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Ad.CMV-CD is a replication incompetent adenoviral vector carrying a cytomegalovirus (CMV)-driven transcription unit of the cytosine deaminase (CD) gene. The CD transcription unit in this vector catalyzes the deamination of the nontoxic pro-drug, 5-fluorocytosine (5-FC), thus converting it to the cytotoxic drug 5-fluorouracil (5-FU). This adenoviral vector prodrug activation system has been proposed for use in selectively sensitizing breast cancer cells, which may contaminate collections of autologous stem cells products from breast cancer patients, to the toxic effects of 5-FC, without damaging the reconstitutive capability of the normal hematopoietic cells. This system could conceivably kill even the nondividing breast cancer cells, because the levels of 5-FU generated by this system are 10 to 30 times that associated with systemic administration of 5-FU. The incorporation of 5-FU into mRNA at these high levels is sufficient to disrupt mRNA processing and protein synthesis so that even nondividing cells die of protein starvation. To test if the CD adenoviral vector sensitizes breast cancer cells to 5-FC, we exposed primary explants of normal human mammary epithelial cells (HMECs) and the established breast cancer cell (BCC) lines MCF-7 and MDA-MB-453 to the Ad.CMV-CD for 90 minutes. This produced a 100-fold sensitization of these epithelial cells to the effects of 48 hours of exposure to 5-FC. We next tested the selectivity of this system for BCC. When peripheral blood mononuclear cells (PBMCs), collected from cancer patients during the recovery phase from conventional dose chemotherapy-induced myelosuppression, were exposed to the Ad.CMV-CD for 90 minutes in serum-free conditions, little or no detectable conversion of 5-FC into 5-FU was seen even after 48 hours of exposure to high doses of 5-FC. In contrast, 70% of 5-FC was converted into the cytotoxic agent 5-FU when MCF-7 breast cancer cells (BCCs) were exposed to the same Ad.CMV-CD vector followed by 5-FC for 48 hours. All of the BCC lines tested were shown to be sensitive to infection by adenoviral vectors when exposed to a recombinant adenoviral vector containing the reporter gene betagalactosidase (Ad.CMV-betagal). In contrast, less than 1% of the CD34-selected cells and their more immature subsets, such as the CD34+CD38- or CD34(+)CD33- subpopulations, were positive for infection by the Ad.CMV-betagal vector, as judged by fluorescence-activated cell sorting (FACS) analysis, when exposed to the adenoviral vector under conditions that did not commit the early hematopoietic precursor cells to maturation. When artificial mixtures of hematopoietic cells and BCCs were exposed for 90 minutes to the Ad.CMV-CD vector and to 5-FC for 10 days or more, a greater than 1 million fold reduction in the number of BCCs, as measured by colony-limiting dilution assays, was observed. To test if the conditions were damaging for the hematopoietic reconstituting cells, marrow cells collected from 5-FU-treated male donor mice were incubated with the cytosine deaminase adenoviral vector and then exposed to 5-FC either for 4 days in vitro before transplantation or for 14 days immediately after transplantation in vivo. There was no significant decrease in the reconstituting capability of the male marrow cells, as measured by their persistence in female irradiated recipients for up to 6 months after transplantation. These observations suggest that adenovirus-mediated gene transfer of the Escherichia coli cytosine deaminase gene followed by exposure to the nontoxic pro-drug 5-FC may be a potential strategy to selectively reduce the level of contaminating BCCs in collections of hematopoietic cells used for autografts in breast cancer patients.

A study was conducted on the roles of nonparenchymal cells and hepatocytes in uridine catabolism as a component of its homeostasis. The findings indicate a cellular basis for the catabolism by dissociation of the liver with collagenase into two cell fractions, hepatocytes and a nonparenchymal cell population. Moreover, the results demonstrate the existence of a Na+-dependent, nitrobenzylthioinosine-insensitive transport system for uridine in the parenchymal cells.

