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J Kropp

Publications and source records attributed to J Kropp.

At least 19 recordsLinked to original sources
PubMed1992

Incorporation of radioiodinated IPPA and BMIPP fatty acid analogues into complex lipids from isolated rat hearts.

Heart lipids were extracted by the Folch technique from Langendorff-perfused rat hearts after administration of 15-(p-[131I]iodophenyl)pentadecanoic acid and 15-(p-[125I]iodophenyl)-3-R,S-methylpentadecanoic acid. Techniques utilizing successive high performance liquid chromatographic (HPLC) analyses have been developed for the evaluation of the uptake of the tracers into neutral lipids and phospholipids of the rat hearts. Phospholipids were separated on a SiO2 column eluted with a gradient of acetonitrile/water (97.5/2.5) and acetonitrile/water (85/15) followed by separation of the neutral lipids on a C-18 reversed phase column with a gradient consisting of acetonitrile and 2-propanol/hexane (60/40) containing 1 N H2SO4 (5 microL/100 mL). Both tracers show the incorporation into the expected major lipid classes.

Animals↗
PubMed1992

Effects of head-down tilt and saline loading on body weight, fluid, and electrolyte homeostasis in man.

We studied the effects of head-down tilt bedrest (HDT) on body weight, fluid and sodium homeostasis. A fluid load session with rapid intravenous infusion of 22 ml/kg body weight (BW) isotonic saline was performed before, during and after HDT. During the pre- and post HDT periods the test subjects were given a diet containing 2600 kcal/day. The energy intake was reduced to 2000 kcal/day during HDT. Water intake was kept constant at 40 ml/kg BW, sodium intake was 2.2 mmol/kg BW and protein intake was 1.4 g/kg BW, while the daily fat and carbohydrate intake was reduced during the HDT period. As expected plasma volume and BW changed rapidly in the beginning of HDT and during early recovery. A total body water loss of 0.6 l was observed within the second day after tilting. Plasma volume was reduced by 16% during HDT-bedrest. The time course of the body fluid loss paralleled a decrease in body sodium that then remained fairly constant during the HDT-bedrest period (except for the interference caused by the fluid loading on day S06). A restoration of body fluid and body sodium content occurred early in the recovery period. Fluid loading caused a negative fluid balance of 0.6-0.9 l over a 48 hr period following infusion regardless of the phase of the HDT study. These results demonstrate that under our strictly controlled conditions 1) HDT alters body fluid and sodium balances, 2) a standard fluid loading causes a net negative 3-day fluid balance during all phases of the study.

Adult↗
PubMed1992

Technetium-99m-labeled anti-granulocyte antibodies in suspected bone infections.

The introduction of 99mTc-labeled anti-granulocyte antibodies seemed to provide advantages in comparison with formerly used in vitro methods to label autologous white blood cells for inflammation imaging. For this reason, we have undertaken a study to evaluate the clinical significance of this method. Thirty unselected patients with suspected bone infections were studied prospectively using the monoclonal 99mTc-labeled anti-granulocyte antibody. Twenty patients were referred with suspected infections of the peripheral bones (Group I), as well as 10 patients with suspected infections of the spine (Group II). Planar whole-body scans were performed 4 hr and 20 to 24 hr after administration of 500 MBq of the labeled antibody. Scans were considered positive for a bacterial (septic) infection when a focally increased antibody accumulation occurred. All scans were evaluated in blinded fashion by two experienced readers. Of the 20 studies from Group I patients, four false-positive scintigraphic findings were observed, and one false-negative, resulting in a specificity of only 64% and a sensitivity of 89%. In Group II (10 studies), five scans were true-negative, and five false-negative. For both groups, the specificity of the scintigraphic method was quite low (75%), and the sensitivity was also relatively low (57%). The results of this study demonstrate that in an unselected patient population in whom the diagnosis is not known, scintigraphy with 99mTc-anti-granulocyte antibodies is not a reliable method for detecting septic inflammatory lesions: In addition, use of this method excludes septic lesions with only a moderate likelihood (83% negative predictive value).

Adolescent↗
PubMed1991

[Scintigraphy with 123I-labelled fatty acids in coronary heart disease].

