Background
Congenital heart diseases (CHDs) have high infant mortality in their severe forms. When adulthood is reached, a heart transplant (HTx) may be required. Spanish adult population ...transplanted for CHD was analyzed and compared with the most frequent causes of HTx and between different subgroups of CHD.
Materials and Methods
A total of 6048 patients (HTx 1984–2009) were included. Pediatric transplants (<15 yr), combined transplants, reHTx, and HTx for heart diseases other than idiopathic dilated cardiomyopathy (IDCM) and ischemic heart disease (IHD) were excluded. Total patients included: 3166 (IHD = 1888; IDCM = 1223; CHD = 55). Subgroups were studied as follows: (1) single ventricle with pulmonary stenosis (n = 18), (2) single ventricle with tricuspid atresia and Glenn/Fontan surgery (n = 10), (3) congenitally corrected transposition of the great vessels (TGV) or with switch atrial surgery (n = 10), and (4) CHD with right ventricle overload (n = 17).
Results
Survival probability was different between groups (p = 0.0001). Post hoc analysis showed some differences between groups (CHD vs. IHD, p = 0.05; CHD vs. IDCM, p = 0.5; IHD vs. IDCM, p = 0.0001). Early mortality was different between CHD subgroups (group 1 = 19%, group 2 = 40%, group 3 = 0%, group 4 = 29%; p < 0.001); however, overall mortality did not show differences between subgroups (p = 0.5).
Conclusions
The percentage of Spanish adult HTx patients for CHD is low (1%). The survival curve is better than for other HTx causes (IHD). Nevertheless, early mortality was higher, particularly in some subgroups (Fontan).
The purpose of this study was to evaluate the reduction in laser power output (PO) at the optical fiber tip during laser curettage of infected periodontal pockets.
The combination of mechanical ...debridement with laser therapy has been used successfully in the treatment of periodontitis.
The study group consisted of 28 teeth selected in 12 patients with chronic periodontitis. The teeth were treated with scaling and root planing (SRP), and infected pocket epithelium was removed with an 810-nm diode laser operating at a laser power of 1.7 W in continuous-wave mode (CW). Laser power was set to 1.0 W at the control panel before each measurement to facilitate mathematical analysis, and PO at the optical fiber tip was measured using a power meter. Four laser applications were performed per tooth (duration, 10-15 sec per application; total duration, 40-60 sec per tooth). The fiber tip was cleaved every four applications. Also, 28 irradiations (four PO measurements per irradiation) were performed in non-contact mode and used as controls.
There were significant PO losses between applications in the study group. PO losses of 20.89%, 30.39%, and 40.26% were found between the first and second, first and third, and first and fourth applications, respectively. A low transmission loss of the optical fiber was observed in the control measurements (mean PO loss of 1.58% between the first and fourth irradiations).
Our results indicated that optical fiber tips need to be cleaved frequently during laser curettage to minimize PO loss.
This work presents a new, simplified and yet efficient model for studying the transient conjugate heat transfer process in pipelines. The simplified model consists of assuming the thermal transport ...by fluid flow in bulk form and the pipe-wall heat conduction as two-dimensional. The scale analysis of the dimensionless equations resulting from the simplified model allows for the identification of two predicting parameters useful in determining when axial diffusion in the pipe wall is important,
ψ
= Pe Γ/
ξ
< 1 and
λ
= 4 Nu E
2
/
ξ
< 1, and when radial diffusion is important,
ψ
> 1 and
λ
> 1. When these criteria are satisfied, in which case the existing analytical solution becomes invalid, the simplified model proposed here becomes an efficient alternative to the full-scale numerical simulations required for solving the problem. The scale analysis predictions and the hybrid analytical-numerical solutions of the simplified model, involving the Laplace transform and the finite-volume method, are validated first by comparison against the existing analytical solution, and then by comparison against experimental results of turbulent flow, showing excellent agreement in both cases.
The brain renin-angiotensin system (RAS) has been related to dopaminergic degeneration, and high expression of the angiotensin II (AngII) type 1 receptor (AT1) gene is a marker of the most vulnerable ...neurons in humans. However, it is unknown whether AngII/AT1 overactivation affects α-synuclein aggregation and transmission. In vitro, AngII/AT1 activation increased α-synuclein aggregation in dopaminergic neurons and microglial cells, which was related to AngII-induced NADPH-oxidase activation and intracellular calcium raising. In mice, AngII/AT1 activation was involved in MPTP-induced increase in α-synuclein expression and aggregation, as they significantly decreased in mice treated with the AT1 blocker telmisartan and AT1 knockout mice. Cell co-cultures (transwells) revealed strong transmission of α-synuclein from dopaminergic neurons to astrocytes and microglia. AngII induced a higher α-synuclein uptake by microglial cells and an increase in the transfer of α-synuclein among astroglial cells. However, AngII did not increase the release of α-synuclein by neurons. The results further support brain RAS dysregulation as a major mechanism for the progression of Parkinson's disease, and AT1 inhibition and RAS modulation as therapeutic targets.