PURPOSE: (E)-2'-fluoromethylene-2'-deoxycytidine is a novel antimetabolite. Preclinical tests have shown antiproliferative activity in various human tumor xenograft models and have also indicated that efficacy is greatest with frequent dosing schedules. We conducted a phase I trial of MDL 101,731 infusion in humans with advanced cancer to determine the maximum tolerated dose and the dose-limiting toxicities of this drug when administered on a twice-weekly schedule. PATIENTS AND METHODS: The drug was administered on a twice-weekly schedule for 3 weeks, followed by a 2-week rest. The initial dose was 16 mg/m2. This was reduced to 12 mg/m2 if persistent neutropenia occurred. All toxicity in the first six patients resolved by the end of the first rest week. The schedule was changed to 3 weeks of therapy followed by 1 rest week for the subsequent four patients. RESULTS: Dose escalation beyond 16 mg/m2 was not feasible because of dose-limiting toxicities, principally hematologic. No irreversible or life-threatening toxicity was seen. Grade 2 noninfectious fever, mucositis, and anorexia were also seen. In patients with stable disease, there was a heavily pretreated patient with rectal cancer in whom a 38% reduction in indicator lesions of 7 months' duration occurred. DISCUSSION: (E)-2'-fluoromethylene-2'-deoxycytidine is a novel antimetabolite with evidence of anticancer activity in heavily pretreated patients. The maximum tolerated dose when the agent is given twice weekly is 16 mg/m2. [ABSTRACT FROM AUTHOR]

Purpose: Based on preclinical data demonstrating synergy between camptothecin analogues and taxanes, we determined the maximum tolerated dose (MTD) of irinotecan that could be given in combination with a fixed dose of paclitaxel of 75 mg/m2, when both drugs were delivered on a weekly schedule. The pharmacokinetics of this combination were explored to determine whether the sequence of administration affected the elimination of irinotecan.Methods: For the first cycle patients with advanced cancer were treated with irinotecan given as a 90-min infusion followed immediately by paclitaxel given at a dose of 75 mg/m2 over 1 h. The sequence of drug administration was reversed in subsequent cycles for most patients. Chemotherapy was given weekly for 4 weeks, followed by a 2-week rest. In selected patients, plasma concentrations of irinotecan were determined by high-performance liquid chromatography during the first 24 h of cycle 1 and after the first dose of cycle 2 to determine whether the order of drug administration affected the elimination of irinotecan, or the toxicologic effects of the chemotherapy.Results: A total of 53 cycles were delivered to 21 patients. Reversible neutropenia was dose-limiting. Suppression of the other blood cell elements was modest. There was one partial response in a man with a previously treated cholangiocarcinoma that lasted 26 weeks. Prolonged stabilization of disease (6 months or more) was observed in five of the patients (24%). At the recommended dose of irinotecan (50 mg/m2), transfusions of red cells and platelets were not required. The sequence of drug administration produced no significant differences in the pharmacokinetic parameters of irinotecan or SN-38, which were similar to the values reported when irinotecan is administered alone. The most prominent nonhematologic toxicities were mild diarrhea and fatigue.Conclusions: The recommended dose of irinotecan on this schedule is 50 mg/m2. The sequence of drug administration affects neither the elimination of irinotecan nor the chemotherapy-related toxicity. This combination is well tolerated and causes minimal clinical side effects. [ABSTRACT FROM AUTHOR]

