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Biomedical subjects

A Gottschalk

Publications and source records attributed to A Gottschalk.

At least 109 records · Page 6Linked to original sources
PubMed1985

A modified procedure for rapid labelling of low concentrations of bioactive proteins with indium-111.

We describe the conjugation of DTPA to 100-500 micrograms of protein in concentrations of 0.6-1.0 mg/mL utilizing the mixed anhydride method. Free DTPA is removed by minicolumn gel filtration and centrifugation with minimal protein dilution. Radiolabelling at any selected pH can be achieved easily by diluting the protein in the desired buffer. The radiolabelling process can be monitored by instant thin layer chromatography. Any radiochemical impurity detected can be eliminated either by additional minicolumn filtration or further chelation with more conjugated protein. In citrate buffer at pH 6 with minicolumn gel chromatography we prepared 111In-DTPA-D3 (3.0 microCi/micrograms) monoclonal antibody and used it to image hepatocarcinoma in guinea pigs.

Animals↗
PubMed1984

Tc-99m-DTPA aerosol and radioactive gases compared as adjuncts to perfusion scintigraphy in patients with suspected pulmonary embolism.

To evaluate the clinical utility of improved methods for radioaerosol inhalation imaging, we obtained preperfusion radioaerosol images in 107 patients (mean age = 62 years), who were referred for evaluation of suspected pulmonary embolism (PE). For each patient, we compared six-view aerosol images with accompanying perfusion scans and chest radiographs and with Xenon-133 (Xe-133) or Krypton-81m (Kr-81m) studies. Four observers at four different institutions independently evaluated aerosol-perfusion and gas-perfusion pairs, classifying the probability of PE as low, high, or indeterminate. The radioaerosol images were good to excellent in quality; excessive central deposition of activity was infrequent and did not interfere with image interpretation. The aerosol-perfusion studies showed 86% agreement with Xe-133 perfusion interpretations (n = 299) and 80% agreement with Kr-81m perfusion interpretations (n = 99). These rates of agreement were comparable with those of intraobserver agreement for gas-to-gas and aerosol-to-aerosol comparisons, and higher than interobserver agreement rates. In a limited number (n = 9) of angiographically documented cases, aerosol-perfusion and gas-perfusion studies provided accurate and equivalent diagnoses. The results suggest that radioaerosol inhalation studies, performed with improved nebulizers, are diagnostically equivalent to ventilation imaging as an adjunct to perfusion scintigraphy in evaluating patients with suspected PE.

Adult↗
PubMed1984

Chromaticity coordinates of frequency-limited functions.

We compute the gamut of coordinates in the Commission Internationale de l'Eclairage chromaticity diagram that correspond to positive frequency-limited functions having only three degrees of freedom (a trichromatic system). The results suggest that practical colors are either suitably frequency limited to be represented by three samples or have suitably frequency-limited metamers.

Color Perception↗
PubMed1983

Trichromacy, opponent colours coding and optimum colour information transmission in the retina.

This paper presents a systematic analysis of the role of opponent type processing in colour vision and the relation between opponent type colour transformations and the initial three colour mechanisms. It is shown that efficient information transmission is achieved by a transformation of the initial three colour mechanisms into an achromatic and two opponent chromatic channels. The derivation of the transformation is dependent solely on criteria from information theory. Thus it provides a logical rationale reconciling opponent type processing as an optimal necessary step after the initial three colour mechanisms, unifying respectively the Hering and Young-Helmholtz approaches to colour vision. The effects of chromatic adaptation on the spectral response of the achromatic and two chromatic channels are discussed from the point of view of information theory. It is argued that adaptation serves as a dynamic readjustment of these responses, necessary to meet criteria of efficient colour information transmission. The results are confronted with empirical observations to test the principles of the theory and the relation to other theories is discussed. Within the same framework the issue of trichromacy is discussed. It is argued that a broad class of typical colour spectra can effectively be represented by three significant degrees of freedom that make up a trichromatic system.

Color Perception↗
PubMed1983

Serial radionuclide assessment of doxorubicin cardiotoxicity in cancer patients with abnormal baseline resting left ventricular performance.

