Efficacy and safety of brivudine for the treatment of herpes zoster: a systematic review and meta-analysis.

BACKGROUND AND OBJECTIVE: Brivudine has been used in herpes zoster (HZ) treatment for years, but the safety and efficacy of brivudine are inconclusive. Here we perform a meta-analysis to assess the efficacy, safety, incidence of postherpetic neuralgia of brivudine. METHODS: Data of randomized controlled Trials (RCTS) were obtained from the databases of both English (PubMed, Embase, and Cochrane Library) and Chinese (China National Knowledge Infrastructure, China Science Journal Database, and WanFang Database) literatures from inception to 12 September 2022. Meta-analyses of efficacy and safety of Brivudine for the treatment of herpes zoster for RCTS were conducted. RESULTS: The analyses included seven RCTS (2095 patients in experimental group and 2076 patients in control group) in the treatment of HZ with brivudine. It suggested that the brivudine group was superior to the control group in terms of efficacy (p = .0002) and incidence of postherpetic neuralgia (p = .04). But the incidence of adverse reactions has no significant difference between the brivudine and the control groups (p = .22). In addition, subgroup analysis of adverse events also showed that brivudine was about the same safety as other modalities in the treatment of HZ (p > .05). CONCLUSIONS: Brivudine is effective for HZ. However, the evidence on the safety of brivudine is insufficient.

New Mechanism of Acyclovir Resistance in Herpes Simplex Virus 1, Which Has a UAG Stop Codon between the First and Second AUG Initiation Codons.

Morphological changes in the structure of the herpes simplex virus 1 (HSV-1) viral thymidine kinase (vTK) polypeptide usually lead to conferring acyclovir (ACV) resistance. HSV-1 I4-2, in which a UAG stop codon is present at the 8th position between the 1st initiation AUG codon (1st position) and the 2nd initiation AUG codon (46th position) of the HSV-1 vTK gene, showed sensitivity to ACV. In contrast, HSV-1 KG111, in which a UAG stop codon was artificially inserted at the 44th position, showed resistance to ACV at 39˚C. The mechanism underlying the difference in the sensitivity profiles was elucidated. The virus recombinants HSV-1-TK(8UAG) and HSV-1-TK(44UAG) containing a UAG stop codon at the 8th and 44th positions counted from the 1st initiation codon, respectively, were generated and tested for susceptibility to antiviral compounds. HSV-1-TK(8UAG) and HSV-1-TK(44UAG) were sensitive and resistant to ACV and BVdU at 37˚C, respectively. The expression level of the truncated vTK translated from the 2nd initiation codon in Vero cells infected with HSV-1-TK(44UAG) was clearly less than that with HSV-1-TK(8UAG) in a temperature-dependent manner. The differences in the antiviral sensitivity profiles were due to the position of the UAG stop codon between the 1st and the 2nd initiation codons.

A life-threatening drug-drug interaction between capecitabine and brivudine in a patient with metastatic breast cancer.

In the current report we present the case of a patient experiencing a life-threatening drug-drug interaction involving the concurrent administration of capecitabine and brivudine. A 65- year-old female with metastatic breast cancer was commenced on brivudine for Herpes Zoster, while on capecitabine treatment, by a physician unfamiliar with the potential repercussions of this drug-drug interaction. As a result, she developed skin rash, severe oral mucositis, and severe and prolonged pancytopenia. These side effects were attributed to a serious interaction of capecitabine with brivudine, resulting in inhibition of dihydropyrimidine dehydrogenase. The patient was admitted for supportive care including intravenous hydration, parenteral nutrition, mouth care solutions, fluconazole, antimicrobial therapy, filgrastim, red blood cell and platelet transfusions. She successfully recovered and was discharged on the 26th day after her admission. Drug-drug interactions can be serious, even life-threatening; thus the physicians should be cautious when prescribing new drugs.

Separating host and microbiome contributions to drug pharmacokinetics and toxicity.

