Optimizing Oxygen-Production Kinetics of Manganese Dioxide Nanoparticles Improves Hypoxia Reversal and Survival in Mice with Bone Metastases

Persistent hypoxia in bone metastases induces an immunosuppressive environment, limiting the effectiveness of immunotherapies. To address chronic hypoxia, we have developed manganese dioxide (MnO2) nanoparticles with tunable oxygen production kinetics for sustained oxygenation in bone metastases lesions. Using polyethylene glycol (PEG)-stabilized MnO2 or poly(lactic[50]-co-glycolic[50] acid) (50:50 PLGA), poly(lactic[75]-co-glycolic[25] acid) (75:25 PLGA), and polylactic acid (PLA)-encapsulated MnO2 NPs, we demonstrate that polymer hydrophobicity attenuates burst oxygen production and enables tunable oxygen production kinetics. The PEG-MnO2 NPs resulted in rapid hypoxia reduction in spheroids, which was rapidly attenuated, while the PLA-MnO2 NPs exhibited delayed hypoxia control in cancer spheroids. The 50:50 PLGA-MnO2 NPs exhibited the best short- and long-term control of hypoxia in cancer spheroids, resulting in sustained regulation of the expression of HIF-1α and immunosuppressive genes. The sustained control of hypoxia by the 50:50 PLGA-MnO2 NPs enhanced the cytotoxicity of natural killer cells against cancer spheroids. In vivo, 50:50 PLGA-MnO2 showed greater accumulation in the long bones and pelvis, common sites for bone metastases. The NPs decreased hypoxia in bone metastases and decreased regulatory T cell levels, resulting in enhanced survival of mice with established bone metastases.

Nuclear receptors and AMPK: resetting metabolism

Obesity, and in particular central adiposity, is a key feature of metabolic syndrome, which includes trends toward increased triglycerides, insulin resistance, high blood pressure, hypercholesterolemia, and heart disease. It has a prevalence of 25% or more and is a dominant component of the health care budgets in Western societies. In addition to genetic causes, high-fat diets and disrupted sleep patterns have major influences on the development of metabolic syndrome. Recent studies have demonstrated active roles for the nuclear receptor superfamily and the energy-sensing kinase adenosine monophosphate (AMP)-activated protein kinase (AMPK) in regulating metabolism and circadian rhythm. In this chapter, we review these findings and attempt to develop a better understanding of the interplay between metabolism and circadian rhythm and their coordinated regulation by nuclear receptors and AMPK. This supraregulatory network may be considered a target for novel therapeutic applications against metabolic syndrome.

Profiles of polycyclic aromatic hydrocarbons and polychlorinated biphenyls from the combustion of biomass pellets

An investigation was made into the emissions of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) as well as inorganic gases (e.g. CO) from a wood fired combustion boiler using wood pellets, under two different boiler operating modes. Levels of total PAHs varied from 6.4 and 154 microg m(-3), and were found to be dominating in the gas phase (>80%), regardless of pellet type and boiler operating mode. In addition to this, PAH concentrations were higher in slumber mode than in full flame, and increased with the moisture content of pellets, consistent with the lower combustion efficiency in slumber mode (58.6-64.3%) than in full flame (74.4-82.3%). PAHs in the gas phase comprised mainly of low molecular mass compounds, while PAHs in the particulate phase were mostly composed of high molecular mass compounds, consistent with the physicochemical properties of such compounds. In comparison to PAHs, significantly lower concentrations of PCBs (a maximum of 2.5 microg m(-3)) were released from pellet combustion, consistent with the virgin nature of the pellets. The PCBs in both the gas and particulate phases were dominated by hexachlorinated congeners, although congeners with more chlorine substitution were more abundant in the particulate phase than in gas phase. Significant relationships were established between CO and organic pollutants, and between PAHs and PCBs, which are useful tools for prediction purposes.

Development of the technical capabilities needed to build and position a prepolarization coil for a magnetic resonance imaging magnet

An experiment to show that a magnetic resonance imaging (MRI) magnet could be assembled around a patient, and used as part of a prepolarization system in which substantial transient forces are applied to parts of it, is described. The paper describes the circumstances that develop as a result of the application of the large transient fields used in this type of study, and outlines the reason for the tolerances that are permissible on the alignment of the system components. It then describes a test rig used to evaluate how the various problems might be overcome, and reports on the performance achieved with this rig. On the basis of this work, it appears that a system could be developed that would allow the application of these methods in clinical MRI.

