Metformin to treat Huntington disease: A pleiotropic drug against a multi-system disorder.

Huntington disease (HD) is a neurodegenerative disorder produced by an expansion of CAG repeats in the HTT gene. Patients of HD show involuntary movements, cognitive decline and psychiatric impairment. People carrying abnormally long expansions of CAGs (more than 35 CAG repeats) produce mutant huntingtin (mHtt), which encodes tracks of polyglutamines (polyQs). These polyQs make the protein prone to aggregate and cause it to acquire a toxic gain of function. Principally affecting the frontal cortex and the striatum, mHtt disrupts many cellular functions. In addition, this protein is expressed ubiquitously, and some reports show that many other cell types are affected by the toxicity of mHtt. Several studies reported that metformin, a widely-used anti-diabetic drug, is neuroprotective in models of HD. Here, we provide a review of the benefits of this substance to treat HD. Metformin is a pleiotropic drug, modulating different targets such as AMPK, insulin signalling and many others. These molecules regulate autophagy, chaperone expression, and more, which in turn reduce mHtt toxicity. Moreover, metformin alters gut microbiome and its metabolic processes. The study of potential targets, interactions between the drug, host and microbiome, or genomic and pharmacogenomic approaches may allow us to design personalised medicine to treat HD.

Consensus of experts from the Spanish Pharmacogenetics and Pharmacogenomics Society and the Spanish Society of Medical Oncology for the genotyping of DPYD in cancer patients who are candidates for treatment with fluoropyrimidines.

5-Fluorouracil (5-FU) and oral fluoropyrimidines, such as capecitabine, are widely used in the treatment of cancer, especially gastrointestinal tumors and breast cancer, but their administration can produce serious and even lethal toxicity. This toxicity is often related to the partial or complete deficiency of the dihydropyrimidine dehydrogenase (DPD) enzyme, which causes a reduction in clearance and a longer half-life of 5-FU. It is advisable to determine if a DPD deficiency exists before administering these drugs by genotyping DPYD gene polymorphisms. The objective of this consensus of experts, in which representatives from the Spanish Pharmacogenetics and Pharmacogenomics Society and the Spanish Society of Medical Oncology participated, is to establish clear recommendations for the implementation of genotype and/or phenotype testing for DPD deficiency in patients who are candidates to receive fluoropyrimidines. The genotyping of DPYD previous to treatment classifies individuals as normal, intermediate, or poor metabolizers. Normal metabolizers do not require changes in the initial dose, intermediate metabolizers should start treatment with fluoropyrimidines at doses reduced to 50%, and poor metabolizers are contraindicated for fluoropyrimidines.

Measuring Infection Transmission in a Stochastic SIV Model with Infection Reintroduction and Imperfect Vaccine.

An additional compartment of vaccinated individuals is considered in a SIS stochastic epidemic model with infection reintroduction. The quantification of the spread of the disease is modeled by a continuous time Markov chain. A well-known measure of the initial transmission potential is the basic reproduction number [Formula: see text], which determines the herd immunity threshold or the critical proportion of immune individuals required to stop the spread of a disease when a vaccine offers a complete protection. Due to repeated contacts between the typical infective and previously infected individuals, [Formula: see text] overestimates the average number of secondary infections and leads to, perhaps unnecessary, high immunization coverage. Assuming that the vaccine is imperfect, alternative measures to [Formula: see text] are defined in order to study the influence of the initial coverage and vaccine efficacy on the transmission of the epidemic.

Impact of NADPH oxidase functional polymorphisms in acute myeloid leukemia induction chemotherapy.

Efficacy and toxicity of anthracycline treatment in acute myeloid leukemia (AML) is mediated by reactive oxygen species (ROS). NADPH oxidase is the major endogenous source of ROS and a key mediator of oxidative cardiac damage. The impact of NADPH oxidase polymorphisms (CYBA:rs4673, NCF4:rs1883112, RAC2:rs13058338) was evaluated in 225 adult de novo AML patients. Variant alleles of NCF4 and RAC2 were related to higher complete remission (P=0.035, P=0.016), and CYBA homozygous variant showed lower overall survival with recessive model (P=0.045). Anthracycline-induced cardiotoxicity was associated to NCF4 homozygous variant (P=0.012) and CYBA heterozygous genotype (P=0.027). Novel associations were found between variant allele of CYBA and lower lung and gastrointestinal toxicities, and a protective effect in nephrotoxicity and RAC2 homozygous variant. Moreover, RAC2 homozygous variant was related to delayed thrombocytopenia recovery. This study supports the interest of NADPH oxidase polymorphisms regarding efficacy and toxicity of AML induction therapy, in a coherent integrated manner.

