AM Levels Research Articles

Studies on transformations of plutonium-239 and americium-241 in three major Indian soils

These studies were carried out to elucidate the behaviour of 239Pu and 241Am in three major soil groups of India, namely oxisol, vertisol-pellustert and entisol-haplaquent, over extended periods up to 400 days. The influences of soil characteristics, addition of organic matter and the chemical form of the radionuclides added to soils were investigated. A large fraction, ranging from 60 to 90% of the soluble radionuclides added as nitrates, underwent rapid conversion to precipitated hydrous oxides and hydroxides (0.3 M sodium citrate-dithionite extracts). At 3 h after contamination, ion-exchangeable forms (0.1 M MgCl 2 extracts) contained low levels of total added Pu (0.7 to 19.1%) and from 0.1 to 2.8% of total Am. These levels decreased further with increasing periods of incubation of up to 400 days. In contrast, on addition of chelated forms of radionuclides (as DTPA and EDTA complexes) up to 85% of total Pu, and about 50% of total Am were associated with 0.1 M MgCl 2 extracts 3 h post-contamination and significant amounts were extractable when maintained over extended periods of incubation of up to 400 days. The levels of Pu and Am associated with organic-bound forms (0.1 M NaOH extracts) did not show consistent trends, although in all three soil types the contents of these radionuclides in the insoluble residue fraction (including refractory compounds) generally increased with time of incubation.

Serum levels of Etretinate (Ro 10-9359) and its metabolite (Ro 10-1670).

ABSTRACTSerum levels of Etretinate (ET, Ro 10‐9359) and its metabolite (AM, Ro 10‐1670) were monitored during and after cessation of ET treatment in 12 patients with acquired disorders of keratinization who underwent the ET therapy at initial doses of 30 to 60 mg/day. Studies were made of the possible correlations between ET and AM serum levels, the appearance and disappearance of side effects, and elimination time profiles. Side effects appeared 1 to 2 weeks after the initiation of ET administration in all cases, although serum ET and AM levels at this time varied considerably, indicating individual differences in ET and AM susceptibility in the appearance of side effects. Serum ET and AM levels at the time of disappearance of side effects were lower than those at the time of appearance, suggesting some correlation of side effects with serum levels of ET, AM, or both. Serum level curves for ET and AM after cessation of ET administration were diverse. The maximum ET and AM elimination times from serum were 3 and 6 months, respectively.

Effects of anterior hypothalamic deafferentation and arcuate nucleus lesions on the feedback actions of estradiol benzoate on luteinizing hormone and follicle-stimulating hormone secretion in the female hamster.

This investigation studied theeffectsof anterior hypothalamic deafferentation (EFC), a monosodium glutamate (MSG)-induced lesion of the arcuate nucleus (ARC), or a combination of these two procedures on the regulation of luteinizing hormone (LU) and follicle-stimulating hormone (FSH) secretion in the chronically ovariectomized hamster given estradiol benzoate (EB) or oil. MSG-treated or control animals were ovariectomized and subjected to EFC or sham deafferentation (SFC) at 2-3 months of age. Three weeks later, animals were given a single injection of 50 �ig of EB or oil and the inhibitory and stimulatory actions of EB were determined by measuring LH and FSH by radioimmunoassay (RIA) of plasma obtained at 0900 h (AM) and 1600 h (PM) 3 days later. The tonic secretion of LH in SFC hamsters given oil was significantly reduced by EFC or MSG-induced lesions of the ARC. EFC in combination with these lesions did not further reduce LH levels in these animals. EB suppressed AM levels of LU in SFC animals and induced a PM surge which was prevented by EFC. Although EB did not further suppress AM levels of LH in the MSGtreated animals, a PM elevation was apparent and was prevented by EFC. In contrast to oil-treated animals, MSG-treated hamsters with EFC and given EB had significantly reduced levels of LH in both the AM and PM when compared to all other treatment groups. In contrast to LH, plasma FSH levels were not altered by EFC in control animals given oil, whereas FSH was reduced in MSG-treated animals with or without EFC. EB did not suppress AM levels of FSH in either control or MSG-treated animals, but did induce a significant surge of FSH in the PM in both groups of animals that was prevented by EFC. These results suggest that in the ovariectomized hamster, the ARC and anterior hypothalamus (AH) act as a functional unit in regulating the tonic secretion of LH, whereas the AH has little role in regulating tonic FSH secretion. The results also confirm previous reports suggesting that the ARC is involved in the tonic regulation of FSH secretion and that the AH is necessary for the stimulatory effects of estrogen on gonadotropin secretion.

