Primary Pneumocystis carinii prophylaxis with aerosolized pentamidine after bone marrow transplantation.
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Aerosols↗
Biomedical subjects
A C Silva
Publications and source records attributed to A C Silva.
Outbreak of cryptosporidiosis in dairy goats in Brazil.
An outbreak of cryptosporidiosis is reported among 22 suckling kids aged one to two weeks which were maintained for experimental purposes at the veterinary hospital of the University of Minas Gerais. They were divided into three groups. Group A consisted of 10 animals with acute diarrhoea; initially their faeces were pasty but later they were excreted in watery streams. The animals were treated with gentamicin and fluid therapy but did not respond to treatment and died within a week. Postmortem examination revealed liquid intestinal contents, enlarged mesenteric lymph nodes, and hyperaemia and haemorrhage were observed in the final third of the small intestine of some of the animals. Of the 10 animals in group B four had diarrhoea and six were normal; postmortem examination showed that the macroscopic changes were similar to those observed in group A. Three of the animals with diarrhoea had a massive Cryptosporidium infection in the final third of the small intestine, caecum and colon. Four of the six normal animals had a moderate Cryptosporidium infection in the same organs. The two kids in group C died; they had pasty faeces, and there were many Cryptosporidium oocysts in the faecal smears.
Animals↗
Estimation of water extraction fractions in rat brain using magnetic resonance measurement of perfusion with arterial spin labeling.
The model used for calculating perfusion by MRI techniques that use endogenous water as a tracer assumes that arterial water is a freely diffusible tracer. Evidence shows that this assumption is not valid in the brain at high blood flow rates, at which movement of water into and out of the microvasculature becomes limited by diffusion across the blood-brain barrier. In this work, the arterial spin-labeling technique is used to show that fraction of arterial water that is dependent on blood flow rate remains in the vasculature and does not exchange with brain tissue water. By using perfusion measurements without and with magnetization transfer (MT) effects, one can distinguish arterial label that exchanges into tissue because blood has much smaller MT than brain tissue. Using this technique, the extraction fraction for water is measured in the rat brain at various cerebral blood flow rates. At high flow rates (approximately 5 ml/g/min), the extraction fraction for water is found to be about 45% in rat brain. Disruption of the blood-brain barrier with D-mannitol caused an increase in the extraction fraction for water. It was possible to form an image related to the extraction fraction for water. The ability to estimate the amount of vascular water exchanging with tissue water by MRI may represent a noninvasive approach to detect the integrity of the blood-brain barrier.
Animals↗
Evidence for the exchange of arterial spin-labeled water with tissue water in rat brain from diffusion-sensitized measurements of perfusion.
The extraction fraction of vascular water in rat brain is investigated by means of diffusion measurements of arterial spin labeled water at varying cerebral blood flow (CBF) values. The apparent diffusion coefficient (ADC) of the difference of the proton magnetization signal in the brain acquired with and without continuous arterial spin labeling is modeled to provide a measure of the amount of arterial water in tissue and vasculature and thus of the extraction fraction. The tissue and vascular portion of the arterial spin labeled water are differentiated based on their diffusion characteristics in a manner analogous to the intravoxel incoherent motion (IVIM) method. The amount of labeled arterial water that exchanges with tissue water is determined by estimating the fraction of the total signal that is associated with the slow-decaying component of a biexponential fit to the normalized difference signal between the magnetization of brain tissue acquired with and without arterial spin labeling. The results indicate that, at normal CBF (1.15 +/- 0.21 ml x g(-1) x min[-1]), about 90% of the arterial spin labeled water diffuses with an ADC of (1.21 +/- 0.37) x 10[-3] mm2 s[-1]), which is equal to tissue. At high CBF, an increasing fraction of the labeling water has a fast-pseudo-diffusion coefficient due to a decrease in water extraction fractions. The results also show that the contribution of vascular water to the measurement of perfusion by techniques that use endogenous water as a tracer can be efficiently eliminated by the use of diffusion sensitizing gradients with small effective b values (b approximately 20 s/mm2), enabling these techniques to monitor true changes in tissue perfusion.
Animals↗
Clinical features and successful recovery from disseminated nocardiosis after BMT.
