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Biomedical subjects

F S Prato

Publications and source records attributed to F S Prato.

At least 91 records · Page 5Linked to original sources
PubMed1985

Quantitation of lung water by nuclear magnetic resonance imaging. A preliminary study.

Pulmonary edema was produced in four anesthetized dogs by saline lavage. The animals were maintained by assisted ventilation with O2/halothane and examined by a nuclear magnetic resonance (NMR) 0.15T resistive-magnet imager. The distribution of edematous fluid was clearly observed. Image contrast increased with prolongation of the cycle time (TR). Tomographic maps of spin-lattice relaxation times (T1) of the lungs were calculated from the NMR images. Comparison of T1 values with gravimetric measurements of water content of lung samples showed significant correlation (r = .7, P less than .02, n = 12) suggesting a potential for in vivo lung water quantitation by NMR imaging. This in vivo correlation is qualitatively similar to the in vitro correlation. Accurate in vivo determinations of pulmonary T2 values may require respiratory gating.

Animals↗
PubMed1985

Early detection of canine myocardial infarction by magnetic resonance imaging in vivo.

This study was undertaken to assess the ability of proton magnetic resonance imaging (MRI) to detect myocardial ischemia shortly after coronary artery occlusion. Fifteen dogs were studied before and serially for up to 6 hr after anterior descending or circumflex coronary artery ligation in vivo by gated MRI with a 0.15 tesla resistive magnet (resonant frequency of hydrogen 6.25 MHz). Image acquisition was by single-spin echo, with echo times (TE) of 30 msec and TE 60 msec, and modified inversion recovery pulse sequences. Excellent anatomic definition was observed. By 4 hr after coronary artery occlusion the signal in the infarct zone increased to 36 +/- 20% greater than that in the adjacent normal myocardium for the TE 30 msec sequence (p less than .01) and to 116 +/- 100% for the TE 60 msec sequence (p less than .05). The most intense increase in signal was noted with the TE 60 msec pulse sequence and because normal myocardium is not well visualized by this technique, acutely ischemic myocardium was clearly delineated. Inversion recovery imaging did not show areas of ischemia. Changes seen on MR images correlated well with the location of ischemic changes noted on microscopic examination of the excised hearts. MRI thus provides a noninvasive means for detection of ischemia early in the course of myocardial infarction.

Animals↗
PubMed1984

Effects on ventricular function of disopyramide, procainamide and quinidine as determined by radionuclide angiography.

To evaluate the effects of the 3 commonly used antiarrhythmic agents--disopyramide, procainamide and quinidine--on left ventricular (LV) function, these 3 agents were administered in random sequence after control radionuclide angiography performed at rest and during exercise in 17 patients. Drug dosages were tailored to achieve therapeutic blood levels 5 minutes before and 2 to 3 hours after drug administration. The mean dose of disopyramide was 141 +/- 26 mg every 6 hours, procainamide, 441 +/- 100 mg every 4 hours, and quinidine, 401 +/- 101 mg of the gluconate preparation every 6 hours. The patients received the appropriate dosage for 7 or more days before repeat radionuclide angiography was performed. The ejection fraction at rest was: control 60 +/- 13%, disopyramide 55 +/- 11%, procainamide 58 +/- 11%, and quinidine 59 +/- 12%. The exercise ejection fraction was: control 61 +/- 14%, disopyramide 58 +/- 13%, procainamide 58 +/- 12% and quinidine 61 +/- 13%. In neither case, at rest nor during exercise was there any significant difference observed between any of the agents or between any individual agent and control. However, at rest 8 subjects had a 5% or more decrease from the control value with disopyramide, 5 had a 5% or more decrease with procainamide and 6 had a 5% or more decrease with quinidine, whereas during exercise the decreases were 8, 6 and 5%, respectively. These values were not statistically different but suggest that caution should be taken in administering all 3 agents, particularly to patients with impaired LV function, because individual sensitivity to a given agent may precipitate a significant decline in LV function.

Adult↗
PubMed1983

Diazepam sedation reduces functional residual capacity and alters the distribution of ventilation in man.

