Cardiac output determination by fluorescence excitation in the dog.
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Biomedical subjects
Publications and source records attributed to L Kaufman.
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Hepatic iodine concentration was measured in the live dog by external use of fluorescent excitation analysis. The number of characteristic photons produced by interaction of exciting radiation from an americium-241 source with iodine within the tissue is proportional to the tissue iodine concentrations. A correction is made for absorption of radiation by the abdominal wall and other tissues lying between the volume of liver being assayed and the detector collimator. The technique is applicable to the in vivo measurement of iodine concentrations from 0.5 to 40 mg/g. Accuracy of the technique is approximately +/- 10%, which is within the range of variation in iodine concentration at various sites within the liver. Radiation dose is low, and radiolabeled tracer compounds need not be used.
The use of stable tracers assayed by x-ray fluorescent excitation analysis has proven advantageous over other stable or radioisotopic techniques in a number of clinical and investigative situations. An automated fluorescent excitation analysis system for medical application has developed. Its design parameters and performance are described.
A technique is described for obtaining tomographic images of hydrogen distribution in animals using nuclear magnetic resonance (NMR). Resonant frequency is proportional to magnetic field strength, so that spatial resolution is achieved by frequency selection and magnetic field shaping. The results of scanning a phantom and two rats are presented.
A high purity germanium gamma-camera has been developed and is currently being evaluated. This camera incorporates unique performance parameters such as a 2 mm full-width spatial response function with rejection of multiple-scatter in the detector, a 2.2% FWHM energy resolution for 99 mTc, a 180 nsec paralyzable dead-time, and a 2 mu sec non-paralyzable dead-time. Imaging studies demonstrate the superior capabilities of this instrument.
The noninvasive quantification of pulmonary edema could be of importance in patient management. We have developed a portable Compton-scatter densitometer capable of measuring density in the range of 0.1-1 g/cm3 independently of the chest wall. Change in lung density was investigated in 19 dogs with pulmonary edema induced by a combination of raised left atrial pressure and hemodilution. The increase in lung density correlated with the postmortem assessment of lung water (r = 0.862, p less than 0.01) and with hemodynamic indicators of pulmonary edema (r = 0.749, p less than 0.01). Subtracting the intravascular component of lung density did not improve the correlation with postmortem lung water (r = 0.850, p less than 0.01). The measurement of absolute lung density by a Compton-scatter technique may be a potentially useful method of quantifying pulmonary edema.
NMR imaging of rats with implanted hepatomas in the liver demonstrates that under the imaging conditions of this study tumors of over 8 mm2 in area can be detected with high accuracy. Compared to normal liver, approximately 70% of these tumors had a combination of relaxation times (T1-T2) that could be uniquely identified as tumors, while the other 30% demonstrated relaxation time combinations that overlapped those previously found for abscesses, brain, and hematomas.
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A total of 143 cerebrospinal and serum samples, from proven and suspected cases of cryptococcosis, were concurrently examined using a recently introduced enzyme immunoassay (EIA Premier, Meridian Diagnostics, Inc., Cincinnati, OH, USA) and three latex agglutination (LA) procedures (Immunomycologics, Inc., Norman, OK, USA; IBL, Inc., Cranbury, NJ, USA and a non-commercial LA test). Of these 143 specimens, 115 were negative for cryptococcal antigen (CrAg) with the EIA and LA tests. The remaining 28 specimens were evaluated by the LA tests, and all were positive for CrAg (with titres ranging from 1:2 to 1:8192). Of these 28 LA-positive specimens, 26 were also tested by the EIA. This procedure detected CrAg in 23 specimens (88.5%), with antigen levels ranging from 1:4 to 1:266,857. There were 3 LA-positive specimens (tires 1:4 to 1:32) which were negative by the EIA procedure (10.7%). One LA-negative specimen demonstrated CrAg (titre 1:30) by the EIA procedure. The sensitivity of the EIA and LA tests was 85.2 and 100%, respectively. The specificity of the LA test was 100%, whereas that of the EIA was 97%. The agreement among laboratories for testing the specimens with the three LA tests was 100%.