Nocardiosis has rarely been described after BMT. When the doses of immunosuppressive therapy were tapered, a 46-year-old BMT recipient developed chronic graft-versus-host disease (GVHD) and immunosuppresive drugs were increased. Sixteen days later the patient developed nocardiosis diagnosed by lung biopsy. Trimethoprim/sulfamethoxazole (TMP/SMZ) was initiated but the doses were reduced because of rising creatinine levels. Skin and cerebral dissemination of nocardiosis was observed and TMP/SMZ doses were increased. After 4 months, the brain lesion was unaltered despite resolution of pulmonary lesions. Clinical improvement was observed after drainage of the brain abscess.
Anti-Bacterial Agents↗
Correlation between K complex, periodic leg movements (PLM), and myoclonus during sleep in paraplegic adults before and after an acute physical activity.
K complex is the characteristic wave of stage II of sleep. The relationship between periodic limb movements (PLM) and the restless legs syndrome (RLS), and the incidence of K complexes and alpha activity has been previously described. The aim of the present study was to evaluate the effect of an acute physical activity upon K complex, PLM, and myoclonus during sleep in individuals who were paraplegic. We evaluated 84 polysomnograms from 28 volunteers with a spinal cord injury at the level of T7-T12, obtained during three consecutive nights. On day 3, the volunteers were submitted to a test of maximum effort (manual cycloergometer, with the equipment Cybex Met 300, with a progressive load increase of 12.5 w, every 2 min). The analysis of the polysomnographic recordings showed a positive correlation between the incidence of K complex and limb movements on nights 1, 2 and 3. Similarly, a correlation between the incidence of K complex and myoclonus was observed on nights 1, 2 and 3. An increased incidence of the total K complex was seen on night 3, 36 h after the test maximum effort. Both total K complex and K complex/h were reduced on night 2, compared to basal recording (night 1). There was a reduction of sleep latency on night 2, whereas total sleeping time increased progressively on night 3, as well as REM phase on nights 2 and 3. These findings indicate that physical activity can effect or modulate the incidence of K complex and suggest that a positive correlation between PLM and K complex may occur in those who are paraplegic from a spinal cord injury. In conclusion, sleep can be consolidated after physical activity.
Adult↗
Long-lasting mnemotropic effect of substance P and its N-terminal fragment (SP1-7) on avoidance learning.
We investigated the long-lasting effect of peripheral injection of the neuropeptide substance P (SP) and of some N- or C-terminal SP fragments (SPN and SPC, respectively) on retention test performance of avoidance learning. Male Wistar rats (220 to 280 g) were trained in an inhibitory step-down avoidance task and tested 24 h or 21 days later. Immediately after the training trial rats received an intraperitoneal injection of SP (50 micrograms/kg), SPN 1-7 (167 micrograms/kg) or SPC 7-11 (134 micrograms/kg). Control groups were injected with vehicle or SP 5 h after the training trial. The immediate post-training administration of SP and SPN, but not SPC, facilitated avoidance behavior in rats tested 24 h or 21 days later, i.e., the retention test latencies of the SP and SPN groups were significantly longer (P < 0.05, Mann-Whitney U-test) during both training-test intervals. These observations suggest that the memory-enhancing effect of SP is long-lasting and that the amino acid sequence responsible for this effect is encoded by its N-terminal part.
Animals↗
[The healthy life].
This study is based on a comparison of the habits and opinions of a group of pupils on entering the Damaia Preparatory School (5th and 6th years of education) and of the same group on leaving this School. Its aim is to contribute towards an adequate education for health at school in order to promote healthy living habits. The study was based on the comparison of data obtained from two random samples, chosen from the same group of pupils when entering (n1 = 36 out of a total of 368) and leaving (n2 = 32 out of a total of 164) the above mentioned school. The collection of data was carried out by means of a multiple-choice questionnaire given to a total of 532 pupils. The results demonstrated that the frequencies have changed in the following way: a) bathing has increased; b) tea drinking has decreased; c) the image of the teacher as a smoker has become less frequent; d) the number of pupils who have tried alcoholic beverages has increased; e) mother's smoking habits have increased. The other trends that were found in the study showed that there were no significant changes in either the behaviour or opinions that had been studied.
Adolescent↗
[Athlete's heart in elite disabled athletes].