We measured ventilation and static lung volumes in five fit volunteers in the right lateral decubitus position, while they were fully awake and while sedated with diazepam. We also assessed the distributions of ventilation and perfusion in the lungs, using inhalations and intravenous injections of xenon-127. Diazepam, 0.04 mg . kg-1, was administered every three to five minutes as required to induce and maintain a state of sedation which was moderately heavy. Total doses ranged from 0.16 to 0.38 mg . kg-1. Sedation did not alter minute ventilation, but reduced tidal volume, increased breathing frequency and reduced functional residual capacity slightly. Sedation also diminished the normal gradient of ventilation from non-dependent to dependent regions of the lungs. Spontaneous episodes of very small tidal volume breathing during sedation were associated with a marked reduction or cessation of ventilation of the most dependent region of the lungs. There were no sedation-related changes in the distribution of perfusion. These effects of moderately heavy sedation may contribute to the hypoxaemia and impairment of pulmonary gas exchange often present during recovery from general anaesthesia.

Adult↗
PubMed1983

Radiation dose calculations for inhalation of Tc-99m sulfur colloid radioaerosol.

The radiation dose to the lung from the administration of Tc-99m sulfur colloid aerosol (for ventilation investigations) has been calculated. The dose to the ciliated airway epithelium varies between 0.34 to 2.5 rads, compared with 0.31 rads to the lung parenchyma. The calculation was normalized to a total of 1 mCi of Tc-99m deposited in the lung.

Aerosols↗
PubMed1982

An interface between several cameras and two computers, using differential analog transmission.

A system has been built to allow up to four scintillation cameras to be connected in parallel with two computers, yet provide for selection of individual pairs of camera/computer combinations with the exclusion of unwanted connections. Since the distances involved were relatively long, signal drivers were used to transmit the analog signals in a differential mode over multiple twin-paired lines rather than coaxial cable. By transmitting the signals differentially, any noise induced on the signal was subtracted at the receiver. The principal features of this system, which has been installed in two institutions, are described. A problem that occurred in connection with one camera is presented (also its solution), with a suggestion concerning parameters to be assessed at the time of system acceptance.

Computers, Analog↗
PubMed1980

Relation of cord blood thyroxine and thyrotropin levels to gestational age and birth weight.

A program of screening cord blood for evidence of primary neonatal hypothyroidism was implemented in a general hospital. In 13 months 3456 newborns were screened: the thyroxine (T4) and triiodothyronine (T3) concentrations were measured in cord blood samples, and when the T4 level was below 8.0 micrograms/dl thyrotropin was also assayed in the sample. The two-tier program was effective. One hypothyroid newborn was detected and treated. More boys than girls had T4 levels below 8.0 micrograms/dl (9.7% v. 4.7%). The T4 level correlated with birth weight slightly better in the boys (r = 0.28 v. 0.21), and in the boys this correlation was stronger when the birth weight was lower. Regression analysis of the data for 54 sets of twins indicated that the T4 level was more strongly related to gestational age than to birth weight.

Birth Weight↗
PubMed1977

The incidence of radiation pneumonitis as a result of single fraction upper half body irradiation.

The incidence of radiation pneumonitis was determined in 43 patients following a single fraction half body (UHB) irradiation. Radiographs taken before and at least 4 months after UHB treatment were scored for evidence of pneumonitis. Nine patients received only pulmonary irradiation from the UHB treatment. There was no evidence of radiation pneumonitis in eight for whom there was adequate follow up. From this and other supportive evidence presented in this retrospective study, it is suggested that a total lung irradiation of 800 rads produces no changes that can be seen radiographically, provided there has been no previous major pulmonary irradiation or concurrent malignant pulmonary disease. In patients who received additional mediastinal irradiation, severe changes appeared within this field while mild to moderate radiographic changes were seen outside the mediastinal field.

Breast Neoplasms↗
PubMed1977

Physiological and radiographic assessment during the development of pulmonary radiation fibrosis.

