A new technique for staining mast cells using ferroin

We describe here a new method for specific staining of mast cells using ferroin. Different hamster tissues were fixed in 4% formalin and processed for paraffin embedding. Sections were stained with hematoxylin followed by ferroin acidified with 2.5 N sulfuric acid to pH 4.0. Mast cells stained an intense orange color that contrasted markedly with bluish violet nuclei. High contrast was also observed when ferroin colored sections were counterstained with light green instead of hematoxylin. To evaluate the specificity of the stain, hamster cheek pouch sections were stained with toluidine blue, alcian blue-safranin O, and ferroin. Quantitative evaluation of mast cells stained with the three techniques showed no statistical difference. The simplicity and selectivity of this method is sufficient for image analysis of mast cells.     

Fungal virulence studies come of age

Sophisticated molecular biological research has revealed many virulence attributes in at least four pathogenic fungi, but the future study of fungal virulence requires investigators to distinguish between molecules that directly interact with the host, molecules that regulate these, and molecules that are always required for fungal growth and survival, independent of the host.     

Angiopoietins have distinct modular domains essential for receptor binding,dimerization and superclustering

Angiopoietins are a recently discovered family of angiogenic factors that interact with the endothelial receptor tyrosine kinase Tie2, either as agonists (angiopoietin-1) or as context-dependent agonists/antagonists (angiopoietin-2). Here we show that angiopoietin-1 has a modular structure unlike any previously characterized growth factor. This modular structure consists of a receptor-binding domain, a dimerization motif and a superclustering motif that forms variable-sized multimers. Genetic engineering of precise multimers of the receptor-binding domain of angiopoietin-1, using surrogate multimerization motifs, reveals that tetramers are the minimal size required for activating endothelial Tie2 receptors. In contrast, engineered dimers can antagonize endothelial Tie2 receptors. Surprisingly, angiopoietin-2 has a modular structure and multimerization state similar to that of angiopoietin-1, and its antagonist activity seems to be a subtle property encoded in its receptor-binding domain.     

Acute myeloid leukemia: treatment over 60

Undertreatment of older patients with acute myeloid leukemia (AML) can explain, in part, their inferior outcome when compared to that of younger patients. In agreement with the benefit seen by patients under age 60 from high-dose cytosine arabinoside (Ara-C), there are dose effects in the over 60s, in particular for daunorubicin, in induction treatment and for the duration of postremission treatment. The use of these effects can partly overcome the mostly unfavorable disease biology in older age AML, as expressed by the absence of favorable and the over-representation of adverse chromosomal abnormalities as well as the expression of drug resistance. We recommend an adequate dosage of 60 mg/m2 daunorubicin on 3 days in combination with standard dose Ara-C and 6-thioguanine given for induction and consolidation, and followed by a prolonged monthly maintenance chemotherapy for at least 1 year's duration. Further improvements in supportive care may help to deliver additional antileukemic cytotoxicity. As a novel approach, nonmyeloablative preparative regimens may open up the possibility of allogeneic transplantation for older patients with AML. Other new options like multidrug resistance modulators, antibody targeted therapies and molecular targeting are under clinical investigation. A questionnaire study in patients with AML showed that, according to patients' self-assessment, intensive and prolonged treatment did not result in a diminished quality of life. This finding did not vary by age, under or over 60 years. As the median age in this disease is more than 60 years, the adequate management of AML in older patients remains the major challenge.     

The effect of estrogen on muscle damage biomarkers following prolonged aerobic exercise in eumenorrheic women

This study assessed the influence of estrogen (E₂) on muscle damage biomarkers [skeletal muscle - creatine kinase (CK); cardiac muscle - CK-MB] responses to prolonged aerobic exercise. Eumenorrheic women (n=10) who were physically active completed two 60-minute treadmill running sessions at ∼60-65% maximal intensity during low E₂ (midfollicular menstrual phase) and high E₂ (midluteal menstrual phase) hormonal conditions. Blood samples were collected prior to exercise (following supine rest), immediately post-, 30 min post-, and 24 hours post-exercise to determine changes in muscle biomarkers. Resting blood samples confirmed appropriate E₂ hormonal levels Total CK concentrations increased following exercise and at 24 hours post-exercise were higher in the midfollicular low E₂ phase (p<0.001). However, CK-MB concentrations were unaffected by E₂ level or exercise (p=0.442) resulting in the ratio of CK-MB to total CK being consistently low in subject responses (i.e., indicative of skeletal muscle damage). Elevated E₂ levels reduce the CK responses of skeletal muscle, but had no effect on CK-MB responses following prolonged aerobic exercise. These findings support earlier work showing elevated E₂ is protective of skeletal muscle from exercise-induced damage associated with prolonged aerobic exercise.     

Resistin-like molecule-beta is an allergen-induced cytokine with inflammatory and remodeling activity in the murine lung

Resistin-like molecule (RELM)-beta is a cysteine-rich cytokine implicated in insulin resistance and asthmatic responses, but its function remains an enigma. We now report that RELM-beta has a role in promoting airway inflammation and lung remodeling in the mouse lung. RELM-beta is strongly induced by diverse allergens and T helper type 2 (Th2) cytokines by an IL-13- and STAT6-dependent mechanism. To understand the in vivo role of RELM-beta, we delivered recombinant murine RELM-beta intratracheally to na?ve mice. RELM-beta induced dose-dependent leukocyte accumulation (most prominently involving macrophages) and goblet cell hyperplasia. The most prominent effect induced by RELM-beta was increased perivascular and peribronchial collagen deposition. Mice genetically deficient in RELM-beta had reduced accumulation of collagen and goblet cell hyperplasia in an experimental model of allergic airway inflammation. In vitro experiments demonstrated that RELM-beta had fibroblast motogenic activity. These results identify RELM-beta as a Th2-associated cytokine with potent inflammatory and remodeling activity.     

A functional analysis on isolated rat islets of Langerhans: effects of dimethylsulfoxide and low-temperature preservation

Cryopreservation of pancreatic islets of Langerhans offers the possibility of storage of sufficient quantities of this tissue for transplantation in the treatment of certain forms of diabetes, as well as providing a means of precise histocompatibility matching. In these studies, the effects of dimethylsulfoxide and various cooling rates on islet function are examined. These studies demonstrate that islets treated with 1.4 M dimethylsulfoxide and slowly cooled at a rate of 0.3 degrees C/min release insulin biphasically upon glucose challenge. In addition, this stimulated release is significantly improved (P less than 0.05) by increasing the duration of post-thaw culture. After thawing, these cryopreserved islets also retain the capacity to synthesize insulin. Islets frozen at faster cooling rates (3, 14, and 48 degrees C/min) exhibit varying degrees of glucose-induced insulin release, indicative of freeze-induced damage. These manifestations of freeze-induced damage include high basal (nonstimulatory) insulin release rates, little or no increase in the stimulated rate versus the nonstimulated rate, and failure of the stimulated release to return to basal levels when the glucose concentration is reduced.