends from 20 to 380 micrograms/l. Assay detection limit lies around 6 micrograms/l. Coefficient of variation ranged from 2.7 to 7.6%. Correlation coefficient between latex immunoassay and an RIA method was 0.987, calculated from the assay of 37 samples. A statistically significant difference was found between the distribution for females and males. The serum level of myoglobin showed an age-dependent variation. Concentrations up to 60 micrograms/l are considered to be normal.
Adolescent↗
Fuzzy K-nearest neighbor classifiers for ventricular arrhythmia detection.
We report a study of the efficiency of 4 classifiers (the K-nearest-neighbor and single-nearest-prototype algorithms, each as parametrized by both Fuzzy C-Means and Fuzzy Covariance clustering) in the detection of ventricular arrhythmias in ECG traces characterized by 4 features derived from 7 spectral parameters. Principal components analysis was used in conjunction with a cardiologist's deterministic classification of 90 ECG traces to fix the number of trace classes to 5 (ventricular fibrillation/flutter, sinus rhythm, ventricular rhythms with aberrant complexes and 2 classes of artefact). Forty of the 90 traces were then defined as a test set; 5 different learning sets (numbering 25, 30, 35, 40 and 45 traces) were randomly selected from the remaining 50 traces; each learning set was used to parametrize both the classification algorithms using both fuzzy clustering algorithms and the parametrized classification algorithms were then applied to the test set. Optimal K for K-nearest-neighbor algorithms and optimal cluster volumes for Fuzzy Covariance algorithms were sought by trial and error to minimize classification differences with respect to the cardiologist's classification. Fuzzy Covariance clustering afforded significantly better perception of cluster structure than the Fuzzy C-Means algorithm, and the classifiers performed correspondingly with an overall empirical error ratio of just 0.10 for the K-nearest-neighbor algorithm parametrized by Fuzzy Covariance.
Algorithms↗
Ectopic thyroid tissue in the submandibular region.
This report describes an unusual location of ectopic thyroid gland tissue. A growth in the left submandibular area was surgically excised, and the microscopic examination of the specimen revealed thyroid tissue with colloid goiter. Because this entity cannot be clinically distinguished from a salivary gland tumor, ectopic thyroid tissue should be considered in the differential diagnosis of swellings involving the submandibular area.
Choristoma↗
Automated turbidimetry of rheumatoid factor without heat inactivation of serum.
We describe an improved turbidimetric procedure for rheumatoid factor measurement in human serum. Heat-aggregated human IgG is used as antigen. Interference produced by the complement component C1q, which required a previous heat pretreatment of sera, is avoided by the addition of the chemical inhibitor, poly(vinyl sulphonic acid). This inhibitor eliminates C1q interference without affecting the attachment of rheumatoid factor to the Fc part of IgG, thus permitting full automation of the assay. After studying the reactivity of different heat-aggregated IgG preparations, we optimized the procedure for preparing the antigen in order to attain maximal reactivity: IgG was heated at 63 degrees C until the absorbance at 340 nm of a 1/10 dilution of the antigen lay between 0.65 and 0.95 absorbance units. The study of antigen stability showed a maximum aggregation two weeks after preparation. The antigen was then stable and could be used in the assay. The standard curve extends from 30 to 500 x 10(3) IU/l. Intra- and inter-assay CV were less than 5.5%. Relative analytical sensitivity and specificity were 98.3% and 95.2%, respectively. The results agreed well with those obtained by the non-improved turbidimetric procedure (r = 0.996) and with nephelometry values on the Behring nephelometer analyser (r = 0.964). The correlation with an enzyme immunoassay was also good (r = 0.923).
Complement C1q↗
[Neurobrucellosis. Report of a case with elevated ADA in the CSF].
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Adenosine Deaminase↗
Extrinsic compression of the renal artery by diaphragmatic crus.
Extrinsic compression of the renal artery due to a fibromuscular band originating from the diaphragm was encountered in a 26-year-old patient who had systemic hypertension associated with stenosis and kinking of one of her renal arteries. After surgical decompression, the renal artery assumed a normal expansion with disappearance of hypertension. Six other cases of extrinsic compression of the renal artery have been found in the literature. Surgical treatment is mandatory in all cases because the mechanism that causes the lesion makes percutaneous transluminal angioplasty illusory.
Adult↗
Multimicroprocessor system for online monitoring in a CCU.
A real-time monitoring system for physiological signals, developed for patients in coronary care units (CCUs), is described. This system monitors the signals that have the greatest clinical value in a CCU environment (ECG and cardiovascular pressures), taking charge of detecting dangerous situations and of extracting information significant to the correct monitoring of the patient. The information it extracts, mainly from the ECG, is presented to the user in an ergonomic way using written reports and graphs which collect and compile the information, facilitating its interpretation. Some utilities have been developed to allow the user to modify certain monitoring conditions as well as to correct results derived from them, thereby improving the reliability of the monitoring process. The system uses a multimicroprocessor architecture (imposed by the need to perform a large number of tasks in real time) with a block based on the VME bus, charged with acquiring and processing the monitored signals, and an IBM-compatible PC/XT which is used as a system user interface and a massive storage device in which the information resulting from the monitoring of signals is stored.
