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PubMed1994

Rubidium chloride fuses split circadian activity rhythms in hamsters housed in bright constant light.

Chronotypic effects of rubidium (Rb) were examined in hamsters whose circadian activity rhythms had split into two components while they were housed in bright constant light. Seven of 12 hamsters receiving RbCl in drinking water for 10 weeks showed fusing of the components into an intact rhythm compared with none of 7 control hamsters (p = 0.016). Rb may modify coupling between circadian oscillators via reduced photic input to the suprachiasmatic nuclei. Alternative mechanisms include changes in potassium metabolism or endocrine function or behavioral changes that in turn alter circadian function. This normalization of a circadian anomaly by a putative antidepressant suggests that Rb may be valuable in strengthening coupling between oscillators in cases of human chronopathology, including those implicated in the etiology of some affective disorders.

Animals↗
PubMed1996

Hyperosmolar blood-brain barrier disruption in baboons: an in vivo study using positron emission tomography and rubidium-82.

Hyperosmolar blood-brain barrier (BBB) disruption remains controversial as an adjuvant therapy to increase delivery of water-soluble compounds to extracellular space in the brain in patients with malignant brain tumors. To understand the physiological effects of BBB disruption more clearly, the authors used positron emission tomography (PET) to study the time course of BBB permeability in response to the potassium analog rubidium-82 (82Rb, halflife 75 seconds) following BBB disruption in anesthetized adult baboons. Mannitol (25%) was injected into the carotid artery and PET scans were performed before and serially at 8-to 15-minute intervals after BBB disruption. The mean influx constant (K1), a measure of permeability-surface area product, in ipsilateral, mannitol-perfused mixed gray- and white-matter brain regions was 4.9 +/-2.4 microliter/min/ml (+/- standard deviation) at baseline and increased more than 100% (delta K1=9.4 +/-5.1 microliter/min/ml, 18 baboons) in brain perfused by mannitol. The effect of BBB disruption on K1 correlated directly with the total amount of mannitol administered (p< 0.005). Vascular permeability returned to baseline with a halftime of 24.0 +/- 14.3 minutes. The mean brain plasma volume rose by 0.57 +/- 0.34 ml/100 ml in ipsilateral perfused brain following BBB disruption. This work provides a basis for the in vivo study of permeability changes induced by BBB disruption in human brain and brain tumors.

Animals↗
PubMed1995

Short report: dispersal of Aedes aegypti in an urban area after blood feeding as demonstrated by rubidium-marked eggs.

Strategies for the control of Aedes aegypti during urban outbreaks of dengue or yellow fever assume that this species has a maximum flight range of 50-100 meters. Because Ae. aegypti distributes its eggs among several oviposition sites, we postulated that dispersal is driven by the search for oviposition sites, so an ovipositing female may have to fly much further than 50-100 meters to lay all of her eggs. We developed a method for marking Ae. aegypti eggs with a rare alkali metal (rubidium) and showed that in an urban area, oviposition activity in a single gonotrophic cycle lasts several days and covers an area at least 840 meters in diameter (55.4 hectares). We suggest that current practice for the control of dengue and yellow fever transmission by focal treatments with insecticides 50-100 meters around presumed or confirmed cases is unlikely to be effective. Moreover, source reduction (the elimination of breeding sites) may enhance dissemination of virus-infected mosquitoes by reducing the number of available oviposition sites.

Aedes↗
PubMed1999

Rubidium marking of Anopheles stephensi (Diptera: Culicidae).

