2,548 research outputs found
STUDIES OF THE REGULATORY EFFECTS OF THE SEX HORMONES ON ANTIBODY FORMATION AND STEM CELL DIFFERENTIATION
The primary and secondary immune responses to thymus-dependent and -independent antigens were evaluated in normal male and female mice and in castrated male mice. Both IgM antibody production in the primary response and IgG antibody production in the secondary response were enhanced in females vs. males of equivalent age. Castration of the male converted this animal to a female in terms of responsiveness to the thymus-dependent group of antigens, while inducing equivalent or even greater enhanced responsiveness over the female to the thymus-independent antigen, polyvinylpyrrolidone. Further characteristics of the changes in lymphoid organs were determined in the castrated animal vs. normal males and females. It was shown that the spleen and thymus became markedly hyperplastic, the organ weights exceeding the female, which in turn were greater than in the male. The enhanced weight of the thymus was shown to be due to increased numbers of cortisone-sensitive cells, the absolute number of cortisone-resistant cells remaining equivalent to normal males and females. Thus, the increased thymic weight of the female also resided in the cortisone-sensitive population. Peripheral lymphocyte counts in castrated animals exceeded both normal males and females. Further experiments in gonadectomized males provided evidence that increased thymic cell activity per se played a role in enhanced response to thymus-dependent antigens, but that a thymic-derived hormone mediated the enhanced effect to the thymus-independent antigen in the castrated animal. The capacity for loss of androgenic hormone-producing tissue to generate enhanced differentiation of stem cells was denoted by experiments in which numbers of spleen colonies and uptake of 59Fe, employed as an index of hematopoiesis 1 wk after reconstitution of lethally irradiated castrated and normal recipients, were enhanced in gonadectomized male animals. Thus, in summary, changes in sex hormone levels exerted a marked influence on immune responsiveness and stem cell differentiation, by increasing numbers of functioning cells, by promoting cellular differentiation, as well as by promoting cellular function via hormonal effects
Assessment of the Barramundi Fishery in Queensland - 2002
The barramundi, Lates calcarifer, is an important target species of commercial, recreational and indigenous fishers across northern Australia. In Queensland stocks from the Gulf of Carpentaria and the east coast are managed separately. An assessment of both the Gulf and East Coast stocks are reported here
Fiber Optic Accelerometer With Centrally Supported Flexural Disk
PatentAn accelerometer or seismometer has an elastic disk
bearing a mass distributed peripherally around the disk.
The disk is supported for flexure and for isolation from
mounting strain by a stob centrally through the disk.
The accelerometer or seismometer has a pair of flat
spirals of optical fiber, each spiral being fixedly attached
to a corresponding disk side so that disk flexure lengthens
a spiral on one disk side and shortens a spiral on an
oppositely facing disk side and so that temperature differences
between the spirals are minimized. The pair of
spirals are connected as legs of a fiber optic interferometer
so that the interferometer provides an output corresponding
to the flexure. Several of the disks and asociated
pairs of spirals may be coaxially mounted to
provide increased sensitivity
Statistical methods for automated drug susceptibility testing: Bayesian minimum inhibitory concentration prediction from growth curves
Determination of the minimum inhibitory concentration (MIC) of a drug that
prevents microbial growth is an important step for managing patients with
infections. In this paper we present a novel probabilistic approach that
accurately estimates MICs based on a panel of multiple curves reflecting
features of bacterial growth. We develop a probabilistic model for determining
whether a given dilution of an antimicrobial agent is the MIC given features of
the growth curves over time. Because of the potentially large collection of
features, we utilize Bayesian model selection to narrow the collection of
predictors to the most important variables. In addition to point estimates of
MICs, we are able to provide posterior probabilities that each dilution is the
MIC based on the observed growth curves. The methods are easily automated and
have been incorporated into the Becton--Dickinson PHOENIX automated
susceptibility system that rapidly and accurately classifies the resistance of
a large number of microorganisms in clinical samples. Over seventy-five studies
to date have shown this new method provides improved estimation of MICs over
existing approaches.Comment: Published in at http://dx.doi.org/10.1214/08-AOAS217 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
An investigation into the feasibility of myoglobin-based single-electron transistors
Myoglobin single-electron transistors were investigated using nanometer- gap
platinum electrodes fabricated by electromigration at cryogenic temperatures.
Apomyoglobin (myoglobin without heme group) was used as a reference. The
results suggest single electron transport is mediated by resonant tunneling
with the electronic and vibrational levels of the heme group in a single
protein. They also represent a proof-of-principle that proteins with redox
centers across nanometer-gap electrodes can be utilized to fabricate
single-electron transistors. The protein orientation and conformation may
significantly affect the conductance of these devices. Future improvements in
device reproducibility and yield will require control of these factors
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