Cell-based selection of internalizing fully human antagonistic antibodies directed against FLT3 for suppression of leukemia cell growth

FMS-like tyrosine kinase 3 (FLT3) receptor is highly expressed in an array of hematological malignancies including approximately 90% of acute myelogenous leukemia (AML). Ligand stimulation of the receptor promotes the survival and proliferation of leukemia cells. Strategies targeting FLT3 using monoclonal antibodies may therefore constitute an effective therapeutic approach for these leukemia. Towards this, we selected a naïve antibody phage display library on both recombinant FLT3 receptor protein and FLT3-expressing leukemia cells using a tailored selection scheme that was designed to isolate antagonistic phage antibodies that not only interfere with receptor/ligand binding but also trigger receptor internalization upon cell surface binding. Phage antibodies were screened first for their ability to bind to cell surface receptor and induce receptor internalization, followed by their activity in blocking ligand-receptor interaction and neutralizing ligand-stimulated receptor activation and cell proliferation. We identified three fully human antibodies, EB10, A2IN, and D4-3, which bound specifically to both soluble and cell surface-expressed FLT3. All three antibodies were shown to be internalized upon binding to cell surface-expressed receptor in a time-dependent fashion. EB10 and D4-3 blocked ligand binding to the receptor with IC(50)s of 14 and 7 nM, respectively. Further, EB10 and D4-3 inhibited FLT3 ligand-induced receptor phosphorylation and cell proliferation in EOL-1 leukemia cells. Taken together, these results suggest that both EB10 and D4-3 may represent excellent therapeutic candidates for the treatment of FLT3-expressing human leukemia, both as unmodified antibodies and as conjugates of cytotoxic agents.

Two new classes of conopeptides inhibit the alpha1-adrenoceptor and noradrenaline transporter

Cone snails use venom containing a cocktail of peptides ('conopeptides') to capture their prey. Many of these peptides also target mammalian receptors, often with exquisite selectivity. Here we report the discovery of two new classes of conopeptides. One class targets alpha1-adrenoceptors (rho-TIA from the fish-hunting Conus tulipa), and the second class targets the neuronal noradrenaline transporter (chi-MrIA and chi-MrIB from the mollusk-hunting C. marmoreus). rho-TIA and chi-MrIA selectively modulate these important membrane-bound proteins. Both peptides act as reversible non-competitive inhibitors and provide alternative avenues for the identification of inhibitor drugs.

Increased responsiveness of dopamine to atypical, but not typical antipsychotics in the medial prefrontal cortex of rats reared in isolation

Dopaminergic hypofunction in the medial prefrontal cortex (mPFC) has been associated with the aetiology of negative symptoms and cognitive dysfunction of schizophrenia, which are both alleviated by clozapine and other atypical antipsychotics such as olanzapine. In rodents, early life exposure to stressful experiences such as social isolation produces a spectrum of symptoms emerging in adult life, which can be restored by antipsychotic drugs. The present series of experiments sought to investigate the effect of clozapine (5-10 mg/kg s.c.), olanzapine (5 mg/kg s.c.), and haloperidol (0.5 mg/kg s.c.) on dopamine (DA) and amino acids in the prelimbic/infralimbic subregion of the mPFC in group- and isolation-reared rats. Rats reared in isolation showed significant and robust deficits in prepulse inhibition of the acoustic startle. In group-reared animals, both clozapine and olanzapine produced a significant increase in DA outflow in the mPFC. Isolation-reared rats showed a significant increase in responsiveness to both atypical antipsychotics compared with group-reared animals. In contrast, the administration of haloperidol failed to modify dialysate DA levels in mPFC in either group- or isolation-reared animals. The results also show a positive relationship between the potency of the tested antipsychotics to increase the release of DA in the mPFC and their respective affinities for 5-HT1A relative to DA D2 or D3 receptors. Finally, isolation-reared rats showed enhanced neurochemical responses to the highest dose of clozapine as indexed by alanine, aspartate, GABA, glutamine, glutamate, histidine, and tyrosine. The increased DA responsiveness to the atypical antipsychotic drugs clozapine and olanzapine may explain, at least in part, clozapine- and olanzapine-induced reversal of some of the major behavioral components of the social isolation syndrome, namely hyperactivity and attention deficit.