Biochemical modulation can increase the efficacy of 5-fluorouracil (5-FU). Pizzorno et al. have previously shown that brequinar, a de novo pyrimidine synthesis inhibitor, enhances the antitumor effect of 5-FU in vivo [Cancer Res 52: 1660-1665, 1992]. On the basis of their data, we conducted a phase I study of brequinar in combination with 5-FU in patients with refractory solid tumors. The initial dose (100 mg/m2) of brequinar was raised in 100-mg/m2 increments in cohorts of three assessable patients. The initial dose of 5-FU was 500 mg/m2, but escalation was allowed in patients who showed no significant toxic reaction. Brequinar was administered over 1 h and 5-FU over 2 h starting 18-20 h after the initiation of infusion of brequinar. Treatments were repeated weekly. Responses were evaluated after 4 weeks (one course) and then every 8 weeks thereafter. Pharmacokinetics of brequinar and determination of plasma uridine levels were performed in at least three patients at each dose level. Of the 25 patients registered in the study, 21 were assessable for toxicity studies. The dose of brequinar was escalated up to 600 mg/m2. In addition, the dose of 5-FU was increased to 600 mg/m2 as a result of a lack of a significant toxic reaction in the first nine patients. No objective responses were observed. One patient developed grade 3 stomatitis, and one developed grade 3 esophagitis at the 400 and 600 mg/m2 dose of brequinar, respectively. Brequinar produced a dose-dependent decrease in plasma uridine levels at doses up to 500 mg/m2. No additional decrease in plasma uridine occurred with higher doses of brequinar, thus suggesting a plateau effect. This observation prompted us to terminate the study before reaching the maximum tolerated dose of brequinar. Our data indicate that brequinar in doses > or = 400 mg/m2 results in significant biochemical modulation. The lack of toxicity seen at these doses of brequinar suggests that the initial dose of the effector agent 5-FU should be increased in future studies. [ABSTRACT FROM AUTHOR]

The present meta-analysis aimed to assess the impact of electroconvulsive therapy (ECT) in preventing the relapse and recurrence of depression in adults with major depressive disorders. The study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Two authors conducted a systematic search of online databases, such as PubMed, PsycINFO, and EMBASE, using keywords, such as "electroconvulsive therapy," "depressive disorders," and "recurrence." The primary outcome measure was the incidence of relapse and recurrence in adults with major depressive disorder who received ECT alone or in combination with an antidepressant medication compared to those who received antidepressant medication alone. The secondary outcome measure was the change in the Mini-Mental State Examination score from baseline to the end of the trial in both groups. A total of six articles were included in the meta-analysis. The pooled rate of recurrence in the ECT group was 28.4% compared to 30.6% in the antidepressant group, with no significant difference between the two groups (risk ratio (RR) = 0.84, 95% confidence interval (CI) = 0.65-1.10, p = 0.21). However, subgroup analysis showed that the risk of recurrence was significantly lower in patients receiving ECT with antidepressant therapy compared to the antidepressant group alone (RR = 0.65, 95% CI = 0.45-0.93, p = 0.02). On the other hand, when ECT was given alone, the risk was higher in the ECT group compared to the antidepressant group; however, the difference was not statistically significant (RR = 1.17, 95% CI = 0.79-1.75). In conclusion, the results of this meta-analysis suggest that ECT alone or in combination with an antidepressant medication does not significantly impact the incidence of recurrence in adults with major depressive disorder when compared to antidepressant medication alone., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Dar et al.)

This meta-analysis was conducted with the aim to assess the safety and efficacy of favipiravir in treating patients with coronavirus disease 2019 (COVID-19). It was carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We performed a thorough search of online databases including PubMed, EMBASE, and the Cochrane Library from their inceptions to November 30, 2022, using the following search terms: "Favipiravir" AND "COVID-19". We included randomized control trials (RCTs) that were conducted to determine the efficacy and safety of favipiravir for COVID-19. Efficacy outcomes assessed in this meta-analysis included time to viral clearance in days, time to clinical improvement in days, need for supplementary oxygen, and requirement of ICU admission. For safety outcomes, we compared overall adverse events and serious adverse events that had occurred during the treatment between the patients in the treatment group and the control group. Eight studies involving 1,448 patients were included in this meta-analysis. The results showed that no significant differences were found between the two groups in terms of time to viral clearance, time to clinical improvement, and the need for supplementary oxygen and ICU admission. In terms of safety, no significant differences were found between the two groups in relation to adverse events and serious adverse events. The current study found that favipiravir did not exert any beneficial impact on reducing ICU admission, the need for oxygen therapy, and time to viral clearance. However, a slight benefit was reported with regard to the time for clinical improvement, but it was insignificant between the two study groups., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Batool et al.)

