‘Modest’ effect of botox injections on migraine prevention

    Botox injections show ‘small to modest' benefits in preventing migraine and headache, say US researchers.

     The meta-analysis included 315 randomised controlled trials that evaluated the effect of botulinum toxin A injections on the reduction in frequency or severity of headaches.

     Compared with placebo, botox injections were associated with a reduction of 2.06 headaches per month for patients with chronic daily headaches and 2.30 per month for those with chronic migraine. No differences were seen with episodic migraine or chronic tension-type headaches.

     Compared with topiramate and amitriptyline for prophylaxis against chronic migraine headaches, botox injections were not associated with a significant reduction in headache frequency. Topiramate was effective in reducing 1.4 headaches per month, while amitriptyline reduced frequency by 2.1 per month.

     When compared with valproate in patients with chronic and episodic migraines, there was no association in reduction of headache frequency with botox injections.

     Study lead Dr Jeffrey Jackson, of the Medical College of Wisconsin in Milwaukee, said botox injections had only a ‘small to modest' effect' compared with placebo.

     He said: ‘The beneficial association of botulinum toxin A in prophylaxis of headaches appears limited to patients with chronic migraine headaches and the absolute reduction in the number of headaches per month is only two to three days a month.'

JAMA 2012; 307: 1736-1745

Tomado de pulsetoday.co.uk

Rising HbA1c levels ‘predict diabetes’

HbA1c levels rise rapidly in the year before a diagnosis of type 2 diabetes, say Japanese researchers.Their study looked at 1,722 individuals aged 26–80 years without diabetes and measured fasting plasma glucose and HbA1c were measured annually for a mean of 9.5 years.

A diagnosis of diabetes was given to 193 people, who had a mean HbA1c level of over 38mmol/mol (5.6%) each year before diagnosis.

Average blood glucose and HbA1c values throughout the observational period were significantly higher in incident cases compared with non-cases, with differences of 1.02 mmol/L and 18 mmol/mol (0.471%) higher, respectively.

In the entire group, marked increases in HbA1c of 20 mmol/mol (0.3%) per year and fasting plasma glucose of 0.63 mmol/L/year predicted a diagnosis of diabetes.

Professor Hirohito Sone, diabetologist at the University of Tsukuba Institute of Clinical Medicine, Tsukuba, Japan, said their findings showed the value of screening regularly in those at risk of diabetes.

He said: ‘To confirm our findings, further investigations are needed that include participants of other ethnicities.'

Diabetes Care 2012, online 28 March 2012

http://care.diabetesjournals.org/content/early/2012/03/26/dc11-1793

Tomado de Pulsetoday.com.uk

Las mujeres fumadoras que toman anticonceptivos multiplican el riesgo de sufrir trombosis o infarto

Un estudio sobre 9,4 millones de mujeres de entre 15 y 49 años demuestra que las usuarias de algún método anticonceptivo con hormonas tienen un mayor riesgo de sufrir trombosis respecto a las no usuarias.

Las mujeres fumadoras que utilizan anticonceptivos hormonales en distintas presentaciones --píldoras, parches o anillos-- tienen un mayor riesgo de sufrir una trombosis o una aparición de episodios cardiovasculares graves como, por ejemplo, los infartos, según advierte la Fundación Española del Corazón (FEC), que cita un estudio de la Universidad de Copenhague, publicado en British Medical Journal (BMJ),y realizado sobre 9,4 millones de mujeres de entre 15 y 49 años.

     Este trabajo ha demostrado que las usuarias de algún método anticonceptivo con hormonas tienen un mayor riesgo de sufrir trombosis respecto a las no usuarias. En concreto, los datos de este estudio reflejan que la aparición de estas enfermedades es 8 veces mayor con los parches transdérmicos, 6,5 veces mayor con los anillos vaginales y 3 veces mayor con las pastillas.

     Asimismo, otro estudio, también publicado en BMJ, efectuado a partir de la General Practice Research Database UK, en mujeres de entre 15 y 44 años, ha detectado que los episodios de trombosis venosas son más frecuentes en las mujeres que toman anticonceptivos con drospirenona --un análogo de la progesterona natural de las píldoras de tercera generación--, frente a las que usan anticonceptivos en cuya composición figura el levonorgestrel, un tipo de progesterona sintética más antigua.