PURPOSE: To assess the prevalence of the athlete's, heart syndrome in elite disabled Brazilians athletes. METHODS: Seventy-five athletes, age 27.8 +/- 6.7 years, 56 men, with various disabilities (47 physical, 12 visual and 16 cerebral paralysis) underwent clinical, electrocardiographic, vectorcardiographic, ergometric and echocardiographic evaluations. RESULTS: Athlete's heart signs occurred in 33% of the clinical evaluations, in 55% of the electrocardiograms, in 15% of the vectorcardiograms, and in 5% of the echocardiograms. At least one of these signs was presented in 51% of the athletes. There were 2 or more abnormalities in 46% of the athletes and 4 or more signs in 12%. Exercise test was considered not ischemic in 77% of the subjects. There was right bundle branch block in 23% of the tests. CONCLUSION: There were two or more athlete's heart syndrome signs in 46% of Brazilian disabled athletes.
Adult↗
Initial cortical reactions to injury of the median and radial nerves to the hands of adult primates.
The area 3b hand cortex of adult squirrel monkeys was mapped during the first minutes to hours after transecting the radial and median nerves to the hand. The objective was to evaluate initial cortical reactions to this injury and to determine whether patterns and extents of cortical change are similar in different individuals. There are 5 main findings. First, cortical aggregates related to ulnar nerve inputs from the hand rapidly expanded to occupy an additional 21% of the cortical hand map. Second, face and forearm inputs, which normally activate areas adjacent to hand cortex, rapidly expanded into areas of 4% and 1% of the hand cortex respectively. Third, cortical changes involved shifts in receptive field locations that were initiated within minutes after injury. Fourth, the spatial patterns and extents of cortical change were similar in different individuals. Finally, the pattern of cortical change produced after this injury differed from the pattern seen after injury of the median and ulnar nerves. These rapid expansions are a beginning point from which further changes must progress; however, in contrast to changes accompanying chronic hand injuries, these initial cortical reactions do not appear dictated by use of uninjured inputs.
Animals↗
Incidence of periodic leg movements and of the restless legs syndrome during sleep following acute physical activity in spinal cord injury subjects.
The purpose of the present study was to evaluate sleep patterns and complaints, and Periodic Limb Movement (PLM) and the Restless Legs Syndrome (RLS) in subjects with complete spinal cord injury. Volunteers were submitted to two polysomnograms (Oxford Medilog SAC system--EEG, EMG, EOC): (1) basal night, when the volunteer arrived at the Sleep Center, and (2) after a maximal physical test (Cybex Met 300/increase of 12.5 watts/2 min until exhaustion). Eleven volunteers with complete spinal cord injury between T7-T12 were evaluated. Data were analyzed by the paired Student's test (total sleeping time) and by the Wilcoxon matched paired test (change of sleep states, number of awakenings during sleep, latency to REM sleep and leg movements--PLM + RLS). Comparison of sleep recordings from the night before with that from the night after (12 h) practice of physical activity, showed a significant reduction in all of the sleep parameters. The results indicate that physical activity improves the sleep patterns of spinal cord injured volunteers. In particular, we noticed that PLM and RLS after physical activity were inhibited during sleep.
Adult↗
Effect of aging on insulin receptor, insulin receptor substrate-1, and phosphatidylinositol 3-kinase in liver and muscle of rats.
Insulin stimulates the tyrosine kinase activity of its receptor, resulting in the phosphorylation of its cytosolic substrate, insulin receptor substrate-1 (IRS-1), which, in turn, associates with phosphatidylinositol 3-kinase (PI 3-kinase), thereby activating the latter. Aging is associated with insulin resistance, but the exact molecular mechanism is unknown. In the present study, we examined the levels and phosphorylation status of the insulin receptor and IRS-1 as well as the association between IRS-1 and PI 3-kinase in the liver and muscle of 2-, 5-, 12-, and 20-month-old rats. There were no changes in the insulin receptor concentration in the liver and muscle of rats 2-. 5-, 12-, and 20-month rats. There were no changes in the insulin receptor concentration in the liver and muscle of rats 2-20 months old, as determined by immunoblotting using antibody to the COOH-terminus of the receptor. However, insulin stimulation of receptor autophosphorylation, as determined by immunoblotting with antiphosphotyrosine antibody was reduced by 25% (P < 0.05) in the liver and muscle of rats at 20 months. Interestingly, IRS-1 protein levels decrease at an early stage (5 months) by 58 +/- 9%, (P < 0.01) and remained at low levels thereafter in muscle, but not in liver. In samples previously immunoprecipitated with anti-IRS-1 antibody and blotted with antiphosphotyrosine antibody, there were 60 +/- 9% (P < 0.001) and 92 +/- 4% (P < 0.001) decreases in the insulin-stimulated IRS-1 association with PI 3-kinase was decreased by 70 +/- 2% in the liver and muscle, respectively, of 20-month rats. The insulin-stimulated IRS-1 association with PI 3-kinase was decreased by 70 +/- 2% in the liver (P < 0.001) and by 98 +/- 3% (P < 0.001) in the muscle of 20-month-old rats, with no change in the PI 3-kinase protein levels. The phosphotyrosine-associated PI 3-kinase activity after insulin stimulation was dramatically reduced in liver and muscle of 20-month-old rats compared to that in 2-month-old rats. Finally, by immunoprecipitation, the detection of insulin-stimulated IRS-2 phosphorylation followed the same pattern as that for IRS-1 in both liver of 2- and 20-month-old rats. These data suggest that changes in the early steps of insulin signal transduction may have an important role in the insulin resistance observed in old animals.
