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At least 127 records · Page 7Linked to original sources

PubMed2003

Role of radioisotope renal scans in the choice of nephrectomy side in live kidney donors.

PURPOSE: We determined the role of radioisotope renal scans in the choice of nephrectomy side in potential live kidney donors. MATERIALS AND METHODS: The study included 300 consecutive potential live kidney donors. In addition to routine laboratory and radiological evaluation, a radioisotope renal scan with selective determination of glomerular filtration rate (GFR) of each kidney was performed for all donors. Results of the first 100 potential donors were used to standardize the technique and to show the normal difference in GFR of both kidneys due to technical and normal physiological variations. The subsequent 200 potential donors who underwent nephrectomy were considered the study group. In the study group kidneys with a GFR difference less than or equal to mean normal difference were considered equal in function. Disparity in function was considered if the GFR difference between both kidneys was greater than normal mean difference. RESULTS: Of the 100 control donors there was no difference between mean GFR +/- SD of the left and right kidney (57.7 +/- 9.09 vs 58.09 +/- 8.93 ml per minute, respectively). The disparity in clearance of both kidneys ranged from 0 to 14.25 ml per minute and averaged 6.12 +/- 0.42. This average difference represents 5.31% +/- 0.27% of average total renographic GFR. Based on control group results a disparity greater than 5.31% of total GFR was considered significant in the study group. Of the 200 study group donors GFR of both kidneys was comparable in 116 cases (58%), the left had better function in 49 (24.5%) and the right had better function in 35 (17.5%). Therefore, a total of 84 donors (42%) had disparity in function between both kidneys. In all these donors the kidney with less function was chosen for nephrectomy regardless of anatomical considerations such as multiplicity of renal arteries. In donors with comparable GFR in both kidneys the harvested kidney was essentially chosen on an anatomical basis. CONCLUSIONS: When renal function of 2 kidneys is similar or nearly similar, anatomical factors determine the side of the harvested kidney. When there is a significant difference in clearance value (greater than 6 ml per minute) the kidney with lower clearance is chosen irrespective of anatomical findings. Since this difference is expected in about 40% of healthy individuals, radioisotopic determination of split renal function should be an integral part of the preoperative evaluation of potential kidney donors.

Adult↗

PubMed1994

An improved non-radioisotopic reverse transcriptase assay and its evaluation.

We developed an improved, highly sensitive non-radioisotopic (non-RI) reverse transcriptase (RT) assay (RTA). While the original non-RI method previously reported made use of primer immobilization, our improved method was based on a primer-template immobilization procedure. We tested the template specificity, reproducibility and linearity of the new method in assays of human immunodeficiency virus type-1 (HIV-1) RT. The sensitivities of the method previously reported, the improved method and the sensitive radioisotopic (RI-) RTA were compared in assays of recombinant HIV-1 RT, partially purified HIV-1 particles, and the culture supernatant derived from HIV-1-infected cells. For each of these samples except the culture supernatant the improved method was the most sensitive. It appeared that the fetal bovine serum presented in the culture medium interfered with the assay reaction. The curve describing inhibition of the assay reaction by fetal bovine serum showed that the highest degree of sensitivity in the assay was obtained when the culture supernatant sample was diluted four times. With this degree of dilution, the sensitivity of the new method for assay of culture supernatant sample was still half that of the sensitive RI-RTA. Culture supernatants of five peripheral blood mononuclear cell samples obtained from HIV-1-seropositive carriers were assayed by both the improved method and the sensitive RI-RTA; and with each of the methods, however all virus-positive cultures could be detected. The improved non-RI RTA was considered especially useful for assay of culture supernatants for purposes of virus isolation because of its advantages of excellent sensitivity and lack of requirement for radioisotopes.

HIV Reverse Transcriptase↗

PubMed1974

Experience with a commercial kit for the radioisotopic assay of vitamin B12 in serum: the Phadebas B12 test.

The first commercial kit for the radioisotopic assay of vitamin B(12) in serum-the Phadebas B(12) Test produced higher values than the radioisotopic method of Raven, Robson, Walker, and Barkham (1969) and the Lactobacillus leichmannii microbiological assay. Its normal range was 300-1100 pg/ml and its reproducibility was similar to that of the other radioisotopic method. It should be possible to lower the results obtained by the Phadebas method by modifying its standard curve and to reduce the time taken for the assay by shortening its incubation period.

