342 research outputs found
The Inhibition of Arginase by Proline in Cell-free Extracts of Mouse Mammary Tumour
Arginase activity was found to be increased in precancerous nodules and mammary tumour when compared with the mammary gland. Proline inhibited the mammary tumour arginase and up to 30 mmo1 concentration the inhibition follows first order kinetics. Hill analysis of the inhibition of arginase by proline showed that proline inhibits the arginase activity by competing directly at the active site without conformational change. The inhibition may be of regulatory importanec, involving a feedback mechenism in mammary tumours
Fast computation by block permanents of cumulative distribution functions of order statistics from several populations
The joint cumulative distribution function for order statistics arising from
several different populations is given in terms of the distribution function of
the populations. The computational cost of the formula in the case of two
populations is still exponential in the worst case, but it is a dramatic
improvement compared to the general formula by Bapat and Beg. In the case when
only the joint distribution function of a subset of the order statistics of
fixed size is needed, the complexity is polynomial, for the case of two
populations.Comment: 21 pages, 3 figure
Fishery resources of the Exclusive Economic Zone of the northwest coast of India
ï»żFor well over two decades now, trawling operations,
both exploratory and commercial, have been going on
along the north-western region, off the Goa, Maha
rashtra and Gujarat coasts (15°-24°N). A historical
resimie of trawling in India has been given by Jayaraman
et al. (1959) in their account of the demersal fishery
resources of the shelf waters of this area, for the period
1950 to 1955. Similar accoimts on the distribution
patterns of major exploited fisheries for 1961-1967 and
1968-1970, have been given by Rao (1969) and
Rao et al. (1966, 1972) and Nair (1974). Apart from
the above accoimts on the fisheries in general, detailed
studies on the pattern of distribution and abundance
of individual species have been reported by Rao (1965â
Pseudosciaena' diacanthus), Kagwade (1973âPolynemus
heptadactylus), Deshmukh (1973âPomadasys hasta),
Kaikini (1974âLactarius lactarius) and Kagwade
{1966âprawns), as also (Prabhu and Dhawan, 1974)â
regional fisheries off Goa. The results of these
studies, based on bottom-trawling operations mostly
in regions less than 80 metres in depth, have given us a
fair knowledge of the demersal resources potential of
this region
Null cone preserving maps, causal tensors and algebraic Rainich theory
A rank-n tensor on a Lorentzian manifold V whose contraction with n arbitrary
causal future directed vectors is non-negative is said to have the dominant
property. These tensors, up to sign, are called causal tensors, and we
determine their general properties in dimension N. We prove that rank-2 tensors
which map the null cone on itself are causal. It is known that, to any tensor A
on V there is a corresponding ``superenergy'' (s-e) tensor T{A} which always
has the dominant property. We prove that, conversely, any symmetric rank-2
tensor with the dominant property can be written in a canonical way as a sum of
N s-e tensors of simple forms. We show that the square of any rank-2 s-e tensor
is proportional to the metric if N<5, and that this holds for the s-e tensor of
any simple form for arbitrary N. Conversely, we prove that any symmetric rank-2
tensor T whose square is proportional to the metric must be, up to sign, the
s-e of a simple p-form, and that the trace of T determines the rank p of the
form. This generalises, both with respect to N and the rank p, the classical
algebraic Rainich conditions, which are necessary and sufficient conditions for
a metric to originate in some physical field, and has a geometric
interpretation: the set of s-e tensors of simple forms is precisely the set of
tensors which preserve the null cone and its time orientation. It also means
that all involutory Lorentz transformations (LT) can be represented as s-e
tensors of simple forms, and that any rank-2 s-e tensor is the sum of at most N
conformally involutory LT. Non-symmetric null cone preserving maps are shown to
have a causal symmetric part and are classified according to the null
eigenvectors of the skew-symmetric part. We thus obtain a complete
classification of all conformal LT and singular null cone preserving maps on V.Comment: 36 pages, no figures, LaTeX fil
Safety, effectiveness and haemodynamic performance of a new stented aortic valve bioprosthesis
OBJECTIVES: We assessed the safety, effectiveness and haemodynamic performance of a new bovine stented aortic valve bioprosthesis (Avalusâą).
METHODS: The PERIGON Pivotal Trial is a prospective, non-randomized, multicentre study. Subjects had symptomatic moderate or severe aortic stenosis or chronic, severe aortic regurgitation. Death, valve-related adverse events (AEs), functional recovery and haemodynamic performance were assessed at discharge, 3-6 months and 1 year. The primary analysis compared 'late' (>30 days post-implant) linearized rates of valve-related thromboembolism, thrombosis, all and major haemorrhage, all and major paravalvular leak (PVL) and endocarditis after implantation with objective performance criteria (OPC) for AEs, in accordance with EN ISO 5840:2009. We hypothesized that the upper 95% confidence bounds of the true linearized AE rates would be â„â2âĂâOPC; rejection of the null hypothesis would demonstrate that these rates were below acceptable rates. The analysis was required to include at least 150 patients followed to 1 year and 400 valve-years. Kaplan-Meier survival analysis was also performed.