A systematic review and meta-analysis of the impact of WT1 polymorphism rs16754 in the effectiveness of standard chemotherapy in patients with acute myeloid leukemia.

The polymorphism rs16754 of the WT1 gene has been described as a possible prognostic marker in different acute myeloid leukemia (AML) cohorts; however, it is not supported by all the studies. We performed the first meta-analysis evaluating the effect of this polymorphism upon the effectiveness of standard AML therapy. Fourteen cohort studies were included (3618 patients). Patients with the variant allele showed a significant higher overall survival (OS) at 5 years (OR:1.24, 95% CI: 1.06-1.45, P=0.007, with dominant model). WT1 did not influence complete remission, but a higher disease-free survival was observed with the variant allele. In the subgroup analysis, Caucasians, pediatric and patients treated with idarubicin and etoposide carrying the variant allele showed consistent results in OS, whereas patients with cytogenetically normal AML did not show differences. To verify the effect of this polymorphism upon other outcomes, studies in larger and multiracial populations are needed.

Influence of ABCB1 polymorphisms upon the effectiveness of standard treatment for acute myeloid leukemia: a systematic review and meta-analysis of observational studies.

The ABCB1 gene encodes for P-glycoprotein (P-gp), an efflux pump for a variety of xenobiotics. The role of ABCB1 polymorphisms in acute myeloid leukemia (AML) outcomes of standard chemotherapy (cytarabine plus anthracyclines) remains controversial. A systematic search was made of studies evaluating the association between ABCB1 polymorphisms 1236C>T, 2677G>T/A and 3435C>T and effectiveness variables. We found seven cohort studies (1241 patients) showing a significantly higher overall survival (OS) among carriers of the variant allele of 1236C>T at year 4 (odds ratio (OR): 1.47, 95% confidence interval (CI): 1.07-2.01), 2677G>T/A at years 4-5 (OR: 1.37, 95% CI: 1.01-1.86) and 3435C>T at years 3 (OR: 1.41, 95% CI: 1.03-1.94) and 4-5 (OR: 1.42, 95% CI: 1.05-1.91). In the subgroup analysis according to ethnicity, Caucasians carrying variant allele showed consistent results in OS. ABCB1 influence upon complete remission could not be demonstrated. Future studies based on larger populations and multiethnic groups should help clarify the effect of P-gp polymorphisms upon other outcomes.

A surgical model for isolating the pig liver in vivo for gene therapy.

Several studies report results that suggest the need of vascularization blocking for efficient gene transfer to the liver, especially in nonviral gene therapy. In this study, we describe a surgical strategy for in vivo isolation of the pig liver, resulting in a vascular watertight organ that allows the evaluation of several gene injection conditions. The hepatic artery and portal, suprahepatic and infrahepatic cava veins were dissected. Then, liver vascularization was excluded for 5-7 min. In that time, we first injected 200 ml saline solution containing the p3c-eGFP plasmid (20 µg/ml) simultaneously through two different catheters placed in the portal and cava veins, respectively. Vital constants were monitored during the surgery to assess the safety of the procedure. Basal systolic/diastolic blood pressures were 92.8/63.2 mm Hg and dropped to 40.7/31.3 mm Hg at the end of vascular exclusion; the mean basal heart rate was 58 bpm, reaching 95 bpm when the blood pressure was low. Oxygen saturation was maintained above 98% during the intervention, and no relevant changes were observed in the ECG tracing. Peak plasma AST (aspartate aminotransferase) and ALT (alanine aminotransferase) levels were observed after 24 h (151 and 57 IU, respectively). These values were higher, but not relevant, in 60 ml/s injection than in 20 ml/s injection. Efficiency of gene transfer was studied with simultaneous (cava and portal veins) injection of eGFP gene at flow rates of 20 and 60 ml/s. Liver tissue samples were collected 24 h after injection and qPCR was carried out on each lobe sample. The results confirmed the efficiency of the procedure. Gene delivery differed between 20 ml/s (9.9-31.0 eGFP DNA copies/100 pg of total DNA) and 60 ml/s injections (0.6-1.1 eGFP DNA copies/100 pg of total DNA). Gene transcription showed no significant differences between 20 ml/s (15,701.8-21,475.8 eGFP RNA copies/100 ng of total RNA) and 60 ml/s (12,014-36,371 eGFP RNA copies/100 ng of total RNA). The procedure is not harmful for animals and it offers a wide range of gene delivery options because it allows different perfusion ways (anterograde and retrograde) and different flow rates to determine the optimal conditions of gene transfer. This strategy permits the use of cell therapy and viral or non-viral liver gene therapy, especially appropriated to a wide variety of inherited or acquired diseases because of the liver's ability to produce and deliver proteins to the bloodstream.

