Effects of graphene oxide and reduced graphene oxide on acetoclastic, hydrogenotrophic and methylotrophic methanogenesis.

This study describes the effects of graphene oxide (GO) and reduced graphene oxide (rGO) on the acetoclastic, hydrogenotrophic and methylotrophic pathways of methanogenesis by an anaerobic consortium. The results showed that GO negatively affected the hydrogenotrophic and acetoclastic pathways at a concentration of 300 mg/L, causing a decrease of ~ 38% on the maximum specific methanogenic activity (MMA) with respect to the controls lacking GO. However, the presence of rGO (300 mg/L) promoted an improvement of the MMA (> 45%) achieved with all substrates, except for the hydrogenotrophic pathway, which was relatively insensitive to rGO. The presence of either rGO or GO enhanced the methylotrophic pathway and resulted in an increase of the MMA of up to 55%. X-ray photoelectron spectroscopy (XPS) analysis revealed that GO underwent microbial reduction during the incubation period. Electrons derived from substrates oxidation were deviated from methanogenesis towards the reduction of GO, which may explain the MMA decreased observed in the presence of GO. Furthermore, XPS evidence indicated that the extent of GO reduction depended on the metabolic pathway triggered by a given substrate.

Graphene oxide triggers mass transfer limitations on the methanogenic activity of an anaerobic consortium with a particulate substrate.

Graphene oxide (GO) is an emerging nanomaterial widely used in many manufacturing applications, which is frequently discharged in many industrial effluents eventually reaching biological wastewater treatment systems (WWTS). Anaerobic WWTS are promising technologies for renewable energy production through biogas generation; however, the effects of GO on anaerobic digestion are poorly understood. Thus, it is of paramount relevance to generate more knowledge on these issues to prevent that anaerobic WWTS lose their effectiveness for the removal of pollutants and for biogas production. The aim of this work was to assess the effects of GO on the methanogenic activity of an anaerobic consortium using a particulate biopolymer (starch) and a readily fermentable soluble substrate (glucose) as electron donors. The obtained results revealed that the methanogenic activity of the anaerobic consortium supplemented with starch decreased up to 23-fold in the presence of GO compared to the control incubated in the absence of GO. In contrast, we observed a modest improvement on methane production (>10% compared to the control lacking GO) using 5 mg of GO L-1 in glucose-amended incubations. The decrease in the methanogenic activity is mainly explained by wrapping of starch granules by GO, which caused mass transfer limitation during the incubation. It is suggested that wrapping is driven by electrostatic interactions between negatively charged oxygenated groups in GO and positively charged hydroxyl groups in starch. These results imply that GO could seriously hamper the removal of particulate organic matter, such as starch, as well as methane production in anaerobic WWTS.

Hemiplegia and headache: a review of hemiplegia in headache disorders.

The most common scenario wherein the practicing neurologist is likely to encounter a patient with headache and hemiplegia will vary depending on his/her specific type of practice. A neurologist providing consultative service to an emergency department is far more likely to see patients with "secondary" headache and hemiplegia in the setting of either ischemic or hemorrhagic stroke than hemiplegia as a transient feature of a primary headache disorder. Neurologists subspecializing in headache medicine who practice in a tertiary referral headache clinic are more likely to encounter hemiplegic migraine, but even in that clinical setting hemiplegic migraine is by no means a frequent diagnosis. The acute onset of hemiplegia can be very frightening not only to the patient but also to the medical personnel. Given the abundance of mimicry, practitioners must judiciously ascertain the correct diagnosis as treatment may greatly vary depending on the cause of both headache and hemiplegia. In this review, we will address the most common causes of hemiplegia associated with headache.

Altitude headache.

High altitude headache (HAH) has been defined by the International Headache Society as a headache that appears within 24 hours after ascent to 2,500 m or higher [1••]. The headache can appear in isolation or as part of acute mountain sickness (AMS), which has more dramatic symptoms than the headache alone. If symptoms are ignored, more serious conditions such as high altitude cerebral edema (HACE), high altitude pulmonary edema (HAPE), or even death may ensue. While there is no definitive understanding of the underlying pathophysiologic mechanism, it is speculated that HAH occurs from the combination of hypoxemia-induced intracranial vasodilation and subsequent cerebral edema. There are a number of preventive measures that can be adopted prior to ascending, including acclimatization and various medications. A variety of pharmacological interventions are also available to clinicians to treat this extremely widespread condition.

Headache and vasculitis.

Although headaches are common in the general population and have many causes, headaches secondary to inflammatory processes in the blood vessels in the Central Nervous System (CNS) are not so common. The most common types of vasculitis that are associated with headaches include primary CNS vasculitis, systemic necrotizing arteritis, granulomatous vasculitis, and systemic collagen diseases. It is important to differentiate between "true" vasculitides and a condition known and reversible cerebral vasoconstriction syndrome (RCVS). While treatment for many of the vasculitides consists of anti-inflammatory medications, this approach may produce significant complications in RCVS. It is up to the clinician to judiciously use imaging and laboratory data to reach the proper diagnosis and therefore offer the correct treatment to these patients.

Medical management of hunger strikers.

Hunger strikes are not infrequent occurrences in military and civilian prisons. Although practicing clinicians are familiar with the management of patients who have limited oral intake, managing hunger strikers is unfamiliar to most. The psychological, physiological, and social events that surround hunger strikes are very complex and need to be understood by those caring for hunger strike patients. To provide adequate medical care to hunger strike patients, clinicians most understand the physiological events that ensue after prolonged starvation. Careful vigilance for development of refeeding syndrome is of key importance. A multidisciplinary approach to hunger strikes is of utmost importance, and involvement of a multidisciplinary clinical team as well as prison officials is essential.

Administration of intravenous tissue plasminogen activator in a pediatric patient with acute ischemic stroke.

Intravenous tissue plasminogen activator is the only therapy approved by the US Food and Drug Administration (FDA) for the treatment of acute ischemic strokes. The National Institutes of Health (NIH)-sponsored study that led to the approval of tissue plasminogen activator to be used in acute ischemic strokes included only individuals 18 years of age and older. We report a case of a pediatric patient who suffered a dominant-hemisphere acute ischemic stroke who was treated with intravenous tissue plasminogen activator. Our patient's symptoms began to resolve 4 hours after treatment, and he had a complete recovery after 8 hours. The clinical outcome was excellent and without complications. Tissue plasminogen activator administration can be safe and effective in younger patients. Randomized, controlled, double-blind studies are needed.