Generation of micro-particles of proteins for aerosol delivery using high pressure modified carbon dioxide

PURPOSE

To investigate the feasibility of using the Aerosol Solvent Extraction System (ASES) to generate microparticles of proteins suitable for aerosol delivery from aqueous-based solutions.

METHODS

The ASES technique using high-pressure carbon dioxide modified with ethanol was utilised for the generation of microparticles of proteins (lysozyme, albumin, insulin and recombinant human deoxyribonuclease (rhDNase)) from aqueous solutions. Particle size, morphology, size distributions and powder aerosol performance were examined. The biochemical integrity of the processed proteins was assessed by testing the level of molecular aggregation using size exclusion chromatography and by bioassay technique for lysozyme.

RESULTS

Proteins were precipitated as spherical particles ranging in size from 100 to 500 nm. The primary nano-sized particles agglomerated to form micron-sized particles during the precipitation process. The median size of the particles was a function of the operating conditions. In-vitro aerosol performance tests showed that the percent fine particle mass (< 5 microm) was approximately 65%, 40% and 20% for lysozyme, albumin and insulin, respectively. Negligible loss in the monomer content or biological activity was observed for lysozyme. Insulin exhibited slight aggregation and 93% of the monomer was retained after processing. Albumin was affected by processing and only 50-75% of the monomer was retained compared with 86% in the original material. However, rhDNase was substantially denatured during processing as shown by the significantly reduced monomer content.

CONCLUSIONS

Micron-sized particles of lysozyme, albumin and insulin with satisfactory inhalation performance were successfully generated from aqueous solutions using the modified ASES technique. The biochemical integrity of the processed proteins was a function of the operating conditions and the nature of the individual protein.

Neurofilament H immunoreaction in oligodendrogliomas as demonstrated by a new polyclonal antibody

We have characterized a new polyclonal antibody against heavy chain (H) of neurofilament which can be used to demonstrate neurofilament H in normal brain tissue and oligodendroglioma cells immunocytochemically and immunochemically. Using this antibody we found neurofilament H-immunoreactive tumor cells in 13 oligodendrogliomas (6 WHO grade II, 7 WHO grade III) out of 84 oligodendrogliomas investigated (59 WHO grade II and 25 WHO grade III). Double immunolabeling and confocal laser scanning microscopy showed colocalization of neurofilament H and glial fibrillary acidic protein in certain oligodendroglioma cells. Colocalization of neurofilament and synaptophysin was observed only rarely. The results support the notion that oligodendrogliomas consists of a heterogeneous cell population displaying various stages of differentiation and dedifferentiation. The occurrence of neurofilament H-immunoreactive tumor cells in oligodendrogliomas is not related to the survival of the patients.

A gp91phox containing NADPH oxidase selectively expressed in endothelial cells is a major source of oxygen radical generation in the arterial wall

Reactive oxygen species (ROS) play an important role in regulating vascular tone and intracellular signaling; the enzymes producing ROS in the vascular wall are, however, poorly characterized. We investigated whether a functionally active NADPH oxidase similar to the leukocyte enzyme, ie, containing the subunits p22phox and gp91phox, is expressed in endothelial cells (ECs) and smooth muscle cells (SMCs). Phorbol 12-myristate 13-acetate (PMA), a stimulus for leukocyte NADPH oxidase, increased ROS generation in cultured ECs and endothelium-intact rat aortic segments, but not in SMCs or endothelium-denuded arteries. NADPH enhanced chemiluminescence in all preparations. p22phox mRNA and protein was detected in ECs and SMCs, whereas the expression of gp91phox was confined to ECs. Endothelial gp91phox was identical to the leukocyte form as determined by sequence analysis. In contrast, mitogenic oxidase-1 (mox1) was expressed in SMCs, but not in ECs. To determine the functional relevance of gp91phox expression, experiments were performed in aortic segments from wild-type, gp91phox(-/-), and endothelial NO synthase (eNOS)(-/-) mice. PMA-induced ROS generation was comparable in aortae from wild-type and eNOS(-/-) mice, but was attenuated in segments from gp91phox(-/-) mice. Endothelium-dependent relaxation was greater in aortae from gp91phox(-/-) than from wild-type mice. The ROS scavenger tiron increased endothelium-dependent relaxation in segments from wild-type, but not from gp91phox(-/-) mice. These data demonstrate that ECs, in contrast to SMCs, express a gp91phox-containing leukocyte-type NADPH oxidase. This enzyme is a major source for arterial ROS generation and affects the bioavailability of endothelium-derived NO.

