Ravidasvir hydrochloride for genotype 1 hepatitis C treatment

Effective oral combination regimens have been approved for treatment of hepatitis C virus (HCV) infection and demonstrated high cure rates in different HCV genotypes. These direct-acting agents target a variety of HCV proteins, including HCV-NS5A (nonstructural protein 5A). Ravidasvir hydrochloride, a potent pan-genotypic HCV-NS5A inhibitor approved in Egypt for treatment of HCV genotype 4 (G4), demonstrated impressive efficacy, safety profiles and a high barrier to resistance in multiple clinical trials when used as a key component in combination with other direct-acting agents in treating patients with HCV-G1.

Abnormal acute changes in upper limb muscle cortical representation areas in the patients with writer's cramp during co-activation of distal and proximal muscles

AIM

We analysed cortical muscle representation areas during single muscle activation and during the co-activation of several upper arm muscles in the patients with writer's cramp to determine the possible occurrence of abnormal dynamic somatotopic changes in M1, in addition to the static map abnormalities already described in this form of dystonia.

METHODS

Using transcranial magnetic stimulation, we assessed cortical representations of medial deltoid, extensor carpi radialis and the first dorsal interosseus muscles in eight patients with writer's cramp and in eight healthy control subjects. Cortical maps were obtained during distal muscles' activation either in isolation or in conjunction with voluntary medial deltoid co-activation.

RESULTS

This study showed a difference in the organization of cortical representations of these muscles between the patients with dystonia and control subjects. The first dorsal interosseus and the extensor carpi radialis cortical representation areas were larger in the dystonic group. The cortical representations became larger when the medial deltoid was simultaneously co-activated, and this effect was not observed in the control group. In the dystonic group, the three cortical muscle representations largely overlapped and their centres of gravity were closer.

CONCLUSION

Patients with dystonia showed not only a different spatial organization of muscle cortical representation areas, but also abnormal acute somatotopic changes during proximal muscle co-activation. Task-specific motor impairment in writer's cramp may result not only from lack of cortical inhibition and the well-known anomalous cortical organization observed in these patients, but also from abnormal patterns of proximo-distal functional muscle coupling.

Writer's cramp: cortical excitability in tasks involving proximo-distal coordination

AIM

The aim of this work was to analyse how writer's cramp patients coordinate each element of the proximal to distal upper arm muscle chain during voluntary movement.

METHODS

Using transcranial magnetic stimulation, we have assessed motor cortex excitability properties in patients by recording motor-evoked potentials and silent periods in both the extensor carpi radialis (ECR) and the first dorsal interosseus muscles (FDI), activated either in isolation, or in conjunction with voluntary medial deltoid (MD) co-activation during performance of precise tasks. Ten dystonic patients and ten healthy controls were tested.

RESULTS

In both test groups, the ECR muscle displayed a similar active motor threshold, but the excitability curves reached higher plateau values, when the proximal MD muscle was co-activated. In the dystonic group, the FDI muscle excitability curves reached higher plateau values when the MD was co-activated, whereas co-activation had no effect on the control group. In the control group, silent periods, in both the ECR and the FDI were longer when the MD was co-activated. This effect was not observed in the dystonic group.

CONCLUSION

In the dystonic group, facilitation of the FDI was observed during a task involving proximo-distal coordination. No differences in silent periods were observed when the muscle was activated alone. Our results suggest that such abnormal facilitation is not only an impairment of the central inhibitory mechanisms reported for dystonic patients, but, in addition, represents true abnormality in cortical muscle activation strategies.

Clinical outcomes for Saudi and Egyptian patients receiving deceased donor liver transplantation in China

Long waiting list times in liver transplant programs in Saudi Arabia and unavailability of deceased donor transplantation in Egypt have led several patients to seek transplantation in China. All patients who received transplants in China and followed in three centers from January 2003-January 2007 were included. All patients' charts were reviewed. Mortality and morbidity were compared to those transplanted in King Faisal Specialist Hospital & Research Centre (KFSH&RC) during the same period. Seventy-four adult patients were included (46 Saudi nationals; 28 Egyptians). One-year and 3-year cumulative patient survival rates were 83% and 62%, respectively compared to 92% and 84% in KFSH&RC. One-year and 3-year cumulative graft survival rates were 81% and 59%, respectively compared to 90% and 84% in KFSH&RC. Compared to KFSH&RC, the incidence of complications was significantly higher especially biliary complications, sepsis, metastasis and acquired HBV infection posttransplant. Requirements of postoperative interventions and hospital admissions were also significantly greater. Our data show high mortality and morbidity rates in Saudi and Egyptian patients receiving transplants in China. This could be related to more liberal selection criteria, use of donation after cardiac death (DCD) donors or possibly more limited posttransplant care.

Sustained attention in cranial dystonia patients treated with botulinum toxin

BACKGROUND

Primary cranial dystonia (PCD) is related to a functional disorder in basal ganglia usually accompanied by impaired executive function.

AIM

To investigate symptom relief and neurocognitive change in response to treatment with botulinum toxin (BTX) in a group of patients with PCD.

METHODS

We assessed nine patients with PCD and nine age- and educationally matched healthy individuals using tests of memory, sustained attention, span of auditory attention, and perceptual flexibility.

