Phenformin increases early hematopoietic progenitors in the Jak2V617F murine model.

BACKGROUND: Myeloproliferative neoplasms (MPN) are disorders characterized by an alteration at the hematopoietic stem cell (HSC) level, where the JAK2 mutation is the most common genetic alteration found in classic MPN (polycythemia vera, essential thrombocythemia, and primary myelofibrosis). We and others previously demonstrated that metformin reduced splenomegaly and platelets counts in peripheral blood in JAK2V617F pre-clinical MPN models, which highlighted the antineoplastic potential of biguanides for MPN treatment. Phenformin is a biguanide that has been used to treat diabetes, but was withdrawn due to its potential to cause lactic acidosis in patients. AIMS: We herein aimed to investigate the effects of phenformin in MPN disease burden and stem cell function in Jak2V617F-knockin MPN mice. RESULTS: In vitro phenformin treatment reduced cell viability and increased apoptosis in SET2 JAK2V67F cells. Long-term treatment with 40 mg/kg phenformin in Jak2V617F knockin mice increased the frequency of LSK, myeloid progenitors (MP), and multipotent progenitors (MPP) in the bone marrow. Phenformin treatment did not affect peripheral blood counts, spleen weight, megakaryocyte count, erythroid precursors frequency, or ex vivo clonogenic capacity. Ex vivo treatment of bone marrow cells from Jak2V617F knockin mice with phenformin did not affect hematologic parameters or engraftment in recipient mice. CONCLUSIONS: Phenformin increased the percentages of LSK, MP, and MPP populations, but did not reduce disease burden in Jak2V617F-knockin mice. Additional studies are necessary to further understand the effects of phenformin on early hematopoietic progenitors.

Biguanides sensitize leukemia cells to ABT-737-induced apoptosis by inhibiting mitochondrial electron transport.

Metformin displays antileukemic effects partly due to activation of AMPK and subsequent inhibition of mTOR signaling. Nevertheless, Metformin also inhibits mitochondrial electron transport at complex I in an AMPK-independent manner, Here we report that Metformin and rotenone inhibit mitochondrial electron transport and increase triglyceride levels in leukemia cell lines, suggesting impairment of fatty acid oxidation (FAO). We also report that, like other FAO inhibitors, both agents and the related biguanide, Phenformin, increase sensitivity to apoptosis induction by the bcl-2 inhibitor ABT-737 supporting the notion that electron transport antagonizes activation of the intrinsic apoptosis pathway in leukemia cells. Both biguanides and rotenone induce superoxide generation in leukemia cells, indicating that oxidative damage may sensitize toABT-737 induced apoptosis. In addition, we demonstrate that Metformin sensitizes leukemia cells to the oligomerization of Bak, suggesting that the observed synergy with ABT-737 is mediated, at least in part, by enhanced outer mitochondrial membrane permeabilization. Notably, Phenformin was at least 10-fold more potent than Metformin in abrogating electron transport and increasing sensitivity to ABT-737, suggesting that this agent may be better suited for targeting hematological malignancies. Taken together, our results suggest that inhibition of mitochondrial metabolism by Metformin or Phenformin is associated with increased leukemia cell susceptibility to induction of intrinsic apoptosis, and provide a rationale for clinical studies exploring the efficacy of combining biguanides with the orally bioavailable derivative of ABT-737, Venetoclax.

Metformin and phenformin block the peripheral antinociception induced by diclofenac and indomethacin on the formalin test.

