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PubMed1978

Nutrient pathways to flexor tendons of chickens using tritiated proline.

The nutrient pathway to the flexor tendons within the digital flexor sheath of adult chickens was investigated using tritiated proline. There was no difference in the uptake of the radioactive tracer by free segment tendons (detached from blood vessels) and the intact tendon lying in synovium. The uptake of tracer by tendons isolated from the synovium (but with unaltered vascular attachments) was significantly less than by the intact tendons. Radioactive tracer not only diffused across the synovium into the tendon, but along the course of the tendon itself. There was no difference in the uptake of radioactive tracer by 2-week-old tendon grafts with and without adhesions.

Animals↗
PubMed1999

[Collection conditions of ECG-gated myocardial SPECT].

In ECG-gated myocardial SPECT, we evaluated the effects of data acquisition and imaging conditions on the parameters of left ventricular cardiac function by a phantom experiments and in patients (n = 50) and normal controls (n = 15). Data acquisition was performed under the following conditions: (1) matrix size, 64 x 64 or 128 x 128; R-R interval, 8 or 6 frames; (3) presence or absence of attenuation and scatter corrections; and (4) changes in the accumulation rate of the radioactive tracer (information content) in the myocardium. When the matrix size was 64 x 64 and an R-R interval was divided into 8 frames, end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF) were 98.30 +/- 13.74 ml, 44.20 +/- 7.45 ml, and 54.91 +/- 2.84%, respectively, for normal controls. These values were slightly lower than those under other conditions. When attenuation and scatter corrections were not performed, the values of the above parameters were even lower. In patients with high accumulation of the radioactive tracer in the liver affecting the myocardial area, the cardiac function parameters were markedly decreased. In phantom experiments in which a decreased accumulation of the radioactive tracer was assumed, the left ventricular volume increased.

Adult↗
PubMed1994

Pharmacokinetics from multiple intraosseous and peripheral intravenous site injections in normovolemic and hypovolemic pigs.

OBJECTIVES: To examine: a) the rate and extent of delivery of radioactive tracers to the central circulation from the tibial, medial malleolar, distal femoral, and humeral intraosseous sites, as well as from a peripheral intravenous site; and b) the end-tidal CO2 response to injected sodium bicarbonate at these sites. DESIGN: Prospective, descriptive study. SETTING: Animal laboratory at a university medical center. SUBJECTS: Twenty anesthetized and mechanically ventilated piglets were cannulated with 18-gauge bone marrow needles at intraosseous sites and 22-gauge Teflon catheters in peripheral veins. A 22-gauge angiocath was placed in the right carotid artery of each subject. Drug kinetics were studied in the normovolemic and hypovolemic (acute bleeding of 25 mL/kg) states. INTERVENTIONS: Sodium bicarbonate (1 mEq/kg) was injected into each of the three intraosseous and one intravenous sites with simultaneous monitoring of end-tidal CO2. A 10-min period for stabilization was allowed between injections. Aliquots of 99mtechnetium were injected at randomly selected sites and blood samples were obtained at 1.5-sec intervals via carotid artery for radioactive counts. Experiments were repeated after withdrawal of 25 mL/kg of blood. MEASUREMENTS AND MAIN RESULTS: Assessment by end-tidal CO2 monitoring after 1-mEq/kg injections of bicarbonate demonstrated a mean initial end-tidal CO2 increase at 12.8 secs and a mean maximal end-tidal CO2 increase of 8 torr (1.06 kPa), with no significant site differences noted. Radioactive tracer injections were detected in the carotid artery after 15.4 secs in normovolemic animals and after 21.4 secs in hypovolemic animals, with no significant site differences detected. The proportion of injected tracer at 2, 5, 10, 20, 30, and 40 mins identified no significant differences between various intraosseous and intravenous sites. CONCLUSIONS: Our study demonstrated similar rapid transit and proportion of bicarbonate and radioactive tracers, reaching the central circulation from multiple intraosseous sites and a peripheral intravenous site. This finding suggests that adjustments in drug dosage may not be required, using various intraosseous locations as an alternative to peripheral intravenous drug therapy.