The gut microbiota is implicated in the metabolism of many medical drugs, with consequences for interpersonal variation in drug efficacy and toxicity. However, quantifying microbial contributions to drug metabolism is challenging, particularly in cases where host and microbiome perform the same metabolic transformation. We combined gut commensal genetics with gnotobiotics to measure brivudine drug metabolism across tissues in mice that vary in a single microbiome-encoded enzyme. Informed by these measurements, we built a pharmacokinetic model that quantitatively predicts microbiome contributions to systemic drug and metabolite exposure, as a function of bioavailability, host and microbial drug-metabolizing activity, drug and metabolite absorption, and intestinal transit kinetics. Clonazepam studies illustrate how this approach disentangles microbiome contributions to metabolism of drugs subject to multiple metabolic routes and transformations.

Engineered Thymidine-Active Deoxycytidine Kinase for Bystander Killing of Malignant Cells.

Suicide transgenes encode proteins that are either capable of activating specific prodrugs into cytotoxic antimetabolites that can trigger cancer cell apoptosis or are capable of directly inducing apoptosis. Suicide gene therapy of cancer (SGTC) involves the targeted or localized delivery of suicide transgene sequences into tumor cells by means of various gene delivery vehicles. SGTC that operates via the potentiation of small-molecule pharmacologic agents can elicit the elimination of cancer cells within a tumor beyond only those cells successfully transduced. Such "bystander effects ", typically mediated by the spread of activated cytotoxic antimetabolites from the transduced cells expressing the suicide transgene to adjacent cells in the tumor, can lead to a significant reduction of the tumor mass without the requirement of transduction of a high percentage of cells within the tumor. The spread of activated cytotoxic molecules to adjacent cells is mediated primarily by diffusion and normally involves gap junctional intercellular communications (GJIC). We have developed a novel SGTC system based on viral vector-mediated delivery of an engineered variant of human deoxycytidine kinase (dCK), which is capable of phosphorylating uridine- and thymidine-based nucleoside analogues that are not substrates for wild-type dCK, such as bromovinyl deoxyuridine (BVdU) and L-deoxythymidine (LdT). Since our dCK-based SGTC system is capable of mediating strong bystander cell killing, it holds promise for clinical translation. In this chapter, we detail the key procedures for the preparation of recombinant lentivectors for the delivery of engineered dCK, transduction of tumor cells, and evaluation of bystander cell killing effects in vitro and in vivo.

Review for Disease of the Year: Treatment of Viral Anterior Uveitis: A Perspective.

PURPOSE: To define a clinically tailored therapeutic strategy for the treatment of viral anterior uveitis (VAU). METHODS: A PubMed search spanning the past 5 years was conducted using the MesH-terms "viral anterior uveitis" and "therapy." RESULTS: The herpes simplex virus (HSV), the varicella zoster virus (VZV), and the cytomegalovirus (CMV) are the predominant pathogens in VAU. Other viruses, including rubella, chikungunya, and zika, have been linked with distinct forms of the disease. Depending on the causative agent and the host immunocompetence, the mainstay treatment for suspected VAU is a combination of topical or systemic antivirals and topical corticosteroids, supplemented with cycloplegics and intraocular-pressure-lowering medication. CONCLUSIONS: Oral acyclovir, valacyclovir, and famciclovir are the mainstay of treatment for HSV- and VZV-induced infections. Brivudin serves as an alternative in insufficiently responsive cases. CMV-induced infections respond well to valganciclovir. A 3- to 12-month course of prophylactic treatment against recurrences is worth considering.

Efficacy of lentivirus­mediated Drosophila melanogaster deoxyribonucleoside kinase combined with (E)­5­(2­bromovinyl)­2'­deoxyuridine or 1­ß­D­arabinofuranosylthymine therapy in human keloid fibroblasts.