Immature Anopheles stephensi Liston were reared in untreated water and water containing eight 2-fold dilutions of rubidium (Rb) from 1,000 to 7.8 ppm to determine the concentration that allowed reliable detection and produced the least toxic effects as measured by adult emergence, weight, and survival. The amount of Rb detected in mosquitoes increased positively with increasing concentrations in the rearing water. Concentrations > or = 31.2 ppm Rb in the rearing water provided high and consistent detection levels of > or = 3,500 ppm Rb/mg of adult mosquito. There were no adverse effects of Rb on the weights of mosquitoes. However, increased Rb concentrations in the rearing water were associated with decreased emergence and survival. After 8 d, percentage emergence from Rb concentrations of 0-31.2 ppm was > or = 50%. At day 21, Rb concentrations of 0-31.2 ppm showed < or = 29% reduction of female survival compared with controls. The recommended concentration for reliable Rb detection with minimal toxic effects in An. stephensi was 32 ppm.

Animals↗
PubMed1976

Determination of improved myocardial perfusion after aortocoronary bypass surgery by exercise rubidium-81 scintigraphy.

Practical and noninvasive means are needed for evaluating efficacy of coronary bypass surgery (CBS) in improving blood flow (CBF) to ischemic myocardium in coronary patients. Revascularization was assessed in 15 patients by pre- and post-CBS rest and exercise rubidium-81 myocardial images with a scintillation camera equipped with pinhole collimator and high-energy shield. Ischemic areas were detected by decreased 81Rb activity after exercise compared to rest. Before CBS all patients had exercise angina (EA), positive treadmill ECG (TECG), and abnormal exercise 81Rb scans. After CBS all 15 patients had increased physical activity before angina or completion of treadmill exercise with increased heart rate-blood pressure product (HRBP) (+ 63 +/- 3.2 X 10(2) bpm - mm Hg) in 14 of 15 patients indicating increased CBF; four had positive TECG, and five had EA. The increased HRBP in 14 patients was associated with improved post-CBS exercise 81Rb scans: six had normal patterns while nine were improved with less ischemic patterns. Further, lack of angina and increased exercise tolerance correlated closely with increased 81Rb myocardial perfusion. Thus pre- and postoperative rest and exercise 81Rb scintigraphy gives an accurate, noninvasive, objective approach for evaluation of CBF following CBS and demonstrates the usefulness of this revascularization procedure in coronary patients.

Coronary Artery Bypass↗
PubMedDate not supplied

Rubidium deficiency in dialysis patients.

BACKGROUND: Since dialysis has brought long-term survival to uremic patients, we can now speculate on more subtle problems derived from imbalance or sub-optimal regulation of some elements such as trace metals. We focused on the rubidium (Rb) status in dialysis patients (HD), as concerns about its possible deficiency have been raised. METHODS: Rb in uremic patients was evaluated by: A) serum concentration (graphite furnace atomic absorption spectroscopy) from blood samples of 70 patients on chronic hemodialysis (HD) in comparison with 75 controls; B) tissue concentration (neutron activation analysis) from autopsy or biopsy samples (20) of HD patients in comparison with 21 controls; C) in vivo intradialytic mass balance during standard bicarbonate dialysis in 8 HD patients. RESULTS: A) Serum Rb concentrations in HD patients significantly were lower than in normal controls (304 +/- 81 micrograms/L versus 350 +/- 74 micrograms/L p < 0.001, log-transformed 5.68 +/- 0.28 versus 5.84 +/- 0.20, p < 0.001). Univariate logistic regression analysis found a significantly higher risk of serum Rb < 250-300 and 350 micrograms/L in uremic patients than in controls (Odd ratios or 12.6, 95% CI 2.77-57.04; 4.0, 95% CI 1.92-8.4; 2.08, 95% CI 1.02-4.25, respectively). B) Rb was significantly lower in tissues of HD patients, including brain (2250 +/- 1520 ng/g versus 5490 +/- 1250 ng/g, p = 0.0002) than normal controls. C) Rb was transferred from the patients' blood to the dialysis bath during a standard bicarbonate dialysis session, giving mean intradialytic Rb removal of 4.0 +/- 1.1 mg/session. CONCLUSIONS: These results confirm that Rb deficiency may arise in uremic patients, and indicate that diffusive dialysis treatments allow Rb removal which, however, with a standard bicarbonate schedule does not seem to be any greater than that expected with normal urine output (20 mg/week). Further studies are needed to clarify the roles of many factors in this Rb deficiency, including the effects of uremia by itself, pre-dialysis factors (diet, impaired renal function and drugs), dialysis procedures (frequency, hours, diffusive/convective components) or other biochemical/clinical parameters (hemoglobin, body mass index, age). The finding of a Rb deficiency in uremia is important as it has a role in neurobehavioural functions, mainly as an antidepressant. As Rb deficiency may be implicated in central nervous system alterations which strongly influence the quality of life, we believe that monitoring serum Rb in uremic patients and clarifying the causal mechanisms of deficiency will facilitate future therapeutic approaches.