     "Estos estudios ponen de manifiesto que el uso de los anticonceptivos hormonales no está libre de efectos secundarios, especialmente en lo que a seguridad cardiovascular se refiere. Por lo tanto se debe informar a las mujeres de sus potenciales riesgos, sobre todo en el colectivo de mujeres con riesgo de trombosis aumentado. No obstante, se debe individualizar, a la hora de prescribir la contracepción hormonal, porque no es lo mismo una mujer sana fumadora de 24 años que una mujer de 40 años obesa y fumadora activa", destaca la presidenta de la sección de Cardiología Preventiva y Rehabilitación de la Sociedad Española de Cardiología (SEC), Almudena Castro.

Efecto sobre la coagulación

     Concretamente, los anticonceptivos favorecen la formación de trombos por su efecto sobre la coagulación y estos trombos se forman tanto a nivel venoso como arterial. Además tienen efecto sobre los lípidos en la sangre, aumentando la concentración de colesterol y triglicéridos.

     En la actualidad, la drospirenona y levonorgestrel son dos de los componentes que se utilizan más en los anticonceptivos hormonales, pero no son los únicos. El arsenal de posibles anticonceptivos se ha ampliado notablemente y algunos de segunda y tercera generación se asocian a un menor riesgo cardiovascular.

     "La oferta de estos productos ha mejorado, pero eso no significa que haya mejorado del todo desde el punto de vista de la salud cardiovascular. Existen anticonceptivos, como la minipíldora, que solo contiene progestágeno, que al parecer confieren menor riesgo de trombosis. Pero este riesgo no es nulo, aunque está bastante disminuido al no llevar el estrógeno entre sus componentes", avisa la doctora.

     No obstante, la respuesta a estos medicamentos es variable y no se puede predecir qué mujeres van a sufrir uno de estos episodios aunque, según informa Castro, la primera señal de sus efectos es en ocasiones un infarto de miocardio.

     Por esta razón, la FEC recomienda individualizar muy bien la recomendación del uso de estos métodos anticonceptivos hormonales y comprobar previamente, con una historia clínica detallada, cuál es el riesgo de cada mujer. Además, se debe conocer si la mujer es fumadora, si tiene hipercolesterolemia, es diabética, si tiene algún tipo de cardiopatía, trombofilia o alguna enfermedad que favorezca la formación de trombos, así como la historia familiar o personal de eventos trombóticos.

British Medical Journal (2012); doi: 10.1136/bmj.e2990

Tomado de Jano.es

Researchers at the University of Leeds have found a previously unknown mechanism through which pain is signalled by nerve cells.

     A discovery that could explain the current failings in the drug development process for painkillers and which may offer opportunities for a new approach.

     The team, led by Dr Nikita Gamper of the University's Faculty of Biological Sciences, is investigating the difference between persistent pain, such as toothache, and pain that results from the increased sensitivity of nerves in injured or diseased tissue (for example when we touch inflamed skin), known as hyperalgesia.

    In research published online this week, (w/c 14 May) in Proceedings of the National Academy of Sciences (PNAS), Dr Gamper's team has discovered that these two types of pain are generated by the same nerves, but result from different underlying mechanisms.

    The project, funded jointly by the Wellcome Trust and the Medical Research Council, investigated the painful effects of two substances that cause local inflammation: bradykinin and substance P. Both substances bind to specific receptors on nerve cells, generating signals to the central nervous system. Because the receptors are from the same family, it has always been presumed they stimulate the same signalling pathway.

     However, the team found that each receptor produces different signals; the one associated with bradykinin causing both hyperalgesia and persistent pain, whereas the one associated with substance P only caused hyperalgesia.

    "Dr Gamper says: "Pain originates from a series of electrical signals sent by nerve cells in to the central nervous system and ultimately the brain. Despite much progress, we still don't know enough about the mechanisms by which these pain signals are generated. However, this research has shown that whilst the sensation of pain can be similar between various conditions, the underlying molecular mechanisms may in fact be very different."

    Existing painkillers are 'non-specific', designed to generally dull the reception of these signals in the central nervous system, and some stronger pain killers can provoke unwanted side effects such as disorientation, drowsiness or nausea. So while the search for new better drugs is pressing, the lack of progress in developing truly targeted analgesics has led to several pharmaceutical companies dropping this area of research altogether.

     "What's exciting about these findings is that substance P may actually suppress the activation of the pain sensing nerves themselves," says Dr Gamper.

     "It's increasingly evident that current strategies for testing and validating new painkillers often do not take into account a possible difference in how pain signals are generated. For instance, drugs for persistent pain are often tested solely for their ability to reduce hyperalgesia, and as a result, some of the drugs that are effective in the lab, fail in subsequent clinical trials. These findings challenge current approaches in drug development research and may offer new strategies," he says

University of Leeds. "Different mechanisms of pain revealed." ScienceDaily, 14 May 2012. Web. 18 May 2012.