We consider the equivalence of quasinormal modes and geodesic quantities recently brought back due to the black hole shadow observation by Event Horizon Telescope. Using WKB method we found an ...analytical relation between the real part of quasinormal frequencies at the eikonal limit and black hole shadow radius. We verify this correspondence with two black hole families in 4 and D dimensions, respectively.
In this work we consider black holes surrounded by anisotropic fluids in four dimensions. We first study the causal structure of these solutions showing some similarities and differences with ...Reissner–Nordström–de Sitter black holes. In addition, we consider scalar perturbations on this background geometry and compute the corresponding quasinormal modes. Moreover, we discuss the late-time behavior of the perturbations finding an interesting new feature, i.e., the presence of a subdominant power-law tail term. Likewise, we compute the Bekenstein entropy bound and the first semiclassical correction to the black hole entropy using the brick wall method, showing their universality. Finally, we also discuss the thermodynamical stability of the model.
We investigate the dynamical behavior of a scalar field non-minimally coupled to Einstein’s tensor and Ricci scalar in geometries of asymptotically de Sitter spacetimes. We show that the quasinormal ...modes remain unaffected if the scalar field is massless and the black hole is electrically chargeless. In the massive case, the coupling of both parameters produces a region of instability in the spacetime determined by the geometry and field parameters. In the Schwarzschild case, every solution for the equations of motion with
ℓ
>
0
has a range of values of the coupling constant that produces unstable modes. The case
ℓ
=
0
is the most unstable one, with a threshold value for stability in the coupling. For the charged black hole, the existence of a range of instability in
η
is strongly related to geometry parameters presenting a region of stability independent of the chosen parameter.
SUMMARY
Background
Five oral nucleos(t)ide analogues are available to treat chronic hepatitis B (CHB). With the availability of newer agents, their efficacy on incidence of hepatocellular carcinoma ...(HCC) is not well described.
Aim
To determine the efficacy of oral anti‐viral agents in reducing HCC risk in relationship with other known factors.
Methods
Published studies of at least 20 CHB patients treated with an oral anti‐viral agent and followed for >2 years were analysed for incidence of HCC per 100 person years follow‐up.
Results
Pooled homogeneous data from six studies showed lamivudine (LAM) treatment (n = 3306) to reduce HCC risk by 51% compared with no treatment (n = 3585) (3.3 vs. 9.7 per 100 person years, P < 0.0001). Pooled data from 49 studies (23 with LAM; 16 with adefovir; and 10 with entecavir, tenofovir or telbivudine) of 10 025 treated patients showed HCC incidence of 1.3 per 100 person years, independent of the agent used. Patient age >50 years and hepatitis B virus‐DNA detectability at HCC diagnosis increased risk of HCC by twofold with a 10‐fold higher risk among patients with cirrhosis compared with chronic hepatitis. Meta‐regression showed patient age, study location (Eastern vs. Western) and type of study (randomised or not) contributed to heterogeneity.
Conclusions
Lamivudine treatment significantly reduces the incidence of HCC compared with no treatment. However, HCC still develops at a rate of 1.3 per 100 patient years in CHB patients receiving an oral anti‐viral agent. This finding highlights the need for continued HCC surveillance, particularly in CHB patients with inadequate viral suppression, older age and cirrhosis.
Recurrent HCV infection following liver transplantation can lead to accelerated allograft injury that is difficult to treat with interferon. The aim of this study is to describe the first ever use of ...an interferon‐free, all oral regimen in a liver transplant recipient with severe recurrent HCV. A 54‐year‐old male with HCV genotype 1b developed severe cholestatic HCV at 6 months posttransplant with ascites, AST 503 IU/mL, alkaline phosphatase of 298 IU/mL, HCV RNA of 12 000 000 IU/mL, and histological cholestasis with pericellular fibrosis. Sofosbuvir, an HCV polymerase inhibitor (400 mg/day), and daclatasvir, an HCV NS5A replication complex inhibitor (60 mg/day), were co‐administered for 24 weeks. Within 4 weeks of initiating treatment, serum HCV RNA levels became undetectable and liver biochemistries normalized with concomitant resolution of ascites. The patient achieved a sustained virological response with undetectable HCV RNA at 9 months posttreatment. During and following treatment, the daily dose and blood level of tacrolimus remained stable and unchanged. The rapid and sustained suppression of HCV replication in this liver transplant recipient provides great promise for the use of combination oral antiviral regimens in other immunosuppressed and interferon refractory HCV patients.
A patient with severe cholestatic hepatitis C virus genotype 1b infection at nine months after liver transplantation was successfully treated with a six‐month course of oral sofosbuvir in combination with daclatasvir and remains HCV RNA negative during posttreatment follow‐up with improved liver biochemistries and health.
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