Search PubMed⌕ Search

Biomedical subjects

F Miranda

Publications and source records attributed to F Miranda.

At least 37 records · Page 2Linked to original sources
PubMed1995

"Helper:" A critical events prompter for unexpected emergencies.

OBJECTIVE: The medical practitioner is faced with an increasing list of protocols and algorithms related to patient care. These recommendations are often difficult to recall, particularly in stressful emergency situations. Using advanced cardiac life support (ACLS) protocols, we built a computer-based system to exhibit precompiled response plans for medical emergencies. To validate the usefulness of this prompting device, we tested application of two of the nine ACLS algorithms, pulseless ventricular fibrillation/ventricular tachycardia (Vfib/Vtach) and bradycardia, in a simulated operating room (OR) environment. METHODS: The system utilized the software authoring system IconAuthor (Aimtec Inc., Nashua, NH) and a touch-screen monitor (DiamondScan, Microtouch, Methuen, MA). Prior to testing our system, all 39 subjects were given time to familiarize themselves with its operation. Subsequently, all subjects were videotaped while managing a standard simulated anesthetic. During the anesthetic, the subjects were presented with two emergency scenarios, not viewed during the familiarization period. The electrocardiographic (EKG) signals for normal sinus rhythm, ventricular fibrillation, and second-degree heart block were presented. By random selection, the prompter was available to half of the subjects for help with arrhythmia management (experimental group), while to half it was not (control group). RESULTS: A total of 39 subjects completed the exercise. Use of the prompter enabled significantly more subjects to administer correct drugs and dosages during ventricular fibrillation. The correct lidocaine dose was chosen more often by the experimental group than by the control (p = 0.015); similarly MgSO4 was appropriately ordered more often in the experimental group (p = 0.003). During second-degree heart block, atropine was correctly followed with a dopamine infusion (p = 0.004), and epinephrine infusion was ordered for refractory bradycardia (p = 0.002) more often in the experimental than the control group. CONCLUSIONS: These data demonstrate the value of a prompting device at the anesthesia workstation. We foresee the use of such prompters in many areas of medicine.

Algorithms↗
PubMed1995

Hemodynamic improvement in hemorrhagic shock by aortic balloon occlusion and hypertonic saline solutions.

The initial treatment of uncontrolled hemorrhage shock from an abdominal source is controversial. The hemodynamic effects of transfemoral diaphragmatic aortic occlusion with a balloon followed by a single bolus of hypertonic saline solutions have been evaluated in 28 dogs. The animals were submitted to pressure-driven hemorrhage for 90 min, according to mean arterial pressure in the abdominal aorta and randomized into four groups, according to the treatment employed at 34 min after hemorrhage. Group 1 dogs (controls) received isotonic NaCl (0.9%, 208 mOsm/l, 4 ml/kg) without aortic occlusion; group 2 underwent aortic occlusion and received isotonic NaCl (0.9%, 308 mOsm/l, 4 ml/kg): group 3 were occluded and received hypertonic NaCl (7.5%, 2400 mOsm/l, 4 ml/kg); group 4 were occluded and received hypertonic sodium acetate (10.5%, 2400 mOsm/l, 4 ml/kg). There were no significant differences between groups at basal measures and also after 30 min of continuous bleeding, when animals presented with severe shock, and significant decreases in mean arterial pressure, cardiac index, systolic index and cardiac filling pressures; the systemic vascular resistance index was increased. Control animals remained in severe shock throughout the experiment and three died. The recovery of mean arterial pressure in aortic-occluded dogs given isotonic NaCl was associated with a marked increase in systemic vascular resistance index, without improvements in cardiac index, systolic index and cardiac filling pressures. In occluded dogs given hypertonic NaCl and NaAc the mean arterial pressure recovery lasted longer, with lower increases in systemic vascular resistance index, while the cardiac index, systolic index and cardiac filling pressures showed a marked albeit transient increase. Injection of hypertonic saline following aortic occlusion produced significantly better hemodynamic profiles and should be seriously considered for the first treatment in severe uncontrolled hemorrhagic shock from an abdominal vascular source.

Analysis of Variance↗
PubMed1994

Pavlovian inhibitory conditioning and tolerance-reversal to scopolamine-induced adipsia in rats.

In the present experiment the effect of a conditioned inhibitory stimulus on tolerance to scopolamine-induced adipsia was evaluated. Long-Evans rats were injected with 0.6 mg/kg scopolamine bromidrate in the presence of a tone or a noise, and physiological saline with a compound tone-odor. A summation test with the compound stimulus noise-odor showed a tolerance reversal effect to scopolamine adipsic effects in tolerant subjects. This reduction of tolerance was similar to adipsia produced by the first scopolamine administration, only when the odor stimulus was present. However, the inhibitory stimulus alone has no effect upon water intake. Results confirmed that a Pavlovian conditioned inhibition procedure can reduce conditioned tolerance to a drug.

