Acute effects of estradiol infusion and naloxone on luteinizing hormone secretion in pubertal boys

We have shown previously in pubertal boys that testosterone (T) suppresses the nocturnal augmentation of luteinizing hormone (LH) secretion principally by decreasing LH pulse frequency. As T can be aromatised to estradiol (E2), and E2 effects on LH secretory dynamics may be separate from those of T, we examined the effects of acute E2 infusion on LH secretion in pubertal boys. Opioid receptor blockade has been reported to increase LH secretion after estradiol suppression in adult men, so we also examined whether naloxone might augment LH secretion during E2 treatment in pubertal boys. Starting at 1000 h, eight pubertal boys were given a 33 h saline infusion, followed 1 week later by an E2 infusion at 4.6 nmol/m2/h. During both infusions, four iv boluses of saline were given hourly beginning at 1200 h on the first day, and four naloxone iv boluses, 0.1 mg/kg each, were given hourly beginning at 1200 h on the second day. Blood was obtained every 15 min for LH, and every 60 min for T and E2, from 1200 h until the end of the infusion. Pituitary responsiveness to gonadotropin-releasing hormone (GnRH) was assessed after both infusions by iv administration of 250 ng/kg synthetic GnRH. Estradiol infusion increased the mean plasma E2 concentration from 23 +/- 4 to 46 +/- 6 pmol/L (P < 0.01) and suppressed mean plasma T from 4.9 +/- 1.4 to 3.0 +/- 3.5 nmol/L (saline vs. E2 infusion, P < 0.05). The overall mean LH was suppressed by E2 infusion from 3.7 +/- 0.5 to 2.2 +/- 0.4 IU/L (saline vs. E2 infusion, P < 0.01). LH pulse frequency was suppressed by 50%, whereas mean LH pulse amplitude was not different between saline and E2 infusions. Administration of naloxone did not alter the mean LH, LH pulse frequency, or amplitude during either saline or E2 infusions. Pituitary responsiveness to exogenous GnRH was similar during both infusions. These studies indicate that E2 produces its negative feedback in pubertal boys principally by suppression of LH pulse frequency, and naloxone does not reverse these suppressive effects. Thus E2 suppression of LH secretion is mediated by a decrease of hypothalamic GnRH secretion that is independent of endogenous opioid pathways.     

Formation of unilamellar liposomes from total polar lipid extracts of methanogens

Unilamellar liposomes were formed by controlled detergent dialysis of mixed micelles consisting of acetone-insoluble total polar lipids extracted from various methanogens and the detergent n-octyl-beta-D-glucopyranoside. The final liposome populations were studied by dynamic light scattering and electron microscopy. Unilamellar liposomes with mean diameters smaller than 100 nm were obtained with lipid extracts of Methanococcus voltae, Methanosarcina mazei, Methanosaeta concilii, and Methanococcus jannaschii (grown at 50 degrees C), whereas larger (greater than 100-nm) unilamellar liposomes were obtained with lipid extracts of M. jannaschii grown at 65 degrees C. These liposomes were shown to be closed intact vesicles capable of retaining entrapped [14C]sucrose for extended periods of time. With the exception of Methanospirillum hungatei liposomes, all size distributions of the different liposome populations were fairly homogeneous.     

Application of FELTRAN to NEACRP TN12 shipping cask benchmark

The finite element technique has received attention as a method of solving the Boltzmann equation in one, two and three spatial dimensions. In particular much work has been published concerning the geometrical flexibility, speed and accuracy of the method.

British Nuclear Fuels plc and Imperial College have collaborated in developing the finite element code FELTRAN to near production code status. FELTRAN solves the even parity form of the Boltzmann equation using a functional approach. The solution is found in one or two spatial dimensions using various orders of finite elements to specify the problem geometry. The angular dependence of the even parity flux is expressed using spherical harmonics. FELTRAN has been interfaced to ANISN formatted nuclear data libraries such as CASK and BUGLE. Anisotropic scattering may be specified to any order. Methods have been incorporated within the code to analyse systems with voids. FELTRAN is currently undergoing further development as part of a BNFL sponsored MSc research programme at the University of Salford.

The purpose of this paper is to consider the application of FELTRAN to a practical shield design problem. The OECD have adopted a benchmark experiment to measure the neutron and gamma ray radiation dose rates around a spent fuel transport flask. As part of an international collaboration the physical details of the flask design and contents have been provided to the nuclear industry. The objective is to perform an international comparison of the methods used in the analysis of cask shielding. BNFL is one of the companies involved, using the well established codes RANKERN and MCBEND. The FELTRAN calculations are performed using the same source and geometry data and equivalent angular flux expansions as for these two codes. FELTRAN is then compared with experimental and calculated results.     