Signal transduction in the rodent pineal organ. From the membrane to the nucleus

The rodent pineal organ transduces a photoneural input into a hormonal output. This photoneuroendocrine transduction leads to highly elevated levels of the hormone melatonin at night-time which serves as a message for darkness. The melatonin rhythm depends on transcriptional, translational and posttranslational regulation of the arylalkylamine-N-acetyltransferase, the key enzyme of melatonin biosynthesis. These regulatory mechanisms are fundamentally linked to two second messenger systems, namely the cAMP- and the Ca(2+)-signal transduction pathways. Our data gained by molecular biology, immunohistochemistry and single-cell imaging demonstrate a time- and substance-specific activation of these signaling pathways and provide a framework for the understanding of the complex signal transduction cascades in the rodent pineal gland which in concert not only regulate the basic profile but also fine-tune the circadian rhythm in melatonin synthesis.

Filamentous tau pathology in nerve cells, astrocytes, and oligodendrocytes of aged baboons

Intracellular filamentous inclusions containing abnormally phosphorylated tau protein are hallmarks of several human neurodegenerative disorders. This study reveals tau-positive cytoskeletal abnormalities in neurons and glial cells of aged baboons. The brains of four baboons (Papio hamadryas, 20-30 yr of age) were examined using the Gallyas silver technique for neurofibrillary changes and phosphorylation-dependent anti-tau antibodies (AT8, AT100, AT270, PHF-1, TG-3). Conspicuous changes were noted in two animals, 26 and 30 yr of age. In both animals, a combination of neuronal and glial cytoskeletal pathology was seen preferentially affecting limbic brain areas, including the hippocampal formation. In the 30-yr-old animal, numerous tau-positive inclusions were seen in the granule cells of the fascia dentata. These cells even exhibited an accumulation of argyrophilic neurofibrillary tangles. The glial changes affected both astrocytes and oligodendrocytes. Tau-positive astrocytes were seen in perivascular, subpial, and subependymal locations. Tau-positive oligodendrocytes preferentially occurred in limbic fiber tracts including the entorhinal perforant path. Ultrastructurally, tau-positive straight filaments (10-14 nm) in both neurons and glial cells were revealed by anti-tau immunoelectron microscopy. This study thus indicates the potential usefulness of aged baboons for experimental investigation of neuronal and glial filamentous tau pathology. This nonhuman primate species may provide valuable information pertinent to the broad spectrum of human tauopathies.

CREB phosphorylation and melatonin biosynthesis in the rat pineal gland: involvement of cyclic AMP dependent protein kinase type II

Phosphorylation of cyclic AMP response element binding protein (CREB) at amino acid serine 133 appears as an important link between the norepinephrine (NE)-induced activation of second messenger systems and the stimulation of melatonin biosynthesis. Here we investigated in the rat pineal gland: 1) the type of protein kinase that mediates CREB phosphorylation: and 2) its impact on melatonin biosynthesis. Immunochemical or immunocytochemical demonstration of serine133-phosphorylated cyclic AMP regulated element binding protein (pCREB) and radioimmunological detection of melatonin revealed that only cyclic AMP-dependent protein kinase (PKA) inhibitors suppressed NE-induced CREB phosphorylation and stimulation of melatonin biosynthesis, whereas inhibitors of cyclic GMP-dependent protein kinase (PKG), mitogen-activated protein kinase kinase, protein kinase C, or calcium-calmodulin-dependent protein kinase (CaMK) were ineffective. Investigations with cyclic AMP-agonist pairs that selectively activate either PKA type I or II link NE-induced CREB phosphorylation and stimulation of melatonin biosynthesis to the activation of PKA type II. Our data suggest that PKA type II plays an important role in the transcriptional control of melatonin biosynthesis in the rat pineal organ.