Repeated regional measurements of pulmonary blood flow and ventilation were performed in 25 patients irradiated for breast cancer. Patients were studied before and at varying times after (16 to 47 days) the start of radiotherapy. At the same time, chest radiographs were taken and symptoms recorded. Of all the parameters measured, blood flow showed the earliest and greatest decrease. Since changed in blood flow at 60 days are predictive of the changes at 300 days, we believe that earlier studies during the course of irradiation could be useful in predicting long-term effects.

Breast Neoplasms↗
PubMed1976

Long-distance transmission of digital scintillation camera signals.

A system is described for the long-distance transmission of digital positional information from a scintillation camera to a computer through a shielded multiple-twisted-pair cable. Data errors caused by noise induction along the cable are completely eliminated. The operation of the complete interface and its routine testing are described.

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

A novel fast T1-mapping method.

The authors present a novel fast T1-mapping technique that allows a T1 map to be reconstructed from data acquired in less than 3 seconds. Data were acquired by using two modified TurboFLASH (fast low-angle shot) sequences and were processed with a combination of one-dimensional Fourier transforms and a parameter-fitting routine, instead of a standard two-dimensional Fourier transform. Apparent T1 (T1*) maps were obtained, from which T1 maps were calculated. Comparisons of T1 values obtained in phantoms and the human brain by using this technique with those obtained with multipoint inversion-recovery T1 mapping showed that the new method yielded accurate T1 values. Optimization of the method will further improve speed and accuracy. The general approach of this T1-mapping technique is believed to be also applicable to other problems, such as T2 and T2* mapping.

Algorithms↗
PubMedDate not supplied

Sex differences in conditioned taste aversion and in the effects of exposure to a specific pulsed magnetic field in deer mice Peromyscus maniculatus.

Although conditioned taste aversion (CTA) has been investigated and described in laboratory rodents and domestic animals, less is known regarding wild rodents. Here, we describe CTA in males and females of a "wild" species of rodent, the deer mouse (Peromyscus maniculatus). In addition, as CTA has often been induced by exposure to intense electromagnetic, X or gamma, radiation, in a second study, we also investigated the effects of a specifically designed, pulsed extremely low-frequency and low-intensity magnetic field on the flavor preferences of male and female deer mice. The results of these investigations showed that: (i) deer mice quickly developed a marked CTA for a novel flavor after a single pairing with LiCl; (ii) although the intensity of the CTA was the same in males and females, there was a sex difference in the duration of the flavor aversion, with males displaying it for a longer period (4 days) than females (3 days); (iii) both males and females showed a rapid and complete extinction of the aversion, in contrast to what has been reported for laboratory rodents; (iv) there was no recovery of CTA on re-test 10 days after extinction; (v) neither male or female deer mice developed a taste aversion as a consequence of exposure to a weak electromagnetic field; and (vi) there was a sex difference in response to the magnetic field, with exposure to the magnetic field significantly enhancing novel taste preference in male but not in female deer mice. Overall, our results show that there are several sex differences in the behavior of deer mice, both in the characteristics of the CTA and in the response to magnetic field exposure. The sex differences are discussed in terms of a sexually dimorphic sensitivity to experimental manipulation and the induction of stress and/or anxiety.

Animals↗
PubMedDate not supplied

Recent advances in research on radiofrequency fields and health.

Since the Royal Society of Canada report on potential health risks of radiofrequency (RF) fields from wireless telecommunications in the spring of 1999, there have been several newly published reports on risks associated with the use of mobile phones. This article provides a summary of scientific research on the potential health effects of radiofrequency fields that has been reported since the original Royal Society report was published. This update also discusses several earlier results not included in the original report.

Animals↗
PubMedDate not supplied

Regional and total lung function in patients following pulmonary irradiation.

Regional and total lung function measurements and chest radiographs were obtained from 18 patients with cancer of the breast from 3 months to 6.7 years after the start of treatment. A control group of 20 patients was studied before radiotherapy but after mastectomy. The functional parameter most affected by radiation was blood flow. In some cases in which the radiographic changes were mild the functional measurements indicated severe vascular damage. The radiation appears to reduce the number and efficiency of functioning lung units within the irradiated region.

Adult↗