Forty-two patients (6 women, 36 men; mean age 55 [39-69] years), with one-, two- or three-vessel disease on coronary angiography, were studied using single-photon emission computer tomography with 15-p-123I-iodophenyl-pentadecanoic acid (IPPA), in order to evaluate this new method of demonstrating abnormalities of myocardial perfusion. The reference range for fatty acid turnover was determined in eleven controls (4 women, 7 men; mean age 41 [20-51] years) with no coronary stenosis. 185 MBq (5 mCi) of IPPA was administered intravenously during submaximal stress on a bicycle ergometer. Comparison between different regions of the tomograms revealed changes in fatty acid utilization typical of ischaemia. The sensitivity, specificity and predictive value of a positive result compared with coronary angiography were 95%, 89% and 93%, respectively, for the area supplied by the anterior interventricular artery, 92%, 91% and 93% for the circumflex branch and 89%, 91% and 90% for the right coronary artery. In 25 out of 31 patients (81%) with myocardial infarction, IPPA scintigraphy infarct localization agreed with the clinical findings. In two cases with unremarkable scintigrams left ventriculography showed hypokinesia, while in four cases neither method demonstrated any abnormality. There was one false-positive scintigram. IPPA scintigraphy has greater sensitivity and specificity than conventional nuclear medicine techniques in the demonstration of coronary heart disease.

Adult↗
PubMed1991

Single photon emission tomography imaging of myocardial oxidative metabolism with 15-(p-[123I]iodophenyl) pentadecanoic acid in patients with coronary artery disease and aorto-coronary bypass graft surgery.

A total of 29 patients with coronary artery disease (CAD) were investigated with 15-(p-[123I] iodophenyl)pentadecanoic acid (123I-IPPA) and sequential single photon emission tomography (SPET). Of these, 19 were studied after aorto-coronary bypass graft surgery. Some 13 patients without evidence of CAD served as a control group. Two SPET studies (early and late) were carried out within 45 min after intravenous administration of 200 MBq 123I-IPPA at peak sub-maximal exercise. Semi-quantification of uptake (related to perfusion) and turnover (linked to metabolism) was obtained by segmental comparison of oblique slices. Taking coronary arteriography as the "gold standard", 123I-IPPA scintigraphy had the following figures of merit for sensitivity and specificity in the diagnosis of CAD: for the left anterior descending artery territory 93% and 95%, for the left circumflex artery region 96% and 92%, and for the right coronary artery territory 77% and 92%, respectively. In all, 90% of the reperfused myocardial segments showed an improvement of uptake. Of these, 61% exhibited increased turnover after revascularization and 39% had pathologic turnover and thus a dissociation of improvement of perfusion and oxidative metabolism after surgery.

Adult↗
PubMed1991

Single photon emission computed tomography imaging of brain tumors.

Five radiotracers may be used for single-photon emission computed tomography (SPECT) imaging of brain tumors, namely technetium 99m pertechnetate, iodine-123 amphetamine derivatives, 99mTc-hexamethyl propylene amine oxime (HMPAO), thallium 201, and 123I alpha methyl tyrosine. Of these, pertechnetate may be considered as an "historical" procedure in brain tumors. However, there may be some equivocal cases in computed tomography or magnetic resonance imaging, where this procedure may still be used. In 1981, 123I isopropyl amphetamine was first used in brain tumors. Further studies showed, however, that IMP is not a useful tool for brain imaging in tumorous lesions. In 1986, 99mTc HMPAO appeared on the European market as a new tumor imaging agent. Some useful clinical results were obtained in patients before and after chemotherapy or radiotherapy. Thallium-201 was incidentally noted to accumulate in tumors. Using a threshold index, this agent can be used to distinguish low-versus high-grade lesions. The most promising agent for brain tumor SPECT is 123I-alpha methyl tyrosine, which shows potential to evaluate therapeutic procedures in brain tumors and may improve the differentiation between abscess and glioblastoma. The most promising aspect is the differentiation of tumor recurrences and scar tissue after brain surgery.

Brain Neoplasms↗
PubMed1991

[A comparison of 201Tl and 99mTc-MIBI in the follow-up of differentiated thyroid carcinomas].