Keloid scarring is a type of fibroproliferative disease with a high recurrence rate. However, no effective treatment is currently available. Combined therapy with recombinant lentivirus­mediated Drosophila melanogaster deoxyribonucleoside kinase (Dm­dNK) and prodrug has been widely studied and used for cancer treatment. Due to the similarities between keloid scars and tumors, the aim of the present study was to investigate the efficacy of a Dm­dNK/nucleoside analog system for the treatment of keloid scars. Recombinant lentivirus expression of the Dm­dNK suicide gene was assessed. Western blotting was used to examine the protein expression of lentivirus mediated Dm­dNK in keloid fibroblasts. Enzyme activity assays were conducted using [3H]­labeled substrates. Furthermore, cytotoxicity and bystander effects were evaluated using MTT assays. The expression of green fluorescent protein was observed using fluorescence microscope and results indicated that there was no notable difference in lentivirus infectivity between the multiplicity of infection (MOI) of 1 and 10 in cells. Notably, western blotting revealed that Dm­dNK was stably expressed in keloid fibroblasts and the enzymatic activity assays revealed that the enzyme was activated following introduction into the keloid fibroblasts via the lentivirus. The cytotoxicity and bystander effects of Dm­dNK combined with cytotoxic nucleoside analogs were both observed in Dm­dNK+ keloid fibroblasts. These results demonstrated that the lentivirus­mediated Dm­dNK therapy may be effective in treating keloid fibroblasts, which provides some evidence for the use of Dm­dNK/prodrug therapy for keloid treatment in vivo in the future.

Comparison of Famciclovir, Valaciclovir, and Brivudine Treatments in Adult Immunocompetent Patients With Herpes Zoster.

Herpes zoster (HZ) is a common disease characterized by the recurrence of varicella zoster, that stays dormant in sensory ganglia. The primary goal of this study was to compare efficiencies of famciclovir, valaciclovir, and brivudine in terms of pain relief in HZ patients. Records of patients who were admitted to the Dermatology Clinic of our hospital due to acute HZ between the years 2012 and 2014 were retrospectively analyzed. Treatment decisions were at the discretion of caring physicians as valaciclovir (VACV), famciclovir (FCV), and brivudine (BRV) based on the clinical observations. BRV, FCV, and VACV were effective in treating pain in acute HZ. There was no significant difference between mild and moderate HZ patients. In severe cases, a significant reduction in intensity of pain was observed on day 3 in the BRV group, on day 7 in the FCV group, and at 2-3 weeks in the VACV group. There were no significant side effects observed in any of the groups. Results of this study indicate that brivudine may be the first choice in severe HZ cases as it controls pain earlier and is easier to use because of its once daily administration.

Discovery of BVDU as a promising Drug for autoimmune diseases Therapy by Dendritic-cell-based functional screening.

Dendritic cells (DCs) play a critical role in the pathogenesis of autoimmune diseases including multiple sclerosis, and targeting DCs' cytokines production is an important strategy for autoimmune diseases treatment. By establishing a high-throughput screening system, we analyzed LOPAC drug library to identify drugs that control the secretion of IL-6 by DCs, we selected the most likely candidate drug, BVDU, and found that it affected not only IL-6 production, but also that of IL-12, IL-1ß during the DCs differentiation and maturation. The mechanism studies showed that BVDU treatment restricted the phosphorylation of MAP kinase, which played an important role in DC cytokine production. We further assessed the in vivo therapeutic potentials of BVDU on mouse models including EAE and STZ-induced T1D, and found that BVDU treated EAE mice exhibited significantly lower EAE clinical scores, decreased leukocyte infiltration in central nervous system lesions, and reduced demyelination. As in T1D mice, BVDU treatment also showed promising therapeutic effects based on both alleviated disease symptoms and tissue pathogenesis. More interestingly, the modulating effect of BVDU on IL-6 production was further verified in human primary DCs. The above data supported the promising application of our screen model, and also the potential of BVDU for autoimmune diseases therapy.