Anemia, Pernicious↗

PubMed1994

p53 expression in cultured cells following radioisotope labelling.

p53 inhibits division following cellular damage. Cultured cells were found to express p53 protein following pulse labelling with radioisotopes, even at low doses normally used for growth and metabolic labelling studies. Some stem cells are exquisitely sensitive to radiation and thus p53 may have evolved as a major regulator of stem cell function. Therefore any genetic damage may be able to induce p53 expression, which in turn will affect the biochemical outcome of many experiments by both cell cycle arrest and other mechanisms. In some cases the use of radioisotopes may directly change the results of the experiment. This will require a careful re-evaluation of the current literature and experimental protocols utilising radioisotopes.

Cell Cycle↗

PubMed2000

Recent advances in the applications of radioisotopes in drug metabolism, toxicology and pharmacokinetics.

Radioisotopes have proven to be an indispensable tool in biomedical research and have played a pivotal role in the investigation of absorption, distribution, metabolism and excretion (ADME) properties of new chemical entities over the past several decades. The main advantage of using radioisotopes in studying the disposition of new drug candidates is the ease of detection and the achievement of high sensitivity, especially when compounds with high specific activity are used. The recent advances and applications of radioisotopes in designing and conducting ADME studies and its impact in the field of drug metabolism and pharmacokinetics are discussed in this review.

Animals↗

PubMed1999

[Present status of unsealed radioisotope therapy in Japan based on the nation-wide questionnaire].

In Japan, clinical application of unsealed radioisotopes is strictly regulated. Especially in the field of therapy, we are allowed to use only Na131I at present. Under such circumstances, the present status of therapeutic nuclear medicine in Japan was surveyed by means of a nation-wide questionnaire, conducted in 193 hospitals. Then, 113 hospitals replied to such questionnaire (recovery rate: 58.5%), and it was found that in 77 hospitals, radioisotope therapy is being performed for Graves' disease and/or thyroid cancer. The questionnaire covered the following points: for Graves' disease the basic strategy of 131I therapy, its indications, absorbed doses planned to be given, whether the therapy had been conducted on outpatient basis or in-patient basis, method of thyroid weight estimation, interval of administration in case of multiple doses, number of patients treated per year (1996) etc., and for thyroid cancer--strategy for thyroid remnant, the doses to be given, the maximum doses permitted by the authorities in each hospital both per day and per year, handling of highly contaminated urine in each hospital, interval of administration in case of multiple doses, number of patients treated per year (1996) etc. Also questioned were dissatisfaction with the present regulation by the authorities and/or requests for the better daily work, if any. Based on the above questionnaire, the present status of unsealed radioisotope therapy in Japan was investigated.

3-Iodobenzylguanidine↗

PubMed1976

Electrophoretic separation of radioisotopically labeled mouse lymphocytes.

A new preparative method is described for the separation and direct electrophoretic comparison of the distribution profile of radioisotopically labeled cells. The cell populations to be compared are labeled separately with different radioisotopes (e.g., 51Cr and 99mTc) and mixed. The cell mixture is subjected to density gradient electrophoresis and the distribution of each radioisotope in the collected fractions is ascertained by differential gamma counting. In the case of uniform label uptake by the cells in each distribution, the radioactivity counts represent cell frequency. Nonuniform labeling allows useful comparisons only in terms of relative mobility distribution. Model experiments performed with 51Cr- and 99mTc-labeled mouse thymocytes and spleen cells are in general agreement with mobility distribution results obtained previously by free flow electrophoresis.

Animals↗

PubMed2003

Why and how to use radioisotopes in human nutrition research.

Tracer methodology using radioisotopes in human nutrition research has been the object of unjustified limitations in its use. These limitations have encumbered research studies where micronutrient and macronutrient deficiencies are prevalent. Stable isotope methodologies are expensive, including the cost of the isotopes, equipment and its maintenance, and are often fraught with serious pitfalls. We have been developing safe radioisotopic methods to study the metabolism of micronutrients, especially iron and zinc in the developing world. These should allow scientists everywhere to conduct their own research without having to depend on facilities and laboratories in the industrial world, and thus enhance productive collaborative research. All radioisotopic research must be subjected to strict safety criteria, based on scientific evidence of risk, but should not be hampered by unscientific fears. Examples on the use of radio and stable isotopes to study iron and zinc absorptions are given including the radiation exposure and risk calculations.

Costs and Cost Analysis↗

PubMed1980

[Radioisotope ventriculography for functional evaluation of the Ommaya Reservoir (author's transl)].