12 patients with suspected recurrence of differentiated thyroid carcinoma following thyroidectomy, radioiodine therapy and, in some cases, external radiation therapy had 201Tl and 99mTc-MIBI scintigraphy. Except in one case, the findings concerning tumor localization and extension were identical. In all cases, locoregional lymph node metastases as well as osseous metastases were imaged by 201Tl and 99mTc-MIBI scintigraphy. MRI images obtained in all patients with suspected lymph node metastases revealed inoperable situations in 2 cases, whereas there was no correlation in 1 patient with positive 201Tl and 99mTc-MIBI scintigraphy. In contrast, the sensitivity of the two methods was relatively low in the detection of pulmonary metastases which were imaged in 1 out of 3 patients only. Discrepancies between 201Tl and 99mTc-MIBI were observed in a case of axillary lymph node metastasis. Although tumor-/background ratios were slightly higher for 201Tl, 99mTc-MIBI SPECT showed a higher imaging quality compared to 201Tl SPECT, especially in deeply situated tumor lesions. In conclusion, 99mTc-MIBI seems to be a promising alternative imaging agent in the follow-up of differentiated thyroid carcinomas.

Adenocarcinoma↗
PubMed1990

The effects of microsphere injections into the left atrium on the myocardial blood supply measured by thermal conductance probes.

Former experiments with thermal conduction probes showed signs of reductions or increases of myocardial perfusion shortly after injection of microspheres into the left atrium. Because of this, 210 measurements made during experiments on 66 dogs under propionyl-promazine/pentobarbital narcosis were newly analysed to verify a possible influence of microspheres (9 microns phi) injected into the left atrium on microcirculation. Using 20 additional dogs in identically performed experiments, the myocardial perfusion was measured using thermal conductance probes, following injections of isotonic NaCl solution (8 ml each), Ringer's solution, 5% glucose, the subject's blood, and isotonic NaCl solution mixed with the surface-active substance Tween 80. These suspension media were injected both with and without unlabelled microspheres (8.6 microns phi). The results led to the following conclusions: An obligatory decrease in the blood supply as the result of a mechanical blocking of capillaries by microspheres can be ruled out. The particles, the suspension media, and a suspension temperature not sufficiently adjusted to the body temperature induce reactive negative or positive changes in the microcirculation of the myocardium. This was found in approx. 45%-75% of cases. Solutions containing particles cause, in the majority of cases, a decrease. The suspension medium with the smallest effect proved to be isotonic NaCl solution. From the results one can conclude that artefacts may arise from the application of the heat conductance probe method when the temperatures are not perfectly matched. However, the injected solution itself can often lead to various reactions in microcirculation which may last up to 5 min. (ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Inhalation scintigraphy of the lung using the new ultrafine aerosol Technegas].

Evaporation of 99mTc-pertechnetate at about 2500 degrees C on a carbon surface generates an ultrafine aerosol of labelled carbon clusters. Its particle size of about 2-5 nm enables the aerosol to behave similarly to a gas regarding the ability of penetration. After inhalation, the radioactive particles adhere to the walls of the respiratory bronchioli and alveoli. The high concentration of the radioactivity in the argon carrier gas makes it possible to record a scintigram after a single deep breath. We studied four healthy volunteers and 79 patients including 34 with a tentative diagnosis of pulmonary embolism, 20 with bronchus carcinoma, and 15 with various other lung diseases. Ten of these patients were infants, the youngest being nine months old. All patients also had a perfusion scintigraphy.

Administration, Inhalation↗
PubMed1989

[SPECT in reversible symptoms of cerebrovascular diseases].

In 16 patients with reversible symptoms of cerebrovascular disease a HMPAO- and/or IMP-SPECT was performed. 12 of these patients were suffering from TIA, 4 from PRIND. Using HMPAO-SPECT in 8 out of 9 patients with TIA and in 1 of 2 with PRIND a hypoperfusion could be demonstrated; IMP-SPECT showed a pathological pattern in 3 of 5 patients with TIA and in none of 2 patients with PRIND. A semiquantitative evaluation showed a tracer accumulation reduced by 13 +/- 12% (HMPAO) and 8 +/- 7% (IMP), respectively, in the clinically involved hemisphere, compared to the contralateral side. In circumscript SPECT lesions a reduction by 21 +/- 8% (HMPAO) or 17 +/- 7% (IMP) was observed. The interhemispheric ratio from the HMPAO-SPECT showed a significant correlation to that of the 133Xe-rCBF measurement (r = 0.86; p less than 0.001). SPECT was positive in a higher percentage than TCT, Doppler sonography, radioangiography and 133Xe-rCBF measurement. This does not imply a higher specificity or sensitivity, because a slight inhomogeneous SPECT pattern may occasionally be observed even in normal persons.

Adult↗
PubMed1988

The effect of speed of deoxygenation on the percentage of aligned hemoglobin in sickle cells. Application of differential polarization microscopy.