Animals↗
PubMed1981

Detection of IgG antibodies against Bordetella pertussis with 125I-protein A.

A method for the detection of IgG antibodies against Bordetella pertussis is described, based on the principle of 'sandwich' radioimmunoassay. 125I protein A is used as radioactive tracer. The influence of amounts of antigen, antibody, radioactive tracer, incubation time and temperature were tested and the optimal conditions for the assay are described. The procedure offers a simple, quick, and sensitive method for detecting antibodies against B. pertussis. Application and limitation of the test are discussed.

Antibodies, Bacterial↗
PubMed1987

D-[3H]aspartate retrograde labelling of callosal and association neurones of somatosensory areas I and II of cats.

Experiments were carried out on cats to ascertain whether corticocortical neurones of somatosensory areas I (SI) and II (SII) could be labelled by retrograde axonal transport of D-[3H]aspartate (D-[3H]Asp). This tritiated enantiomer of the amino acid aspartate is (1) taken up selectively by axon terminals of neurones releasing aspartate and/or glutamate as excitatory neurotransmitter, (2) retrogradely transported and accumulated in perikarya, (3) not metabolized, and (4) visualized by autoradiography. A solution of D-[3H]Asp was injected in eight cats in the trunk and forelimb zones of SI (two cats) or in the forelimb zone of SII (six cats). In order to compare the labelling patterns obtained with D-[3H]Asp with those resulting after injection of a nonselective neuronal tracer, horseradish peroxidase (HRP) was delivered mixed with the radioactive tracer in seven of the eight cats. Furthermore, six additional animals received HRP injections in SI (three cats; trunk and forelimb zones) or SII (three cats; forelimb zone). D-[3H]Asp retrograde labelling of perikarya was absent from the ipsilateral thalamus of all cats injected with the radioactive tracer but a dense terminal plexus of anterogradely labelled corticothalamic fibres from SI and SII was observed, overlapping the distribution area of thalamocortical neurones retrogradely labelled with HRP from the same areas. D-[3H]Asp-labelled neurones were present in ipsilateral SII (SII-SI association neurones) in cats injected in SI. In these animals a bundle of radioactive fibres was observed in the rostral portion of the corpus callosum entering the contralateral hemisphere. There, neurones retrogradely labelled with silver grains were present in SI (SI-SI callosal neurones). Association and callosal neurones labelled from SI showed a topographical distribution similar to that of neurones retrogradely labelled with HRP. The laminar patterns of corticocortical neurones labelled with D-[3H]Asp or with HRP were also similar, with one exception. In the inner half of layer II, SII-SI association neurones and SI-SI callosal neurones labelled with the radioactive marker were much less numerous than those labelled with HRP. In cats injected in SII, D-[3H]Asp retrogradely labelled cells were present in ipsilateral SI (SI-SII association neurones). Their topographical and laminar distribution overlapped that of neurones labelled with HRP but, as in cats injected in SI, association neurones labelled with silver grains were unusually rare in the inner layer III.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

An automated liquid chromatographic plasma analysis of amino acids used in combination with positron emission tomography (PET) for determination of in vivo plasma kinetics.