An Early Iron-Age Layer of Glass Made from Plants at Tel Yin'am, Israel

AbstractA layer of vesicular blue-green glass occurs in the 12th century–B.C. level of Tel Yin'am. The glass was formed by fusion of plant parts rich in opal phytoliths, and is 75% SiO2 with a high K2O/Na2O ratio. Surviving plant structures (now converted to tridymite pseudomorphs) indicate that the material fused was from a grain of some type, perhaps wheat beards. The glass layer overlies nests of probable rodent droppings, now converted mainly to aragonite by the heat of combustion. We believe the glass to be the product of accidental burning of a layer of straw or chaff from threshing, though there is still a possiblity of a deliberate attempt at glass manufacture.

805 AMIKACIN (AM) AND TICARCILLIN (TI) AS EMPIRIC THERAPY IN FEBRILE NEOTROPENIC CHILDREN WITH CANCER

Efficacy and toxicity of Am (600 mg/M2/d IV) and Ti (12 gm/M2/d IV) as empiric therapy were evaluated in 46 febrile neutropenic (≤1000 PMNs/mm3) children with cancer. Documented infection (DI), clinically apparent infection (CA), possible infection (PI) and doubtful infections (DOI) were evaluated as follows: Bacterial pathogens identified were E. coli-5, P. aeurginosa-2, Klebsiella sp.-2, Serratia sp-1, Staph. sp.-5 and Strep. sp.-1. The 4 non-responders did not have documented infections. Blood urea nitrogen, creatinine, creatinine clearance, potassium and urine analysis obtained before and after antibiotic therapy showed no significant differences. Comparisons of mean peak/trough serum levels of Am obtained on day 2 (23.9/< 2μg/ml) and day 5 (24.2/< 2μg/ml) showed no accumulation. Two of 23 paired audiograms obtained early in the course of and after Am therapy showed transient mild high frequency hearing loss. Am and Ti have low toxicity, are well tolerated and are adequate empiric therapy for the febrile neutropenic child.

Diurnal changes in circulating myeloid progenitor cells in man.

To examine the diurnal changes in circulating myeloid progenitor cells (CFU-Cs), 15 normal human volunteers were studied. Total and differential peripheral blood leukocyte counts and CFU-C levels, using the in vitro agar culture method, were obtained at 8 AM, 11 AM, 3 PM, and 8 AM the following morning (in nine subjects) or only at 8 AM and 3 PM (in six subjects). On the average, an approximate twofold rise in circulating CFU C levels (per ml of blood) was found at 3 PM as compared to the 8 AM levels (P 0.002), and a smaller rise at 11 AM was found than at 8 AM levels (P 0.03). The ratios of CFU-C per ml of blood to mononuclear cells per ml of blood and neutrophils per ml of blood, respectively, were significantly higher at 3 PM than at 8 AM (p 0.002 and 0.004, respectively). The rise in CFU-C levels is usually significantly higher when compared to that in peripheral leukocyte counts.

Pituitary-adrenal function in women treated with low doses of prednisone

In order to assess whether long-term low-dose glucocorticoid administration results in suppression of the hypothalamic-pituitary-adrenal (H-P-A) axis, we examined the response of plasma cortisol to insulin-induced hypoglycemia in 23 women treated with prednisone (5 mg/day) compared with that in 19 untreated women. Basal AM levels of plasma cortisol were unaffected (mean +/- SE, 11.6 +/- 0.9 versus 11.2 +/- 0.7 microgram/dl). The plasma cortisol increment at 609 minutes after insulin-induced hypoglycemia was significantly smaller in the treated group than in the untreated group (6.7 +/- 1.0 versus 11.6 +/- 1.2 microgram/dl, p less than 0.005). Thirteen of 23 women (56.5%) in the steroid-treated group compared to one of 19 (5.3%) in the untreated group, showed a rise in plasma cortisol of less than 6 microgram/dl at 60 minutes. Furthermore, a similar reduction in the increment of plasma cortisol was also found in a subset of 10 women tested both before and during prednisone treatment. These results indicate that the concept that low doses of glucocorticoids are free of suppressive effects on H-P-A function is not justified.