AIMS: Recent evidence has shown that systemic administration of sulfonylureas and biguanides block the diclofenac-induced antinociception, but not the effect produced by indomethacin. However, there are no reports about the peripheral interaction between analgesics and the biguanides metformin and phenformin. Therefore, this work was undertaken to determine whether glibenclamide and glipizide and the biguanides metformin and phenformin have any effect on the peripheral antinociception induced by diclofenac and indomethacin. MAIN METHODS: Diclofenac and indomethacin were administered locally in the formalin-injured rat paw, and the antinociceptive effect was evaluated using the 1% formalin test. To determine whether peripheral antinociception induced by diclofenac or indomethacin was mediated by either the ATP-sensitive K(+) channels or biguanides-induced mechanisms, the effect of pretreatment with the appropriates vehicles or glibenclamide, glipizide, metformin and phenformin on the antinociceptive effect induced by local peripheral diclofenac and indomethacin was assessed. KEY FINDINGS: Local peripheral injections of diclofenac (50-200 µg/paw) and indomethacin (200-800 µg/paw) produced a dose-dependent antinociception during the second phase of the test. Local pretreatment with glibenclamide, glipizide, metformin and phenformin blocked the diclofenac-induced antinociception. On the other hand, the pretreatment with glibenclamide and glipizide did not prevent the local antinociception produced by indomethacin. Nonetheless, metformin and phenformin reversed the local antinociception induced by indomethacin. SIGNIFICANCE: Data suggest that diclofenac could activate the K(+) channels and biguanides-dependent mechanisms to produce its peripheral antinociceptive effects in the formalin test. Likewise, a biguanides-dependent mechanism could be activated by indomethacin consecutively to generate its peripheral antinociceptive effect.

Study of phenformin metabolism in rat liver microsomes by HPLC, CE and on-line HPLC-electrospray ionization mass spectrometry.

Methods for the analysis of phenformin and its metabolite by high-performance liquid chromatography (HPLC), capillary electrophoresis (CE) and high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESIMS) are developed. The effects of pH, buffer concentration and proportion of organic modifier on the retention of the compounds in HPLC have been studied. The optimum condition was used for the separation and identification of phenformin and its metabolite in microsomal metabolism by HPLC-ESIMS. A simple CE method is also described for the separation of these compounds. Optimum incubation conditions and cofactor requirements for the formation of 4-hydroxyphenformin by microsomal preparations of rat liver were determined. A linear response in the formation of product was found with increasing concentrations of protein and up to 15 min incubation. High concentrations of phenformin inhibited its metabolite formation, and K(m) was 4 microM.

Tratamiento de intoxicaciones / Treatment of the intoxications

Se trataron 8 pacientes intoxicados por diferentes métodos: hemoperfusión, hemodiálisis, diálisis peritoneal afectados de diferentes tóxicos (se desarrolla botulismo, bromato de potasio y metanol), se discuten las indicaciones de tratamiento

Tratamiento de intoxicaciones / Treatment of the intoxications

Se trataron 8 pacientes intoxicados por diferentes métodos: hemoperfusión, hemodiálisis, diálisis peritoneal afectados de diferentes tóxicos (se desarrolla botulismo, bromato de potasio y metanol), se discuten las indicaciones de tratamiento

Tratamiento de intoxicaciones / Treatment of the intoxications

Se trataron 8 pacientes intoxicados por diferentes métodos: hemoperfusión, hemodiálisis, diálisis peritoneal afectados de diferentes tóxicos (se desarrolla botulismo, bromato de potasio y metanol), se discuten las indicaciones de tratamiento

Biguanide related lactic acidosis: incidence and risk factors.

The objective of this study was to evaluate in an open population the incidence and risk factors of biguanide related lactic acidosis. All patients currently treated in the Department of Diabetes and Lipid Metabolism of the Instituto Nacional de la Nutrición and their records were reviewed for the present use or history of administration of biguanides. The study was complemented with a revision of all admissions of diabetic patients to the emergency room during 1987-1990. In the outpatient study, 235 cases were included. No case of lactic acidosis was found. A high percentage of the biguanide treated patients had one or more lactic acidosis related risk factors. In the emergency study, 609 admissions of 273 patients were included. In 17 patients a metabolic non-ketotic acidosis was diagnosed. The frequency of non-ketotic acidosis for the different treatments was: 29.4 cases x 1000 emergency admissions for sulphonylurea treated group, 32 for sulphonylurea plus phenformin treated and 47.94 for type II insulin treated patients. All cases had severe precipitant diseases that can cause lactic acidosis with or without associated biguanide administration. No metformin related cases were found. The conclusions of this study are that biguanides in general and metformin in particular are not associated with a high risk of lactic acidosis. Severe systemic dysfunction associated with intercurrent diseases, frequently observed in diabetic patients, is the main determinant for the appearance of lactic acidosis.

