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PubMed1997

Standards for radioiodines.

The National Institute of Standards and Technology, NIST (formerly National Bureau of Standards), is the nation's standards laboratory for civilian technology. NIST develops and maintains the nation's physical measurement standards for medical therapy and diagnostics. For the past 50 years, NIST has developed radioactivity Standard Reference Materials (SRMs) for radioiodines as well as decay-scheme data and test methods for use by the radiopharmaceutical manufacturers in their quality assurance and quality control at the point of manufacture. Methods of standardizing radioiodines include 4 pi beta-gamma coincidence counting (131I), 4 pi beta-gamma anti-coincidence counting (129I), 4 pi(e,x)-gamma coincidence counting (123I), and x-gamma sum peak coincidence counting (125I). NIST also uses sources standardized by these techniques to calibrate re-entrant ionization chambers (dose calibrators) and scintillation counters. SRMs of 131I and 125I are now available on an annual basis, and the long-lived 129I has recently been reissued.

Iodine Radioisotopes↗

PubMed1989

Total body potassium in aging humans: a longitudinal study.

Total body potassium (TBK) data calculated from longitudinal measurements over 18 y of 40K by whole-body counting of 564 male and 61 female healthy humans in a 2-pi liquid scintillation counter show little change in females younger than 50 y compared with males of those ages. Males show less TBK from 41 y onward as they age, with most rapid rate of loss between 41 and 60 y. Females have a rapid loss of TBK when they are older than 60 y; the loss is at a greater rate than that of males. Percent total body fat calculated from total body weight and lean body mass (LBM) derived from TBK document greater adiposity in females at all ages except ages 51-60 y when females are similar to males in change in percent fat per year per centimeter.

Adipose Tissue↗

PubMed1985

Lea blood group antigen on human platelets.

One- and two-stage radioligand assays were used to determine if human platelets possess the Lea antigen. Goat IgG anti-Lea antibody was purified by multiple adsorptions with Le(a-b-) human red blood cells, followed by affinity chromatography with synthetic Lea substance and labeling with 125I. Human IgG anti-Lea antibody was used either in a two stage radioassay with 125I-labeled mouse monoclonal IgG anti-human IgG as the second antibody or, alternatively, purified by Staph protein A chromatography, labeled with 125I, and used in a one-stage radioassay. Platelets from donors of appropriate red blood cell phenotypes were incubated with the antisera, centrifuged through phthalate esters, and assayed in a gamma scintillation counter. Dose response and saturation curve analysis demonstrate the presence of Lewis a antigen on platelets from Lea+ donors. Furthermore, platelets from an Le(a-b-) donor incubated in Le (a+b-) plasma adsorb Lea antigen in a similar manner to red blood cells. The clinical significance of these antigens in platelet transfusion remains undefined.

Blood Platelets↗

PubMed1982

Quantitation of radiolabeled compounds eluting from the HPLC system.

Three techniques are compared for the quantitation of various radiolabeled compounds eluting in the high performance liquid chromatography system. The first technique requires fraction-collecting the effluent from the HPLC, removing an aliquot to scintillation vials, and counting each fraction in a liquid scintillation counter. The second uses direct interface of the HPLC effluent to a flow-through radioactivity detector. The third involves quantitation of various radiolabeled compounds (proteins, steroids, and nucleotides) by splitting the effluent from the HPLC with an electronic steam splitter, thus diverting a present portion to the fraction collector for further chemical characterization and the remainder to the radioactivity flow detector for direct quantitation. A direct comparison of the chromatograms and the radioactivity counting efficiencies of these three techniques is presented.

Adrenal Glands↗

PubMed1983

Avidin-biotin radioimmunoassay for human rotavirus.