Adult↗
PubMedDate not supplied

Utilization statistics and diagnostic accuracy of a nonhospital-based positron emission tomography center for the detection of coronary artery disease using rubidium-82.

A retrospective analysis has been carried out to determine utilization and diagnostic accuracy of positron emission tomography of the heart with rubidium-82 at a nonhospital-based center. Utilization statistics were derived for the first 27 months of operation of the center from a total of 1,670 patients scanned. Diagnostic accuracy for detection of coronary artery disease was assessed using three readers, blinded to the clinical information, who read 225 rest and dipyridamole-stress scans of patients that had a coronary angiogram. Utilization statistics show that the center averaged 64 patients per month, 66% were males, 38% of the patients scanned had a coronary angiogram, 25% had a history of myocardial infarction, 12% had coronary artery bypass graft surgery, and 18% had percutaneous transluminal coronary angioplasty. Sensitivity was 82%, 96%, and 100% for myocardial regions perfused with greater than 67%, 84%, and 100% diameter stenosis, respectively. Specificity was 91% for all normal regions of the heart. Accuracy was 89%, 93%, and 93% for regions with greater than 67%, 84%, and 100% diameter stenosis, respectively. These results compare well with published results from major hospital based centers.

Ambulatory Care Facilities↗
PubMed1991

Lithium and rubidium activities on platelet aggregation.

Lithium (Li) has been shown to increase the platelet number after chemotherapy. The present paper suggests that Li may increase the platelet aggregation induced by sub-optimal concentrations of ADP. Conversely, rubidium does not modify platelet aggregation in the present experiments.

Adenosine Diphosphate↗
PubMed1990

A prospective comparison of rubidium-82 PET and thallium-201 SPECT myocardial perfusion imaging utilizing a single dipyridamole stress in the diagnosis of coronary artery disease.

The purpose of the present study is to prospectively compare myocardial perfusion imaging with rubidium-82 (82Rb) by positron emission tomography (PET) with thallium-201 (201Tl) imaging by single-photon emission tomography (SPECT) by recording both studies with a single dipyridamole handgrip stress, and reading both sets of images with the same display technique. In a series of 202 patients with previous coronary arteriography, the sensitivity, specificity, and accuracy of 82Rb PET were 93%, 78%, and 90% and for 201Tl SPECT 76%, 80%, and 77%, respectively. When 70 patients with previous therapeutic interventions were excluded, the remaining 132 patients showed a sensitivity, specificity, and accuracy of 95%, 82% and 92% for 82Rb PET and 79%, 76%, and 78% for 201Tl SPECT. The improved contrast resolution of PET resulted in markedly superior images and a more confident identification of defects.

Coronary Circulation↗
PubMedDate not supplied

Rubidium is a possible supporting element for bone marrow leukocyte differentiation.

In the present paper the possible role of rubidium (Rb) on leukocyte differentiation is evaluated. When the metal was added to human mononuclear bone marrow cells cultured for 14 days in soft agar, it was able to increase the number of clusters and to reduce the number of colonies. This activity depended upon the presence of conditioned medium. Rb induced a faster differentiation of HL 60 cells cultured in a medium able to promote granulocyte differentiation. The metal did not show any activity on continuously cultured HL 60. These data suggest that Rb is a supporting element for cell differentiation. Toxicity tests on rats are also reported.