Structure-function relationships of a novel bacterial toxin, hemolysin E. The role of alpha G

The novel pore-forming toxin hemolysin E (HlyE, ClyA, or SheA) consists of a long four-helix bundle with a subdomain (beta tongue) that interacts with target membranes at one pole and an additional helix (alpha(G)) that, with the four long helices, forms a five-helix bundle (tail domain) at the other pole. Random amino acid substitutions that impair hemolytic activity were clustered mostly, but not exclusively, within the tail domain, specifically amino acids within, adjacent to, or interacting with alpha(G). Deletion of amino acids downstream of alpha(G) did not affect activity, but deletions encompassing alpha(G) yielded insoluble and inactive proteins. In the periplasm Cys-285 (alpha(G)) is linked to Cys-87 (alpha(B)) of the four-helix bundle via an intramolecular disulfide. Oxidized HlyE did not form spontaneously in vitro but could be generated by addition of Cu(II) or mimicked by treatment with Hg(II) salts to yield inactive proteins. Such treatments did not affect binding to target membranes nor assembly into non-covalently linked octameric complexes once associated with a membrane. However, gel filtration analyses suggested that immobilizing alpha(G) inhibits oligomerization in solution. Thus once associated with a membrane, immobilizing alpha(G) inhibits HlyE activity at a late stage of pore formation, whereas in solution it prevents aggregation and consequent inactivation.

E. coli hemolysin E (HlyE, ClyA, SheA): X-ray crystal structure of the toxin and observation of membrane pores by electron microscopy

Hemolysin E (HlyE) is a novel pore-forming toxin of Escherichia coli, Salmonella typhi, and Shigella flexneri. Here we report the X-ray crystal structure of the water-soluble form of E. coli HlyE at 2.0 A resolution and the visualization of the lipid-associated form of the toxin in projection at low resolution by electron microscopy. The crystal structure reveals HlyE to be the first member of a new family of toxin structures, consisting of an elaborated helical bundle some 100 A long. The electron micrographs show how HlyE oligomerizes in the presence of lipid to form transmembrane pores. Taken together, the data from these two structural techniques allow us to propose a simple model for the structure of the pore and for membrane interaction.

The relationship of prorenin values to microvascular complications in patients with insulin-dependent diabetes mellitus

We have performed a cross-sectional analysis of the relationship between prorenin values and the microvascular complications of diabetes in a well controlled population of insulin-dependent diabetes mellitus (IDDM) subjects. One hundred and thirty-nine subjects (75 men, 64 women, age 44 +/- 17 years; duration of diabetes 19 +/- 15 years), formed the study group. Sixty-seven subjects (48.2%) had no complications, 55 (39.6%) had retinopathy alone, and 17 (12.2%) had retinopathy and albuminuria. Patients with no complications had lower prorenin values than those with microvascular complications (p < 0.001), whilst patients with both albuminuria and retinopathy had higher values than those with retinopathy alone (p < 0.05). Retinopathy was associated with duration of diabetes (p < 0.0001), diastolic blood pressure (p < 0.02) and albuminuria (p < 0.0001) while albuminuria was associated with prorenin (p < 0.02), serum triglyceride (p < 0.01) and retinopathy (p < 0.001). Patients with albuminuria were 5.5 times more likely to have raised prorenin values (>80 ng/mL/h) than those with normal albumin excretion [95% confidence interval (CI): 1.48-20.12] and those with retinopathy alone were 2.5 times as likely (95% CI: 1.19-5.15). Eighty patients with IDDM (40 males, 40 females; age: 47 +/- 17 years; duration of diabetes: 20 +/- 15 years), had retinal photography performed to determine the association between the severity of retinopathy and prorenin values. Retinopathy was more severe in patients with retinopathy and albuminuria than in those with retinopathy alone (p < 0.002). When the prorenin values of patients with more marked retinopathy (eye grade greater than 3) were compared, prorenin values of those with retinopathy and albuminuria were greater than those of patients with retinopathy alone [269 (139-1406) versus 91 (41-273) ng/mL/h: geometric mean (range); p < 0.05]. Furthermore, when patients without albuminuria were considered, there was no significant difference between the prorenin levels of patients with more severe retinopathy (eye grade >3) when compared to patients with lesser degrees of retinopathy [91 (41-273) versus 69 (23-375). In patients with microvascular complications, prorenin values were independently predicted by albuminuria (p < 0.0001) and diastolic blood pressure (p < 0.02) but not the severity of retinopathy. In conclusion, prorenin values are significantly associated with the presence of microvascular complications in patients with IDDM. The association with albuminuria may be stronger than the association with retinopathy.