RIAs have a number of advantages which make them ideally suited for use in diagnostic microbiology. These advantages include sensitivity, objectivity, and versatility. However, the widespread application of RIAs has been limited by the instability of the reagents required for the performance of available solid-phase RIAs. The relatively short half-life of gamma-emitting isotopes is particularly a problem in cases where multiple antigens must be assayed, since distinct radioactively labeled reagents are required for each antigen to be measured. The problems associated with the use of standard RIAs could be avoided if the specific immunoglobulin directed at the antigen were labeled with a stable, nonradioactive isotope and if a generally reactive radioactive ligand were bound in a subsequent reaction. We have thus developed RIA systems that use immunoglobulin linked with biotin by reaction with biotin N-hydroxysuccinamide ester [1]. The biotin bound to the solid phase is subsequently measured by reaction with unlabeled avidin and 3H-labeled biotin (New England Nuclear Corp, Boston). The reaction is quantitated by the measurement of tritiated biotin in a standard scintillation counter. This reaction format takes advantage of the stability of biotin-immunoglobulin conjugates, the high affinity of biotin to avidin, and the fact that a single molecule of avidin can react with four molecules of biotin [2]. We devised an avidin-biotin RIA that uses goat and guinea pig antisera directed at human rotavirus and used it to detect rotavirus in 44 stool specimens obtained from children with acute gastroenteritis during the winter months [3].(ABSTRACT TRUNCATED AT 250 WORDS)

Avidin↗

PubMed2006

Thiolysis of poly(3-hydroxybutyrate) with polyhydroxyalkanoate synthase from Ralstonia eutropha.

Poly(3-hydroxybutyrate) (PHB) is synthesized from 3-hydroxybutyryl-CoA by polyhydroxyalkanoate synthase and hydrolyzed by PHB depolymerase. In this study, we focused on the reverse reaction of polyhydroxyalkanoate synthase, and propose the possibility that PHB can be degraded through a novel process, that is thiolysis of PHB with CoASH. Polyhydroxyalkanoate synthase of Ralstonia eutropha was incubated with 14C-labeled PHB and CoASH. The reaction mixture was fractionated by HPLC and then analyzed with a scintillation counter. The analysis revealed 3-hydroxybutyryl-CoA to be a product of the reaction. When NADP+ and acetoacetyl-CoA reductase were added to the reaction mixture, an increase in absorbance at 340 nm was observed. Native PHB inclusion bodies from R. eutropha also showed thiolytic activity. This is the first indication that polyhydroxyalkanoate synthase catalyzes both the synthesis and degradation of PHB, and that native PHB inclusion bodies has thiolytic activity.

Acyltransferases↗

PubMed1993

Effects of tumor necrosis factor-alpha on muscle-protein turnover in female Wistar rats.

BACKGROUND: Many cancer patients experience a wasting syndrome (cachexia) characterized by weight loss and abnormalities in carbohydrate, protein, and lipid metabolism. Recent experimental studies suggest that the development of cancer cachexia involves the host's production of inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha). PURPOSE: Our goal was to evaluate in rats the effects of an 8-day TNF-alpha treatment on overall protein metabolism in the liver, diaphragm, heart, and hind-leg muscles. METHODS: Four experimental groups corresponding to specific tissues (liver, diaphragm, heart, and hind-leg muscles) in female Wistar rats (100-150 g) were studied. Each group consisted of 25 TNF-alpha-treated and 25 control female Wistar rats. The TNF-alpha-treated rats were given intraperitoneal injections of recombinant-derived human TNF-alpha (0.5 mL) that was administered in two daily injections of 50 micrograms/kg (total dose of 100 micrograms/kg per day) for 8 days. Control animals followed the same injection schedule as the treatment group and received 0.5 mL of physiological saline instead of TNF-alpha. All rats were radioactively labeled with NaH14CO3 24 hours prior to TNF-alpha treatment. At 0, 1, 2, 4, and 8 days during TNF-alpha treatment, five rats per group were killed to measure the radioactive decay of labeled protein in specific tissues in order to estimate fractional protein turnover. During necropsy, the liver, hind-leg muscles (soleus muscle analyzed separately on 8th day only), heart, and diaphragm were rapidly weighed, and each was homogenized. Total protein content and total DNA were also determined. Total protein radioactivity and specific protein radioactivity (per milligram of protein) were evaluated for liver, diaphragm, heart, and hind-leg muscles. Radioactivity was counted in a liquid scintillation counter. Fractional rates of protein synthesis, protein degradation, total protein, and protein accumulation or loss were calculated. RESULTS: The TNF-alpha treatment administered to female Wistar rats for 8 days resulted in a transient decrease in food intake and body weight 24 hours after the beginning of the TNF-alpha treatment. In all types of tissues studied, TNF-alpha treatment resulted in increases in both the protein synthesis and protein degradation, with a greater increase in the protein degradation that resulted in a reduced protein accumulation following TNF-alpha treatment. This reduction in protein accumulation was directly associated with a decreased soleus muscle mass on day 8 of the treatment. CONCLUSIONS: Data suggest that TNF-alpha enhances muscle degradation in experimental situations where body weight loss is not apparent.

