Potassium channel blockers and openers as CNS neurologic therapeutic agents

Potassium (K+) channels are the most heterogeneous and widely distributed class of ion channels. K(+) channels are dynamic pore-forming transmembrane proteins known to play important roles in all cell types underlying both normal and pathophysiological functions. Essential for such diverse physiological processes as nerve impulse propagation, muscle contraction, cellular activation and the secretion of biologically active molecules, various K(+) channels are recognized as potential therapeutic targets in the treatment of multiple sclerosis, Alzheimer's disease, Parkinson's disease, epilepsy, stroke, brain tumors, brain/spinal cord ischemia, pain and schizophrenia, migraine, as well as cardiac arrhythmias, pulmonary hypertension, diabetes, cervical cancer, urological diseases and sepsis. In addition to their importance as therapeutic targets, certain K(+) channels are gaining attention for their beneficial roles in anesthesia, neuroprotection and cardioprotection. The K(+) channel gene families (subdividing into multiple subfamilies) include voltage-gated (K(v): K(v)1-K(v)12 or KCNA-KCND, KCNF-KCNH, KCNQ, KCNS), calcium-activated (K(Ca): K(Ca)1-K(Ca)5 or KCNM-KCNN), inwardly rectifying (K(ir): K(ir)1-K(ir)7 or KCNJ) and background/leak or tandem 2-pore (K(2P): K(2P)1-K(2P)7, K(2P)9-K(2P)10, K(2P)12-K(2P)13, K(2P)15-K(2P)18 or KCNK) K(+) channels. Worldwide, the pharmaceutical industry is actively developing better strategies for targeting ion channels, in general, and K(+) channels, in particular, already generating over $6 billion in sales per annum from drugs designed to block or modulate ion channel function. This review provides an overview of recent patents on emerging K(+) channel blockers and activators (openers) with potential for development as new and improved nervous system therapeutic agents.     

Adult respiratory distress syndrome associated withMycoplasma pneumoniae infection

A 13-year-old boy is described who developed severe adult respiratory distress syndrome (ARDS), biochemical pancreatitis and skin vasculitis after an acute respiratory infection due toMycoplasma pneumoniae. The boy was mechanically ventilated for 17 days, but could be discharged in good clinical condition after 36 days of hospitalization. However, major disturbances of the lung function tests persisted, suggesting interstitial fibrosis. To the best of our knowledge, this is the first case of ARDS afterM. pneumoniae infection in childhood.     

From the Cover: A long-snouted,multihorned tyrannosaurid from the Late Cretaceous of Mongolia

Tyrannosaurid theropods are characterized by a generalized body plan, and all well-known taxa possess deep and robust skulls that are optimized for exerting powerful bite forces. The fragmentary Late Cretaceous Alioramus appears to deviate from this trend, but its holotype and only known specimen is incomplete and poorly described. A remarkable new tyrannosaurid specimen from the Maastrichtian (Late Cretaceous) of Mongolia, including a nearly complete and well-preserved skull and an extensive postcranium, represents a new species of Alioramus, Alioramus altai. This specimen conclusively demonstrates that Alioramus is a small, gracile, long-snouted carnivore that deviates from other tyrannosaurids in its body plan and presumably its ecological habits. As such, it increases the range of morphological diversity in one of the most familiar extinct clades. Phylogenetic analysis places Alioramus deep within the megapredatory Tyrannosauridae, and within the tyrannosaurine subclade that also includes Tarbosaurus and Tyrannosaurus. Both pneumatization and ornamentation are extreme compared with other tyrannosaurids, and the skull contains eight discrete horns. The new specimen is histologically aged at nine years old but is smaller than other tyrannosaurids of similar age. Despite its divergent cranial form, Alioramus is characterized by a similar sequence of ontogenetic changes as the megapredatory Tyrannosaurus and Albertosaurus, indicating that ontogenetic change is conservative in tyrannosaurids.     

N-Desmethylclozapine,an Insensitive Marker of Clozapine-Induced Agranulocytosis and Granulocytopenia

We reviewed the charts of 58 patients with treatment-refractory schizophrenia who were receiving clozapine, to determine if the drug's active metabolite, N-desmethylclozapine, is a biologic marker for impending clozapine-induced granulocytopenia and agranulocytosis. No significant correlation between granulocyte counts and patient demographic variables of clozapine and N-desmethylclozapine steady-state plasma concentrations, clozapine: N-desmethylclozapine ratio, age, gender, clozapine dosage, smoking status, and race were found. We believe N-desmethylclozapine is not a clinically useful marker for monitoring the effect of clozapine on granulocyte integrity On the contrary, its plasma concentrations correlated positively with granulocyte counts.     