Animals↗
PubMed1989

Rubidium (Rb) treatment of rats: biological effects and implications for psychiatry.

Experiments were carried out on rats in order to find out the implications for psychiatry of the basic biological effects of rubidium (Rb). The forced swimming test (FST), used to evaluate the effects on rats of treatment with Rb, was conducted after 1 or 3 mEq/kg Rb was given chronically or subacutely. The weight of rats treated with 1 or 3 mEq/kg Rb, once daily, was observed daily for two weeks. Rb levels in the blood and brain of rats treated with Rb chronically or subacutely were determined by atomic absorption spectrophotometry. The rectal temperature was observed at 30, 60, 90, 120, 180, and 240 min after injections of 1 or 3 mEq/kg Rb. The increase in the mean body weight of treated rats was almost the same as that of the control. The rectal temperature in rats treated with Rb showed a hyperthermic response. With both the 1 and 3 mEq/kg Rb treatments, Rb levels in the brains were significantly higher in the chronic experiments than in the subacute experiments. The experiments conducted to determine the effect of chronic and subacute treatment of Rb are hereafter termed 'chronic experiment' and 'subacute experiment' respectively. Almost the same significant difference was also observed in the Rb levels in the blood. In the FST, a decrease in the mean immobility time was not observed in either the subacute or the chronic experiments. Thus, antidepressant effects, as judged from the FST, were not observed although Rb did actually accumulate in both brain and blood.

Animals↗
PubMed1989

Economic analysis of clinical positron emission tomography of the heart with rubidium-82.

This report describes a cost analysis for clinical positron emission tomography (PET) of the heart using generator produced rubidium-82 (82Rb). Considered sequentially are the clinical problem, current noninvasive radionuclide methods, positron emission tomograph, and the cost of PET per study. Also analyzed are the costs of PET versus thallium imaging in the management of chest pain, for screening asymptomatic men at high risk for coronary artery disease and for evaluating myocardial viability after myocardial infarction or thrombolytic therapy. Noninvasive assessment of coronary artery stenosis and myocardial ischemia/viability in symptomatic or asymptomatic subjects remains a major medical problem because the sensitivity and specificity of thallium imaging are only 70-85% and 50-70%, respectively, in recent studies. Cardiac positron imaging has an accuracy for noninvasive diagnosis of coronary artery disease in symptomatic or asymptomatic patients with a sensitivity and specificity of 95-98%. It can also be used for assessing physiologic stenosis severity, for imaging myocardial infarction and viability, for assessing effects of interventions such as thrombolysis, percutaneous transluminal coronary angioplasty (PTCA) or bypass surgery on myocardial perfusion, metabolism or coronary flow reserve, for assessing collateral function noninvasively in man, and for diagnosing cardiomyopathy not due to coronary artery disease. Although the cost for cardiac PET with 82Rb may be modestly higher than for 201Tl, the greater diagnostic yield of PET results in comparable or lower overall medical management costs than no diagnostic tests/interventions and lower overall costs compared to thallium imaging for evaluating patients with chest pain, asymptomatic high risk males, and patients after acute myocardial infarction/thrombolysis for myocardial viability.

Adult↗
PubMed1986

The accumulation of myoinositol and rubidium ions in galactose-exposed rat lens.

When rat lens is incubated in 30 mM galactose overnight, the extent of accumulation of rubidium ions (Rb) and myoinositol (MI) are affected, as well as the Na-K ATPase activity. Rb accumulation and Na-K ATPase activity are only slightly affected compared to the dramatic drop in MI accumulation. These changes are completely abolished by sorbinil, which blocks polyol formation, or by rendering the galactose medium hypertonic to offset the osmotic effect of polyol formation. On the other hand, the addition of excess MI to the galactose medium had no effect on correcting these changes. The results obtained are consistent with the polyol-osmotic theory of sugar cataract formation.