A total of 178 sera, including 68 from proven cases of histoplasmosis (65 positive for the presence of Histoplasma capsulatum var. capsulatum antibodies and three positive for antigen), 93 from patients with suspected histoplasmosis but with no laboratory evidence of H. capsulatum var. capsulatum infection, 14 from humans with heterologous fungal and non-fungal infections and three from normal individuals, were tested for IgG H. capsulatum antibodies and M or M and H precipitins by enzyme immunoassay (EIA) (Meridian Diagnostics, Cincinnati, OH, USA) and microimmunodiffusion (MID) respectively. Sixty-three of the 68 histoplasmosis case sera demonstrated IgG antibody, and 65 of 68 demonstrated the presence of specific precipitins in the MID test. Nine positive case sera, when tested with the Laboratory Branch complement fixation (LBCF) test, reacted positively to whole yeast and histoplasmin antigens (titres 1:8 to 1:512). Three histoplasmosis case sera repeatedly tested negative for IgG, specific precipitins and complement-fixing antibodies, whereas they were positive for Histoplasma antigen. Eighteen of 95 sera from patients without evidence of histoplasmosis demonstrated IgG antibody in the EIA only. Among these positive sera, three out of three cases of aspergillosis and three out of five cases of blastomycosis were confirmed. Sera from HIV-infected and healthy individuals did not show IgG or M and/or H antibodies to H. capsulatum. Ninety-three sera were negative by both EIA and MID. The EIA for IgG was less sensitive (97%) than MID (100%). The specificity of EIA and MID was 84% and 100% respectively.
Mercuric iodide (HgI2) presents a set of attractive features as a semiconductor x-ray detector for computed tomography (CT). Its response is stable, it operates at room temperature, and thin detectors have a high detection efficiency. The properties of HgI2 permit the assembly of high spatial resolution detectors in a compact configuration. On the other hand, HgI2 exhibits a long memory, and some detectors also exhibit polarization effects, both of which are detrimental in CT. A pulse-shaping technique has been used to overcome these effects, thus demonstrating the suitability of HgI2 for use in CT.
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Exfoliative colonic cytology for the diagnosis of colorectal cancer has been largely abandoned due to (1) the widespread use of colonoscopy, (2) the cumbersome methods of cell collection and (3) the occasional difficulty of interpreting the cytologic findings in the presence of inflammatory bowel disease or adenomas. This paper describes a newly formulated bowel preparation for routine colonoscopy, based on imbibing 2 L to 4 L of a balanced electrolyte solution, in which the recovered precolonoscopic effluent (using a convenient disposable collecting kit) yielded cells for cytologic evaluation from 70% of a group of 80 patients at high risk for large bowel neoplasia. Cytology demonstrated neoplastic cells in most cases of endoscopically proven cancer. These results suggest that colonic exfoliative cytology may be useful as a supplemental test to routine colonoscopy. This could be enhanced by further methodologic modifications to the collecting and cytologic methods; large long-term studies are needed to evaluate the potential usefulness of colonic exfoliative cytology.
A computer program was written to detect blood flow in a sequence of magnetic resonance images, using reduction in first echo intensity and prolongation of calculated T2 value, and to construct three-dimensional vessel maps from the detected flow regions. Reconstructed vessel images were coded to show cross-sectional area of the lumen and relative flow velocity along the length of the vessel. The program was applied to imaging the aorta and iliac arteries in 11 patients with atherosclerosis and results were compared with angiography. All sites of narrowing were identified by the algorithm, but no flow at all was detected at one site of partial occlusion.
An investigation was conducted to examine correlates of emotional concerns and personality characteristics in a general freshman population. The scores were analysed using agglomerative and divisive hierarchical clustering methods. The results indicate the presence of a coherent group which concerns emotional factors, and show a distinct user group strongly related to the first group. The data do not determine the importance of various personality factors in influencing emotional concerns.
This epidemiological study in a psychiatric emergency ward demonstrates the existence of a population in Psychosocial Crisis. An operational definition of Psychosocial Crisis is proposed on the basis of psychopathological and psychosocial scales. Suicide attempts are extremely frequent in this population. It appears to be very difficult to bring a prospective study in an emergency ward to a successful conclusion.
Differences between primary and secondary depression have been studied from different viewpoints. This study aimed at determining a possible difference in terms of personality factors and psychodynamic variables. Two psychological tests (the MMPI and the Gottschalk-Gleser) were administered to 32 depressed inpatients, diagnosed according to Feighner criteria. A statistically significant difference was found only for the Psychasthenia scale on the MMPI. However a discriminant analysis using the MMPI results yielded approximately 80% correct classification. The Gottschalk-Gleser test did not provide any significant difference.