Myosin isoforms in skeletal muscle in patients with chronic heart decompensation: distribution and correlation with with exercise tolerance

Chronic heart failure (CHF) is accompanied by a reduced exercise capacity, and the symptoms can be at least in part explained by qualitative and quantitative changes in the skeletal muscle composition and metabolism. We have correlated the myosin heavy chain (MHC) composition of the gastrocnemius in 20 patients with different degrees of CHF to expiratory gases measured during maximal cardiopulmonary exercise testing, NYHA functional class and echocardiographic parameters. MHC composition was determined electrophoretically in skeletal muscle needle microbiopsies and the percent distribution calculated by laser densitometry. There was no correlation between ejection fraction, left ventricular end-diastolic and end-systolic diameters and MHC composition. The percentage of MHC 1 (slow aerobic isoform) was positively correlated with peak VO2 (r2 = 0.5, p = 0.0004), ventilatory threshold (VT, r2 = 0.33, p = 0.008), and O2 pulse (peak VO2/HR, r2 = 0.40, p = 0.003). There was a negative correlation between MHC 2a and 2b (fast isoforms) and peak VO2 (r2 = 0.38 and 0.37, p = 0.004, respectively), VT (r2 = 0.2, p = 0.05; r2 = 0.34, p = 0.007, respectively) and O2 pulse (r2 = 0.39, p = 0.003; r2 = 0.23, p = 0.03, respectively). NYHA functional class was also negatively correlated with the same parameters (r2 = 0.2, p = 0.01; r2 = 0.4, p = 0.001; r2 = 0.34, p = 0.006, respectively) as well as with MHC 1 (r2 = 0.62, p = 0.0001). A positive correlation was found between NYHA functional class and MHC 2a and 2b (r2 = 0.46, p = 0.001; r2 = 0.41, p = 0.002, respectively). The severity of heart failure is paralleled by a shift of the MHC pattern toward the fast MHC 2b. The correlation between the magnitude of the MHCs shift, from the slow aerobic to the fast type, with both clinical parameters (NYHA functional class) and functional measurements (peak VO2, VT, O2 pulse) of exercise capacity seem to suggest that changes in skeletal muscle composition may play a key role in exercise tolerance in patients with CHF.     

High density packaging of the passive components in an automotive DC/DC converter

In this paper, a very high power density DC/DC converter module for automotive applications is investigated. The 14-V/42-V converter is specified to operate at a power level of 2.1 kW with a water cooled heat sink at 85/spl deg/C. The design and implementation of very high density passive components are discussed. Using the results of the passive component design, a prototype converter is built, achieving a final power density of 170W/in/sup 3/. The thermal performance of the passive components and the converter module under different electrical and thermal excitations is investigated and recorded. Results are presented over the full excitation range.     

Small Classes in the Early Grades, Academic Achievement, and Graduating From High School.

This investigation addressed 3 questions about the long-term effects of early school experiences: (a) Is participation in small classes in the early grades (K-3) related to high school graduation? (b) Is academic achievement in K-3 related to high school graduation? (c) If class size is related to graduation, is the relationship explained by the effect of participation in small classes on students' academic achievement? The study included 4,948 participants in Tennessee's class-size experiment, Project STAR. Analyses showed that graduating was related to K-3 achievement and that attending small classes for 3 or more years increased the likelihood of graduating from high school, especially among students eligible for free lunch. Policy and research implications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Biodistribution of radiolabeled monoclonal antibody E48 IgG and F(ab'')2 in patients with head and neck cancer

The amphibian pronephros is fated to die during early development. Pronephric cells undergo apoptosis and their function is replaced by the mesonephros, which becomes the functional kidney of the adult frog. Tadpoles of the northern leopard frog, Rana pipiens, were inoculated with a Lucké tumour herpesvirus (LTV) preparation. Most of the animals developed typical Lucké renal carcinomas at metamorphosis. Fewer developed carcinomas of the pronephric cell type. A pronephric carcinoma, rescued from apoptosis by the herpesvirus, was harvested from a post-metamorphic frog. The tumour was judged to be pronephric by its anatomical location (in the anterior part of the body) and because both mesonephric kidneys were intact and tumour-free upon removal of the tumour mass. A tumour fragment was fixed for histological examination, which confirmed that the tissue was a renal carcinoma. A further fragment was subjected to short-term culture in order to produce metaphase cells for cytogenetical analysis. Based upon silverstained nucleolar organizing region numbers, 14 of 15 metaphase cells were estimated to have the diploid number (2N = 26) of chromosomes and a karyotype was constructed which did not appear to differ from that of normal cells. A single cell was estimated to be tetraploid (4N = 52). This is the first report of chromosomes of a pronephric Lucké carcinoma. LTV replicates only in tumour tissue maintained in the cold. Because the frog in this study had been maintained in the laboratory at 22 degrees C for about 10 months, no viruses would have been detectable with electron microscopy. However, the presence of Lucké herpesvirus DNA was detected in tumour homogenates by polymerase chain reaction amplification of a 1.2 kbp Hind III restriction fragment of the LTV DNA. The presence of LTV DNA provided assurance that the rescued pronephric tumour was indeed a Lucké carcinoma.     

Poly(adenosine diphosphoribose) polymerase in peripheral blood leukocytes from normal donors and patients with malignancies

A two-color flow cytometric technique was developed to analyze poly(ADP-ribose) polymerase (PADPRP) in different individuals as a function of different physiological or pathological conditions and to establish the basis for determining whether enzyme deficiency may predispose to degenerative or malignant disorders. Peripheral blood granulocytes were devoid of enzyme activity, whereas mononuclear cells had variable amounts. PADPRP was highest in B cells, intermediate in T cells, and lowest in monocytes. This pattern of enzyme distribution and relative enzyme content of different types of cells was remarkably constant in normal subjects. In a series of 66 normal donors there was no significant biological variation in enzyme content as a function of age, race, or sex. The mean PADPRP values in peripheral blood mononuclear cells from 81 random patient samples obtained from an ambulatory oncology clinic did not differ significantly from normal subjects. However, groups of patients with breast cancer, lymphocytic malignancies, and esophageal cancer were observed to have below normal levels for peripheral blood mononuclear cell PADPRP.