Aging↗
Multi-slice MRI of rat brain perfusion during amphetamine stimulation using arterial spin labeling.
When a single coil is used to measure perfusion by arterial spin labeling, saturation of macromolecular protons occurs during the labeling period. Induced magnetization transfer contrast (MTC) effects decrease tissue water signal intensity, reducing the sensitivity of the technique. In addition, MTC effects must be properly accounted for in acquiring a control image. This forces the image to a single slice centered between the labeling plane and the control plane. In this work, a two-coil system is presented as a way to avoid saturation of macromolecular spins during arterial spin labeling. The system consists of one small surface coil for labeling the arterial water spins, and a head coil for MRI, actively decoupled from the labeling coil by using PIN diodes. It is shown that no signal loss occurs due to MTC effects when the two-coil system is used for MRI of rat brain perfusion, enabling three-dimensional perfusion imaging. Using the two-coil system, a multi-slice MRI sequence was used to study the regional effects of amphetamine on brain perfusion. Amphetamine causes significant increases in perfusion in many areas of the brain including the cortex, cingulate, and caudate putamen, in agreement with previous results using deoxyglucose uptake to monitor brain activation.
Amphetamine↗
NMR measurement of perfusion using arterial spin labeling without saturation of macromolecular spins.
When measuring perfusion by arterial spin labeling, saturation of tissue macromolecular spins during arterial spin labeling greatly decreases tissue water magnetization, reducing the sensitivity of the technique. In this work, a theory has been developed for perfusion measurement by arterial spin labeling without saturation of macromolecular spins. A two-coil system was used to achieve arterial spin labeling without saturation of brain tissue macromolecular spins for NMR measurement of rat cerebral perfusion. The effects of cross-relaxation on the measurement of perfusion have been studied in the absence of macromolecular spin saturation, and it is demonstrated that at 4.7 Tesla, perfusion is underestimated by approximately 17% when the effect of cross-relaxation is neglected in the calculation of perfusion. However, assuming water to be a freely diffusable tracer, the effect of cross-relaxation is predicted to be flow independent, and it can, thus, be accounted for in the calculation of perfusion. The theory and experiments are presented to estimate tissue perfusion, magnetization transfer rate constants, and spin-lattice relaxation times of water and macromolecular spins in rat brain.
Algorithms↗
Tissue specific perfusion imaging using arterial spin labeling.
Quantitative magnetic resonance measurements of regional tissue perfusion can be obtained using magnetically labeled arterial water as a diffusable tracer. Continuous labeling is achieved in flowing spins using adiabatic inversion. The effects of continuous labeling of proximal arterial spins and T1 relaxation in distal tissue magnetization result in a steady-state change in tissue magnetization which is tissue specific, i.e., it can be quantified in units of blood flow per gram of tissue per unit time. This magnetization is sampled using standard imaging sequences. The theoretical basis for this method, including the effects of macromolecular spin saturation, is reviewed. Recent results demonstrating the successful implementation of this technique in vitro and in vivo in rat brain, heart, and kidney, and in human brain and kidney are presented, as well as the use of a separate RF coil for arterial labeling to produce selective perfusion images in rat brain. This approach allows quantitative perfusion images to be obtained completely non-invasively at the resolution of 1H MRI, and is useful in the clinical and investigational evaluation of organ physiology.
Animals↗
Anatomical basis for the separation of four cardiac zones in the walls of human heart ventricles.