Synthesis and Ativiral Activity of 5-(Benzylthio)-4-carbamyl-1,2,3-triazoles Against Human Cytomegalovirus (CMV) and Varicella-zoster Virus (VZV).

BACKGROUND: All of the clinical drugs for herpesvirus infections exhibit high toxicity and suffer from significant drug-resistantance. There is a great need for the development of new, effective, and safe anti-herpesvirus agents with different mechanisms of action. METHODS: A series of novel 5-(benzylthio)-1H-1,2,3-triazole-4-carboxamides were efficiently synthesized and EC50 values against human cytomegalovirus (HCMV), varicella-zoster virus (VZV) and herpes simplex virus (HSV) were evaluated in vitro. RESULTS: Some compounds possess antiviral activity. Compound 7f exhibits promising inhibitory activity against both HCMV and VZV. Our results also indicate that these derivatives are independent of the viral thymidine kinase (TK) for activation, which is indispensable for current drugs. CONCLUSION: 4,5-Bissubstiuted triazoles are active against herpesviruses and the nature and the position of substituents in the benzene ring remarkably affect their activity, such as bromo, cyano and cyanovynil substituents. Future studies should be undertaken to investigate the mechanism of action of these compounds.

ProTides of BVdU as potential anticancer agents upon efficient intracellular delivery of their activated metabolites.

Nucleosides represent a major chemotherapeutic class for treating cancer, however their limitations in terms of cellular uptake, nucleoside kinase-mediated activation and catabolism are well-documented. The monophosphate pro-nucleotides known as ProTides represents a powerful strategy for bypassing the dependence on active transport and nucleoside kinase-mediated activation. Herein, we report the structural tuning of BVdU ProTides. Forty six phosphoramidates were prepared and biologically evaluated against three different cancer cell lines; murine leukemia (L1210), human CD4+ T-lymphocyte (CEM) and human cervical carcinoma (HeLa). Twenty-fold potency enhancement compared to BVdU was achieved against L1210 cells. Interestingly, a number of ProTides showed low micromolar activity against CEM and HeLa cells compared to the inactive parent BVdU. The ProTides showed poor, if any measurable toxicity to non-tumourigenic human lung fibroblast cell cultures. Separation of four pairs of the diastereoisomeric mixtures and comparison of their spectral properties, biological activities and enzymatic activation rate is reported.

Structure of the Varicella Zoster Virus Thymidylate Synthase Establishes Functional and Structural Similarities as the Human Enzyme and Potentiates Itself as a Target of Brivudine.

Varicella zoster virus (VZV) is a highly infectious human herpesvirus that is the causative agent for chicken pox and shingles. VZV encodes a functional thymidylate synthase (TS), which is the sole enzyme that produces dTMP from dUMP de novo. To study substrate binding, the complex structure of TSVZV with dUMP was determined to a resolution of 2.9 Å. In the absence of a folate co-substrate, dUMP binds in the conserved TS active site and is coordinated similarly as in the human encoded TS (TSHS) in an open conformation. The interactions between TSVZV with dUMP and a cofactor analog, raltitrexed, were also studied using differential scanning fluorimetry (DSF), suggesting that TSVZV binds dUMP and raltitrexed in a sequential binding mode like other TS. The DSF also revealed interactions between TSVZV and in vitro phosphorylated brivudine (BVDUP), a highly potent anti-herpesvirus drug against VZV infections. The binding of BVDUP to TSVZV was further confirmed by the complex structure of TSVZV and BVDUP solved at a resolution of 2.9 Å. BVDUP binds similarly as dUMP in the TSHS but it induces a closed conformation of the active site. The structure supports that the 5-bromovinyl substituent on BVDUP is likely to inhibit TSVZV by preventing the transfer of a methylene group from its cofactor and the subsequent formation of dTMP. The interactions between TSVZV and BVDUP are consistent with that TSVZV is indeed a target of brivudine in vivo. The work also provided the structural basis for rational design of more specific TSVZV inhibitors.