Aldehyde Reductase↗
PubMed1988

Exploration of the clinical profile of rubidium chloride in depression: a systematic open trial.

Thirty-one female inpatient depressives underwent a systematic open trial with rubidium chloride, 180 to 720 mg/day. By week 2, at least two-thirds had improved significantly (p less than 0.01) as measured by standard rating instruments such as the Brief Psychiatric Rating Scale and the Hamilton Depression Scale. Regression analysis suggested that the retarded endogenous pattern was most predictive of positive response. Treatment-emergent symptomatology, such as diarrhea, polyuria, and excitement, was generally mild and rarely necessitated interruption of the trial. The authors conclude that this salt has shown sufficient clinical promise to warrant more extensive trials under double-blind conditions.

Adult↗
PubMed1987

The effect of mercurials on amino acid transport and rubidium uptake by isolated rat brain microvessels.

The present studies were undertaken to investigate the in vitro effects of mercuric chloride (HgCl2) and methylmercury chloride (CH3HgCl) on the uptake of [3H]alanine, [3H]phenylalanine, [3H]glutamic acid, [14C]alpha-methylamino-isobutyric acid, and Rubidium (86Rb), as well as on the activity of gamma-glutamyl transpeptidase (gamma-GTP) in rat brain microvessels. Similar patterns of inhibition of uptake by capillaries of amino acids and 86Rb were observed in the presence of both mercury compounds. Marked inhibition of uptake was seen at concentrations of 10(-5) and 10(-4) M of both compounds, but the uptake was not inhibited at concentrations less than 10(-5) M. Capillary gamma-GTP activity was not influenced by either HgCl2 or CH3HgCl, suggesting that this enzyme does not play any role in the transport of the amino acids studied in these experiments. The results indicate that the main toxic effect of mercury compounds is inhibition of amino acid transport. The concentration at which mercury exerts its inhibitory effect in this study is similar to that estimated to have been present in the brains of victims during the Minamata epidemic.

Amino Acids↗
PubMed1986

Positron imaging of myocardial infarction with rubidium-82.

Positron imaging provides tomographic images of regional myocardial perfusion but has required an on-site cyclotron. Rubidium-82 (82Rb) is a short-lived (T1/2 = 75 sec) positron emitter available from a generator. In order to determine the feasibility for its use to image acute myocardial infarction, 18 patients with transmural infarctions who had coronary arteriography were given 30-40 mCi of 82Rb intravenously and positron tomographic imaging was carried out within 96 hr after onset of symptoms. Nine simultaneous transaxial slices were obtained for each patient with a positron camera. Images were also reconstructed in a long-axis, short-axis, and three-dimensional display. One study could not be interpreted because of excessive lung activity. Fourteen normals were also studied. The infarct related artery determined by angiography was correctly diagnosed by positron imaging in all 17 patients as were all three prior infarcts by readers blinded to the clinical data. No defects were observed in normals or in noninfarcted myocardial regions. This study indicates that 82Rb should be useful for perfusion imaging in patients with acute myocardial infarction. The short half-life of 82Rb should make it ideal for providing serial assessment of perfusion in patients undergoing thrombolytic therapy.

Acute Disease↗
PubMed1978

[Effect of cesium, lithium and rubidium on several effects of morphine].

The effect of chlorous salts of cesium, lithium, and rubidium on the analgetic action of morphine (according to the vocalization test) and also on the pattern of the dependence on it (according to the so-called "two-bottle test") was studied. As shown, the salts under investigation decreased both the algesic reaction threshold and the duration of morphine-induced analgesia; cesium chloride proved most active in this respect. All the compounds studied decrease the morphine preference coefficient. The greatest effect was found in cesium chloride which decreased the morphine preference coefficient 40-fold as compared to the control.

Animals↗