The coronary vessels of 70 human hearts were visualized postmortem by injection of the coronary arteries with a X-ray opaque substance (for angiographic studies) or with a low viscosity resin (to obtain vascular casts). Analysis of the data suggests a new anatomical systematization of the vascularization of the myocardial tissue of human heart ventricles: it can be divided into four zones each having a different origin of the arterial vessels. These four components of the heart ventricles are the antero-septal (AS), postero-septal (PS), left-lateral (LL), and right-lateral (RL) zones. They correspond to the territories of the anterior interventricular branch of the left coronary artery (AS zone), of the posterior interventricular branch of the right coronary artery (PS zone), of the left circumflex artery (LL zone), and of the right coronary artery (RL zone) up to the origin of the posterior interventricular artery. This systematization of the arterial heart ventricles in zones offers a balanced division of the myocardial tissue, since each of the four zones occupied about one fourth of the total volume of the ventricles. In our samples, the most common distribution of segments in the wall of heart ventricles was the following: 16 segments in the AS zone, 11 segments in the PS zone, 5 segments in the LL zone, and 4 segments in the RL zone. The separation of four zones in the walls of heart ventricles, each of them made up of different segments, may be helpful in the understanding of the pathophysiology of myocardial ischemia, and also in the choice of surgical strategies to treat aneurisms of the heart ventricle wall.
Adolescent↗
Cardiorespiratory alterations produced by pharmacological agents applied to the ventrolateral medulla (intermediate area) of the cat. Effect of exercise condition on glycine-induced inhibition.
1. To study the action of the intermediate area (IA), coextensive with the rostral ventrolateral medulla, on the neurophysiological mechanisms involved in the regulation of respiration, in terms of inspiratory drive and respiratory timing, cats were submitted to topical application of sodium pentobarbital (30 mg/ml), leptazol (200 mg/ml), glutamate (50 mg/ml) and glycine (100 and 50 mg/ml) to the IA. The effects of electrically induced exercise on the ventilatory response and oxygen uptake (VO2) obtained by topical application of glycine (50 mg/ml) to the IA were also studied. 2. Leptazol reduced minute ventilation (VE) and inspiratory drive (VT/TI) and changed the timing mechanism. Glutamate only increased tidal volume (VT), VE and VT/TI. Arterial blood pressure (AP) increased and heart rate (HR) did not change with either drug. 3. Sodium pentobarbital reduced VT and changed the timing mechanism. Glycine only reduced VE, VT and VT/TI. AP decreased and HR did not change with either drug. 4. The depressor effects of glycine on respiratory pattern, VO2 and CO2 production (VCO2) tended to be attenuated by exercise. 5. The fall in AP due to glycine application did not differ between resting and exercise conditions. 6. Our results indicate that at least two different nervous structures are involved in the IA: one responsible for the respiratory drive and sensitive to glycine and glutamate, and the other responsible for the regulation of the timing mechanism and sensitive to sodium pentobarbital and leptazol.
Animals↗
Effect of exercise during pregnancy, graded as a percentage of aerobic capacity: maternal and fetal responses of the rat.
1. A number of variables were studied in pregnant rats that underwent strenuous exercise during pregnancy. They were: total weight gain, daily weight gain, length of pregnancy, number of offspring. Also the weight, the heart weight and fibre/capillary ratio of the newborn male rats and their VO2 max at 90 days were measured. 2. The exercise was graded in accordance to previous aerobic capacity as determined by VO2 max with relative loads of 60% (E60), 70% (E70), 80% (E80) and 90% (E90) of VO2 max being applied to the various groups (N = 6 per group). 3. The total weight gain and daily weight gain was significantly less in the E70, E80 and E90 groups. Weight gain in the anabolic phase (0-14d) was not different, but during the first week the weight gain in the E90 group was significantly less than control group. In the catabolic phase the observations were similar the first week of the anabolic phase. 4. Length of pregnancy, heart weight offspring and VO2 max of 90-day-old male rats were not significantly different. The number of offspring of the E90 group was significantly smaller than the control, E60 and E70 groups. 5. The offspring body weight was less in the E70, E80 and E90 groups than control group and was significantly less in the E90 group compared to the E60 and E70 groups. 6. The fibre/capillary ratio of the offspring was different in the E90 group compared to the control group. 7. These results suggest that the effect of exercise depends on the relative work load applied to the mother and these effects are particularly marked at high work loads.
Animals↗