The erythroblastic island niche: modeling in health, stress, and disease.

Erythropoiesis is one of the most demanding processes in the body, with more than 2 million red blood cells produced every second. Multiple hereditary and acquired red blood cell disorders arise from this complex system, with existing treatments effective in managing some of these conditions but few offering a long-term cure. Finding new treatments relies on the full understanding of the cellular and molecular interactions associated with the production and maturation of red blood cells, which take place within the erythroblastic island niche. The elucidation of processes associated within the erythroblastic island niche in health and during stress erythropoiesis has relied on in vivo modeling in mice, with complexities dissected using simple in vitro systems. Recent progress using state-of-the-art stem cell technology and gene editing has enabled a more detailed study of the human niche. Here, we review these different models and describe how they have been used to identify and characterize the cellular and molecular pathways associated with red blood cell production and maturation. We speculate that these systems could be applied to modeling red blood cell diseases and finding new druggable targets, which would prove especially useful for patients resistant to existing treatments. These models could also aid in research into the manufacture of red blood cells in vitro to replace donor blood transfusions, which is the most common treatment of blood disorders.

Impact of special patient populations on the pharmacokinetics of echinocandins.

Echinocandins belong to the class of antifungal agents. Currently, three echinocandin drugs are licensed for intravenous treatment of invasive fungal infections: anidulafungin, caspofungin and micafungin. While their antifungal activity overlaps, there are substantial differences in pharmacokinetics (PK). Numerous factors may account for variability in PK of echinocandins including age (pediatrics vs adults), body surface area and body composition (normal weight vs obesity), disease status (e.g., critically ill and burn patients) and organ dysfunction (kidney and liver impairment). Subsequent effects of altered exposure might impact efficacy and safety. Knowledge of PK behavior is crucial in optimal clinical utilization of echinocandin in a specific patient or patient population. This review provides up-to-date information on PK data of anidulafungin, caspofungin and micafungin in special patient populations. Patient populations addressed are neonates, children and adolescents, obese patients, patients with hepatic or renal impairment, critically ill patients (including burn patients) and patients with hematological diseases.

Treatment of invasive fungal infections in high-risk haematological patients: what have we learnt in the past 10 years?

La infección fúngica invasora (IFI) por hongos filamentosos (HF) sigue constituyendo una complicación infecciosa muy grave en los pacientes con enfermedades onco-hematológicas. Las últi¬mas aportaciones en el campo del diagnóstico y la terapéutica, hoy sabemos que son limitadas. Algo parecido se puede decir de los ensayos clínicos, en especial por algunos cambios en las características del huésped. La aparición de técnicas diagnós¬ticas esperanzadoras y la relativa ampliación en el número de antifúngicos, dio lugar a una diversificación de las estrategias terapéuticas (profilaxis y tratamiento anticipado). Pero la falta de sensibilidad del AGA bajo algunas circunstancias y el poten¬cial retraso en el inicio del tratamiento por motivos logísticos en su realización, se ha traducido en una mayor mortalidad en determinados tipos de pacientes y en un aumento significativo de los días de tratamiento. Todas estas circunstancias han vuelto a colocar el abordaje empírico como una estrategia central en los pacientes de alto riesgo. El objetivo de este artículo es revisar la experiencia clínica en el tratamiento de las IFI en el paciente onco-hematológico publicada en el curso de la última década y hacer unas recomendaciones en base a ésta (AU)

Invasive fungal infection (IFI) caused by filamentous fungi remains a very severe infectious complication in patients with onco-haema¬tological diseases. Last advances in the diagnostic and therapeu¬tic fields, today we know that their contributions are limited. So¬mething similar can be said of clinical trials especially in relation to some changes in the characteristics of the host. The development of promising diagnostic techniques and the relative expansion in the number of antifungal agents has been associated with diversifica¬tion of therapeutic strategies (prophylaxis with extended-spectrum azoles and preemptive antifungal treatment). However, the low sen¬sitivity of AGA testing in some circumstances, and the potential de¬lay in starting treatment due to logistic reasons, has been reflected by a greater mortality in certain type of patients and a significant increase in the days of treatment. All these circumstances has once again focus attention to the empirical approach as a central strate¬gy in high-risk patients. The objective of this article is to review the clinical experience in the treatment of IFI in onco-haematological patients according to data published in the literature in the last de¬cade and to present a set of recommendations (AU)

Chronobiology and chronotherapy in medicine.

There is a fascinating and exceedingly important area of medicine that most of us have not been exposed to at any level of our medical training. This relatively new area is termed chronobiology; that is, how time-related events shape our daily biologic responses and apply to any aspect of medicine with regard to altering pathophysiology and treatment response. For example, normally occurring circadian (daily cycles, approximately 24 hours) events, such as nadirs in epinephrine and cortisol levels that occur in the body around 10 PM to 4 AM and elevated histamine and other mediator levels that occur between midnight and 4 AM, play a major role in the worsening of asthma during the night. In fact, this nocturnal exacerbation occurs in the majority of asthmatic patients. Because all biologic functions, including those of cells, organs, and the entire body, have circadian, ultradian (less than 22 hours), or infradian (greater than 26 hours) rhythms, understanding the pathophysiology and treatment of disease needs to be viewed with these changes in mind. Biologic rhythms are ingrained, and although they can be changed over time by changing the wake-sleep cycle, these alterations occur over days. However, sleep itself can adversely affect the pathophysiology of disease. The non-light/dark influence of biologic rhythms was first described in 1729 by the French astronomer Jean-Jacques de Mairan. Previously, it was presumed that the small red flowers of the plant Kalanchoe bloss feldiuna opened in the day because of the sunlight and closed at night because of the darkness. When de Mairan placed the plant in total darkness, the opening and closing of the flowers still occurred on its intrinsic circadian basis. It is intriguing to think about how the time of day governs the pathophysiology of disease. On awakening in the morning, heart rate and blood pressure briskly increase, as do platelet aggregability and other clotting factors. This can be linked to the acrophase (peak event) of heart attacks. During the afternoon we hit our best mental and physical performance, which explains why most of us state that "I am not a morning person." Even the tolerance for alcohol varies over the 24-hour cycle, with best tolerance around 5 pm (i.e. "Doctor, I only have a couple of highballs before dinner"). Thus, all biologic functions, from those of the cell, the tissue, the organs, and the entire body, run on a cycle of altering activity and function.(ABSTRACT TRUNCATED AT 400 WORDS)