1,611 research outputs found
Nitrogen Trichloride and Grignard Reagents
Nitrogen trichloride reacts with Grignard reagents to produce primary amines, ammonia, and a small amount of secondary amines. No tertiary amine was isolated. The percentage yield of these products obtained in a typical reaction with n-butyl magnesium chloride were as follows: n-butyl amine 35%, ammonia 15%, and di-n-butyl amine 3%
Changes in renal tri-iodothyronine and thyroxine handling during fasting
OBJECTIVE: Liver handling of thyroid hormones (TH) has been known to alter
significantly during fasting. This study investigates whether renal
handling of TH is also changed during fasting. METHODS: We measured
urinary excretion rates and clearances of free tri-iodothyronine (T(3))
and free thyroxine (T(4)) in healthy subjects prior to and on the third
day of fasting. RESULTS: During fasting, both mean T(3) and T(4) urinary
excretion decreased significantly to a mean value of 42% of control. Also,
total and free (F) serum T(3) concentrations declined significantly, but
serum T(4) did not change. Both FT(3) and FT(4) clearance decreased
significantly during fasting (62% and 42% of control). The fasting-induced
decrease in uric acid clearance correlated well with the decrease in FT(3)
clearance (r=0.94; P<0.001). Serum concentrations of non-esterified fatty
acids (NEFA) were significantly elevated during fasting. CONCLUSIONS: The
findings cannot be fully explained by the fasting-induced decrease in
serum T(3), a
How ownership rights over microorganisms affect infectious disease control and innovation: A root-cause analysis of barriers to data sharing as experienced by key stakeholders.
Genetic information of pathogens is an essential input for infectious disease control, public health and for research. Efficiency in preventing and responding to global outbreaks relies on timely access to such information. Still, ownership barriers stand in the way of timely sharing of genetic data from pathogens, frustrating efficient public health responses and ultimately the potential use of such resources in innovations. Under a One Health approach, stakeholders, their interests and ownership issues are manifold and need to be investigated. We interviewed key actors from governmental and non-governmental bodies to identify overlapping and conflicting interests, and the overall challenges for sharing pathogen data, to provide essential inputs to the further development of political and practical strategies for improved data sharing practices
Search for Possible Variation of the Fine Structure Constant
Determination of the fine structure constant alpha and search for its
possible variation are considered. We focus on a role of the fine structure
constant in modern physics and discuss precision tests of quantum
electrodynamics. Different methods of a search for possible variations of
fundamental constants are compared and those related to optical measurements
are considered in detail.Comment: An invited talk at HYPER symposium (Paris, 2002
Uptake of triiodothyroacetic acid and its effect on thyrotropin secretion in cultured anterior pituitary cells
The uptake of [125I]triiodothyroacetic acid ([125I]Triac) in anterior
pituitary cells was investigated and compared with that of [125I]T3.
Furthermore, the effects of Triac, T3, and T4 on TSH release were
compared. Cells isolated from adult male Wistar rats were cultured for 3
days in medium with 10% fetal calf serum. Uptake was measured at 37 C with
[125I]Triac (100,000 cpm; 120 pM) or [125I]T3 (50,000 cpm; 50 pM) in
medium with 0.5% BSA. In this medium, the ratio of the free fractions of
Triac, T3, and T4 was 1:8:1. Exposure of cells to 100 nM TRH for 2 h
stimulated TSH release by 80-110% (P < 0.001). Comparing total hormone
levels (1 nM to 1 microM), Triac and T3 were equally effective in reducing
this response, and both were 10-fold more effective than T4. The time
course (15 min to 4 h) of [125I]Triac uptake was similar to that of
[125I]T3, showing equilibrium after 1 h. Unlabeled Triac (1 microM)
reduced the uptake of [125I]Triac and [125I]T3 at all time intervals.
Expressed per pM free hormone, the cellular and nuclear uptake of
[125I]Triac were twice those of [125I]T3. The 15-min uptake of [125I]Triac
was reduced by incubation with 10 nM unlabeled Triac (35%; P < 0.001).