Quantification of physiological processes measured with positron emission tomography (PET) requires an "input" function which can be the concentration of administered radio-tracer in plasma. Radioactive nuclides used in PET have short half lives (2-20 min) and a limited time is available for the PET investigation including analysis of the composition of the radioactive signal in plasma. Therefore, an automated method for the analysis and separation of beta-[11C]-L-5-hydroxy-tryptophan ([11C]-L-5-HTP), beta-[11C]-L-3,4-dihydroxy-phenylalanine ([11C]-L-DOPA) and L-[methyl-11C]-methionine and their respective metabolites in plasma was developed. A size exclusion exclusion column was used for isolation of the low molecular weight fraction. In the case of [11C]-L-5-HTP and [11C]-L-DOPA, the low molecular weight fraction was injected onto a liquid chromatographic system for separation of radioactive tracer from in vivo formed radio-labelled metabolites. The elution volume from the size exclusion column was 7.0, 5.0 and 3.5 ml for [11C]-L-5-HTP, [11C]-L-DOPA and L-[methyl-11C]-methionine, respectively. An interaction with the column matrix and the solutes was observed for both [11C]-L-5-HTP and [11C]-L-DOPA. The yield in the isolation step was > 98%. Separation of [11C]-L-5-HTP and [11C]-L-DOPA from their respective metabolites was performed with high-performance liquid chromatography with automated collection of fractions of the eluate corresponding to those of administered tracer and metabolites. The fractions were measured for radioactivity in a well counter.(ABSTRACT TRUNCATED AT 250 WORDS)

5-Hydroxytryptophan↗
PubMed2000

Determination of biokinetic parameters for ingestion of radionuclides of zirconium in animals using stable tracers.

Exposure to the radioactive isotope 95Zr, as in nuclear accidents, and to stable zirconium, due to its use in industry, has increased the interest in the biokinetics of this element. Information has been derived mainly from tests performed on animals by means of radioactive tracers. Due to the fact that extrapolation from animals to humans is always open to question, there is an increasing need of a methodology which allows data to be obtained directly from humans. The use of stable tracers, being ethically justifiable, is a powerful tool for providing this information. As two tracers of the same element must be utilized in order to evaluate gut absorption, an analytical technique which is capable of distinguishing and measuring simultaneously different isotopes of zirconium in biological samples is required. Preliminary tests on laboratory animals were performed in order to assess the feasibility of the double tracer technique combined with proton activation analysis.

Animals↗
PubMed1986

Studies of the renal excretion of the hydroxyl analogue of methionine by the chick.

Athens-Canadian Random Bred adult cockerels and chicks were used to compare the metabolism of the free acid form of the methionine hydroxyl analogue (HMB-FA) to L-methionine (LMET). The first experiment was to determine whether HMB-FA was excreted by the kidneys, thus reducing the amount available for protein synthesis. Fasted adult male chickens were given a single oral dose of HMB-FA or LMET containing a radioactive tracer. Urine was collected and analyzed for the amount of radioactive tracer present; blood samples were subjected to blood gas analyses to assess the physiological status of the bird. It was concluded that LMET was the major methionine analogue excreted from roosters dosed with either HMB-FA or LMET, and that HMB-FA was not excreted by the avian kidney. The second experiment was to determine whether the acid-base status of the diet influences the utilization of HMB-FA. Two levels of dietary LMET or HMB-FA and six levels of dietary base were fed to chicks in a complete 2 X 2 X 6 factorial design for a period of 20 days, after which weight gain and feed consumption were determined. The results indicated that the acid-base status of the diet can play a role in maximizing the gain of chicks fed HMB-FA. Optimal dietary conditions for comparing the efficacy of HMB-FA with LMET and the poor performance of HMB-FA in crystalline amino acid diets are discussed.

Acid-Base Equilibrium↗
PubMed1992

RP-30A: new tracer for detection of changes in testicular blood flow in rat torsion model.

RP-30A is a radioactive tracer being evaluated for the detection of regional myocardial blood flow. This study compares RP-30A to technetium 99m pertechnetate as radioactive tracers for the detection of testicular blood flow changes in early testicular torsion. The left testis of adult male Sprague-Dawley rats was subjected to either thirty or sixty minutes of 720 degrees torsion. Injections of RP-30A or 99mTc-pertechnetate followed by sacrifice and scintillation counting of the testes was performed. No significant difference was detected between the torted testes and the right control testes in both groups receiving 99mTc-pertechnetate and the thirty-minute group receiving RP-30A. The torted testes of the sixty-minute group receiving RP-30A revealed a significant difference (decrease) in uptake indicating that RP-30A may be a more sensitive tracer in detecting testicular blood flow changes in early testicular torsion.