We intended to summarize the most recent research pertaining to the use of phosphodiesterase-5 (PDE5) inhibitors in pulmonary hypertension in light of recent developments in the knowledge of the pathophysiological mechanisms and treatments for pulmonary hypertension, with major contributions in the area in the last decade. The aim of this meta-analysis is to determine the efficacy of PDE5 inhibitors for pulmonary hypertension in adults. We followed the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines to carry out this meta-analysis. Online database searching to identify eligible trials was performed in MEDLINE, EMBASE, and the Cochrane Library by two authors independently. Outcomes assessed in the current meta-analysis included change in the cardiac index from baseline in liters per minute per square meter (L/min/m 2 ), mean peripheral arterial pressure (PAP) in mm Hg, mortality, hospitalization, and six-minute walking distance (6MWD) in meters (m). Overall, 17 articles met the inclusion criteria and were included in the current meta-analysis. PDE5 inhibitors significantly improve cardiac index (mean difference: 0.18, 95% CI: 0.04, 0.32, p-value: 0.01), mean PAP (mean difference: -5.61, 95% CI: -7.60, -3.62, p-value: 0.01), and 6MWD (mean difference: 26.26, 95% CI: 16.95, 35.57, p-value: 0.001) as compared to the patients in the control group. No significant difference was found in terms of risk of mortality (risk ratio (RR): 0.51, 95% CI: 0.17, 1.54) and risk of hospitalization (RR: 0.59, 95% CI: 0.23, 1.55) between the two groups. The current meta-analysis concluded that PDE5 inhibitors improve 6MWD, mean PAP, and cardiac index in patients with pulmonary hypertension. However, no significant difference was reported in terms of mortality and hospitalization between the two groups., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Karedath et al.)

In the present minireview, we intend to provide a brief history of the field of CD9 involvement in oncogenesis and in the metastatic process of cancer, considering its potential value as a tumor-associated antigenic target. Over the years, CD9 has been identified as a favorable prognostic marker or predictor of metastatic potential depending on the cancer type. To understand its implications in cancer beside its use as an antigenic biomarker, it is essential to know its physiological functions, including its molecular partners in a given cell system. Moreover, the discovery that CD9 is one of the most specific and broadly expressed markers of extracellular membrane vesicles, nanometer-sized entities that are released into extracellular space and various physiological body fluids and play a role in intercellular communication under physiological and pathological conditions, notably the establishment of cancer metastases, has added a new dimension to our knowledge of CD9 function in cancer. Here, we will discuss these issues as well as the possible cancer therapeutic implications of CD9, their limitations, and pitfalls.

Uridine is a pyrimidine nucleoside that exerts restorative functions in tissues under stress. Short-term co-administration of uridine with multiple unrelated drugs prevents drug-induced liver lipid accumulation. Uridine has the ability to modulate liver metabolism; however, the precise mechanism has not been delineated. In this study, long-term effects of uridine on liver metabolism were examined in both HepG2 cell cultures and C57BL/6J mice. We report that uridine administration was associated with O-GlcNAc modification of FOXO1, increased gluconeogenesis, reduced insulin signaling activity, and reduced expression of a liver-specific fatty acid binding protein FABP1. Long-term uridine feeding induced systemic glucose intolerance and severe liver lipid accumulation in mice. Our findings suggest that the therapeutic potentials of uridine should be designed for short-term acute administration.