Maximum inhibition (56%; P < 0.001) was found with 10 microM Triac. A
similar effect was seen with 10 microM T3, T4, or
3,3',5,5'-tetraiodothyroacetic acid. Preincubation (30 min) and incubation
(15 min) with 10 microM oligomycin reduced the cellular ATP content by 51%
(P < 0.001), [125I]T3 uptake by 77% (P < 0.001), and [125I]Triac uptake by
only 25% (P < 0.001). The temperature dependence of [125I]Triac and
[125I]T3 uptake was the same. Preincubation and incubation with 10 microM
monensin (reduces the Na+ gradient) or 10 microM monodansylcadaverine
(inhibits receptor-mediated endocytosis) reduced 15-min [125I] Triac
uptake by 15% (P < 0.005) and 19% (P < 0.005), respectively. The data show
that 1) Triac, on the basis of the free hormone concentration, is more
potent than T3 or T4 in suppressing TSH secretion; and 2) the rapid uptake
of [125I]Triac by the anterior pituitary occurs by a carrier-mediated
mechanism that is only partially dependent on ATP or the Na+ gradient
Uptake of 3,3',5,5'-tetraiodothyroacetic acid and 3,3',5'-triiodothyronine in cultured rat anterior pituitary cells and their effects on thyrotropin secretion
We compared the uptake, metabolism, and biological effects of
tetraiodothyroacetic acid (Tetrac) and rT3 in anterior pituitary cells
with those of T4 and T3. Cells were isolated from adult male Wistar rats
and cultured for 3 days in medium with 10% fetal calf serum. Uptake was
measured at 37 C in medium with 0.1% BSA for [125I]Tetrac (200,000 cpm;
240 pM) and [125I]T4 (100,000 cpm; 175 pM) or with 0.5% BSA for [125I]rT3
(100,000 cpm; 250 pM) and [125I]T3 (50,000 cpm; 50 pM). The free fraction
of Tetrac was 1% that of T4 (in medium with 0.1 and with 0.5% BSA), and
the free fraction of rT3 was half that of T3. Uptake of the four tracers
increased sharply up to 1 h of incubation and then leveled off. Expressed
as femtomoles per pM free hormone, uptake at equilibrium was 1.16 +/- 0.16
(n = 6) for Tetrac, 0.15 +/- 0.01 (n = 6) for T4, 0.023 +/- 0.003 (n = 6)
for rT3, and 0.21 +/- 0.02 (n = 6) for T3. Cell-associated radioactivity
after incubation for 24 h with [125I]Tetrac was represented for 15% by
[125I]Triac; after incubation with [125I]T4 for 15-20% by [125I]T3, after
incubation with [125I]rT3 for 6% by [125I]3,3'-T2, while [125I]T3 was
still for 98% [125I]T3. Exposure of cells for 2 h to 100 nM TRH stimulated
TSH release by 90-135%. Tetrac was effective in reducing this response at
a free concentration of 0.05 pM, but rT3 was effective only at a free
concentration of 16 nM. A free Tetrac concentration of 5 pM was equally
effective as 50 pM free T4 in reducing the TSH response to TRH. In human
serum, Tetrac was exclusively bound to T4-binding prealbumin. The free
Tetrac fraction was 0.001% in control subjects and rose 2- to 12-fold in
patients with nonthyroidal illness. As uptake of [125I]Tetrac in the
pituitary was higher than that of T4 and T3, and it was more potent than
T4 in reducing TSH release, Tetrac may be of potential significance for
the regulation of TSH secretion in vivo
Redshift-independent Distances in the NASA/IPAC Extragalactic Database: Methodology, Content, and Use of NED-D
Estimates of galaxy distances based on indicators that are independent of cosmological redshift are fundamental to astrophysics. Researchers use them to establish the extragalactic distance scale, to underpin estimates of the Hubble constant, and to study peculiar velocities induced by gravitational attractions that perturb the motions of galaxies with respect to the "Hubble flow" of universal expansion. In 2006 the NASA/IPAC Extragalactic Database (NED) began making available a comprehensive compilation of redshift-independent extragalactic distance estimates. A decade later, this compendium of distances (NED-D) now contains more than 100,000 individual estimates based on primary and secondary indicators, available for more than 28,000 galaxies, and compiled from over 2000 references in the refereed astronomical literature. This paper describes the methodology, content, and use of NED-D, and addresses challenges to be overcome in compiling such distances. Currently, 75 different distance indicators are in use. We include a figure that facilitates comparison of the indicators with significant numbers of estimates in terms of the minimum, 25th percentile, median, 75th percentile, and maximum distances spanned. Brief descriptions of the indicators, including examples of their use in the database, are given in an appendix
Short-Term Trends in Bastardy in Taiwan
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68002/2/10.1177_036319908000500303.pd
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