Comparative antitumor effect among GM-CSF, IL-12 and GM-CSF+IL-12 genetically modified tumor cell vaccines.

Genetically modified cells have been shown to be one of the most effective cancer vaccine strategies. An evaluation is made of the efficacy of both preventive and therapeutic antitumor vaccines against murine melanoma, using C57BL/6 mice and irradiated B16 tumor cells expressing granulocyte and macrophage colony-stimulating factor (GM-CSF), interleukin-12 (IL-12) or both. Tumor was transplanted by the injection of wild-type B16 cells. Tumor growth and survival were measured to evaluate the efficacy of vaccination. Specific humoral response and immunoglobulin G (IgG) switch were evaluated measuring total IgG and IgG1 and IgG2a subtypes against tumor membrane proteins of B16 cells. In preventive vaccination, all treated groups showed delayed tumor growth. In addition, the group vaccinated to express only GM-CSF achieved 100% animal survival (P<0.005). Vaccination with GM-CSF+IL-12-producing B16 cells yielded lesser results (60% survival, P<0.005). Furthermore, all surviving animals remained disease-free after second tumor implantation 1 year later. The therapeutic vaccination strategies resulted in significantly delayed tumor growth, mainly using B16 cells producing GM-CSF+IL-12 cytokines, with 70% tumor growth inhibition (P<0.001)-although none of the animals reached overall survival. The results obtained suggest that the GM-CSF+IL-12 combination only increases the efficacy of therapeutic vaccines. No differences in classical regulatory T cells were found among the different groups.

Charcot neuroarthropathy triggered and complicated by osteomyelitis. How limb salvage can be achieved.

BACKGROUND: Charcot neuroarthropathy is a severe complication in the feet of patients with diabetes, which can lead to a major amputation. Osteomyelitis and surgery for osteomyelitis have been reported as trigger mechanisms of developing Charcot neuroarthropathy. However, the development of acute Charcot neuroarthropathy triggered by osteomyelitis during conservative antibiotic treatment is not well outlined in the medical literature. CASE REPORTS: Two patients apparently developed mid and rear foot Charcot neuroarthropathy, which was clinically suspected while being treated with antibiotics for osteomyelitis. One of them presented osteomyelitis of the navicular bone and subsequently developed acute Charcot neuroarthropathy of the tarsometatarsal joints. The other presented calcaneal osteomyelitis with pathological fracture and developed Charcot neuroarthropathy of the transverse tarsal joint. No offloading had been implemented in either case. A major amputation had been indicated in both cases in their teaching hospitals. Limb salvage was achieved in both cases by means of surgery, culture-guided post-operative antibiotics, intraosseus instillation of super-oxidized solution, bed rest before placing a total contact cast and stabilization of the unstable foot with a total contact cast with an opening for checking the healing course and to detect any complications. The mechanisms of the development of acute Charcot neuroarthropathy in a patient with osteomyelitis are discussed. CONCLUSIONS: Osteomyelitis in the feet of patients with diabetes and neuropathy may trigger the development of acute Charcot neuroarthropathy. Fractures and dislocated joints may subsequently become infected from the index focus, producing a severe infected and unstable foot that may require a major amputation. Limb salvage can be achieved in specialized departments.

On the exact measure of disease spread in stochastic epidemic models.