RESULTS: Total number of valve-years was 459.5 (nâ=â686). Linearized rates were <2âĂâOPC for death and valve-related thromboembolism, valve thrombosis, all and major PVL, and endocarditis, but â„2âĂâOPC for all and major haemorrhage. Survival at 1 year (nâ=â270) was 96.4%. Patients showed good functional recovery, and haemodynamic performance was within expected range.
CONCLUSIONS: This analysis demonstrated a good safety profile and clinical effectiveness of the Avalus valve except for bleeding rates. The linearized rates of all and major haemorrhage may be related to long-term anticoagulation for non-valvular indications and the length of follow-up of this cohort.
Trial registration: NCT02088554 (www.clinicaltrials.gov)
One-year outcomes associated with a novel stented bovine pericardial aortic bioprosthesis
Thoracic Surger
The concept of negative pressure wound therapy (NPWT) after poststernotomy mediastinitis â a single center experience with 54 patients
Deep sternal infections, also known as poststernotomy mediastinitis, are a rare but often fatal complication in cardiac surgery. They are a cause of increased morbidity and mortality and have a significant socioeconomic aspect concerning the health system. Negative pressure wound therapy (NPWT) followed by muscular pectoralis plasty is a quite new technique for the treatment of mediastinitis after sternotomy. Although it could be demonstrated that this technique is at least as safe and reliable as other techniques for the therapy of deep sternal infections, complications are not absent. We report about our experiences and complications using this therapy in a set of 54 patients out of 3668 patients undergoing cardiac surgery in our institution between January 2005 and April 2007
Plasma synthesis of single crystal silicon nanoparticles for novel electronic device applications
Single-crystal nanoparticles of silicon, several tens of nm in diameter, may
be suitable as building blocks for single-nanoparticle electronic devices.
Previous studies of nanoparticles produced in low-pressure plasmas have
demonstrated the synthesis nanocrystals of 2-10 nm diameter but larger
particles were amorphous or polycrystalline. This work reports the use of a
constricted, filamentary capacitively coupled low-pressure plasma to produce
single-crystal silicon nanoparticles with diameters between 20-80 nm. Particles
are highly oriented with predominant cubic shape. The particle size
distribution is rather monodisperse. Electron microscopy studies confirm that
the nanoparticles are highly oriented diamond-cubic silicon.Comment: accepted for publication in Plasma Physics and Controlled Fusion,
scheduled for Dec. 2004 F
Ascorbic acid pre-treated quartz stimulates TNF-α release in RAW 264.7 murine macrophages through ROS production and membrane lipid peroxidation
<p>Abstract</p> <p>Background</p> <p>Inhalation of crystalline silica induces a pulmonary fibrotic degeneration called silicosis caused by the inability of alveolar macrophages to dissolve the crystalline structure of phagocytosed quartz particles. Ascorbic acid is capable of partially dissolving quartz crystals, leading to an increase of soluble silica concentration and to the generation of new radical sites on the quartz surface. The reaction is specific for the crystalline forms of silica. It has been already demonstrated an increased cytotoxicity and stronger induction of pro-inflammatory cyclooxygenase-2 (COX-2) by ascorbic acid pre-treated quartz (QA) compared to untreated quartz (Q) in the murine macrophage cell line RAW 264.7.</p> <p>Methods</p> <p>Taking advantage of the enhanced macrophage response to QA as compared to Q particles, we investigated the first steps of cell activation and the contribution of early signals generated directly from the plasma membrane to the production of TNF-α, a cytokine that activates both inflammatory and fibrogenic pathways.</p> <p>Results</p> <p>Here we demonstrate that TNF-α mRNA synthesis and protein secretion are significantly increased in RAW 264.7 macrophages challenged with QA as compared to Q particles, and that the enhanced response is due to an increase of intracellular ROS. Plasma membrane-particle contact, in the absence of phagocytosis, is sufficient to trigger TNF-α production through a mechanism involving membrane lipid peroxidation and this appears to be even more detrimental to macrophage survival than particle phagocytosis itself.</p> <p>Conclusion</p> <p>Taken together these data suggest that an impairment of pulmonary macrophage phagocytosis, i.e. in the case of alcoholic subjects, could potentiate lung disease in silica-exposed individuals.</p
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