Thirty nine patients with diagnosis of meningeal leukemia, meningeal lymphoma and leukemia having high risk of meningeal involvement were treated with intraventricular administration of chemotherapeutic drugs via Ommaya reservoir. In all of those patients, radioisotope ventriculography was always performed with ytterbium-169 diethyltriamine pentaacetic acid (169Yb-DTPA) at 1 week after placement of the Ommaya reservoir. In the patients who had normal cerebrospinal (CSF) flow, majority of the radioactivity injected moved to cisterna magna and basal cistern at 4 hours after injection and to subarachnoid space of the cortical surface at 24 hours. Two cases of ventricular catheter occlusion were diagnosed by this method. Two cases of catheter tip misplacement were suspected with computed tomography and confirmed with radioisotope ventriculography. One of the misplacement cases developed focal leukoencephalopathy possibly due to high concentration of methotrexate (MTX) in the brain adjacent to the ventricular cathter. Two cases showed delayed CSF circulation, and the doses of MTX were decreased to be half of the ordinary dose (12 mg/M2 once a week) during initial phase of the treatment. The dose was increased after successful treatment of meningeal dissemination and restoration of the normal CSF flow. Radioisotope ventriculography might be quite useful for detection of the flow of materials placed into Ommaya reservoir. Routine use of this procedure may be helpful to prevent reservoir- and drug-related complications.

Cerebral Ventricles↗

PubMedDate not supplied

[Radioisotope diagnosis of kidney function in diabetes mellitus].

The results of the radioisotopic methods of the renal function study in 102 patients suffering from diabetes mellitus are presented. Age, type of the disease, its duration, and the therapy instituted were taken in consideration. Depending on the disturbances the patients were distributed in four groups. The radioisotopic methods permitted to reveal early preclinical renal function derangements in the diabetic patients. The necessity of radioisotopic methods in complex examination of the kidneys in diabetic patients, particularly with no clinical manifestations of the renal affection is discussed.

Adolescent↗

PubMed1993

Quantitation of renal function using radioisotopic techniques.

Radioisotopic methods are practical for clinical use because they do not require continuous intravenous infusion or urine collection. This obviously is of great advantage in infants and small children, in whom accurate urine collection is difficult, but the techniques apply to adults as well. The ability to determine individual kidney function is a major benefit. Accuracies of the radioisotopic techniques vary but generally are within clinically acceptable ranges. The need for accuracy and reproducibility can be balanced with the desire for speed and convenience when choosing among the different techniques. Methods that use plasma sampling provide greater accuracy and are recommended in cases of severe dysfunction, whereas methods such as Gates' camera method, which eliminates plasma samples, can be completed in minutes. Radioisotopic techniques are most useful in the ranges of mild to moderately decreased function, in which serum creatinine concentration is nondiagnostic, and although they are much less accurate at markedly low renal function levels, so is 24-hour creatinine clearance. In conclusion, radiopharmaceutical agents offer a wide array of possible techniques for simple, accurate, and noninvasive measurement of global as well as individual GFR and ERPF.

Glomerular Filtration Rate↗

PubMed1977

[Study of kidney function by radioisotopic methods in Balkan endemic nephropathy].

The authors studied the renal function in 80 patients with Balkan endemic nephropathy (BEN), 27 males and 53 females, aged from 29-67, by radioisotope clearance (EDTA--16 9yb and hippuran--131J) and isotope nephrogram (ING). The patients were subdivided into four groups according to the creatinine level: first group--creatinine up to 1,5 mg%, 20 patients: second group--creatinine from 1,6 to 8 mg%, 34 patients, third group--creatinine from 8,1 to 15 mg%--16 patients and in the fourth--with creatinine over 15 mg%--10 patients. The examinations revealed that radioisotope clearances, provide significant information about renal function with various stages of nitrogen decompensation. EDTA clearance, according to the authors, can detect the changes in glomerul filtration of patients with BEN at an early compensated stage. The authors compare the results obtained from the investigation of the glomerular filtration by creatinine and EDTA clearance and found the radioisotope clearance more accurate. The effective renal plasma flow in patients with BEN at the early stage of the disease, was established not to be disturbed. That provides grounds to admit that in BEN glomeruli are very likely damaged earlier as compared with the tubules. Isotope nephrogram, according to the authors, is not changed at the early BEN stages. The changes are most frequently bilateral in the advanced stages of the disease.

Adult↗

PubMed2001

Radioisotope studies of root activity and root-level interactions in tree-based production systems: a review.