The basic reproduction number, R0, is probably the most important quantity in epidemiology. It is used to measure the transmission potential during the initial phase of an epidemic. In this paper, we are specifically concerned with the quantification of the spread of a disease modeled by a Markov chain. Due to the occurrence of repeated contacts taking place between a typical infective individual and other individuals already infected before, R0 overestimates the average number of secondary infections. We present two alternative measures, namely, the exact reproduction number, Re0, and the population transmission number, Rp, that overcome this difficulty and provide valuable insight. The applicability of Re0 and Rp to control of disease spread is also examined.

Stochastic epidemic models with random environment: quasi-stationarity, extinction and final size.

We investigate stochastic [Formula: see text] and [Formula: see text] epidemic models, when there is a random environment that influences the spread of the infectious disease. The inclusion of an external environment into the epidemic model is done by replacing the constant transmission rates with dynamic rates governed by an environmental Markov chain. We put emphasis on the algorithmic evaluation of the influence of the environmental factors on the performance behavior of the epidemic model.

Stochastic epidemic models revisited: analysis of some continuous performance measures.

We deal with stochastic epidemic models having a set of absorbing states. The aim of the paper is to study some continuous characteristics of the epidemic. In this sense, we first extend the classical study of the length of an outbreak by investigating the whole probability distribution of the extinction time via Laplace transforms. Moreover, we also study two almost new epidemic descriptors, namely, the time until a non-infected individual becomes infected and the time until the individual is removed from the infective group. The obtained results are illustrated by numerical examples including an application to a stochastic SIS model for head lice infections.

DNA delivery to 'ex vivo' human liver segments.

Hydrodynamic injection is an efficient procedure for liver gene therapy in rodents but with limited efficacy in large animals, using an 'in vivo' adapted regional hydrodynamic gene delivery system. We study the ability of this procedure to mediate gene delivery in human liver segments obtained by surgical resection. Watertight liver segments were retrogradely injected from hepatic vein with a saline solution containing a plasmid bearing the enhanced green fluorescent protein (eGFP) gene, under different conditions of flow rate (1, 10 and 20 ml s(-1)) and final perfused volume. Samples were cultured for 1 to 2 days and used for microscopy and molecular analysis of gene expression. The fluorescent and immunohistochemistry studies indicated that in segments injected at ≥10 ml s(-1), good and wide gene expression was present in the liver sections and the molecular analysis reinforced the histological observation in a quantitative manner (index of apparent gene delivery: 10(2)-10(4) eGFP DNA copy per 100 pg of total DNA; transcription index: 10(5)-2 × 10(6) eGFP RNA copy per 100 ng of total RNA). In addition, injected gold nanoparticles (15 nm diameter) suggested that DNA delivery to hepatocytes must involve a facilitated permeation process without membrane disruption. In summary, we show that retrograde venous injection of watertight human liver segment is an anadromous procedure that results in wide liver gene delivery and good gene expression. However, additional studies will be necessary to clarify the influence of the prolonged ischemia injury to hepatocytes in our model.

Does osteomyelitis in the feet of patients with diabetes really recur after surgical treatment? Natural history of a surgical series.

AIMS/HYPOTHESIS: The aim of this study was to determine the rate of recurrence, reulceration and new episodes of osteomyelitis and the duration of postoperative antibiotic treatment in a prospective cohort of patients with diabetes who underwent conservative surgery for osteomyelitis. METHODS: The prospective cohort included patients with diabetes and a definitive diagnosis of osteomyelitis who were admitted to the Diabetic Foot Unit (Surgery Department, La Paloma Hospital, Las Palmas de Gran Canaria, Spain) and underwent surgical treatment from 1 November 2007 to 30 May 2010. RESULTS: Eighty-one patients were operated on for osteomyelitis during the study period. Seven patients were lost to follow-up at different stages of the study. The median duration of follow-up was 101.8 weeks (quartile 1 = 56.6, quartile 3 = 126.7). Forty-eight patients (59.3%) underwent conservative surgery, 32 (39.5%) had minor amputations and there was one (1.2%) major amputation. Twenty patients (24.7%) required reoperation because of persistent infection. Postoperative antibiotic treatment over a median period of 36 days was provided. Wound healing was achieved by secondary intention for a median of 8 weeks. Sixty-five patients were available for follow-up after healing. The percentage of recurrence, reulceration, and new episodes of osteomyelitis was 4.6% (3/65), 43% (28/65) and 16.9% (11/65), respectively. Mortality during follow-up (excluding in-hospital deaths and patients lost to follow-up) was 13% (9/69). CONCLUSION: A low rate of recurrence of osteomyelitis after surgical treatment for osteomyelitis was achieved. Despite new episodes, our approach to managing this cohort of patients with diabetes and foot osteomyelitis achieved 98.8% limb salvage.

