[en] Highlights: • Characterization of a polymer network with spiroacetal moieties and riboflavin. • The thermal stability of the new compounds is close to that of the starting copolymer. • The dynamic of the system can be detected by fluorescence spectroscopy. • Significant disturbance into the system can be evaluated by circular dicroism. • The dielectric spectroscopy confirms the polymer network formation.

[en] Combination therapy with interferon and ribavirin has become the standard of care in the treatment of Chronic Hepatitis C (CHC) infected patients. Treatment response, however, is not 100% and is accompanied with side effects faced by the patient as well as observed in haematologic indices. Studies are focusing on daily or high-dose induction therapy with interferon, the titration of interferon dosing to initial viral load, higher doses of interferon throughout treatment, and adjustment of interferon dosing to the viral responses. The safety and efficacy of these approaches have not been sufficiently established. Objectives were to see the response of 2 different dosage regimens, effects and side effects and to assess the efficacy and side effects of 2 treatment regimens of Interferon and Ribavirin in CHC. A total of 32 patients with CHC at Department of Gastroenterology and Hepatology, Shaikh Zayed Postgraduate Medical Institute Lahore from June 2001 to February 2003 were included in the study and were divided into two groups for treatment. Group A (14 patients) received 5 MU of injection Interferon alpha 2 b S/C daily for 2 weeks followed by 3 MU thrice weekly for the next 22 weeks. Group B (18 patients) received injection interferon alpha 2 b 3 MU S/C thrice weekly for 24 weeks. Ribavirin therapy was started at 1200 mg daily in 3 divided doses and later modified according to side effects. Patients were evaluated at 2, 4, 8, 12, 16, 20 and 24 weeks during the therapy and then 24 weeks after the completion of treatment. Out of 32 adult patients included in the study, 18 were males and 14 females. Haemoglobin was more than 12 gm/dl in females and more than 13 gm/dl in males, WBC count was more than 3.0*10/sup 9/L and Platelet count was more than 100*10/sup 9/L. Twenty patients completed 6 months combination treatment, 16 reported with their end of treatment HCV RNA PCR results, 8 from each group. Twelve patients were lost to follow up. End of treatment response (ETR) in group A was 88% and 62.5% in group B. Sustained virological response in group-A was 5/8 (62.5%) and 4/5 (50%) in group-B. The frequency and severity of flu like symptoms like fever, body aches, skin rash, hair loss, cough and psychiatric symptoms were more in group A than in group B. There was no significant difference in the 2 groups for haematologic side effects. Treatment with 5 MU interferon daily for initial two weeks followed by 3 MU thrice weekly for 22 weeks is more effective than 3 MU thrice weekly for 24 weeks but with more side effects. (author)

[en] The NMR method has been used for riboflavin binding protein molecule structure changes determination as an effect of denaturation resulting in disulfide bridges cleavage

[en] A method is described for synthesis of riboflavin selectively labeled in the hydrogens at the 5'-hydroxymethyl position. In this method, a vitamin B₂-aldehyde-forming enzyme from Schizophyllum commune is used to specifically and completely oxidize the 5'-hydroxymethyl of riboflavin to the 5'-aldehyde. This reaction is monitored spectrophotometrically by the reduction of 2,6-dichlorophenolindophenol at 600 nm. Appearance of aldehyde product was directly quantitated by reverse-phase high-performance liquid chromatography. Product is extracted from the incubation mixture by phenol after saturation with (NH₄)₂SO₄ and then further purified by benzyl alcohol extraction. The 5'-aldehyde is reduced with appropriately labeled sodium borohydride to yield the vitamin specifically labeled in the 5'-hydroxymethyl group. (author)

No abstract available

[en] To determine the efficacy of interferon-ribavirin therapy for chronic viral Hepatitis C (HCV) patients. Study Design: A quasi-experimental study. Place and Duration of Study: Medical Unit-III, Ward-7, Jinnah Postgraduate Medical Centre, Karachi, from August 2006 to December 2007. Methodology: Adult patients who had not received any prior anti-HCV therapy and had been infected with positive anti- HCV antibodies and detectable HCV RNA were enrolled in the study. Patients were excluded from the study if there was evidence of de compensated cirrhosis, coexistent HIV, or HBV infection, previous organ transplantation, psychiatric disease, seizure disorder, serious cardiovascular disease and other co-morbid diseases like uncontrolled Diabetes. Patients were given Interferon-alfa-2b 3 million international units three times a week sub-cutaneously and oral ribavirin at 1000-1200 mg in two to three divided doses a day for a 6-month period. At the end of treatment over all efficacy as depicted by non-detectable HCV RNA by PCR and its relation with factors of like age, gender, and serum ALT were assessed. Results: A total of 404 patients with mean age of 36.03+-9.30 years, ranging from 13 to 60 years, were offered combination therapy that satisfied the inclusion criteria. Among these, females were 243 (61.1%) and males were 161 (39.9%), age range 13-60 years with mean of 36.03 years. Out of 404, 336 (83.2%) showed response to combined interferon and ribavirin therapy depicted by HCV RNA by PCR at the end of 24 weeks treatment. Age under 40 years (p < 0.001) was significantly associated with favourable response. Conclusion: Combination therapy of interferon and ribavirin in chronic hepatitis C patients has still better response rate in our set-up. Younger age and female gender were the favourable predictors. (author)