Animals↗
PubMed1994

Status of quantitative EEG (QEEG) in clinical practice, 1994.

Clinical quantitative EEG (qEEG) is a complex specialty that may include not only standard EEG but also digital ("paperless") EEG, topographic mapping, spectral analysis, spectral coherence, long latency and event related potentials (EP), significance probability mapping (SPM), dipole source localization methodology (DLM), and discriminant function analysis. There are three basic clinical uses: non-specific detection of organicity/encephalopathy, specific categorization of disease or clinical condition, and epileptic source localization. Extreme variations exist in the competency of laboratories practicing clinical qEEG; universally agreed upon standards of practice have not been established but there are a number of efforts to do so. As expected, the clinical value of qEEG to patients varies similarly. Criticisms of qEEG have now been answered: Color displays need not be deceptive. Statistical "capitalization upon chance" can be easily avoided. By training and with newer analytic procedures, artifacts can be recognized and often removed. Data based upon spectral analysis and EP can reliably classify clinical conditions thereby demonstrating a greater sensitivity to EEG/EP data than possible by conventional visual inspection. QEEG is clearly of clinical value when performed in concert with standard EEG and analyzed by clinicians with demonstrated competency in standard EEG followed by specialized training and demonstrated competency in qEEG. QEEG is not a simple substitute for conventional EEG and cannot be seen as a substitute for clinical competence. Although continuing to develop, qEEG technology has matured sufficiently and is now well established. Concerns regarding its clinical use have primarily resulted from its misapplication and misinterpretation stemming, largely, from inadequate personnel training and expertise.

Brain Mapping↗
PubMed1993

Characterization of toxin III of the scorpion Leiurus quinquestriatus quinquestriatus: a new type of alpha-toxin highly toxic both to mammals and insects.

The primary structure of toxin III of Leiurus quinquestriatus quinquestriatus (Lqq III) was elucidated by automatic Edman degradation of the reduced and S-carboxymethylated protein and derived tryptic peptides. Like other scorpion toxins that are active on sodium channels, Lqq III, consisting of 64 amino acids, is a 7 kDa single-chain polypeptide crosslinked by four disulfide bridges. It belongs to the alpha-toxin group, as judged by competition experiments with 125I AaH II for binding to rat brain synaptosomes (K0.5 = 7 x 10(-7) M). Lqq III is the first alpha-toxin to be characterized that is highly toxic to mice [LD50 = 50 micrograms (7.1 nmol)/kg body wt], by subcutaneous injection, insects Blatella germanica [LD50 = 60 ng (8.5 pmol)/g body wt.] and Musca domestica [LD50 = 120 ng (17 pmol)/g body wt]. When tested via the intracerebroventricular route, the toxicity for mice [55 micrograms (8 nmol)/kg] was of the same order as that found by subcutaneous injection, indicating that Lqq III has a higher affinity for peripheral sodium channels that for those of the central nervous system. There are three differences between the sequences of Lqq III and Lqh alpha IT, an alpha-toxin isolated from the venom of Leiurus quinquestriatus hebraeus. These substitutions are found at positions 20, 24, and 64 (Ser-->Ala,Asp-->Glu and His-->Arg, respectively). Surprisingly Lqh alpha IT is only weakly active in mice [LD50 = 5 mg (0.7 mumol)/kg], while in insects its toxicity is similar to that of Lqq III [140 ng (20 pmol)/g body wt blowfly larvae]. These observations are relevant to the definition of scorpion toxin structure-activity relationships.

Amino Acid Sequence↗
PubMed1993

Relationships between mandibular canine calcification stages and skeletal maturity.

Hand wrist radiographs and dental panoramic radiographs of 200 boys and 215 girls were assessed to determine the relationship between the developmental stages of the mandibular canine and skeletal maturity indicators of the pubertal growth spurt. Chi-square and Kendall's tau statistics demonstrated significant (P < 0.001) relationships between skeletal maturity indicators. Associations between canine development and skeletal maturity ranged from 0.53 to 0.85. Most children having attained canine stage G showed the presence of the adductor sesamoid (81%), capping of the diaphysis of the third middle phalanx (77%), and capping of the fifth proximal phalanx (87%). Growth reference data for American children suggest that stage G occurred approximately 0.4 years and 1.3 years before peak height velocity for girls and boys, respectively. It is indicated that canine calcification could serve as a useful tool for evaluating childrens' skeletal maturation and, by association, somatic maturity.

Adolescent↗
PubMed1992

[Esophagectomy without thoracotomy for adenocarcinoma in Barrett's esophagus].