While previous studies have demonstrated that sequential radionuclide angiocardiography allows identification of patients at risk for development of congestive heart failure and prediction of the appropriate time for safe discontinuation of doxorubicin, these studies were based predominantly on patients with normal baseline left ventricular performance. This study addresses the use of doxorubicin in patients with abnormal left ventricular ejection fraction (less than 55%) prior to drug administration. Of 337 patients referred for evaluation of left ventricular performance prior to doxorubicin therapy during a 36-month period, 45 (13%) had abnormal baseline left ventricular performance determined by first-pass radionuclide angiocardiography. Sixteen patients had antecedent cardiovascular disease, and 16 patients had received thoracic radiation, while only four patients had both. Left ventricular ejection fraction in each of these subgroups was comparable. In 7 of 16 patients who only had a baseline determination of left ventricular function, doxorubicin was not administered because of a significant concern for the potential risk of doxorubicin cardiotoxicity. In the group of 29 patients followed sequentially over 3 to 15 months (mean, 6 months), there was no significant difference between baseline and final left ventricular ejection fraction (48 +/- 5 vs 47 +/- 9%, p = NS). Only in the 12 patients who received greater than or equal to 350 mg/m2 cumulative dose was there a small but significant fall in left ventricular ejection fraction (48 +/- 4 vs 43 +/- 8%, p less than 0.05). Only one patient developed congestive heart failure. This study demonstrates that doxorubicin can be administered safely to patients with abnormal baseline left ventricular performance using serial radionuclide studies as a means of monitoring therapy. Guidelines for doxorubicin therapy in these patients have been developed.

Adolescent↗
PubMed1983

Tomographic gallium-67 citrate scanning. Useful new surveillance for metastatic melanoma.

Conventional gallium scans are not useful to evaluate patients with metastatic melanoma. We evaluated a new method of tomographic gallium imaging. One hundred fourteen tomographic scans were obtained in a prospective surveillance study of 67 patients over a 3-year period. Scans were evaluated and compared to findings of independent clinical evaluations. Sensitivity of gallium identification of tumor involving peripheral lymph nodes and soft tissues, abdomen, mediastinum, and osseous sites was 68% to 100%; overall sensitivity of this technique is 82% with specificity of 99% in 570 organ system assessments. Analysis of discordant findings when a site was clinically occult but gallium-positive showed gallium uptake to be true-positive in six of seven lymphatic sites, three of three lung and mediastinal sites, six of six abdominal sites, but in no brain or bone sites. Gallium lesions identified by computed tomographic scans proved to be false-positive at one lymphatic and one bone site, and false-negative at four otherwise clinically evident lymph node and soft tissue sites, seven pulmonary sites, and four brain sites. Gallium tomographic scanning provides a composite assessment of melanoma and may eliminate the need for other studies.

Adult↗
PubMed1983

The technetium-99m-sulfur colloid angiogram in suspected gastrointestinal bleeding.

Dynamic radionuclide angiography (5-sec. images) with technetium-99m-sulfur colloid proved to be helpful in 5 patients who presented with gastrointestinal bleeding. In 2, intermittently bleeding hypervascular lesions were seen on dynamic but not on static images; in 2 others, the dynamic images demonstrated hypervascular lesions better than the static scans; and in 1, the radionuclide angiogram localized colonic bleeding more accurately because of rapid peristalsis of extravasated tracer. The addition of the radionuclide angiogram to routine scintigraphy for gastrointestinal bleeding may be crucial for identification of hypervascular lesions and precise localization of bleeding sites.

Adult↗
PubMed1983

Perfusion of nonventilated lung: failure of hypoxic vasoconstriction?

Alveolar hypoxia is a well established cause of regional vasoconstriction such that nonventilated segments are not perfused. The paradoxical situation of retained perfusion of nonventilated lung has seldom been discussed. Three clinical examples are illustrated. In each case coexistent chronic obstructive lung disease may have contributed to this unexpected finding by reducing pulmonary vascular capacity such that blood flow diversion from hypoxic segments was not possible.