Animals↗
PubMed2005

The in vivo degradation, absorption and excretion of PCL-based implant.

The in vivo degradation of poly (epsilon-caprolactone)(PCL) was observed for 3 years in rats. The distribution, absorption and excretion of PCL were traced in rats by radioactive labeling. The results showed that PCL capsules with initial molecular weight (Mw) of 66000 remained intact in shape during 2-year implantation. It broke into low molecular weight (Mw=8000) pieces at the end of 30 months. The Mw of PCL deceased with time and followed a linear relationship between logMw and time. Tritium-labeled PCL (Mw 3000) was subcutaneous implanted in rats to investigate its absorption and excretion. The radioactive tracer was first detected in plasma 15 days after implantation. At the same time radioactive excreta was recovered from feces and urine. An accumulative 92% of the implanted radioactive tracer was excreted from feces and urine by 135 days after implantation. In the mean while, the plasma radioactivity dropped to the background level. Radioactivity in the organs was all close to the background level confirming that the material did not cumulate in body tissue and could be completely excreted.

Absorbable Implants↗
PubMed1983

Theobromine metabolism and pharmacokinetics in pregnant and nonpregnant Sprague-Dawley rats.

The plasma kinetics of po administered theobromine (TBR) were determined in timed-pregnant (P) and nonpregnant (NP) Sprague-Dawley rats at doses of 5, 10, 50, and 100 mg/kg using TBR sodium acetate with 10 microCi [8-14C]TBR as a radioactive tracer. Since plasma radioactivity consisted of greater than 99% TBR and less than 1% metabolites as shown by high-performance liquid chromatographic (HPLC) methods, liquid scintillation counting was used to quantify plasma TBR. No dose-dependent kinetics were observed in mean TBR plasma half-life, volume of distribution, systemic clearance, area under the curve-dose normalized, or time to reach maximum plasma concentration in either P or NP rats. The kinetic parameters of P rats were strikingly similar to NP rats at all TBR dosage levels employed. Analysis of urinary metabolites by HPLC and a radioactivity monitoring system after a single po TBR dose of 5 and 100 mg/kg with 10 microCi [8-14C] TBR revealed similar qualitative metabolic patterns in P and NP rats. Compounds identified in the urine were TBR (39 to 62%), 6-amino-5-[N-methylformylamino]-1-methyluracil (20 to 32%), 3-methylxanthine and 7-methylxanthine (8 to 15%), 3,7-dimethyluric acid (5 to 10%), and 7-methyluric acid (5 to 7%).

Animals↗
PubMed1986

Quantitative determination of total and specific human IgE with the use of monoclonal antibodies.

We have used two monoclonal antibodies (BS17 and Le27) that recognize two different epitopes of the constant region of human IgE in order to determine the total and specific IgE contained in human serum. Both types of assay are based on classic PRIST and RAST procedures and involve one or two monoclonal antibodies labeled with 125I iodine. The performance of these two assays were compared systematically with those obtained with a commercially available polyclonal tracer. We first investigated the 125I-labeling conditions for monoclonal antibodies. In our hands the best results were obtained by use of a tracer of specific radioactivity close to 10 microCi/micrograms. We have been able to demonstrate that as a consequence of its limited affinity, the radioactive tracer is always incompletely bound to the solid-phase IgE. Nonetheless, the sensitivity of the assay is comparable to that obtained with the polyclonal antibody, since less than 0.5 IU/ml can be measured by the PRIST procedure. In contrast, the dilution curves obtained in the RAST with the monoclonal antibodies are very different from those observed with the polyclonal tracer. In fact, these curves are strictly parallel to the dilution curve and to the standard curve derived from the PRIST method, thus indicating that the monoclonal antibodies recognize all IgE equally well regardless of the way in which they are bound to the solid phase. On the basis of this observation, we propose a quantitative assay of specific IgE with the PRIST standard curve as reference. Our results demonstrate that this approach is indeed possible if high-capacity, solid-phase as well as long incubation times are used.