[en] As part of a study of radiolytic degradation of pharmaceuticals during radiosterilization, the basic radiation chemistry of the B-group vitamins, nicotinamide, pyridoxin, riboflavin and thiamine, and the reaction of hydrogen peroxide with these same materials has been investigated. The various aspects studied were - radiolysis under controlled conditions, effects of phase, temperature, pH and nature and concentration of additives. Some of the conclusions are: 1) with oxygen saturated aqueous solutions containing glucose, the radiolytic degradation of the vitamins is reduced: 2) results a similar for N₂O saturated aqueous solutions; 3) in glucose-containing solutions, the protective effect is considerably modified at higher temperatures; and 4) irradiation of air-saturated aqueous solutions in the frozen state leads to reduced decomposition. It is concluded that in the presence of oxygen, in frozen matrices at low temperature, it appears possible to reduce the radiolytic breakdown of vitamins to low levels

[en] Highlights: • Steel corrosion is more severe in carbon starvation station than full carbon medium. • Addition of electron mediators accelerates X70 steel corrosion. • Biocatalytic activity of the SRB biofilm is enhanced by adding electron mediators. • Addition of cytochrome c induces more severe corrosion of X70 steel than riboflavin. • Cytochrome c promotes the biocatalytic current more strongly than riboflavin. In microbiologically influenced corrosion (MIC) induced by sulfate-reducing bacteria (SRB), the electrons released from iron were transferred via extracellular electron transfer (EET) to the inner cells. Electron mediators and carbon starvation have also been found to promote steel corrosion. This study aimed to investigate the synergistic effects of electron mediators and carbon starvation on MIC and their effect on biofilm catalytic activity. The results demonstrated that the weight losses of X70 steel were 0.68 and 1.03 mg/cm² in 100% and 10% carbon source (CS) SRB solution, respectively. The addition of riboflavin and cytochrome c increased the corrosion rate by 1.76 and 1.87 times, respectively, in the 100% CS SRB medium compared to the medium without exogenous redox mediators. For the 10% CS SRB medium, the corrosion rate increased by 1.40 and 1.89 times, respectively, when riboflavin and cytochrome c were added. The addition of riboflavin and cytochrome c also enhanced the biocatalytic activity of the SRB biofilm in both the 100% and 10% CS SRB media.

[en] An improved two-photon excited fluorescence contrast difference between autofluorescent vitamins is reported by using shaped laser pulses after a kagome fiber. Specifically phase-tailored laser pulses are applied for two-photon excited fluorescence of retinol and riboflavin in solution at the distal end of the fiber. The pulse distortions due to the fiber properties are precompensated to achieve predefined tailored pulses after the kagome fiber. A clear two-photon excited fluorescence contrast difference is received between vitamin A and B₂ for various third order phase parameters. Moreover, selective excitation is observed for retinal versus retinol, although they differ only in a side chain. The presented approach of guiding shaped pulses through kagome fibers has large perspectives for endoscopic applications. (paper)

[en] Two mutants of Escherichia coli unable to synthesize riboflavin were grown with limiting (2 μg ml^-1) and non-limiting (10 μg ml^-1) concentrations of riboflavin. These riboflavin auxotrophs when grown to exponential phase with non-limiting riboflavin are more sensitive to broad spectrum near-ultraviolet light (NUV, 320-400 nm) inactivation than when they are grown with limiting riboflavin. Exponential phase cells of the riboflavin auxotrophs grown with limiting riboflavin are sensitized when irradiated in saline supplemented with riboflavin. This suggests that extracellular riboflavin is important as a NUV sensitizer when intracellular levels of riboflavin are reduced. The concentration of riboflavin in crude extracts from exponentially growing cells correlates well with the sensitivity of these mutants to NUV inactivation. The level of riboflavin supplementation has little effect on the NUV sensitivity of the parental strain. (author)