Animals↗

PubMed1998

Phorbol esters and synthetic diacylglycerols inhibit gamma-aminobutyric acid uptake in human spermatozoa: an effect mediated by protein kinase C?

Protein kinase C (PKC) and protein kinase A (PKA) are present in human spermatozoa and probably involved in the cascade systems leading to acrosomal exocytosis. We have investigated the possibility that these two protein kinases are involved in the regulation of gamma-aminobutyric acid (GABA) uptake in human spermatozoa. Swim-up preparations of human spermatozoa were exposed to phorbol 12-myristate 13 acetate (PMA) and 1-oleoyl-2-acetyl-sn-glycerol (OAG), which are activators of PKC, and to dibutyryl cyclic AMP (dbcAMP), a PKA activator, and subsequently incubated with radiolabelled GABA. Accumulated intracellular GABA was measured in a scintillation counter. Both PMA and OAG caused inhibition of GABA uptake while dbcAMP was without effect. The inhibitory effect on GABA uptake observed following exposure to the PKC activators could, however, not be counteracted by preincubation of the sperm samples with the PKC inhibitors staurosporine or H-7. The inhibitory effect on GABA uptake following addition of PMA was enhanced by prolonged exposure to the reagent and by increased capacitation prior to addition of the reagent. A small numerical increase in the percentage of acrosome-reacted cells was observed following exposure of the sperm cells to the highest concentrations of PMA, OAG and dbcAMP. No sperm motility parameters were affected by the treatment protocols as measured using computer-assisted semen analysis (CASA).

Diglycerides↗

PubMed1985

Quantitative analysis of in situ hybridization methods for the detection of actin gene expression.

We have implemented an efficient, quantitative approach for the optimization of in situ hybridization using double-stranded recombinant DNA probes. The model system studied was actin mRNA expression in chicken embryonic muscle cultures. Actin and control (pBR322) probes were nick-translated with p32 labeled nucleotides, hybridized to cells grown on coverslips, and quantitated in a scintillation counter. Cellular RNA retention was monitored via the incorporation of H3-Uridine into RNA prior to cell fixation. Over a thousand samples were analyzed, and among the technical variables examined were the fixation protocol, proteolytic cell pretreatment, the time course of hybridization, saturation kinetics, hybridization efficiency, and effect of probe size on hybridization and network formation. Results have allowed us to develop a reproducible in situ hybridization methodology which is simpler and less destructive to cellular RNA and morphology than other protocols. Moreover, this technique is highly sensitive and efficient in detection of cellular RNAs. Lastly, the rapid quantitative approach used for this analysis is valuable in itself as a potential alternative to filter or solution hybridizations.

Actins↗

PubMed2003

Combined radioguided parathyroidectomy and intravenous vitamin D therapy for the treatment of uraemic hyperparathyroidism.

