One-pot synthesis of nanochain particles for targeting brain tumors.

To synthesize multi-component nanochains, we developed a simple 'one-pot' synthesis, which exhibited high yield and consistency. The nanochains particles consist of parent nanospheres chemically linked into a higher-order, chain-like assembly. The one-pot synthesis is based on the addition of two types of parent nanospheres in terms of their surface chemical functionality (e.g., decorated with PEG-NH2 or PEG-COOH). By reacting the two types of parent nanospheres at a specific ratio (∼2 : 1) for a short period of time (∼30 min) under rigorous stirring, nanochains were formed. For example, we show the synthesis of iron oxide nanochains with lengths of about 125 nm consisting of 3-5 constituting nanospheres. The chain-like shaped nanoparticle possessed a unique ability to target and rapidly deposit on the endothelium of glioma sites via vascular targeting. To target and image invasive brain tumors, we used iron oxide nanochains with the targeting ligand being the fibronectin-targeting peptide CREKA. Overexpression of fibronectin is strongly associated with the perivascular regions of glioblastoma multiforme and plays a critical role in migrating and invasive glioma cells. In mice with invasive glioma tumors, 3.7% of the injected CREKA-targeted nanochains was found in gliomas within 1 h. Notably, the intratumoral deposition of the nanochain was ∼2.6-fold higher than its spherical variant. Using MR imaging, the precise targeting of nanochains to gliomas provided images with the exact topology of the disease including their margin of infiltrating edges and distant invasive sites.

Alterations in respiratory behavior, brain neurochemistry and receptor density induced by pharmacologic suppression of sleep in the neonatal period.

UNLABELLED: The present study examined if drug suppression of active sleep (AS) in the neonate affected the development and expression of respiratory behavior. Secondly, we assessed brain neurochemistry and receptor density in specific supra-medullary brain regions to identify coincident biochemical alterations. Sprague-Dawley newborn rat pups were randomized and divided among six rat mothers (n=10/mother/group), each mother housed separately. Two untreated control (UC) groups received either no interventions or were fed milk vehicle twice daily and were handled similarly to the drug intervention animals. Pharmacological disruption of sleep was achieved by administration (2 groups of each) of either clonidine (CLO) 100 microm/kg, or scopolamine (SCO) 800 microm/kg, given orally twice daily for the first 7 days of life. On postnatal (P) days P10 and P19 of life, pups were assessed for metabolism, minute ventilation (VE), tidal volume (Vt) and frequency (f). On P21 (14 days after the end of drug exposure), pups from each condition were sacrificed and punch biopsies of the frontal cortex, hypothalamus, and hippocampus were examined for hydroxytryptophan (5-HT), and norepinepherine (NE) by HPLC. An equal number of pups were sacrificed and brains examined for muscarinic acetylcholine (mAch), alpha2-adrenergic and I1-imidazoline receptor density. RESULTS: Both CLO and SCO exposed animals had a lower V(t) and respiratory quotient than UC animals (p<0.01). CLO animals exhibited a higher f (p<0.01) and both CLO and SCO exhibited a lower V(t) (p<0.05) than the UC groups; VE was reduced in the SCO groups, compared with CLO and UC groups (p<0.01). Pattern of breathing in response to brief hypoxia exposure was altered for CLO and SCO. The normal decline in VE during sleep was not observed in CLO rats. Both drug exposures resulted in a comparable reduction in hypothalamic NE and 5-HT levels (p<0.05), while in the frontal cortex, and the hippocampus variable changes in NE and 5-HT, occurred. In CLO and SCO rats mAch receptors were increased in cortex, and reduced in hypothalamus; I1-imidazoline receptors were increased in hypothalamus and decreased in hippocampus (p<0.05 for each). In contrast, alpha2-adrenergic receptors were increased in cortex for both CLO and SCO, decreased in hypothalamus for CLO, and decreased in hippocampus for SCO (p<0.05 for each). CONCLUSIONS: these data show that drug-induced neonatal sleep suppression will alter ventilatory pattern, metabolism, and site-specific concentrations of adrenergic neurotransmitters and in receptor density, perhaps as a result of suppression of neonatal AS.

Extended survival time following pseudorabies virus injection labels the suprapontine neural network controlling the bladder and urethra in the rat.

The central neurons that are involved in control of the urinary bladder and proximal urethra in adult male rats were identified by retrograde transport of the viral transneural tracer pseudorabies virus (PRV, Bartha strain). At 5 days post-injection, PRV-infected neurons were found in suprapontine central nervous system nuclei including ventrolateral periaqueductal gray, magnocellular division of the red nucleus, lateral hypothalamus and paraventricular nucleus, retrochiasmic region and suprachiasmatic nucleus. At days 6 and 7 PRV-infected neurons were observed in the amygdala, lateral septal nucleus, hippocampus, and frontal motor, piriform, and perirhinal cortices. These results identify the supraspinal neural networks that are involved in control of the lower urinary tract, and demonstrate the utility of long survival times to label higher-order neurons with PRV.