Recolonization of Mutans Streptococci after Application of Chlorhexidine Gel

Streptococcus mutans is specifically suppressed by intensive treatment with chlorhexidine gel, but the time for recolonization and the effect on other oral bacteria are not totally clear. In this study, recolonization of mutans streptococci was evaluated in nine healthy adult volunteers, who were highly colonized with this microorganism. Stimulated saliva was collected before (baseline) and at 1, 7, 14, 21 and 28 days after application of 1% chlorhexidine gel on volunteers' teeth for two consecutive days. On each day, the gel was applied using disposable trays for 3 x 5 min with intervals of 5 min between each application. Saliva was plated on blood agar to determine total microorganisms (TM); on mitis salivarius agar to determine total streptococci (TS) and on mitis salivarius agar plus bacitracin to determine mutans streptococci (MS). Chlorhexidine was capable of reducing the counts of MS and the proportion of MS with regard to total microorganisms (%MS/TM) (p<0.05), but these values did not differ statistically from baseline (p>0.05) after 14 days for MS and 21 days for %MS/TM. The counts of TM and TS and the proportion of MS to total streptococci did not differ statistically from baseline (p>0.05) after chlorhexidine treatment. The results suggest that the effect of chlorhexidine gel treatment on suppression of mutans streptococci is limited to less than a month in highly colonized individuals.

Streptococcus mutans é especificamente suprimido pelo tratamento intensivo com clorexidina em gel, mas o tempo de recolonização e o efeito em outras bactérias orais não está totalmente claro. Nesse estudo, a recolonização de estreptococos do grupo mutans foi avaliado em nove voluntários adultos saudáveis, os quais eram altamente colonizados por esse microrganismo. Saliva estimulada foi coletada antes (baseline) e 1, 7, 14, 21 e 28 dias após a aplicação de clorexidina em gel a 1% nos dentes dos voluntários por dois dias consecutivos. Em cada dia, o gel foi aplicado utilizando moldeiras descartáveis por 3 x 5 min com intervalos de 5 min entre cada aplicação. A saliva foi inoculada em ágar sangue para determinação dos microrganismos totais (MT); em mitis salivarius ágar para determinação dos estreptococos totais (ET) e em meio mitis salivarius com bacitracina para determinar a contagem de estreptococos do grupo mutans (EGM). O tratamento com clorexidina foi capaz de reduzir as contagens de EGM e a proporção de EGM em relação aos microrganismos totais (%EGM/MT) (p<0,05), mas esses valores não diferiram estatisticamente do baseline (p>0,05) após 14 dias para EGM e 21 dias para %EGM/MT. As contagens de MT e ET e a proporção de EGM em relação a estreptococos totais não difereriram estatisticamente do baseline (p>0,05) após o tratamento com clorexidina. Os resultados sugerem que o efeito do tratamento com clorexidina em gel na supressão de estreptococos do grupo mutans é limitado a menos de um mês em indivíduos altamente colonizados. .

Predictive factors of alcohol and tobacco use in adolescents / Fatores preditivos do uso de álcool e tabaco em adolescentes / Factores predictivos del uso de alcohol y tabaco en los adolescentes

OBJECTIVES: to analyze the effect of self-esteem, assertiveness, self-efficacy and resiliency on alcohol and tobacco consumption in adolescents. METHOD: a descriptive and correlational study was undertaken with 575 adolescents in 2010. The Self-Esteem Scale, the Situational Confidence Scale, the Assertiveness Questionnaire and the Resiliency Scale were used. RESULTS: the adjustment of the logistic regression model, considering age, sex, self-esteem, assertiveness, self-efficacy and resiliency, demonstrates significance in the consumption of alcohol and tobacco. Age, resiliency and assertiveness predict alcohol consumption in the lifetime and assertiveness predicts alcohol consumption in the last year. Similarly, age and sex predict tobacco consumption in the lifetime and age in the last year. CONCLUSION: this study can offer important information to plan nursing interventions involving adolescent alcohol and tobacco users. .