RESULTS

Despite well-preserved intellectual skills relative to controls, we identified a sustained attention deficit in patients with PCD. After BTX treatment, there was an increase in the scores of the concentration endurance test (sustained attention) and the values did not differ significantly from control group patients' scores.

CONCLUSION

The results support the view that executive dysfunction in PCD is secondary to the disrupting effects of the symptoms. Treatment with BTX alleviates the symptoms and, consequently, improves sustained attention.

Molecular interaction of tubulin with 1-deaza-7,8-dihydropteridines: a comparative study of enantiomers NSC 613862 (S) and NSC 613863 (R) by Raman and Fourier transform infrared spectroscopy

Pre-resonance Raman spectroscopy has been applied to compare the vibrational modes of the R and S chiral isomers of 1-deaza-7,8-dihydropteridine when they are bound to tubulin. The main Raman bands are due to the chromophore and are coupled with the pi-pi electronic transition of C = C and C = N vibrational stretching. On binding to tubulin, the Raman spectra of both isomers are modified. However, the modifications induced are different for each isomer. The Raman bands due to C = C stretching from the phenyl ring are more strongly modified for the bound R isomer than for the S isomer. This leads us to suggest that R and S isomers differ in terms of their orientation in front of the binding locus of tubulin. In fact, with respect to the orientation of the bulky methyl group, the chromophore of the R isomer is more likely to be positioned against the external surface of either tubulin or GTPase proteins, while that of the S isomer is likely to be positioned away from the surface. The conformational changes induced in tubulin by R and S isomers have also been studied by Fourier transform infrared spectroscopy and by the analysis of amide I and II absorption bands. Both enantiomers induce similar minor changes to the tubulin secondary structure, corresponding to a decrease in the disordered alpha-helical content and accompanied by an increase in the undefined conformation content.

Characterisation of a navelbine-resistant bladder carcinoma cell line cross-resistant to taxoids

A bladder carcinoma cell line (J82) was selected for resistance to the new vinca alkaloid navelbine. The resistance factor of the resistant subline (J82-NVB) to navelbine was 17. P-glycoprotein was not detected in the membrane of J82-NVB cells. The lack of cross-resistance to multidrug-resistant (MDR) drugs such as doxorubicin, epipodophyllotoxins and colchicine, the absence of increase in navelbine efflux and the fact that a reduced accumulation of the drug cannot account for the resistance level confirmed that the phenotype of resistance of J82-NVB cells is not a classical MDR phenotype. Moreover, verapamil did not reverse the resistance of J82-NVB cells. The cells were cross-resistant to vinca alkaloids and taxoids which share the same target protein: tubulin. Analysis of microtubules using immunofluorescence showed that disassembly of the microtubular network occurred for the same concentration of navelbine in sensitive and resistant cells. However, after treatment with a concentration of navelbine inducing depolymerisation in both sensitive and resistant cells, reassembly of the microtubular network was observed only in resistant cells. This study suggests that the mechanism of resistance of J82-NVB cells involves recovery from the inhibition of microtubule dynamics induced by drug treatment.

[Characterization of the mechanism of cross-resistance to vinca alkaloids and taxoids in the human J82 bladder tumor cell line]

A phenotype of resistance to the new vinca alkaloid Navelbine was induced in the J82 human bladder carcinoma cells. The resistance factor of the resistant cell line (J82-NVB) to Navelbine was 17. The resistance phenotype of these cells is not a multidrug-resistance (MDR) phenotype. J82-NVB cells lack overexpression of P-glycoprotein and cross-resistance to MDR drugs like doxorubicin, epipodophyllotoxins or colchicine. Navelbine efflux was similar in sensitive and resistant cells, and resistance could not be explained by a difference of drug accumulation in these two cell lines. The cells were cross-resistant to vinca alkaloids and taxoids whose targets are microtubules. Immunofluorescence study of microtubules showed that depolymerization occured for the same Navelbine concentration in sensitive and resistant cells. This concentration induced growth inhibition in sensitive but not in resistant cells. Moreover, depolymerization induced by Navelbine treatment was reversible, after drug removal, in resistant cells only. This study suggests that J82-NVB cell resistance mechanism involves alterations of microtubule dynamics, allowing recovery of microtubules functions after treatment.

Treatment with botulinum toxin injections does not change brainstem interneuronal excitability in patients with cervical dystonia

Brainstem interneuronal excitability is enhanced in patients with cervical dystonia. Treatment with local botulinum toxin (BTX) injections temporarily alleviates the pain and weakens the muscle spasms, characteristics of this condition. In 10 patients with cervical dystonia, we studied whether the clinical improvement induced by BTX was associated with modification of the blink reflex excitability recovery curve to paired supraorbital nerve electrical shocks. We found that the mean percentage recovery of the R2 to the test stimulus was abnormally enhanced before treatment and that it did not significantly change after treatment, at the time of maximal clinical improvement, in any of the interstimulus intervals tested. We conclude that the clinical improvement induced by BTX in patients with cervical dystonia is largely symptomatic and is not related to any change of the known abnormalities in brainstem interneuronal excitability that possibly underlie the pathophysiology of cervical dystonia.