Allergens↗
PubMedDate not supplied

Evaluation of cerebrospinal fluid flow through a Pudenz 12 mm or a standard Rickham reservoir: phantom experiments.

We have investigated the assessment of fluid flow through a Pudenz and a Rickham shunt using radioactive tracer. Experimentally, the radioactivity clearance curve obtained, using either shunt, is defined by two exponents. The relationship between flow-rate (F) and clearance half-time (T1/2) of the first component is identical with the clearance formula (formula: see text) or log10(F) =-LOG10(T1/2) + LOG100.693V using the physical volume. The value of the second component in a Pudenz 12 mm and a standard Rickman reservoir is log10(F) = -1.3LOG10(T1/2) + 0.087 and log 10(F) =-1.8log10(T1/2) + 0.019 respectively. In clinical practice, the first component may not be recorded adequately because the interval between appearance of the first and second components is very short. To calculate the CSF flow, we recommend referring to the line of "radioactivity clearance half-time and flow-rate" of the second component instead of the calculation based on clearance formula using a physical volume.

Cerebrospinal Fluid↗
PubMed1975

Spontaneous reversal of portal blood flow: the case for and against its occurrence in patients with cirrhosis of the liver.

Because of its presumed serious clinical significance, we made an analysis of the evidence for and against the occurrence of spontaneous reversal of portal flow in cirrhosis of the liver. We examined the evidence obtained from manometric studies, radioactive tracer studies, radiologic studies, and actual measurements of magnitude and direction of portal blood flow. Concerning manometric studies, we introduced a physical analysis, based on first principles, which demonstrates that the occluded portal pressures cannot be used to construct a hydraulic gradient for portal flow. Similarly, we examined the weakness of the evidence derived from radioactive tracer and radiologic studies and, in the latter, the drastically opposite results reported by different investigators. Finally, we found that actual measurements of magnitude and direction of portal flow provide impressive evidence against the occurrence of spontaneous reversal of portal flow in cirrhosis. We conclude that unless new and convincing evidence is provided, it may not serve the best interests of medicine and of our patients to continue accepting spontaneous reversal of portal flow in cirrhosis as if it were a proven phenomenon.

Cineangiography↗
PubMedDate not supplied

Sentinel lymph node identification for patients with breast cancer using large-size radiotracer particles: technetium-99m-labeled tin colloids produced excellent results.

Sentinel lymph node (SLN) biopsies using radioactive tracers have been reported to detect the metastatic status of the axillary lymph nodes in breast cancer patients. However, the optimal radioactive tracer particle sizes remain to be determined. In this study, identification of SLNs with large radiolabeled tin colloid particles was evaluated. Seventy-five patients with T1-2, N0 breast cancer were enrolled. Two hours prior to surgery, 1 to 2.5 mL technetium-99m-labeled tin colloid particles were injected around the tumor under ultrasonographic guidance. Immediately before the operation, dye fluids were also injected around the tumor to increase the interstitial pressure. After axillary dissection, lymph nodes with x100 or more uptake of radioactivity than the mean of the other lymph nodes are considered to be SLN. All lymph nodes from the axillary dissections were pathologically investigated, and the characteristics of SLNs were evaluated. SLNs were clearly identified in 74 of 75 patients (98.7%). Of 37 patients without SLN metastasis, pathological investigation revealed no further involvement of the remaining non-SLNs. The SLNs tended to be larger in size, and more than 50% were located in the lower medial site of the axilla. This is the first study to show that SLNs could successfully be identified with radiolabeled tin colloid particles. When SLNs were negative for metastases, non-SLNs were always negative.

Breast Neoplasms↗