Therapy combining radioguided parathyroidectomy (PTx) followed by intravenous maxacalcitol was given to a 50-year-old Japanese man referred for treatment of uraemic secondary hyperparathyroidism. After laboratory and radiological examinations, the patient underwent uncomplicated, successful surgery, but glands that had not been detected radiologically before the procedure became apparent with a scintillation counter immediately after the removal of the swollen gland. To prevent relapse of secondary hyperparathyroidism in the remaining glands, 10 microg of maxacalcitol was injected intravenously after each dialysis session. Following a minimally invasive radioisotope-guided PTx, the potential risk of relapse in the remaining glands has to be considered and intensive medical therapy should be instituted immediately after the operation. Further study needs to elucidate whether this treatment strategy can improve the long-term prognosis of patients with secondary hyperparathyroidism

Calcitriol↗

PubMed1999

Effect of selection for increased body weight on mitogenic responses in turkeys.

Mitogenic responses were examined for purified peripheral blood mononuclear cells (PBMC) and whole blood from individuals in a line (F) of turkeys selected for increased 16-wk BW and its corresponding randombred control (RBC2). The PBMC were isolated by centrifugation over Histopaque-1077 density gradient and tested for mitogenic responses to concanavalin A (Con A; 25 microg/mL) and phytohemagglutinin (PHA)-M; 100 microg/mL). For the whole blood assay, 6-wk-old poults from both lines were injected with inactivated Pasteurella multocida. Heparinized blood samples were collected prior to injection (0 d) and at 2, 4, 7, and 14 d postinjection. The diluted whole blood was then tested for the mitogenic responses to Con A (25 microg/mL) and PHA-M (25 microg/mL). The cultures were then pulsed with 3H-thymidine, and incorporation was measured using a liquid scintillation counter. There was a line difference in the mitogenic responses to Con A for PBMC and whole blood assays, but no line difference was observed in the response to PHA-M for both assays. For the purified PBMC assay, the F line had a lower response than its randombred control line (P < or = 0.05) to Con A expressed as either cpm or a stimulation index (SI; ratio of cpm for stimulated cells to the cpm for unstimulated cells). For the whole blood assay, the F line had generally lower SI values in the responses to Con A than the RBC2 line, with differences being significant at 0 and 2 d postinjection (P < or = 0.01) and at 14 d postinjection (P < or = 0.05). Genetic selection for increased BW might have affected the lymphoblastogenic potential of Line F that could affect disease resistance.

Animals↗

PubMed2006

Radiological studies in the hot spring region of Mahallat, Central Iran.

Five hot springs called 'Abegarm-e-Mahallat', located in the central part of Iran, have a mean water temperature of 46 +/- 1 degrees C and are used by visitors as spas. This is an area of high natural radiation background due to the presence of (226)Ra and its decay products in the deposited travertine (CaCO(3)). The mean concentration of (226)Ra in these hot springs, measured by the emanation method, ranged from 0.48 +/- 0.05 to 1.35 +/- 0.13 Bq l(-1). (222)Rn concentrations measured in the hot springs using a liquid scintillation counter ranged from 145 +/- 37 to 2731 +/- 98 Bq l(-1). Mean radon concentrations in air were 487 +/- 160 and 15.4 +/- 2.7 Bq m(-3) for indoor and outdoor, respectively. Radiation levels above that of normal background ( approximately 100 nGy h(-1)) were mainly limited to the Quaternary travertine formations in the vicinity of the hot springs. The results of environmental radiological studies in this region are presented and discussed.

Air Pollutants, Radioactive↗

PubMed1983

Ectopic testes: a heritable mutation in the King-Holtzman rat: androgen-binding protein in testes and epididymides.