Foliar Absorption of Transuranic Elements: Influence of Physicochemical Form and Environmental Factors

AbstractThe accumulation of plutonium (238Pu) and americium (241Am) in seeds and roots of Phaseolus vulgaris L. was investigated following foliar interception. Under controlled conditions plants were exposed to well‐characterized aerosols of fresh and aged Pu‐dioxide, fresh Am‐oxides, and Pu‐nitrate and Pu‐citrate complexes to assess the influence of chemical form and long‐term weathering on foliar absorption and subsequent translocation to other plant parts. Mean values for Pu and Am accumulated in seeds and roots 28 days after foliar exposure ranged from 9 to 427 × 10−4% of that deposited on foliage. These results and previous plant uptake studies indicate that the foliar route is potentially of equal importance to the soil‐root pathway as a route of transport. The levels of Pu and Am in seeds and roots resulting from foliar absorption and translocation from foliage were significantly affected by simulated rainfall and by the size of particles to which foliage was exposed. The influence of relative humidity and solution aging of oxides was less definitive; however, results suggest that either or both may influence foliar absorption and subsequent translocation of Pu and Am to seeds and roots.

Plasma cyclic AMP level in psychiatric diseases of childhood.

Determinations were made of the plasma cyclic AM level to examine its relationship with hyperkinesis (Werry-Weiss-Peters Activity Scale, WWPAS) and other features of mental disorders in 80 children, of whom 21 had early infantile autism, 15 hyperkinetic mental retardation, 12 minimal brain dysfunction and 32 Down's syndrome. In autistic and hyperkinetic mentally retarded children, the plasma cyclic AMP levels were higher than in normal children and were positively correlated with the WWPAS score. In children with minimal brain dysfunction, the plasma cyclic AMP level was significantly lower than in normal children and was not correlated with the WWPAS score. In children with Down's syndrome, the plasma cyclic AMP level was somewhat higher than in normal children.

Modes of regional chemotherapy

Injection of Am (2 mg/kg) into the hepatic artery or portal vein of dogs gives higher liver tissue levels (15.1 μg/g) than systemic intravenous administration (6.4 μg/g). This difference is increased by injection of the drug distal to the temporarily occluded hepatic artery or portal vein. Bolus injection of Am (1 mg/kg) into the femoral artery of dogs results in no detectable ipsilateral calf muscle levels and no subsequent macroscopic changes in the extremity. When injected distally to the temporarily occluded femoral artery, muscle drug levels were below the level of sensitivity of the fluorometric assay used, but all animals showed varying degrees of ipsilateral skin ulcerations and melanosis. With a tight tourniquet applied to the extremity proximally and maintained for 15 min after Am injection, 40-fold or higher muscle levels of Am were found, compared to those after simple intraarterial injection. There was fairly uniform drug distribution throughout the infused limb and minimal systemic leak. Severe ulcerations occurred after injection of 1 mg Am/kg with tourniquet application. With reduction of the dose to 0.25 and 0.125 mg/kg, erythema in the first 2 weeks and melanosis of the skin at 2 to 4 weeks occurred and involved the whole extremity. This technique of intraarterial injection of chemotherapeutic drug(s) with a proximal tourniquet has a potential clinical applicability in extremity tumors; high tissue drug levels are obtained and frequent administration is possible via an indwelling catheter. With the present development of the ability to assay microconcentrations of drugs in tissues, a critical reappraisal of the methods of regional infusion chemotherapy should now be possible, in association with the physiochemical characteristics of the drugs used.

Intermediate states of subfragment 1 and actosubfragment 1 ATPase: reevaluation of the mechanism.

The kinetics of the increase in protein fluorescence following the addition of ATP to subfragment-1 (SF-1) and acto-SF-1 have been reinvestigated. The concentration dependence of the rate obtained with SF-1 did not fit a hyperbola and at high ATP concentration, approximately 40% of the signal amplitude was lost due to a fast phase at the beginning of the transient (20 degrees C). At lower temperature (less than or equal to 10 degrees C) the fluorescence transient was biphasic, with a fast phase observed at high ATP concentration. These results indicate that there are two steps in the SF-1 pathway in which there is a change in protein fluorescence. Measurements of ATP binding and hydrolysis by chemical quench-flow methods indicate that the rate of ATP binding is correlated with the fast fluorescence step and hydrolysis is correlated with the slow fluorescence change. The SF-1 mechanism can thus be described as: (formula: see text) where M represents SF-1 and states of enhanced fluorescence are given by M (16%) and M (36% enhancement, relative to SF-1). Step 1 is a rapid equilibrium with K1 approximately 10(3) M-1. Tight binding of ATP occurs in step 2 and the loss of signal amplitude requires k2 greater than or approximately 1500--2000 s-1. The maximum observed fluorescence rate defines the rate of hydrolysis, k3 + k-3 = 125 s-1 (20 degrees C, 0.1 M KCl, pH 7.0). The steps in the mechanism correspond to the Bagshaw--Trentham scheme, with the important difference that the assignment of rate constant is altered. Formation of the acto-SF-1 complex gave a fluorescence enhancement of approximately 14% relative to SF-1. Dissociation of acto-SF-1 by ATP produced a 20--22% enhancement in fluorescence. There was no detectable fluorescence change during dissociation as evidenced by a lag in the fluorescence transient which corresponded to the kinetics of dissociation. The fluorescence change occurred at the same maximum rate as for SF-1 but there was no loss in signal amplitude at high ATP concentration. The kinetics of the fluorescence change corresponded to the rate of ATP hydrolysis, whereas tight ATP binding occurred at a much faster rate in approximate agreement with the rate of dissociation. Thus the fluorescence change in the acto-SF-1 pathway corresponds to step 3 in the SF-1 mechanism. The complete scheme can be described as follows: (formula: see text) where AM represents acto-SF-1. The tight binding step in the SF-1 pathway (k2) is sufficiently fast so that a similar step (k2') in the acto-SF-1 pathway could precede dissociation but the AM-ATP intermediate has not been detected. Following hydrolysis on the free SF-1, actin recombines with M.ADP.Pi or possibly with a second SF-1 product intermediate as proposed by Chock et al. (1976) and the fluorescence returns to the original AM level with product release.