Coronary Care Units↗
Fuzzy beat labeling for intelligent arrhythmia monitoring.
The performance in automatic diagnosis of cardiac rhythm based on the analysis of the electrocardiographic signal (ECG) is strongly conditioned by the correct classification of each beat detected. In this work we present a fuzzy classifier of beats that applies empiric criteria and that permits it to ignore the frequent lack of clarity in the information coming from previous stages within ECG processing. The classification of each beat is performed applying diffuse conditional statements which represent the knowledge of the cardiologist expert and that use a set of descriptions of the temporal and morphological attributes of the analyzed beat. The process of classification is completed with information derived from the consideration of "families," which group beats that have QRSs of similar morphology, and with information brought in by the user himself in the monitoring process. The modularity of the classifier that has been developed facilitates the incorporation of new descriptions and classification criteria in order to increase its reliability. The design process proposed has a structure that is transferable to other analysis and event classification processes.
Arrhythmias, Cardiac↗
Antinociceptive effect of taurine and its inhibition by naxolone.
1. We have tested the effect of taurine on nociceptive stimulation provoked by chemical agent (acetic acid) and by the hot-plate test. 2. In the acetic acid test, taurine exerts an antinociceptive effect at every dose and time assayed. The observed effect was dose-related. 3. Naxolone pretreatment antagonizes the antinociceptive effect of taurine in the acetic acid test. 4. The results obtained in hot-plate test show that taurine did not significantly affect latency time for paw licking.
Acetates↗
Cutis marmorata telangiectatica congenita and glaucoma.
A case of cutis marmorata telangiectatica congenita (CMTC) is described in association with congenital glaucoma. Approximately 68 cases of CMTC and only four cases associated with glaucoma have been reported. The type of glaucoma seems to be related to an abnormality of the filtration in the anterior angle, due to increased pressure in the episcleral vessels. The surgical treatment is trabeculectomy, and opening an alternative drainage pathway.
Glaucoma↗
Voice analysis to predict the psychological or physical state of a speaker.
A vocal message, apart from its semantic content, carries information on the psychological and physiological condition of the speaker. Physical fatigue and especially psychological stress are the pathological elements of the condition. The accepted term for the cause of these effects is the "workload." This article describes the main research carried out since the 1940's to measure the acoustic modifications of the voice brought about by a workload. It concludes by a critical analysis of the studies and a short description of the perspectives for research. Their results mainly concern astronauts and pilots involved in specific high-stress tasks and possible users of voice recognition systems. All the studies show an excellent approach to this field of research but deserve to be widened, deepened, and made more accurate to enable estimating the nature or level of reaction to a workload.
Aerospace Medicine↗
Menstrual patterns and progesterone circulating levels following different procedures of tubal occlusion.
This study was undertaken to assess the effects of different tubal occlusion procedures on ovarian function. Three groups of subjects randomized to tubal occlusion by laparoscopy and Yoon ring (24 subjects), minilaparotomy and Yoon ring (19 subjects) and minilaparotomy and Pomeroy (22 subjects), and one separate control group of 26 healthy subjects not using any form of contraception were studied in a prospective design. The characteristics of the menstrual patterns were studied for one year after sterilization. Determination of the circulating progesterone levels were made on days 15, 20 and 25 of menstrual cycles initiated 1, 3, 6 and 12 months following the tubal ligation. In the analysis of the bleeding pattern there was a statistically significant difference in the mean segment length and in the longest bleeding-free interval in the subjects who had been sterilized by minilaparotomy with Yoon ring, when compared to the other two study groups and to the control group. However, the magnitude of this difference in number of days was not considered clinically significant. There was no statistically significant difference in the percentage of ovulatory cycles within the study and the control groups, or when the results of the study groups were compared with each other or to the control group.
Adult↗
Algorithmic sequential decision-making in the frequency domain for life threatening ventricular arrhythmias and imitative artefacts: a diagnostic system.
A preliminary study to approach the problem of reliably detecting life threatening ventricular arrhythmias in real time is described. An algorithm (DIAGNOSIS) has been developed in order to classify ECG signal records on the basis of the computation of four simple parameters calculated from a representation in the frequency domain. This algorithm uses a set of rules constituting an operative classification scheme based on the comparison of the parameters with a set of pre-established thresholds. This allows us to differentiate four general categories: ventricular fibrillation-flutter, ventricular rhythms, imitative artefacts and predominant sinus rhythm.