Bacterial inactivation by using near- and supercritical carbon dioxide

The three most common methods of sterilization in use today are ethylene oxide exposure, gamma-irradiation, and steam sterilization. Each of these methods has serious limitations for the sterilization of some materials used in medicine, especially thermally and hydrolytically sensitive polymers by themselves and in combination with proteins. In this work, we demonstrate a potential new method of sterilization by using supercritical fluid carbon dioxide. Using this method we achieve complete inactivation of a wide variety of bacterial organisms at moderate temperatures and in the absence of organic solvents or irradiation. Sterilization is a function of both the proximity to the fluid's critical point and the chemical nature of the fluid itself. When biodegradable polymers poly(lactic-co-glycolic) acid and polylactic acid were included in the sterilization process, there was no effect on the inactivation efficiency, yet no physical or chemical damage to these thermally and hydrolytically labile materials was observed.

Transcription factors in neuroendocrine regulation: rhythmic changes in pCREB and ICER levels frame melatonin synthesis

Neurotransmitter-driven activation of transcription factors is important for control of neuronal and neuroendocrine functions. We show with an in vivo approach that the norepinephrine cAMP-dependent rhythmic hormone production in rat pineal gland is accompanied by a temporally regulated switch in the ratio of a transcriptional activator, phosphorylated cAMP-responsive element-binding protein (pCREB), and a transcriptional inhibitor, inducible cAMP early repressor (ICER). pCREB accumulates endogenously at the beginning of the dark period and declines during the second half of the night. Concomitant with this decline, the amount of ICER rises. The changing ratio between pCREB and ICER shapes the in vivo dynamics in mRNA and, thus, protein levels of arylalkylamine-N-acetyltransferase, the rate-limiting enzyme of melatonin synthesis. Consequently, a silenced ICER expression in pinealocytes leads to a disinhibited arylalkylamine-N-acetyltransferase transcription and a primarily enhanced melatonin synthesis.

Pituitary adenylate cyclase-activating polypeptide and melatonin in the suprachiasmatic nucleus: effects on the calcium signal transduction cascade

The suprachiasmatic nucleus (SCN) harbors an endogenous oscillator generating circadian rhythms that are synchronized to the external light/dark cycle by photic information transmitted via the retinohypothalamic tract (RHT). The RHT has recently been shown to contain pituitary adenylate cyclase-activating polypeptide (PACAP) as neurotransmitter/neuromodulator. PACAPergic effects on cAMP-mediated signaling events in the SCN are restricted to distinct time windows and sensitive to melatonin. In neurons isolated from the SCN of neonatal rats we investigated by means of the fura-2 technique whether PACAP and melatonin also influence the intracellular calcium concentration ([Ca2+]i). PACAP elicited increases of [Ca2+]i in 27% of the analyzed neurons, many of which were also responsive to the RHT neurotransmitters glutamate and/or substance P. PACAP-induced changes of [Ca2+]i were independent of cAMP, because they were not mimicked by forskolin or 8-bromo-cAMP. PACAP caused G-protein- and phospholipase C-mediated calcium release from inositol-trisphosphate-sensitive stores and subsequent protein kinase C-mediated calcium influx, demonstrated by treatment with GDP-beta-S, neomycin, U-73122, calcium-free saline, thapsigargin, bisindolylmaleimide, and chelerythrine. The calcium influx was insensitive to antagonists of voltage-gated calcium channels of the L-, N-, P-, Q- and T-type (diltiazem, nifedipine, verapamil, omega-conotoxin, omega-agatoxin, amiloride). Immunocytochemical characterization of the analyzed cells revealed that >50% of the PACAP-sensitive neurons were GABA-immunopositive. Our data demonstrate that in the SCN PACAP affects the [Ca2+]i, suggesting that different signaling pathways (calcium as well as cAMP) are involved in PACAPergic neurotransmission or neuromodulation. Melatonin did not interfere with calcium signaling, indicating that in SCN neurons the hormone primarily affects the cAMP signaling pathway.