Introduction: More than one-third of US adults are obese. Workplace programs to reduce obesity and improve overall health are not available or accessible to all workers, particularly low-wage workers among whom obesity is more prevalent. The goal of the study was to identify modifiable workplace factors and behaviors associated with diet and exercise to inform future workplace interventions to improve health., Methods: We distributed paper and online surveys to 2 groups of low-wage workers, hospital workers and retail sales workers, at the worksites. The surveys assessed obesity, obesogenic behaviors, workplace factors, and worker participation in workplace health programs (WHPs). Descriptive and regression analyses were conducted to examine workplace factors associated with obesogenic behaviors., Results: A total of 529 surveys were completed (219 hospital workers and 310 retail workers). More than 40% of workers were obese and 27% were overweight. In general, workers had poor diets (frequent consumption of sugary and high-fat foods) and engaged in little physical activity (only 30.9% met recommended physical activity guidelines). Access to and participation in workplace health programs varied greatly between hospital and retail sales workers. We identified several modifiable workplace factors, such as food source and work schedule, that were associated with diet, exercise, or participation in workplace health programs., Conclusion: This study illustrates the high prevalence of obesity and obesogenic behaviors workers in 2 low-wage groups. The differences between work groups indicated that each group had unique facilitators and barriers to healthy eating and exercise. An understanding of how socioeconomic, demographic, and work-related factors influence health will help to identify high-risk populations for intervention and to design interventions tailored and relevant to the target audiences.

Purines and pyrimidines are complementary bases of the genetic code. The roles of purines and their derivatives in cellular signal transduction and energy metabolism are well-known. In contrast, the roles of pyrimidines and their derivatives in cellular function remain poorly understood. In this study, the roles of uridine, a pyrimidine nucleoside, in liver metabolism are examined in mice. We report that short-term uridine administration in C57BL/6J mice increases liver protein glycosylation profiles, reduces phosphorylation level of insulin signaling proteins, and activates the HRI-eIF-2α-ATF4 heme-deficiency stress response pathway. Short-term uridine administration is also associated with reduced liver hemin level and reduced ability for insulin-stimulated blood glucose removal during an insulin tolerance test. Some of the short-term effects of exogenous uridine in C57BL/6J mice are conserved in transgenic UPase1-/- mice with long-term elevation of endogenous uridine level. UPase1-/- mice exhibit activation of the liver HRI-eIF-2α-ATF4 heme-deficiency stress response pathway. UPase1-/- mice also exhibit impaired ability for insulin-stimulated blood glucose removal. However, other short-term effects of exogenous uridine in C57BL/6J mice are not conserved in UPase1-/- mice. UPase1-/- mice exhibit normal phosphorylation level of liver insulin signaling proteins and increased liver hemin concentration compared to untreated control C57BL/6J mice. Contrasting short-term and long-term consequences of uridine on liver metabolism suggest that uridine exerts transient effects and elicits adaptive responses. Taken together, our data support potential roles of pyrimidines and their derivatives in the regulation of liver metabolism.

Background: Tamoxifen, an agonist of estrogen receptor, is widely prescribed for the prevention and long-term treatment of breast cancer. A side effect of tamoxifen is fatty liver, which increases the risk for non-alcoholic fatty liver disease. Prevention of tamoxifen-induced fatty liver has the potential to improve the safety of long-term tamoxifen usage., Methods: Uridine, a pyrimidine nucleoside with reported protective effects against drug-induced fatty liver, was co-administered with tamoxifen in C57BL/6J mice. Liver lipid levels were evaluated with lipid visualization using coherent anti-Stokes Raman scatting (CARS) microscopy, biochemical assay measurement of triacylglyceride (TAG), and liquid chromatography coupled with mass spectrometry (LC-MS) measurement of membrane phospholipid. Blood TAG and cholesterol levels were measured. Mitochondrial respiration of primary hepatocytes in the presence of tamoxifen and/or uridine was evaluated by measuring oxygen consumption rate with an extracellular flux analyzer. Liver protein lysine acetylation profiles were evaluated with 1D and 2D Western blots. In addition, the relationship between endogenous uridine levels, fatty liver, and tamoxifen administration was evaluated in transgenic mice UPase1-/-and UPase1-TG., Results: Uridine co-administration prevented tamoxifen-induced liver lipid droplet accumulation in mice. The most prominent effect of uridine co-administration with tamoxifen was the stimulation of liver membrane phospholipid biosynthesis. Uridine had no protective effect against tamoxifen-induced impairment to mitochondrial respiration of primary hepatocytes or liver TAG and cholesterol export. Uridine had no effect on tamoxifen-induced changes to liver protein acetylation profile. Transgenic mice UPase1-/-with increased pyrimidine salvage activity were protected against tamoxifen-induced liver lipid droplet accumulation. In contrast, UPase1-TG mice with increased pyrimidine catabolism activity had intrinsic liver lipid droplet accumulation, which was aggravated following tamoxifen administration., Conclusion: Uridine co-administration was effective at preventing tamoxifen-induced liver lipid droplet accumulation. The ability of uridine to prevent tamoxifen-induced fatty liver appeared to depend on the pyrimidine salvage pathway, which promotes biosynthesis of membrane phospholipid.