Moxonidine acting centrally inhibits airway reflex responses.

We examined the role of I1-imidazoline (I1-IR) receptors in control of airway function, by testing the effects of systemic administration of the I1-IR agonist moxonidine on reflex responses of tracheal smooth muscle (TSM) tone to either lung deflation or mechanical stimulation of intrapulmonary rapidly adapting receptors. Experiments were performed in either alpha-chloralose anesthetized or decorticate, paralyzed, and mechanically ventilated beagle dogs. Moxonidine (10-100 micrograms/kg) administered via three different routes (femoral vein, muscular branch of superior thyroid artery, and vertebral artery) attenuated TSM responses to stimulation of airway sensory nerve fibers by two different ways and caused a decrease in arterial pressure and heart rate. These effects were dose dependent and were significantly reversed by efaroxan (an I1-IR and alpha 2-adrenergic blocker) administered via the vertebral artery. Intravertebral efaroxan abolished the hemodynamic effects of moxonidine. Intravenous moxonidine (10-100 micrograms/kg) did not alter airway smooth muscle responses to electrical stimulation of the peripheral vagus nerve. In addition, in vitro moxonidine (1-100 micrograms/ml) had no effect on contractile responses to increasing doses of acetylcholine. These findings indicate that moxonidine may act at a central site to suppress reflex airway constriction, even when given into the systemic circulation. Given the presence of I1-IR sites and alpha 2-adrenergic receptors in brain regions participating in airway reflexes, these receptor classes may be involved in brainstem control of the cholinergic outflow to the airways.

I1-imidazoline receptors and cholinergic outflow to the airways.

We examined the role of I1-imidazoline receptors in the control of airway function, by testing the effects of systemic administration of the I1-imidazoline agonist moxonidine on reflex responses of tracheal smooth muscle (TSM) tone to either lung deflation or mechanical stimulation of intrapulmonary rapidly adapting receptors. Experiments were performed in either alpha-chloralose anaesthetized or decorticate, paralyzed and mechanically ventilated beagle dogs. Moxonidine (10-100 microg/kg) administered via three different routes (the femoral vein, muscular branch of superior thyroid artery, and vertebral artery) attenuated TSM responses to stimulation of airway sensory nerve fibers by two different ways, and caused a decrease in arterial pressure and heart rate. These effects were dose-dependent, and were significantly reversed by efaroxan (an I1-imidazoline and alpha2-adrenergic blocker) administered via the vertebral artery. Intravertebral efaroxan abolished the hemodynamic effects of moxonidine. Intravenous moxonidine (10-100 microg/kg) did not alter airway smooth muscle responses to electrical stimulation of the peripheral vagus nerve. In addition, in vitro moxonidine (1-100 microg/ml) had no effect on contractile responses to increasing doses of acetylcholine. These findings indicate that moxonidine may act at a central site to suppress reflex airway constriction, even when given into the systemic circulation. Given the presence of I1-imidazoline sites and alpha2-adrenergic receptors in brain regions participating in airway reflexes, these receptor classes may be involved in brainstem control of the cholinergic outflow to the airways.

The brainstem network involved in coordination of inspiratory activity and cholinergic outflow to the airways.

The respiratory rhythm modulates cholinergic outflow to the tracheal smooth muscle through the parasympathetic nerves. To determine the basis of this modulation, we combined the retrograde tracer technique to identify bulbospinal cells projecting to phrenic motoneurons, and the transneuronal labeling method to visualize medullary neurons that innervate airway-related vagal preganglionic cells. Following injections of fluorogold into the ventral horns of the cervical spinal cord and injections of pseudorabies virus (PRV) into the wall of the extrathoracic trachea of superior cervical ganglioctomized Sprague-Dawley rats. A large number of the double-labeled cells were identified along the ventral aspect of the medulla oblongata. Most frequently, double-labeled neurons were seen in the medial tegmental field, particularly in the parapyramidal region, within the gigantocellular nuclei, and the caudal raphe nuclei. Less frequently, double-labeled neurons were found in the ventrolateral medulla. No double-labeled cell was observed in the dorsal aspect of the medulla oblongata. This study indicates that a subset of medullary neurons that project to phrenic motoneurons also innervate the airway-related vagal preganglionic cells, allowing the coupling of inspiratory activity and parasympathetic outflow to the airways.