Aged↗
PubMed1983

Problems in noninvasive imaging of pulmonary embolism.

The V/Q scintigram is the mainstay of pulmonary embolism diagnosis, but there are limitations, such as the need for sophisticated interpretation, the production of indeterminate readings, and the lack of specificity. The authors discuss these problems and the emerging techniques that may be more of a help to the radiologist faced with diagnosing pulmonary embolism.

Female↗
PubMed1982

Improvement in cardiac performance by oral long-acting theophylline in chronic obstructive pulmonary disease.

Although oral theophylline is a widely used bronchodilator in chronic obstructive pulmonary disease (COPD), its effects upon cardiac performance have not been fully established. The effect of slow release oral theophylline upon right ventricular and left ventricular ejection fraction was evaluated using first-pass quantitative radionuclide angiocardiography in 15 patients with COPD. After 72 hours of therapy, oral theophylline significantly increased right ventricular ejection fraction (42% to 48%, p less than 0.005). In 7 of 10 patients with depressed baseline right ventricular performance, including two with cor pulmonale, right ventricular ejection fraction normalized (greater than or equal to 45%). After long-term therapy, an average of 16 weeks, right ventricular fraction also increased (43% to 48%, p less than 0.005). Left ventricular ejection fraction improved significantly from 64% to 68% (p less than 0.05) at 72 hours and from 61% to 65% (p less than 0.025) after long-term therapy. These data indicate that oral theophylline produces a sustained modest enhancement of resting biventricular performance in COPD.

Administration, Oral↗
PubMed1982

Radionuclide assessment of left ventricular function in patients requiring intraoperative balloon pump assistance.

Twenty-three surviving patients who were weaned from cardiopulmonary bypass with intraaortic balloon pump assistance returned for follow-up radionuclide left ventricular (LV) function and thallium 201 perfusion studies at a mean of 23 +/- 3 months following operation. It was found tat despite profound intraoperative myocardial depression requiring intraaortic balloon assistance, 13 patients had no change (within 10%) in the resting LV ejection fraction compared with the preoperative measurement. Among all 23 patients, there was no difference between mean (+/- standard error of the mean) preoperative and postoperative resting LV ejection fraction (48 +/- 4 vs 46 +/- 4%, p = not significant [NS]). Only 11 patients had perioperative myocardial infarction documented by new Q waves in the electrocardiogram, by elevation of creatine kinase-MB fraction, or by defects on thallium 201 imaging not explained by documented myocardial infarction before operation. Overall, postoperative resting LV ejection fraction was not different from the preoperative value in patients with perioperative myocardial infarction (44 +/- 7 vs 47 +/- 5%, p = NS). Postoperative resting LV ejection fraction rose by greater than 10% compared with preoperative values in 4 patients (3 with aortic valve replacement), remained within the 10% limit in 9 patients, and fell by greater than 10% in 10 patients (7 with perioperative myocardial infarction). Only 4 out of 16 patients studied at follow-up with exercise radionuclide studies demonstrated a normal LV response to exercise (greater than 5% increase in LV ejection fraction). Thus, among survivors requiring intraaortic balloon pump assistance for weaning from cardiopulmonary bypass, LV performance at rest is frequently preserved. In addition, 11 of the 23 patients had evidence of perioperative myocardial infarction, indicating a component of reversible intraoperative LV dysfunction.

Adult↗
PubMed1982

The stripe sign: a new sign for diagnosis of nonembolic defects on pulmonary perfusion scintigraphy.

A total of 47 patients who underwent both lung ventilation-perfusion scintigraphy and pulmonary arteriography were evaluated for presence on the scintigram of perfusion defects that did not extend to the lung edge, leaving a peripheral parenchymal stripe (PPS) of perfused lung between the defect and the adjacent pleural surface. Scans were scored both with and without regard for the PPS according to probability of pulmonary embolism; these predictions were then compared with the official lung scan report given initially to the referring physician. Predictions were then verified by pulmonary arteriography. Of the 13 patients who showed one or more PPSs, four reports would have been more accurate using the revised criteria that included the "stripe sign." In this study, visualization of a PPS in an area of defect on a perfusion lung scan was extremely accurate for predicting absence of pulmonary emboli in the specific area of the stripe. Further studies that would be needed to confirm this finding are discussed.