Assays of androgen-binding protein (ABP) were carried out on testes, and epididymal heads and tails. This strain of rat exhibits a heritable mutation physically manifested as unilateral or bilateral maldescended (ectopic) testes. When present, they are found immediately cranial to the external inguinal ring in the superficial connective tissue on the ventral body wall. Charcoal-extracted cytosols were preincubated with 16 nM tritiated 5 alpha-dihydrotestosterone ( [3H] DHT) for 16-20 h at 4 degrees C and ABP was separated by polyacrylamide gel electrophoresis under steady-state conditions in the presence of 2 nM [3H] DHT. The gels were transversely cut into 2.1-mm thick slices and serially counted in a liquid scintillation counter. Binding of [3H] DHT to ABP was assumed to be 1:1 and the sum dpm of the ABP-containing slices corrected for background was expressed as pmol DHT bound/mg protein. Compared to normal male siblings, cytosol ABP levels on the ectopic side in unilateral ectopic rats were 78% and 93% lower than normal in epididymal heads and tails, respectively; whereas similar values for either side in bilateral ectopic rats were 88% and 99%. The above differences indicated in the cytosol ABP levels were significant at P less than 0.0001. On the other hand, in no case were differences in ABP levels in normal and ectopic testes in bilateral ectopic, unilateral ectopic and normal male rats significant. Also, epididymal heads and tails on the descended side of unilateral ectopic rats demonstrated no significant difference when compared to corresponding tissues in normal male siblings.(ABSTRACT TRUNCATED AT 250 WORDS)

Androgen-Binding Protein↗

PubMed1996

Anticholinesterase drugs stimulate phosphatidylinositol response in rat tracheal slices.

Some anticholinesterase (anti-ChE) drugs induce airway smooth muscle contraction. Whether anti-ChE drugs stimulate muscarinic receptors in airway smooth muscle as well as nicotinic receptors in neuromuscular junction is unknown. Since there is a direct relationship between phosphatidylinositol (PI) response and airway smooth muscle contraction induced by muscarinic agonists, we examined the effects of neostigmine, physostigmine, pyridostigmine, and edrophonium on PI response in the airway smooth muscle. The rat tracheal slices were incubated in Krebs-Henseleit solution containing LiCl and [3H]myo-inositol in the presence of carbachol, anti-ChE, or none of them. [3H]inositol monophosphate (IP1), which is a degradation product of PI response, was counted with a liquid scintillation counter. Inositol monophosphate accumulation was stimulated by neostigmine, physostigmine, and pyridostigmine in a dose-dependent manner, but was not affected by edrophonium. These increases were completely inhibited by atropine. The results suggest that neostigmine, physostigmine, and pyridostigmine stimulate PI response in the airway smooth muscle, which would cause bronchoconstriction, while edrophonium does not affect PI response.

Animals↗

PubMed1990

Intraoperative 133Xe cerebral blood flow measurements by intravenous versus intracarotid methods.

To document the comparability of cerebral blood flow (CBF) values determined by quantification of 133Xe washout after either intravenous or intracarotid administration, 12 patients undergoing elective carotid endarterectomy anesthetized with N2O/O2 and either isoflurane or halothane were studied. Scintillation counters were placed over the middle cerebral artery territory ipsilateral to the operated carotid artery. CBF was measured by the intravenous method during dissection of the carotid sheath and was calculated as the initial slope index from head washout curves collected for 11 min after injection of 10-20 mCi 133Xe in saline into a large vein. Immediately prior to carotid occlusion, CBF was determined by direct injection of 1 mCi 133Xe in saline into either the internal carotid artery or the common carotid artery with the external carotid artery occluded. For the intracarotid injections, the initial slope was calculated from the 1st min of washout. Data were analyzed by linear regression and analysis of variance. Values are expressed as mean +/- SD. The mean CBF for intravenous and intracarotid methods were both 29 +/- 10 ml.100 g-1.min-1. The correlation between CBF measured by intravenous and intracarotid methods was excellent and was described by the line y = x + 0.6, r = 0.92. We conclude that in the flow range studied, the intravenous technique may be applied to measure CBF in physiologically stable situations in which direct intracarotid injection is not feasible.

Anesthesia, Inhalation↗

PubMed1992

The responsiveness of cerebral blood flow to changes in arterial carbon dioxide is maintained during propofol-nitrous oxide anesthesia in humans.