Balanced pools of deoxyribonucleoside triphosphate precursors are required for DNA replication, and alterations of this balance are relevant to human mitochondrial diseases including mitochondrial neurogastrointestinal encephalopathy. In this disease, autosomal recessive TYMP mutations cause severe reductions of thymidine phosphorylase activity; marked elevations of the pyrimidine nucleosides thymidine and deoxyuridine in plasma and tissues, and somatic multiple deletions, depletion and site-specific point mutations of mitochondrial DNA. Thymidine phosphorylase and uridine phosphorylase double knockout mice recapitulated several features of these patients including thymidine phosphorylase activity deficiency, elevated thymidine and deoxyuridine in tissues, mitochondrial DNA depletion, respiratory chain defects and white matter changes. However, in contrast to patients with this disease, mutant mice showed mitochondrial alterations only in the brain. To test the hypothesis that elevated levels of nucleotides cause unbalanced deoxyribonucleoside triphosphate pools and, in turn, pathogenic mitochondrial DNA instability, we have stressed double knockout mice with exogenous thymidine and deoxyuridine, and assessed clinical, neuroradiological, histological, molecular, and biochemical consequences. Mutant mice treated with exogenous thymidine and deoxyuridine showed reduced survival, body weight, and muscle strength, relative to untreated animals. Moreover, in treated mutants, leukoencephalopathy, a hallmark of the disease, was enhanced and the small intestine showed a reduction of smooth muscle cells and increased fibrosis. Levels of mitochondrial DNA were depleted not only in the brain but also in the small intestine, and deoxyribonucleoside triphosphate imbalance was observed in the brain. The relative proportion, rather than the absolute amount of deoxyribonucleoside triphosphate, was critical for mitochondrial DNA maintenance. Thus, our results demonstrate that stress of exogenous pyrimidine nucleosides enhances the mitochondrial phenotype of our knockout mice. Our mouse studies provide insights into the pathogenic role of thymidine and deoxyuridine imbalance in mitochondrial neurogastrointestinal encephalopathy and an excellent model to study new therapeutic approaches.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder caused by mutations in TYMP, enconding thymidine phosphorylase (TP). TP deficiency results in systemic accumulation of thymidine and deoxyuridine, which interferes with mitochondrial DNA (mtDNA) replication and leads to mitochondrial dysfunction. To date, the only treatment available for MNGIE patients is allogeneic hematopoietic stem cell transplantation, which is associated with high morbidity and mortality. Here, we report that AAV2/8-mediated transfer of the human TYMP coding sequence (hcTYMP) under the control of a liver-specific promoter prevents the biochemical imbalances in a murine model of MNGIE. hcTYMP expression was restricted to liver, and a dose as low as 2 × 10(11) genome copies/kg led to a permanent reduction in systemic nucleoside levels to normal values in about 50% of treated mice. Higher doses resulted in reductions to normal or slightly below normal levels in virtually all mice treated. The nucleoside reduction achieved by this treatment prevented deoxycytidine triphosphate (dCTP) depletion, which is the limiting factor affecting mtDNA replication in this disease. These results demonstrate that the use of AAV to direct TYMP expression in liver is feasible as a potentially safe gene therapy strategy for MNGIE.