Acebutolol in hypertension: Relationships between drug concentration and effects

Relationships between plasma concentrations of acebutolol (Ac) and its N-acetyl metabolite (Am) and pharmacological effects were studied in patients with essential hypertension. In an acute study (N=7) 400 mg oral acebutolol produced similar peak plasma levels of Ac and Am but Am had a longer half life. Group mean pulse and blood pressure fell significantly, although the size of individual blood pressure fall varied five-fold. There was no significant change in plasma renin activity. Correlations were found between drug concentration and β-blockade, assessed as % reduction in exercise tachycardia, and between both of these and the fall in post exercise systolic blood pressure. Similar comparisons were made in a chronic optimum dose study (N=11) both pre-dose and three hours post-dose. Am concentration was consistently higher than Ac at both times. Blood pressure was lowered equally pre-and post-dose when compared to placebo and plasma renin activity (PRA) was reduced on active treatment. Correlations were again shown between drug concentrations and β-blockade but none were found with changes in blood pressure or PRA. Between subject differences in blood pressure response could not be fully explained in terms of the other measurements but it is unlikely that pharmacokinetic differences are the major source of this variability.

Plasma cortisol and growth hormone responses to intravenous characterization.

Plasma cortisol and growth hormone (HGH) responses to venous catheterization were studied in 29 volunteer subjects. Repeat characterizations were performed in 18 individuals. Mean plasma cortisol levels were significantly elevated during the first hour of the initial catheterization experience. Morning and afternoon levels of cortisol were not distinguishable during the first catheterization, but PM levels were significantly lower than AM levels during the second catheterization experience. Growth hormone responses were much more variable than cortisol and were distributed logarithmically. Growth hormone responses tended to parallel cortisol responses during the first catheterization experience. Individuals who listed more symptoms in response to venipuncture and catheterization after finishing their first catheterization had significantly higher cortisol and growth hormone levels during this experience. These data suggest a definite endocrine adaptation to catheterization by the second or third hour of the experience.

The effect of surgical isolation of the basal hypothalamus on the nycthemeral rhythm of plasma corticosterone concentration in rats with heterotonic pituitaries.

The effect of total hypothalamic deafferentation on the nycthemeral rhythm of plasma corticosterone concentration was studied in rats with in situ or heterotopically transplanted pituitaries. Ten pituitaries from 21-day-old donors were transplanted in 120-g male recipients. Hypophysectomy was performed four weeks following transplantation. One week later the basal hypothalamus was surgically isolated. Post-transplantation AM and PM levels of plasma corticosterone were not different from those of unoperated controls. Following hypophysectomy there was a reduction in the amplitude of the plasma corticosterone rhythm. Surgical isolation of the basal hypothalamus, in both the heterotopic and in situ preparations, abolished the AM-PM differences of plasma corticosterone concentration. It is concluded that the nycthemeral rhythm of ACTH secretion of both in situ and heterotopic pituitaries requires the integrity of neural connections between the basal hypothalamus and the rest of the brain. (Endocrinology 91: 8...

