Enhancement of chemotactic factor-stimulated neutrophil oxidative metabolism by leukotriene B4

Leukotriene B4 (LTB4) is a potent primary stimulator of neutrophil chemotaxis, aggregation, and degranulation and induces superoxide production at higher concentrations. In order to determine whether LTB4 modulates neutrophil responses to oxidative stimuli, human neutrophils (PMNs) were incubated with LTB4 prior to stimulation with f-Met-Leu-Phe (fMLP, 10(-7) mol/L), opsonized zymosan (OZ, 250 micrograms/mL), or phorbol myristate acetate (PMA, 32 nmol/L). Superoxide (O2-) production by stimulated PMNs was assessed by the superoxide dismutase-inhibitable reduction of cytochrome c. LTB4 alone did not stimulate O2- production in concentrations below 10(-7) mol/L and had no effect on the O2- assay. In the concentration range of 10(-12) to 10(-8) mol/L, LTB4 did not alter O2- release induced by OZ or PMA. In contrast, LTB4-treated cells demonstrated enhanced O2- production following exposure to fMLP, and in the presence of 10 nmol/LLTB4, generated 180% +/- 41% of O-2 quantities produced by control cells (n = 23). Enhancement was LTB4 dose-dependent, was maximal in the range of 1 to 10 nmol/L LTB4, was not reversed by removal of the lipid from the medium prior to fMLP stimulation, and was not dependent on the presence of Ca++ or Mg++ in the suspending medium. Chemiluminescence of fMLP-stimulated neutrophils was increased to 323% of controls in neutrophils preincubated with 10 nmol/L LTB4. Unlike augmentation of oxidative responses to fMLP seen with other degranulating stimuli, enhancement by LTB4 was not correlated with an increase in 3H-fMLP receptor binding. These results indicate that, in addition to its primary effects on neutrophil function, LTB4 modulates PMN oxidative responses to the chemotactic peptide and, thus, may amplify the release of oxygen metabolites at inflammatory foci.     

Common bile duct calculi: updated experience with dissolution with methyl tertiary butyl ether

The authors describe their experience with methyl tertiary butyl ether (MTBE) in a larger series of patients than previously reported in order to acquaint physicians with both its effectiveness for dissolution of common bile duct calculi and the limitations of its use. Ten patients with 13 biliary calculi underwent percutaneous stone dissolution treatment with the experimental cholesterol solvent, MTBE. Three stones completely dissolved within 30 minutes, seven were reduced in size, and three were visibly unaffected. All stones not completely dissolved were easily extracted by means of a stone basket except for one in a patient taken to surgery. Although MTBE perfusion is an effective technique for management of biliary calculi, practitioners should be aware that its use is quite time consuming and its odor difficult to control.     

Clinical MR imaging with a Helmholtz-type surface coil

Limited-field-of-view radio-frequency receiver antennas provide improved near-field sensitivity for magnetic resonance imaging by decreasing the antenna volume. The Helmholtz-type surface coil, consisting of two flat rings, is an organ-encompassing antenna that takes advantage of this principle to yield an improved signal-to-noise ratio (S/N). The coil was tested in a group of 50 patients and 16 healthy volunteers. Images obtained with the Helmholtz coil demonstrated quantitatively superior S/N of 2.2-fold or greater than that of comparison body coil images, as well as qualitatively superior anatomic resolution.     

Early-life co-administration of cockroach allergen and endotoxin augments pulmonary and systemic responses

Background Environmental exposures to cockroach allergen and endotoxin are recognized epidemiological risk factors for the early development of allergies and asthma in children. Because of this, it is important to examine the role of early-life concurrent inhalation exposures to cockroach allergen and endotoxin in the pathogenesis of allergic airways disease.
Objective We examined the effects of repeated concomitant endotoxin and cockroach allergen inhalation on the pulmonary and systemic immune responses of newborn and juvenile mice.
Methods C3H/HeBFeJ mice were exposed to inhaled endotoxin and cockroach allergen via intranasal instillation from day 2 to 21 after birth, and systemic and pulmonary responses were examined in serum, bronchoalveolar lavage fluid, and lung tissue.
Results Cockroach allergen exposures induced pulmonary eosinophilic inflammation, total and allergen-specific IgE, IgG₁, and IgG_2a production, and alveolar remodelling. Co-exposures with endotoxin and cockroach allergen significantly increased serum IgE and IgG₁, lung inflammation, and alveolar wall thickness, and decreased airspace volume density. Importantly, compared with exposures with individual substances, the responses to co-exposures were more than additive.
Conclusions Repeated inhalation exposures of neonatal and juvenile mice to endotoxin and cockroach allergen increased the pulmonary inflammatory and systemic immune responses in a synergistic manner and enhanced alveolar remodelling in the developing lung. These data underscore the importance of evaluating the effect of multiple, concurrent environmental exposures, and of using an experimental model that incorporates clinically relevant timing and route of exposures.     

Is the left hemisphere androcentric? Evidence of the learned categorical perception of gender

Effects of language learning on categorical perception have been detected in multiple domains. We extended the methods of these studies to gender and pitted the predictions of androcentrism theory and the spatial agency bias against each other. Androcentrism is the tendency to take men as the default gender and is socialized through language learning. The spatial agency bias is a tendency to imagine men before women in the left–right axis in the direction of one's written language. We examined how gender-ambiguous faces were categorized as female or male when presented in the left visual fields (LVFs) and right visual fields (RVFs) to 42 native speakers of English. When stimuli were presented in the RVF rather than the LVF, participants (1) applied a lower threshold to categorize stimuli as male and (2) categorized clearly male faces as male more quickly. Both findings support androcentrism theory suggesting that the left hemisphere, which is specialized for language, processes face stimuli as male-by-default more readily than the right hemisphere. Neither finding evidences an effect of writing direction predicted by the spatial agency bias on the categorization of gender-ambiguous faces.     

Intracerebral pneumatocele: CT findings

Two cases of intracerebral pneumatocele following trauma are presented. One to two months after initial treatment both patients had deteriorating neurologic status. The diagnosis was made by radiography. When a pneumatocele is suspected clinically, computed tomography can play a vital role in determining the precise location of the gas collection, its relationship to the fracture site, and the amount of mass effect on the brain.     

Acquired Thoracic Aortic Interruption: Percutaneous Repair Using Graft Stents

Two adult patients with isolated, aortic interruption were successfully treated by percutaneous insertion of graft stents. Prior to the intervention, both patients were hypertensive and on medication. In both cases, an ascending aortogram demonstrated a blind ending of the thoracic aorta distal to the left subclavian artery with a large gradient across the interruption and with multiple collaterals. A graft stent was successfully deployed across the interrupted segment in both cases. We believe that this is one of the first reported cases of percutaneous stenting of aortic interruption and represents a promising new therapeutic option for these adult patients.