From April 1985 to November 1990, 12 patients with adenocarcinoma in a Barrett's esophagus, all of them men, with a median age of 62 years (range, 46 to 79 years), were operated by transhiatal esophagectomy and were submitted to a periodic follow-up. Dysphagia was the main symptom. Preoperative investigations included esogastroscopy and CT-scan of the abdomen and thorax in all patients. Esophageal endosonography was performed in the last 4 cases and MRI in one case. All patients recovered postoperatively and were discharged from hospital. The resected specimens were staged according to Rosenberg et al.'s classification: stage 1, 3 patients, stage 2, 2 patients, stage 3, 6 patients, stage 4, 1 patient. An anastomotic stricture occurred in 4 patients and was treated successfully by endoscopic dilatation. Five patients died during the follow-up period. Seven patients are alive without evidence of recurrence. Transhiatal esophagectomy appears to be the procedure of choice for adenocarcinoma arising from Barrett's esophagus.

Adenocarcinoma↗
PubMed1991

Mechanisms of protection against herpes simplex virus type 1-induced retinal necrosis by in vitro-activated T lymphocytes.

In BALB/c mice, acute retinal necrosis occurs in the uninoculated eye 8 to 10 days following uniocular anterior chamber inoculation of the KOS strain of herpes simplex virus type 1 (HSV-1). Retinitis in the uninjected eye can be prevented if HSV-1-specific immune effector cells that have been restimulated with virus in vitro are administered intravenously within 1 day of anterior chamber inoculation of virus. We explored further the mechanism of protection afforded by these activated immune effector cells. The results of our studies revealed that optimal protection from retinitis required in vitro restimulation, since infusion of 50 x 10(6) HSV-1-primed but nonrestimulated cells could not protect as well as 10 x 10(6) activated cells. Analysis of both restimulated and nonrestimulated cells showed that only in vitro-restimulated cells were cytotoxic to HSV-1-infected syngeneic target cells. From these studies, we concluded that the ability to kill virus-infected target cells contributed to optimal protection achieved by intravenous administration of activated immune effector cells. Furthermore, T-cell subset depletion of activated immune effector cells demonstrated that both L3T4+ and Lyt-2+ T cells in the transfer inoculum contributed to protection. Additional studies revealed that although the transferred immune effector cells reached the injected eye within 24 h, virus replication in the injected eye was not affected. In the uninjected eye, virus titers were low, consistent with protection of this eye from retinitis. Taken together, the virus recovery results suggest that the interaction of virus with intravenously administered HSV-1-specific immune effector cells which limits virus spread and/or replication of virus probably occurred within the central nervous system and prevented the second wave of virus from entering the uninoculated eye.

Animals↗
PubMed1990

Glucose-6-phosphate dehydrogenase (G6PD) activity in tumoral tissues of G6PD-deficient subjects affected by larynx carcinoma.

The activity of glucose-6-phosphate dehydrogenase (G6PD), the key enzyme of the hexose monophosphate (HMP) shunt pathway, was measured in both normal and tumoral larynx tissues from normal and G6PD deficient subjects. Significant increases of this enzymatic activity were found in tumoral tissues of both normal and G6PD deficient subjects, who were characterized by very low levels of G6PD activity in erythrocytes as well as in larynx tissue.

Aged↗
PubMed1979

Hypersomnia with simultaneous waking and sleep patterns in the electroencephalogram. A case report with neurotransmitter studies.

A mildly dyslexic boy of 11 years, with no neurological deficit or history of epileptic seizures, had marked hypersomnia for 2 years, which was most pronounced in the morning hours. Repeated EEG studies and power spectral analysis revealed simultaneous posterior alpha rhythm and sleep patterns (spindles, vertex waves, K complexes) over vertex and frontocentral regions, while the patient was behaviorally awake. Bilateral synchronous anterior spikes were frequently noted in association with sleep patterns. A polysomnogram over 24 h confirmed excessive sleep, night and day (especially morning hours) and there was evidence of a large REM sleep percentage (on EMG and EOG basis) while the EEG had predominantly non-REM sleep patterns. Special neurotransmitter studies were performed in view of a presumed disturbance affecting the neurobiochemical sleep regulation. These studies were based on CSF metabolite levels and provided evidence for a high serotonin metabolite (5HIAA) level. It is tempting to hypothesize that the biochemical disturbance has led to encroachment of non-REM sleep patterns on both wakefulness and REM sleep. Further discussion deals with the bilateral-synchronous spike activity and its relationship to arousal patterns in sleep.

Child↗
PubMed1978

Analgesic effect of etorphine in rats with selective depletions of brain monoamines.

The analgesic effect of etorphine was compared with that of morphine in rats with electrolytic lesions of the nucleus medianus raphe or injected intraventricularly with 6-hydroxydopamine. The effect of both compounds was markedly reduced in animals with raphe lesions, but not significantly modified in those receiving 6-hydroxydopamine. Etorphine and morphine significantly increased the forebrain levels of 5-hydroxyindolacetic acid when administered subcutaneously at doses of 5mg/kg and 2 microgram/kg, respectively. Neither drug significantly affected the forebrain levels of monoamines. It is concluded that, as for morphine the integrity of the serotoninergic system in the brain is important for the full analgesic effect of etorphine.

Analgesics↗