Single skeletal muscle fiber behavior after a quick stretch in young and older men: a possible explanation of the relative preservation of eccentric force in old age

The origins of the smaller age-related decrease in eccentric force compared to isometric and concentric conditions in vivo remain unclear. Could this originate from contractile elements of muscle cells? The main intent of the current investigation was to assess the force behavior of muscle cells with aging, during lengthening. Chemically skinned single muscle fibers (n=235) from m. vastus lateralis of six young (mean age 31.6 years) and six older men (mean age 66.1 years) were maximally activated with pCa 4.5 at 15°C. Maximal isometric force and cross-sectional area were measured allowing the calculation of the tension (T ₀). A quick stretch (2 nm per half-sarcomere length) was applied and caused an immediate increase in tension followed by a decrease and a secondary delayed and transient rise in tension (phase 3); finally, the tension recovered a steady state value (phase 4). The tension enhancements during phase 3 (ΔT ₃) and phase 4 (ΔT ₄) were evaluated. The myosin heavy-chain isoform composition of each single fiber was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. ΔT ₃ and ΔT ₄ were preserved in older men for both type I and IIa fibers despite a reduction in T ₀. Therefore, the age-related preservation of the tension increments after a quick stretch in single muscle fibers could explain in part the smaller decrease in force during eccentric contractions compared to isometric and concentric conditions in vivo with aging usually observed.     

Adriamycin dose and time effects on cell cycle, cell death, and reactive oxygen species generation in leukaemia cells

We investigate the relative importance of the different mechanisms of Adriamycin, an anthracycline, and their interrelations, in particular the link between cell cycle arrest, cell death, and generation of reactive oxygen species (ROS) that is suspected to be the origin of cardiotoxic side-effects. We introduced a lifetime fluorescence based technology and used videomicrofluorometry, two efficient analytical methods. We show that depending on the doses and time after incubation, ADR will not reach the same compartments (nucleus, mitochondria, cytosol) in the cells, having consequences on the production of ROS, growth arrest pathways and cell death pathways.     

Brain biopsy is required in steroid-resistant patients with chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS)

Journal of Neuro-Oncology -     

Arsenic trioxide treatment decreases the oxygen consumption rate of tumor cells and radiosensitizes solid tumors

Arsenic trioxide (As(2)O(3)) is an effective therapeutic against acute promyelocytic leukemia and certain solid tumors. Because As(2)O(3) inhibits mitochondrial respiration in leukemia cells, we hypothesized that As(2)O(3) might enhance the radiosensitivity of solid tumors by increasing tumor oxygenation [partial pressure of oxygen (pO(2))] via a decrease in oxygen consumption. Two murine models of radioresistant hypoxic cancer were used to study the effects of As(2)O(3). We measured pO(2) and the oxygen consumption rate in vivo by electron paramagnetic resonance oximetry and (19)fluorine-MRI relaxometry. Tumor perfusion was assessed by Patent blue staining. In both models, As(2)O(3) inhibited mitochondrial respiration, leading to a rapid increase in pO(2). The decrease in oxygen consumption could be explained by an observed decrease in glutathione in As(2)O(3)-treated cells, as this could increase intracellular reactive oxygen species that can disrupt mitochondrial membrane potential. When tumors were irradiated during periods of As(2)O(3)-induced augmented oxygenation, radiosensitivity increased by 2.2-fold compared with control mice. Notably, this effect was abolished when temporarily clamped tumors were irradiated. Together, our findings show that As(2)O(3) acutely increases oxygen consumption and radiosensitizes tumors, providing a new rationale for clinical investigations of As(2)O(3) in irradiation protocols to treat solid tumors.     

Extravasation of liposomal doxorubicin induces irritant reaction without vesicant injury

Anthracycline extravasation is an uncommon but very serious complication. Very few data are available in the literature concerning the consequences and the management of extravasation of liposomal doxorubicin. This report describes the cases of two patients with liposomal doxorubicin extravasation who developed irritant reaction without vesicant or necrotic lesions. It is concordant with other cases described in the literature and suggests that extravasation of liposomal doxorubicin can be relatively well tolerated. The process applied to extravasations of irritant and non-vesicant agents could be used to manage extravasations of liposomal doxorubicin.     

Targeting regulatory T cells

Cancers express tumor-associated antigens that should elicit immune response to antagonize the tumor growth, but spontaneous immune rejection of established cancer is rare, suggesting an immunosuppressive environment hindering host antitumor immunity. Among the specific and active tumor-mediated mechanisms, CD4⁺CD25^high T regulatory cells (Treg) are important mediators of active immune evasion in cancer. In this review, we will discuss Treg subpopulations and the mechanisms of their suppressive functions. Treg depletion improves endogenous antitumor immunity and the efficacy of active immunotherapy in animal models for cancer, suggesting that inhibiting Treg function could also improve the limited successes of human cancer immunotherapy. We will also discuss specific strategies for devising effective cancer immunotherapy targeting Treg.     

Emergent EEG in clinical practice.

OBJECTIVE: Emergency situations require a rapid and precise diagnostic approach. However, the exact role and value of the electroencephalogram (EEG) in emergent conditions have yet to be clearly defined. Our objective was to determine why clinicians order an emergency EEG, to assess to what extent it helps establish a correct diagnosis and to evaluate the result it has on subsequent patient management. METHODS: We studied all successive emergency EEGs ordered during a 3-month period in our institution. We analyzed the reasons why each EEG was ordered and interviewed the prescribing clinicians in order to determine the impact the result of the EEG had on the diagnosis and subsequent therapeutic management. RESULTS: We prospectively studied a total of 111 consecutive recordings. The main reasons for ordering an emergent EEG were: suspected cerebral death (21%), non-convulsive status epilepticus (19.7%), subtle status epilepticus (14%) and follow-up of convulsive status epilepticus (11.2%). In 77.5% of the cases the clinicians considered that the EEG contributed to making the diagnosis and that it helped confirm a clinically-suspected diagnosis in 36% of the cases. When subtle status epilepticus (SSE) or non-convulsive status epilepticus (NCSE) was suspected, the diagnosis was confirmed in 45% and 43.3% of the cases, respectively. In 22.2% of the requests involving follow-up of convulsive status epilepticus after initial treatment, the EEG demonstrated persistent status epilepticus. It resulted in a change in patient treatment in 37.8% of all the cases. When the EEG helped establish the diagnosis, patient treatment was subsequently modified in 46.6% of the cases. CONCLUSIONS: This prospective study confirms the value of an emergent EEG in certain specific clinical contexts: the management of convulsive status epilepticus following initial treatment or to rule out subtle status epilepticus. An emergent EEG can also be ordered if one suspects the existence of non-convulsive status epilepticus when a patient presents with mental confusion or altered wakefulness after first looking for the specific signs suggesting this diagnostic hypothesis. SIGNIFICANCE: After 50 years of development and use in daily practice, the EEG remains a dependable, inexpensive and useful diagnostic tool in a number of clearly-defined emergency situations.