Algorithms↗
Neuronal activity in the subcortically denervated hippocampus: a chronic model for epilepsy.
Spontaneous and evoked field potentials and cellular discharges were studied in the subcortically denervated hippocampus of the freely moving rat. The fimbria fornix, the ventral hippocampal commissure, and the supracallosal afferent fibers were removed by aspiration, and recordings were made 3-5 months after the lesion. Two types of spontaneous interictal spikes were observed. Type 1 interictal spike had identical depth distribution to physiological sharp waves but they were shorter in duration (less than 40 ms), larger in amplitude (greater than 2.5 mV) and population spikes were riding on the main deflection. Type 2 interictal spikes were negative in the stratum oriens and positive in the pyramidal layer and stratum radiatum of both CA1 and CA3. The amplitude of both types of interictal spikes could exceed 6 mV. We suggest that interictal spikes were initiated randomly in different subpopulations of the CA2-3 region and the location of the initiating population burst determined the polarity and amplitude of the extracellular interictal spike. Repetitive stimulation of the perforant path (5 Hz, 6 s) evoked markedly uniform afterdischarges in both intact and fimbria fornix-deprived rats. The threshold of afterdischarges was significantly lower, the seizure spread to the contralateral hippocampus was slower, and secondary afterdischarges lasted significantly longer in the lesioned rats. We suggest that under physiological conditions the electrical stability of the hippocampus is ensured by the feed-forward inhibitory action of subcortical afferents. Removal of tonic inhibitory influences and/or sprouting of local axon collaterals allows extreme synchronization and reverberation of information in the entorhinal-hippocampal-entorhinal cortex circuitry. The presence of interictal spikes and increased susceptibility to seizures for several months after the lesion offers the fimbria-fornix-deprived hippocampus a useful chronic preparation to study the mechanisms of limbic epilepsy.
Action Potentials↗
Comparison of single-dose treatment with norfloxacin and standard 5-day treatment with trimethoprim-sulfamethoxazole for acute shigellosis in adults.
Shigellae have been shown to be highly susceptible to new quinolone agents, with average MICs for 90% of isolates of less than 0.1 microgram/ml. Because these agents also reach high concentrations in the stool after a single dose, the effectiveness of a single 800-mg dose of norfloxacin and of 5-day treatment with trimethoprim-sulfamethoxazole (TMP-SMX) were compared in a randomized trial. Patients with clinical dysentery received one of these treatment regimens, and clinical data and follow-up culture results were analyzed for patients whose stool culture on presentation grew shigellae. When 55 patients with shigellosis (26 treated with TMP-SMX, 29 treated with norfloxacin) whose bacterial isolates were susceptible to the antibiotic given were compared by treatment group, no significant differences were seen in days of illness (mean, 2.5 +/- 0.65 days with TMP-SMX and 2.0 +/- 0.47 days with norfloxacin; P = 0.200) or number of unformed stools after starting treatment (mean, 9.7 +/- 2.37 stools with TMP-SMX and 7.6 +/- 3.19 stools with norfloxacin; P = 0.312). Resistance in vitro to TMP-SMX was seen in 15% of Shigella isolates, whereas none was resistant to norfloxacin. Bacteriologic failure was found in 1 patient among 24 receiving TMP-SMX and in none of 25 patients receiving norfloxacin. One single dose of norfloxacin was as effective as 5 days of treatment with TMP-SMX in these adults with shigellosis.
Adult↗
Electric activity in the neocortex of freely moving young and aged rats.
Electroencephalographic activity of the neocortex was evaluated in young (5-7 months) and aged (26-28 months) rats. All animals in the aged group showed behavioral impairment in a spatial task (water maze). A neocortical electroencephalogram was derived simultaneously from 16 different neocortical locations and was subjected to spectral analysis. The frequency of occurrence and duration of high-voltage spindles was determined in two sessions, each involving a total of 30 min alert immobility. Changes in spectral characteristics and high-voltage spindles in response to scopolamine administration were also evaluated. The power of high-frequency activity (8-20 Hz) was significantly reduced in the aged subjects. This was greatest in the temporo-occipital regions, while no significant changes were seen in the mediofrontal region. Scopolamine resulted in a large power increase in all frequency bands, but the increase in the higher-frequency range (8-20 Hz) was significantly less in the aged group. The incidence of high-voltage spindles was 6 times higher and their total duration was 9 times longer in aged rats, with virtually no overlap with the young group. In young rats, scopolamine increased the incidence and total duration of high-voltage spindles, while it decreased both parameters in the aged subjects. Cholinergic neurons in the nucleus basalis appeared shrunken in the aged animals. These findings demonstrate that reliable electroencephalographic changes are present in the neocortex of the aged rat, and that some of the physiological alterations may be due to the pathological changes in the cholinergic nucleus basalis.
Aging↗