Differential sensitivity of atrial and ventricular K(ATP) channels to metabolic inhibition

OBJECTIVE: The aim is to compare the activation of ATP-sensitive potassium channels (K(ATP) channels) in intact and metabolically impaired atrial and ventricular myocytes. METHODS: The K(ATP) channel current is measured by whole cell and gramicidin-perforated patch clamp recordings in 164 cultured neonate rat cardiomyocytes. RESULTS: In whole cell recordings with 84 micromol/l ADP in pipette, spontaneous activity is significantly higher in atrium than ventricle, and EC(50) for the K(ATP) channel opener diazoxide is 0.13 micromol/l (atrium) versus 3.1 micromol/l (ventricle). With an ATP-regenerating system in pipette, EC(50) for diazoxide is 19.7 micromol/l (atrium) versus 54.9 micromol/l (ventricle). In gramicidin-perforated patch recordings, atrial myocytes respond significantly to 100 nmol/l of the mitochondrial protonophore CCCP, while ventricular myocytes do not. EC(50) for diazoxide is 129 micromol/l (atrium) versus >2500 micromol/l (ventricle) for myocytes exposed to CCCP, and 676 versus >2500 micromol/l, respectively, without CCCP. CONCLUSIONS: (1) K(ATP) channels are significantly more sensitive to metabolic inhibition in atrial than ventricular myocytes. (2) Sensitivity of atrium versus ventricle to the channel opener diazoxide increases from 3:1 to > or = 24:1 with ADP or metabolic inhibition. If extended to intact hearts, the results would predict a higher atrial sensitivity to ischemia, and a high sensitivity of the ischemic atrium to K(ATP) channel openers.     

The influence of childhood atopic dermatitis on health of mothers,and its impact on Asian families

Ho RCM, Giam YC, Ng TP, Mak A, Goh D, Zhang MWB, Cheak A, Van Bever HP. The influence of childhood atopic dermatitis on health of mothers, and its impact on Asian families.
Pediatr Allergy Immunol 2010: 21: 501–507.
© 2010 John Wiley & Sons A/S This study examines maternal perceptions of paediatric atopic dermatitis (AD) on family and determines risk factors including severity of AD, maternal physical and mental health (MH), quality of life of patients and sociodemographics which predict a negative family impact. A cross‐sectional assessment using the Dermatitis Family Impact Questionnaire Scale to assess the impact of AD on family, Infant’s Dermatitis Quality of Life Index (<5‐yrs old) or Children’s Dermatitis Life Quality Index (5–17 yrs old) was used to measure health‐related quality of life (HRQOL) of paediatric patients with AD. A 12‐item Short‐Form Health Survey (SF‐12) was used to assess physical and MH of their mothers. Risk factors of adverse family impact were assessed using multiple regression analysis. One hundred and four patients with AD and their mothers were studied. Their mean ages (±s.d.) were respectively 6.4 ± 4.3 and 37.2 ± 6.6 yrs. In multiple regression analysis, Severity Scoring of Atopic Dermatitis (SCORAD) appeared to be associated with negative family impact and the association remained significant after adjustment for bio‐psycho‐social factors and HRQOL of patients. The association remained insignificant after adjustment for physical and MH of the mothers. Our results show that the severity of paediatric AD leads to negative family impact through reduction of physical and MH of the mothers, and is independent of patients’ HRQOL and sociodemographics. The current approach for managing paediatric AD in Asian society could include early multidisciplinary intervention, aiming at enhancing physical and MH of mothers while minimizing negative impact on family and social isolation. Further research will be welcomed as the results of this study mainly applied to Asian society which could be different to populations from other geographic areas.     

Early introduction of allergenic foods for the prevention of food allergy from an Asian perspective—An Asia Pacific Association of Pediatric Allergy,Respirology & Immunology (APAPARI) consensus statement

Emerging evidence for the early introduction of allergenic foods for the prevention of food allergies, such as peanut allergy in Western populations, has led to the recent publication of guidelines in the USA and Europe recommending early peanut introduction for high‐risk infants with severe eczema or egg allergy. Peanut allergy is, however, much less prevalent in Asia compared to the West. Varying patterns of food allergy are seen even within Asian countries—such as a predominance of wheat allergy in Japan and Thailand and shellfish allergy in Singapore and the Philippines. Customs and traditions, such as diet and infant feeding practices, also differ between Asian populations. Hence, there are unique challenges in adapting guidelines on early allergenic food introduction to the Asian setting. In this paper, we review the evidence and discuss the possible approaches to guide the timely introduction of allergenic food in high‐risk infants in Asia.