We have used differential polarization microscopy, which provides images of linear dichroism, to measure the percentage of aligned hemoglobin (Hb) in 1086 deoxygenated red blood cells from subjects with sickle cell anemia. The percentage was found to be only slightly dependent on the speed of deoxygenation, thus showing that the percentage of aligned Hb was thermodynamically controlled (as has been found previously for the percentage of polymerized Hb in vitro). A slight decrease in the percentage of aligned Hb due to increasing speed of deoxygenation is primarily due to the increase in the number of cells containing no detectable aligned Hb. This class of cells was also the most variable between the different subjects studied. We were able to identify two other groups of cells that contain different numbers of domains of aligned Hb and show that these groups contain statistically different percentages of aligned Hb. The differences between these classes of cells was shown to be primarily due to different numbers of initial nucleation sites within each cell. It appears that the presence of preformed nucleation sites within cells at ambient oxygen tensions results in the thermodynamic control of aligned Hb polymer.

Algorithms↗
PubMed1987

Neurenteric cyst diagnosed by technetium-99m pertechnetate sequential scintigraphy.

Neurenteric cysts are rare congenital anomalies which present as mediastinal tumors associated with vertebra anomalies. Two-thirds of them are lined with gastric mucosa and are potentially life threatening. An exact differential diagnosis is difficult preoperatively but is absolutely necessary because of the grave prognosis if left untreated. We present a case in which [99mTc]pertechnetate sequential scintigraphy demonstrated gastric mucosa in the cyst and helped to confirm the diagnosis. The scintigraphic findings are correlated with radiologic, sonographic, and pathologic features.

Female↗
PubMed1986

[Results of fatty acid SPECT of the myocardium in coronary disease].

New developments in radiopharmacology of 123I-labeled metabolic tracers and single-photon emission computerized tomography (SPECT) allow now-a-days the assessment of parameters of cardiac energy metabolism in well-defined areas of the heart muscle. This article will present a brief outline of the basic pathophysiological principles used in the application of 123I-labeled phenyl fatty acids for the evaluation of CAD. First clinical results suggest an important application of cardiac fatty acid metabolic imaging to the detection, localisation and conceivable quantitation of myocardial ischemia, myocardial infarction and assessment of tissue viability. In addition to the diagnostic applications in CAD, cardiac fatty acid metabolic imaging may provide new perspectives to pathophysiological investigations of the coupling of local flow and substrate utilisation in vivo and the effect of therapeutic interventions.

Coronary Disease↗
PubMed1985

[Reduction of regurgitation in aortic and mitral insufficiency by captopril in acute and long-term trials].

Afterload reduction is an accepted therapeutic principle in the management of acute aortic (Ai) and mitral insufficiency (Mi). The question whether acute and chronic converting-enzyme inhibition by captopril has a beneficial hemodynamic effect in chronic Ai and Mi has been investigated in 17 patients with Ai and 10 with Mi. Ejection and regurgitation fraction (RF) were measured by radionuclide ventriculography (RNV) before, after 25 mg captopril and after 3-5 months of long-term treatment. The humoral response of the renin-angiotensin system (RAS) was quantified by analysis of angiotensin I and II. Captopril lowered under acute and chronic treatment RF in Ai and Mi by 32%. Angiotensin II levels decreased by the same order of magnitude. Acute and chronic vasodilation was followed by a distinct but well tolerated fall in blood pressure, especially in patients with Mi. These favourable hemodynamic effects of captopril make this therapy an adjunct but not an alternative to valve replacement.

Aortic Valve Insufficiency↗
PubMed1985

Captopril mediated decrease of aortic regurgitation.

The effect of captopril mediated afterload reduction on aortic regurgitation was investigated in 10 patients. Regurgitation was quantitated by means of the regurgitation fraction and the relation of regurgitant volume to end diastolic volume. These variables were derived from gated radionuclide ventriculography. After captopril treatment the blood concentration of angiotensin I rose whereas that of angiotensin II fell significantly. The conversion of angiotensin I to II was reduced to about 50% of the control value. Whereas blood pressure and heart rate did not change significantly, the regurgitation fraction and the regurgitant volume, normalised to end diastolic volume, were significantly reduced by captopril treatment. The ejection fraction remained essentially unchanged. These findings suggest that captopril reduces aortic regurgitation by reducing afterload.

Angiotensin I↗