Studies on induction of delta-aminolevulinic acid synthase, ferrochelatase, cytochrome P-450 and cyclic AMP by phenformin. Chlorpropamide, allylisopropylacetamide and lead in hepatocytes from normal and experimental diabetic rats.

The present work demonstrates that phenformin exerted an inducing effect on delta-aminolevulinic acid synthase (ALA-S) and ferrochelatase activities and on cytochrome P-450 content in isolated hepatocytes from rats with experimental diabetes. Similar results were obtained with respect to ALA-S activity and cytochrome P-450 content when chlorpropamide was used. The inducing effect exerted by allylisopropylacetamide (AIA) on ALA-S and ferrochelatase activities in diabetic hepatic cells was markedly greater than that observed in normal hepatocytes. This stimulatory response was not enhanced by adding dibutyryl cyclic AMP (cAMP). When phenformin was added to isolated rat hepatocytes of normal rats, induction of ALA-S and ferrochelatase activities and cytochrome P-450 content was observed only in the presence of added dibutyryl cAMP. Addition of chlorpropamide to this in vitro system did not exert an inducing effect on the same enzymes even in the presence of dibutyryl cAMP. The present results add more experimental evidence about the lability of the heme pathway of diabetic hepatocytes.

El sindrome de la regresion caudal.(A proposito de un caso). / Caudal regression syndroe. (Apropos of a case)

Aunque en 1972 Assemany denomino al sindrome de la regresion caudal, embriopatia diabetica phocomelica y dio de esta forma gran enfasis a la enfermedad metabolica presente en la madre, mas recientemente se ha precisado que solo en el 16% de tales ninos esta presente la diabetes en la madre y que solo en el 1% de los recien nacidos de madre diabetica se hace presente esta malformacion, aunque en nuestro servicio esta ha sido solo del 0,2%. Se discuten algunos fenomenos en relacion con las malformaciones en el hijo de madre diabetica, como son la lesion vascular presente en la madre de modo de tratemienro y el grado de control metabolico al momento de iniciar la gestacion, haciendose enfasis en que esta paciente tenia al momento de iniciado el embarazo un control metabolico que pudo ser calificado de "malo" con perfil promedio en 24 horas de 195 mg% (glucosa-oxidasa)

El sindrome de la regresion caudal.(A proposito de un caso). / Caudal regression syndrome. (Apropos of a case)

Aunque en 1972 Assemany denomino al sindrome de la regresion caudal, embriopatia diabetica phocomelica y dio de esta forma gran enfasis a la enfermedad metabolica presente en la madre, mas recientemente se ha precisado que solo en el 16% de tales ninos esta presente la diabetes en la madre y que solo en el 1% de los recien nacidos de madre diabetica se hace presente esta malformacion, aunque en nuestro servicio esta ha sido solo del 0,2%. Se discuten algunos fenomenos en relacion con las malformaciones en el hijo de madre diabetica, como son la lesion vascular presente en la madre de modo de tratemienro y el grado de control metabolico al momento de iniciar la gestacion, haciendose enfasis en que esta paciente tenia al momento de iniciado el embarazo un control metabolico que pudo ser calificado de "malo" con perfil promedio en 24 horas de 195 mg% (glucosa-oxidasa)

El fenformin y la actividad fibrinolitica en la trombosis venosa recurrencial. / Phenforin and fibrinolitic activity in recurrent venous thrombosis

Se realiza un estudio con el objetivo de determinar el efecto del fenformin sobre la actividad fibrinolitica en los pacientes que presentan trombosis venosa recurrencial (TVRC). Se estudiaron 10 pacientes a quienes se les diagnostico dicha enfermedad en el servicio de flebolinfologia del Instituto de Angiologia en el periodo comprendido de marzo a septiembre de 1980 y que al examen de laboratorio presentaban alteraciones de la actividad fibrinolitica. Se determino el porcentaje de lisis de sangre total y la lisis de euglobulina antes y despues del tratamiento en cada uno de los pacientes, y se compararon estos dos grupos de valores, a traves del estadistico (no parametrico) para muestras pareadas, sin encontrarse diferencias estadisticamente significativas entre los mismos, aunque se observa tendencia al aumento de la actividad fibrinolitica despues del tratamiento