The SIS and SIR stochastic epidemic models: a maximum entropy approach.

We analyze the dynamics of infectious disease spread by formulating the maximum entropy (ME) solutions of the susceptible-infected-susceptible (SIS) and the susceptible-infected-removed (SIR) stochastic models. Several scenarios providing helpful insight into the use of the ME formalism for epidemic modeling are identified. The ME results are illustrated with respect to several descriptors, including the number of recovered individuals and the time to extinction. An application to infectious data from outbreaks of extended spectrum beta lactamase (ESBL) in a hospital is also considered.

Influence of pharmacogenetic polymorphisms in routine immunosuppression therapy after renal transplantation.

Pharmacogenetics is the study of the cause of various individual responses to the same pharmacologic therapy. Genetic alterations in a single nucleotide in the genes responsible for transport and metabolism of an immunosuppression drug may modify patient response. Although pharmacogenetics is of interest, its clinical relevance remains to be demonstrated. The objective of the present study was to evaluate the effect of single-nucleotide polymorphisms (SNPs) in renal transplant recipients and their donors relative to blood concentrations of tacrolimus in the first 2 weeks posttransplantation. Seventy-one blood samples each from renal transplant recipients and their donors were analyzed using a genetic analysis system (MassARRAY; Sequenom, Inc, San Diego, California) in an attempt to characterize the more relevant SNPs of the ABCB1 and CYP3A5 genes for correlation with recipient trough concentrations of drug. Two-way analysis of variance and Bonferroni post hoc tests were used. In agreement with theoretical predictions, the wild-type genotype in ABCB1 SNPs (CC) tended to stabilize drug concentrations within the therapeutic range, whereas the T variant induced a mean increase in blood concentrations of more than 60%. These findings are in agreement with statistical tests that compared mean concentrations in various recipient-donor populations and found significant differences between them (P<.001) in CC vs TT, and P<.01 in CT vs TT). Donor genotype did not seem to be relevant. However, further studies are required to achieve more robust conclusions.

Clinical interest of pharmacogenetic polymorphisms in the immunosuppressive treatment after heart transplantation.

In the transplantation field, genetic changes in a single nucleotide in the genes responsible for the transport and metabolism of an immunosuppressive drug may modify the response of the patient. The aim of this study was to evaluate the effect of single nucleotide polymorphisms (SNPs) in heart transplant recipients and their donors in association with tacrolimus and cyclosporine blood levels during the first 2 weeks after transplantation. A total of 18 blood samples from heart transplant recipients and their donors (n=36) were analyzed using Sequenom to characterize the more relevant SNPs of the ABCB1 and CYP3A5 genes for correlation with C0 (trough concentration) drug blood levels. Differences between groups were evaluated with two-way analysis of variance (ANOVA) and Bonferroni post-test. In agreement with theoretical predictions, the wild type genotype in ABCB1 SNPs (CC) tended to stabilize drug levels within the therapeutic range, whereas the T variant induced a 79% mean increase in blood levels among heterozygous (CT) and 100% among homozygous (TT) recipients. These results agreed with the mean levels in various recipient/donor populations, finding significant differences between them (P<.001 in CC vs CT and P<.01 in CT vs TT), as well as a certain influence of the donor genotype.

On the number of recovered individuals in the SIS and SIR stochastic epidemic models.

The basic models of infectious disease dynamics (the SIS and SIR models) are considered. Particular attention is paid to the number of infected individuals that recovered and its relationship with the final epidemic size. We investigate this descriptor both until the extinction of the epidemic and in transient regime. Simple and efficient methods to obtain the distribution of the number of recovered individuals and its moments are proposed and discussed with respect to the previous work. The methodology could also be extended to other stochastic epidemic models. The theory is illustrated by numerical experiments, which demonstrate that the proposed computational methods can be applied efficiently. In particular, we use the distribution of the number of individuals removed in the SIR model in conjunction with data of outbreaks of ESBL observed in the intensive care unit of a Spanish hospital.