A System for the Precise Calibration of Air Navigational Receivers

A new RF signal generator for the calibration of very high frequency omnidirectional radio (VOR) and instrument landing system (ILS) navigational receivers is presented. This new instrument improves the calibration accuracy of VOR angle and glide slope and localizer angle deviation by an order of magnitude over the calibration systems used up to now. The same order of magnitude improvement applies to the precision of AM level, phase angle settings, RF level, etc., and the stability of the simulated RF carrier in order to make the improved accuracy realizable. A new frequency lock technique allows to cover the RF frequency ranges continuously and still obtain a stability close to frequency synthesizer performance. The two major contributions to the improved performance are a linear and flat carrier amplitude demodulator using a two-diode voltage comparator and a new digital frequency lock technique. The carrier and modulation specifications are discussed which are necessary to achieve the improved accuracies. Measurement techniques are shown which are used to verify these accuracies along with the measurement results.

Effect of lithium-carbonate therapy on adrenocortical activity.

LITHIUM salts are now an increasingly used therapy for manic-depressive illness. They have been shown to be strikingly effective in the treatment of manic attacks and in the prophylaxis of recurrent manic episodes. Lithium salts may also have some prophylactic effect in diminishing the frequency of recurrent depressions.¹Their mode of action remains obscure, however, although effects on several biological systems have been noted.²Platman and Fieve³recently reported a frequent and substantial increase in the 8 AM levels of plasma cortisol in association with lithium ion therapy.³While the serum levels of lithium ion in these patients were not reported, they were all in the therapeutic range (above 0.6 mEq/ liter). To study further the possibility of a significant effect of lithium ion on adrenocortical activity, a group of patients were studied before and during lithium-carbonate therapy, utilizing isotopic measures of corti

Low-Temperature Optical Absorption of Americium Halides

Absorption spectra at low temperatures are reported for AmCl3, AmBr3, and AmI3. Bathochromic shifts have been generally observed in the series from the chloride to the iodide. These shifts are comparable to those observed in lanthanide halides. Hypersensitive transitions have been observed in AmI3. A number of new assignments of excited levels of Am(III) are proposed on the basis of intensity calculations. Electrostatic, spin–orbit, and configuration-interaction parameters were obtained by direct diagonalization and least-squares fitting to 29 observed levels for AmCl3. The parameter values in cm−1 are: E1 = 3582.8, E2 = 17.276, E3 = 334.30, ξ5f = 2593.3, α = 21.634, β = − 158.48, γ = 1240.4.

Energy Levels of Am IV in LaCl3

It has been possible to assign the 10 lowest energy levels of Am IV. By using these assignments and the complete spin—orbit matrices, a fit was obtained with 5f hydrogenic wavefunctions. This fit was then improved by using a fitting program and varying all four parameters. Comparison calculations using hydrogenic wavefunctions are made for Pu I. For Am IV the hydrogenic values are F2=268.6 cm—1 and ζ=2605 cm—1; the corresponding values for Pu I are F2=230.6 cm—1 and ζ=2174.6 cm—1.

The excitation of chromospheric HeI lines.

Relative intensities of singlet and triplet lines of Hei in the solar chromosphere allow a determination of bn exp E~n/Te~, where ~,` is the ionization energy of the level n and bn is a non- thermodynamic equilibrium factor. We have computed bn'5 for values of Te ranging from 10,0000 to 50,0000 for an idealized helium atom consisting of a continuum and IS level and the levels 25, 2P, and n = 3, 4 and 5 in the excited singlets and triplets. Computed and observed values of b exp E~n/Te~ for the triplets agree for all Te even though b varies with Te. The relative populations of the triplets are determined almost entirely by the radiative transitions, which, because of the low chromospheric opacity in the triplets, are independ~nt of the ambient Te. For the singlets, however, the occupation numbers of the excited levels depend critically upon R~, the net radiative transition rates to the ground state, which are functions of TO, the chromospheric opacity in the first resonance line. Thus, both Te and TO are parameters of the calculations, with TO, in turn, being a function of Te and ne. The electron density, ne, may be estimated from the absolute line intensities. In order to relate Re to TO, we use the source- function computations of Jefferies and Thomas (1959). Computed values of be exp E~n/Te~ and TO for the singlets agree satisfactorily with the empirical be exp E~.~/Te~ for Te 4o,ooo0~5o 0000 Uncertainties in atomic constants and Rn may permit a Te as low as 30,0000, but certainly not as low as 25,0000. At chromospheric densities, helium becomes predominantly Heii at Te 20,000, and predominantly Heiii at Te 55,ooo0. Chromospheric helium is, there- fore, predominantly Heii as suggested earlier by Athay and Menzel (1956). REFERENCES Athay, R. G. and Meuzel, D. H. 1956, Ap. J. 123, 285. Jefferies, J. T. and Thomas, R. N. 1959, Ap. J. 129, 401. National Bureau of Standards and High A ltitude Observatory Boulder, Colorado