El fenformin y la actividad fibrinolitica en la trombosis venosa recurrencial. / Phenformin and fibrinolitic activity in recurrent venous thrombosis

Se realiza un estudio con el objetivo de determinar el efecto del fenformin sobre la actividad fibrinolitica en los pacientes que presentan trombosis venosa recurrencial (TVRC). Se estudiaron 10 pacientes a quienes se les diagnostico dicha enfermedad en el servicio de flebolinfologia del Instituto de Angiologia en el periodo comprendido de marzo a septiembre de 1980 y que al examen de laboratorio presentaban alteraciones de la actividad fibrinolitica. Se determino el porcentaje de lisis de sangre total y la lisis de euglobulina antes y despues del tratamiento en cada uno de los pacientes, y se compararon estos dos grupos de valores, a traves del estadistico (no parametrico) para muestras pareadas, sin encontrarse diferencias estadisticamente significativas entre los mismos, aunque se observa tendencia al aumento de la actividad fibrinolitica despues del tratamiento

Control de las macroangiopatías diabéticas del pie / Control of diabetic macroangiopathy of the foot

Se realiza un ensayo clínico controlado en 90 pacientes diabéticos del tipo adulto, dirigido a conocer el efecto de algunos medicamentos sobre la progresión de la macroangiopatía de los miembros inferiores. El fermonmín (diabefén), la vitamina C y la hormona tiroidea demostraron tener un efecto significativamente más beneficioso sobre la evolución de la macroangiopatía que la tolbutamida (diabetón) y la aspirina. La necesidad de estudios ulteriores es enfatizada (AU)

Acidosis láctica y diabefén / Lactic acidosis and diabephen

Un estudio para conocer la aparición de acidosis láctica con el uso del diabefén, fue realizado con 32 pacientes diabéticos ingresados en el Instituto de Angiología, los cuales recibieron una dosis total diaria de 100 mg de diabefén o fenformín, para controlar su diabetes, normalizar la fibrinólisis o ambas. Se evaluó semanalmente (1-6 semanas) la concentración de lactato en sangre venosa, así como niveles sanguíneos de urea y creatinina para correlacionar posible afectación renal. Se concluye que a la dosis y tiempo empleados, no se presentó en nuestra serie ningún caso de acidosis láctica, pero que tampoco existió aparente daño renal(AU)

Eficacia de la asociación ferformín-aspirina en la prevención de las complicaciones tromboembólicas mortales de los pacientes con pie diabético / Efficiency of phenformin-aspirin association on the prevention of mortal thromboembolic complications of diabetic foot patients

Se realiza un estudio en dos grupos similares de pacientes hospitalizados con el diagnóstico de pie diabético, dirigido a conocer la eficacia de la asociación fenformín-aspirina en la prevención de las complicaciones tromboembólicas mortales; no se observó diferencias estadísticamente significativas en los índices de mortalidad por tales complicaciones entre el grupo bajo tratamiento y el grupo control, lo que permite afirmar que la asociación fenformín-aspirina no resultó eficaz en cuanto a su prevención(AU)

Actividad fibrinolítica y phenformín en el pie diabético / Fibrinolytic activity and phenformin in diabetic foot

Se realiza un estudio dirigido a conocer la frecuencia y distribución de la actividad fibrinolítica disminuida, en los pacientes con pie diabético, y a medir la efectividad del phenformín (diabefén) en su capacidad para normalizarla. La frecuencia de actividad fibrinolítica disminuida fue de 63,1 porciento. Dicha frecuencia no guardaba relación con el tipo de lesión inicial (isquémica o neuroinfecciosa) ni con el sexo, la edad, la duración conocida y el tipo de tratamiento de la diabetes. El phenformín resultó infectivo en su capacidad para elevar la actividad fibrinolítica y sí el adecuado para el control metabólico de la enfermedad de base(AU)