This review focuses on the radioisotope methods used for studying the root activity patterns of woody perennials and root competition in multi-species cropping systems. 32P soil-injection is by far the most widely used method. The method is unique as it enables one to delineate the lateral and vertical spread of the absorbing roots. A system of classification of crop plants based on the concept of 'effective foraging space' has been developed. The scope and applicability of the radioisotope methods in different cropping situations as well as from the point of view of radiological safety were discussed.

Phosphorus Radioisotopes↗

PubMed1987

Choice of radioisotope in stereotactic interstitial radiotherapy of small brain tumors.

In stereotactic interstitial radiotherapy, small radioactive sources are placed within the brain tumor to deliver locally high radiation doses. The choice of the radioisotope depends upon the dose distribution around the isotope, energy of the emitted radiation, relative biological effectiveness, and finally, the cost and availability of the isotope. We have analyzed 198gold, 125iodine and 192iridium in terms of these four factors. Our results have shown that 125I is superior to the other two isotopes due to its soft X-rays and dosimetric as well as radiobiological properties. Unfortunately, it is the most expensive of these radioisotopes, and can be difficult to obtain in specific activities.

Brachytherapy↗

PubMed1982

Radioisotope antegrade pyelography in ureterovesical obstruction.

A radioisotope renal scan is commonly used for renal investigation and is especially useful in frequently encountered allergic patients for whom conventional IV pyelography could be hazardous. When retrograde pyelography is technically not feasible in such patients, radioisotope antegrade pyelography provides an effective means for diagnosing, localising and delineating the nature of ureteral obstructions. A case is described of post-operative ureterovesical obstruction with severe septic complications, requiring emergency nephrostomy. Radioisotope antegrade pyelography (nephrostography) with 99mTc-DTPA clearly demonstrated the obstruction and following ureteral reimplantation confirmed free outflow.

Female↗

PubMed1979

The particular usefulness of radioisotope methods in some benign bone diseases.

The authors have performed radioisotope examinations in 271 patients with various non-neoplastic bone diseases. According to their opinion, early diagnosis and follow-up of therapeutic results are the main characteristics which allow radioisotopes to play an important and irreplaceable role. They particularly emphasize the usefulness of radioisotope methods in femoral aseptic necrosis and Paget's disease.

Adolescent↗

PubMed1996

Detection of trace radioisotopes in soil, sediment and vegetation by glow discharge mass spectrometry.

The possibility for the determination of some radioisotopes of cesium, strontium, plutonium, uranium and thorium by glow discharge mass spectrometry (GDMS) in soils, sediments and vegetations is investigated. The preparation of samples is described as a combination of the use of a conductive host matrix and a secondary cathode in order to decrease the dilution effect of the blending material for the trace level determination and to gain a stable discharge. Effects of interferences arising from the nature of the conductive host matrix and of the secondary cathode on the sensitivity of the method are discussed. The determination of (137)Cs and (90)Sr has been attempted and the results obtained were in agreement with those from other analytical techniques. Accuracy, internal and external precisions have been also evaluated. GDMS is shown to be a helpful technique for the determination of radioisotopes in environmental samples. Radioisotopes can be determined according to the matrix of the sample (e.g. grass), also in presence of isobaric interferences. However, limitations still exist on the application of GDMS.

Journal Article↗

PubMed1983

Rapid measurement of drug release from temperature-sensitive liposomes by electron paramagnetic resonance and radioisotope techniques.

We have developed two new methods for quantifying drug release from temperature-sensitive liposomes. Large unilamellar vesicles were made by the reverse phase evaporation process. They contained a water-soluble electron paramagnetic resonance probe, trimethyl-4-amino-2,2,6,6-tetramethyl piperidine N-oxyl and the radioisotope cytosine-[3H]1-beta-D-arabinofuranoside in their aqueous compartment. Release of the electron paramagnetic resonance probe was measured by placing the liposomes in a solution of a spin label quenching agent, potassium ferricyanide, and monitoring the reduction in signal strength. The measurement of radioisotope released involved rapid ultracentrifugation of the liposomes after which the supernatant was tested for the presence of radioactivity. Both methods were found to be rapid and convenient ways of measuring drug release from temperature-sensitive liposomes and both methods gave comparable results. The radioisotope assay provides a direct measurement of drug leakage, whereas the electron spin resonance assay provides a continuous marker for liposome stability as a function of temperature.

Cytarabine↗