OBJETIVOS: analisar o efeito da autoestima, assertividade, autoeficácia e resiliência sobre o consumo de álcool e tabaco em adolescentes. MÉTODO: estudo descritivo correlacional com 575 adolescentes, realizado no ano 2010. Foram utilizadas a Escala de Autoestima, o Questionário de Confiança Situacional, o Questionário de Assertividade e a Escala de Resiliência. RESULTADOS: o ajuste do modelo de regressão logística, considerando a idade, sexo, autoestima, assertividade, autoeficácia e resiliência foi significante em relação ao consumo de álcool e tabaco. A idade, resiliência e assertividade foram preditores do consumo de álcool em algum momento na vida e a idade e a assertividade foram preditores no último ano. Para o consumo de tabaco, a idade e o sexo foram preditores em algum momento na vida e a idade no último ano. CONCLUSÃO: este estudo pode proporcionar informações importantes para o planejamento de intervenções de enfermagem em adolescentes usuários de álcool e tabaco .

OBJETIVOS: analizar el efecto de la autoestima, asertividad, autoeficacia y resiliencia sobre el consumo de alcohol y tabaco en adolescentes. MÉTODO: descritivo correlacional con 575 adolescentes, en 2010. Se utilizaron la Escala de Autoestima, el Cuestionario de Confianza Situacional, el Cuestionario de Asertividad y la Escala de Resiliencia. RESULTADOS: el ajuste del modelo de regresión logística, considerando la edad, sexo, autoestima, asertividad, autoeficacia y resiliencia, muestra significancia en el consumo de alcohol y tabaco. La edad, resiliencia y asertividad predicen el consumo de alcohol alguna vez en la vida y la edad y asertividad en el último año. De la misma forma la edad y sexo predicen el consumo de tabaco alguna vez en la vida y la edad en el último año. CONCLUSIÓN: este estudio puede proporcionar información importante para la planificación de intervenciones en enfermería de los adolecentes usuarios de alcohol y tabaco. .

Spectrum of activity and mechanisms of resistance of various nucleoside derivatives against gammaherpesviruses.

The susceptibilities of gammaherpesviruses, including Epstein-Barr virus (EBV), Kaposi's sarcoma-associated herpesvirus (KSHV), and animal rhadinoviruses, to various nucleoside analogs was investigated in this work. Besides examining the antiviral activities and modes of action of antivirals currently marketed for the treatment of alpha- and/or betaherpesvirus infections (including acyclovir, ganciclovir, penciclovir, foscarnet, and brivudin), we also investigated the structure-activity relationship of various 5-substituted uridine and cytidine molecules. The antiviral efficacy of nucleoside derivatives bearing substitutions at the 5 position was decreased if the bromovinyl was replaced by chlorovinyl. 1-ß-D-Arabinofuranosyl-(E)-5-(2-bromovinyl)uracil (BVaraU), a nucleoside with an arabinose configuration of the sugar ring, exhibited no inhibitory effect against rhadinoviruses but was active against EBV. On the other hand, the fluoroarabinose cytidine analog 2'-fluoro-5-iodo-aracytosine (FIAC) showed high selectivity indices against gammaherpesviruses that were comparable to those of brivudin. Additionally, we selected brivudin- and acyclovir-resistant rhadinoviruses in vitro and characterized them by phenotypic and genotypic (i.e., sequencing of the viral thymidine kinase, protein kinase, and DNA polymerase) analysis. Here, we reveal key amino acids in these enzymes that play an important role in substrate recognition. Our data on drug susceptibility profiles of the different animal gammaherpesvirus mutants highlighted cross-resistance patterns and indicated that pyrimidine nucleoside derivatives are phosphorylated by the viral thymidine kinase and purine nucleosides are preferentially activated by the gammaherpesvirus protein kinase.