Because it is common to manipulate PaCO2 during neurosurgery, it is essential to characterize the relationship between cerebral blood flow (CBF) and changes in PaCO2. The purpose of this study was to investigate the effects of propofol-N2O anesthesia on the CBF response to changes in PaCO2 in healthy subjects. In seven patients, anesthesia was induced with propofol 2.0-2.5 mg/kg and then maintained with a propofol infusion of 12 mg.kg-1.h-1 for 10 min and then 9 mg.kg-1.h-1 for 10 min and then was reduced to 3-6 mg.kg-1.h-1 for the remainder of the study. The subjects' lungs were ventilated with N2O in O2 (FIO2 0.3) to the end-tidal CO2 present before anesthesia, and then CBF was measured using intravenous 133Xe and ten scintillation counters, five over each cerebral hemisphere. ETCO2 then was increased to 50 mmHg and CBF measurement repeated; ETCO2 then was reduced to 30 mmHg and CBF measurement repeated. Concurrent with each CBF measurement, arterial blood was sampled for PaCO2 and hemoglobin measurement. CBF at normocapnia (PaCO2 42 +/- 2 mmHg) was 33 +/- 7 ml.100 g-1.min-1, which increased to 58 +/- 10 ml.100 g-1.min-1 and decreased to 19 +/- 4 ml.100 g-1.min-1 on increasing PaCO2 (53 +/- 4 mmHg) and decreasing PaCO2 (31 +/- 2 mmHg), respectively. Both the PaCO2 and CBF values were statistically different from those measured at any other time (CBF P less than 0.002, PaCO2 P less than 0.001). The slope of CBF versus PaCO2 was 1.56 ml.100 g-1.min-1.mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Carbachol, norepinephrine, and hypocapnia stimulate phosphatidylinositol turnover in rat tracheal slices.

BACKGROUND: The intracellular mechanisms involved in the alpha-adrenoceptor- or hyperventilation-induced bronchoconstriction remain unknown. Because there is a direct relationship between phosphatidylinositol (PI) metabolism and airway smooth muscle contraction induced by muscarinic agonists, the authors examined the effects of carbachol (CCh), norepinephrine (NE), and hypocapnia on PI turnover in the airway smooth muscle. METHODS: Rat tracheal slices were incubated in Krebs-Henseleit solution containing LiCl and [3H]myo-inositol in the presence of NE, CCh, or neither. The PCO2 in the solution was 36 +/- 3 mmHg (normocapnia), 19 +/- 2 mmHg (moderate hypocapnia), or 5 +/- 2 mmHg (severe hypocapnia), respectively. [3H]inositol monophosphate (IP1) formed was counted with a liquid scintillation counter. RESULTS: Basal IP1 formed was greater at severe hypocapnia than at normocapnia. Norepinephrine- and CCh-induced IP1 formation were also greater at hypocapnia than at normocapnia. CONCLUSIONS: These results indicate that CCh, NE, and hypocapnia stimulate PI turnover in the airway smooth muscle, which would cause bronchoconstriction, and hypocapnia also augments NE- and CCh-induced PI turnover, which could cause worsening of exercise-induced asthma and vagotonic asthma, respectively.

Animals↗

PubMed1982

Rate of diffusion of Solu-Medrol across the silastic membranes of breast prostheses-an in vitro study.

Many plastic surgeons have used steroids in breast prostheses in augmentation and postmastectomy reconstruction to prevent capsular contracture. The detection and incidence of complications have increased during the last several years. It is probable that the incidence of complications is related to two factors. First, clinicians have used the same doses in the smaller outer compartments of bilumen implants, giving a much higher concentration of steroid. Second, the more recent implants have thinner envelopes. Tritiated Solu-Medrol was placed in the outer lumen of the bilumen Heyer-Schulte, McGhan, and Surgitek prostheses, and in the only lumen of inflatable Mammatech and Heyer-Schulte prostheses. Diffusion of the Solu-Medrol from each of these identically sized prostheses into the surrounding saline bath was measured with a liquid scintillation counter. Diffusion rates provided concentration-dependent, as predicted by Donnan-Gibbs equilibrium. The silicon gel in bilumen implants was found to represent a second Donnan-Gibbs equilibrium and result in a lower diffusion rate because of affinity for the steroid.

Breast↗