CREB in the mouse SCN: a molecular interface coding the phase-adjusting stimuli light, glutamate, PACAP, and melatonin for clockwork access

The suprachiasmatic nucleus (SCN) is a central pacemaker in mammals, driving many endogenous circadian rhythms. An important pacemaker target is the regulation of a hormonal message for darkness, the circadian rhythm in melatonin synthesis. The endogenous clock within the SCN is synchronized to environmental light/dark cycles by photic information conveyed via the retinohypothalamic tract (RHT) and by the nocturnal melatonin signal that acts within a feedback loop. We investigated how melatonin intersects with the temporally gated resetting actions of two RHT transmitters, pituitary adenylate cyclase-activating polypeptide (PACAP) and glutamate. We analyzed immunocytochemically the inducible phosphorylation of the transcription factor Ca2+/cAMP response element-binding protein (CREB) in the SCN of a melatonin-proficient (C3H) and a melatonin-deficient (C57BL) mouse strain. In vivo, light-induced phase shifts in locomotor activity were consistently accompanied by CREB phosphorylation in the SCN of both strains. However, in the middle of subjective nighttime, light induced larger phase delays in C57BL than in C3H mice. In vitro, PACAP and glutamate induced CREB phosphorylation in the SCN of both mouse strains, with PACAP being more effective during late subjective daytime and glutamate being more effective during subjective nighttime. Melatonin suppressed PACAP- but not glutamate-induced phosphorylation of CREB. The distinct temporal domains during which glutamate and PACAP induce CREB phosphorylation imply that during the light/dark transition the SCN switches sensitivity between these two RHT transmitters. Because these temporal domains are not different between C3H and C57BL mice, the sensitivity windows are set independently of the rhythmic melatonin signal.

Prognostic implication of histopathological, immunohistochemical and clinical features of oligodendrogliomas: a study of 89 cases

Histopathological, immunohistochemical and clinical parameters were correlated with survival in 89 cases of oligodendroglioma (65 patients with grade II and 24 patients with grade III of the WHO classification). Median survival time and 5-year survival rate were 3.5 years and 76% for patients with oligodendroglioma grade II and 0.875 years and 23% for patients with oligodendroglioma grade III. The tumor biopsy specimens were immunohistochemically analyzed for Ki 67 (MIB-1), vimentin, glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE) and synaptophysin. MIB-1 nuclear labeling index ranged from 0.0% to 33.4%; vimentin-immunoreactive tumor cells were found in 25 cases. MIB-1 nuclear labeling index and vimentin immunoreaction showed a significant statistical correlation to the 5-year survival rate of the patients. Tumors with vimentin expression (n=25) and/or high MIB-1 labeling index (n=26) had a poorer prognosis than tumors lacking vimentin expression (n=57) and/or displaying a low MIB-1 labeling index (n=56). The expression of immunoreactivity for GFAP (n=53), NSE (n=23) and synaptophysin (n=15) appeared to be of no prognostic relevance. Patients with gross total tumor resection (n=47) had a median survival time and 5-year survival rate of 3.3 years and 84% compared to 1.2 years and 42% for patients with subtotal resection (n=41). The comparison between patients who underwent surgery alone (n=53) and those who had surgery plus postoperative radiation therapy showed no significant survival benefit from postoperative radiation therapy. In conclusion, tumor grade, MIB-1 labeling index, expression of vimentin and the extent of surgery are shown to be of prognostic relevance for patients with oligodendroglioma.