Humans↗
PubMed1982

Scintigraphic perfusion patterns in patients with diffuse lung disease.

Perfusion scintigrams of 55 patients with radiographic evidence of diffuse lung disease were reviewed. Thirty-nine had acute and/or chronic changes caused by congestive heart failure, and 16 had diffuse reticulonodular disease. A normal or near-normal perfusion pattern was seen in 40/55 (73%), and this finding was equally common in the two groups. The authors conclude that perfusion scintigraphy is useful in excluding pulmonary embolism in patients with radiographic evidence of diffuse, symmetrical lung disease.

Adolescent↗
PubMed1982

Tomographic gallium-67 citrate scanning: useful new surveillance for metastatic melanoma.

Conventional gallium scans are not useful to evaluate patients with metastatic melanoma. We evaluated a new method of tomographic gallium imaging. One hundred fourteen tomographic scans were obtained in a prospective surveillance study of 67 patients over a 3-year period. Scans were evaluated and compared to findings of independent clinical evaluations. Sensitivity of gallium identification of tumor involving peripheral lymph nodes and soft tissues, abdomen, mediastinum, and osseous sites was 68% to 100%; overall sensitivity of this technique is 82% with specificity of 99% in 570 organ system assessments. Analysis of discordant findings when a site was clinically occult but gallium-positive showed gallium uptake to be true-positive in six of seven lymphatic sites, three of three lung and mediastinal sites, six of six abdominal sites, but in no brain or bone sites. Gallium lesions identified by computed tomographic scans proved to be false-positive at one lymphatic and one bone site, and false-negative at four otherwise clinically evident lymph node and soft tissue sites, seven pulmonary sites, and four brain sites. Gallium tomographic scanning provides a composite assessment of melanoma and may eliminate the need for other studies.

Adult↗
PubMed1982

Effect of antiarrhythmic drugs on In-111-labeled leukocytes: chemotaxis and adherence to nylon wool.

The influence of lidocaine (L) and procainamide (P) on the chemotactic ability and adherence to nylon wool of In-111-labeled human polymorphonuclear leukocytes (PMNs) was investigated. At the normal therapeutic levels of L (0.022 mM whole blood) or P (0.03 mM whole blood) no change in PMN function was observed. However, at and above five times the aforementioned blood levels of L, significant reduction in the chemotactic ability of PMNs was noted (p less than 0.005). The adverse effects of In-111 radiation appeared insignificant at all L or P concentrations during the 3-hr observation period. The labeled PMNs were resistant to the toxic effects of a higher concentration of P than that of L, and the reduction in PMN chemotaxis and adherence to nylon wool was not apparent until the P concentration reached 1.5 mM.

Cell Adhesion↗
PubMed1981

Current aspects of nuclear imaging in clinical oncology.

This presentation will focus on the recent developments in nuclear medicine that relate to diagnosis and staging in the cancer patient. The commercial availability of new Agar cameras as well as longitudinal tomographic scanning devices has improved gallium imaging significantly. This has enhanced tumor detection and resulted in better use of gallium scanning in the cancer patient. Areas of controversy have also developed. In particular, the question of whether or not the gallium scan can be used to avoid mediastinoscopy in some case of bronchogenic carcinoma will be detailed. Techniques in nuclear medicine must be carefully integrated with other noninvasive investigation such as CT and ultrasound. At Yale, the authors have gathered considerable data indicating the best way to interact nuclear medicine radionuclide scintigraphy of the liver with the ultrasound examination. Our approach to this problem for the detection of focal disease in the liver will be discussed. 99mTc-HIDA has been proven useful in a wide variety of biliary disorders. Use of scintigraphy in the evaluation of cholangio-enteric bypass procedures in the cancer patient will be reviewed.

Adenocarcinoma↗