Professor Adrian Bejan on his 75th birthday Lage, José L.; Worek, William M.; Amon, Cristina H. ...
International communications in heat and mass transfer,
12/2023, Letnik:
149
Journal Article
The aim of this study is to investigate numerically the steady natural convection resulting from horizontally heating a rectangular enclosure filled with a fluid and containing uniformly distributed, ...conducting, fixed and disconnected solid blocks (i.e., not touching each other). In particular, the effects of solid volume fraction, solid-fluid thermal conductivity ratio, and total number of blocks on the heat transfer process are determined by solving the mass, momentum, and energy conservation equations using the finite-volume method. The enclosure aspect ratio is varied from 0.25 to 4, the Rayleigh number from 10
5
to 10
8
, and the Prandtl number is set as unity. Results of the numerical simulations are presented in terms of the surface-averaged Nusselt number, streamfunction, and streamline and isotherm distributions. The interference phenomenon caused by the solid blocks on the natural convection process is considered in detail and used to explain and predict the surprising and complex behavior of surface-averaged Nusselt number.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Abstract Objectives We sought to investigate the potential impact of preoperative short-term mechanical circulatory support (MCS) with extracorporeal devices on postoperative outcomes after emergency ...heart transplantation (HT). Methods We conducted an observational study of 669 patients who underwent emergency HT in 15 Spanish hospitals between 2000 and 2009. Postoperative outcomes of patients bridged to HT on short-term MCS (n = 101) were compared with those of the rest of the cohort (n = 568). Short-term MCS included veno-arterial extracorporeal membrane oxygenators (VA-ECMOs, n = 23), and both pulsatile-flow (n = 53) and continuous-flow (n = 25) extracorporeal ventricular assist devices (VADs). No patient underwent HT on intracorporeal VADs. Results Preoperative short-term MCS was independently associated with increased in-hospital postoperative mortality (adjusted odds-ratio 1.75, 95% CI 1.05–2.91) and overall post-transplant mortality (adjusted hazard-ratio 1.60, 95% CI 1.15–2.23). Rates of major surgical bleeding, cardiac reoperation, postoperative infection and primary graft failure were also significantly higher among MCS patients. Causes of death and survival after hospital discharge were similar in MCS and non-MCS candidates. Increased risk of post-transplant mortality affected patients bridged on pulsatile-flow extracorporeal VADs (adjusted hazard-ratio 2.21, 95% CI 1.48–3.30) and continuous-flow extracorporeal VADs (adjusted hazard-ratio 2.24, 95% CI 1.20–4.19), but not those bridged on VA-ECMO (adjusted hazard-ratio 0.51, 95% CI 0.21–1.25). Conclusions Patients bridged to emergency HT on short-term MCS are exposed to an increased risk of postoperative complications and mortality. In our series, preoperative bridging with VA-ECMO resulted in comparable post-transplant outcomes to those of patients transplanted on conventional support.
We developed a cost-effective SPECT scanner prototype (rSPECT) for in vivo imaging of rodents based on small-area gamma cameras. Each detector consists of a position-sensitive photomultiplier tube ...(PS-PMT) coupled to a 30 x 30 Nal(Tl) scintillator array and electronics attached to the PS-PMT sockets for adapting the detector signals to an in-house developed data acquisition system. The detector components are enclosed in a lead-shielded case with a receptacle to insert the collimators. System performance was assessed using 99mTc for a high-resolution parallel-hole collimator, and for a 0.75-mm pinhole collimator with a 60° aperture angle and a 42-mm collimator length. The energy resolution is about 10.7% of the photopeak energy. The overall system sensitivity is about 3 cps/μCi/detector and planar spatial resolution ranges from 2.4 mm at 1 cm source-to-collimator distance to 4.1 mm at 4.5 cm with parallel-hole collimators. With pinhole collimators planar spatial resolution ranges from 1.2 mm at 1 cm source-to-collimator distance to 2.4 mm at 4.5 cm; sensitivity at these distances ranges from 2.8 to 0.5 cps/μCi/detector. Tomographic hot-rod phantom images are presented together with images of bone, myocardium and brain of living rodents to demonstrate the feasibility of preclinical small-animal studies with the rSPECT.
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