alpha-conotoxin EpI, a novel sulfated peptide from Conus episcopatus that selectively targets neuronal nicotinic acetylcholine receptors

We have isolated and characterized alpha-conotoxin EpI, a novel sulfated peptide from the venom of the molluscivorous snail, Conus episcopatus. The peptide was classified as an alpha-conotoxin based on sequence, disulfide connectivity, and pharmacological target. EpI has homology to sequences of previously described alpha-conotoxins, particularly PnIA, PnIB, and ImI. However, EpI differs from previously reported conotoxins in that it has a sulfotyrosine residue, identified by amino acid analysis and mass spectrometry. Native EpI was shown to coelute with synthetic EpI. The peptide sequence is consistent with most, but not all, recognized criteria for predicting tyrosine sulfation sites in proteins and peptides. The activities of synthetic EpI and its unsulfated analogue [Tyr15]EpI were similar. Both peptides caused competitive inhibition of nicotine action on bovine adrenal chromaffin cells (neuronal nicotinic ACh receptors) but had no effect on the rat phrenic nerve-diaphragm (muscle nicotinic ACh receptors). Both EpI and [Tyr15]EpI partly inhibited acetylcholine-evoked currents in isolated parasympathetic neurons of rat intracardiac ganglia. These results indicate that EpI and [Tyr15]EpI selectively inhibit alpha3beta2 and alpha3 beta4 nicotinic acetylcholine receptors.

Analysis of the orthopedic content in an occupational therapy curriculum from a clinical reasoning perspective

OBJECTIVES

Recent studies have suggested that occupational therapists working with adults with physical disabilities do not use narrative reasoning in practice as much as they use procedural reasoning. This focus on procedural reasoning may be partially shaped by the occupational therapy educational process. The purpose of this analysis was to see whether one accredited occupational therapy curriculum was promoting narrative reasoning relative to its information on adult orthopedics.

METHOD

An accredited occupational therapy undergraduate and certificate curriculum was analyzed from both student and faculty perspectives to see what types of clinical reasoning were most emphasized relative to treatment of adults with orthopedic injuries. The student analysis, done by a senior as part of an independent study, looked at the clinical reasoning content of journal articles, an occupational therapy textbook, and occupational therapy lectures relative to adult orthopedic injuries. The faculty analysis, part of a curriculum revision process and independent of the student analysis, looked at the clinical reasoning content of all courses in the curriculum.

RESULTS

The student and faculty analyses concurred that although narrative reasoning is taught in this curriculum, narrative reasoning concepts are not well integrated into the adult physical dysfunction course that deals with adult orthopedic injuries.

CONCLUSION

Occupational therapy educators may not be integrating narrative reasoning into more procedurally oriented physical dysfunction courses as fully as possible and may, therefore, be fostering procedurally oriented practice in physical dysfunction settings. Curricula evaluations, like the one described in this article, can be a mechanism for examining the types of clinical reasoning emphasized in a given curriculum for a given diagnostic group.

Identification of a thyroid hormone response element in the mouse myogenin gene: characterization of the thyroid hormone and retinoid X receptor heterodimeric binding site

Thyroid hormones are positive regulators of muscle development in vivo. Triiodo-L-thyronine (T3) treatment of myogenic cell lines results in the precocious expression of myogenin, a muscle specific, helix-loop-helix factor that can trans-activate muscle specific gene expression (G. Carnac et al., Mol. Endocrinol., 6: 1185-1194, 1992). We have identified a T3 response element (TRE) in the mouse myogenin (MM) promoter between nucleotide positions -526 and -494 (5' GTGGTAGGTCTTTAGGGGTCTCATGGGACTGACA 3'). This sequence conferred appropriate hormonal regulation to an enhancerless SV40 promoter. Electrophoretic mobility shift analysis experiments showed that thyroid hormone receptor alpha (TR alpha) and retinoid X receptor alpha (RXR alpha) formed a heterodimeric complex on the MM TRE that was specifically competed by classical TREs and not by other response elements. Analyses of this heterodimer with a battery of steroid hormone response elements indicated that the complex was efficiently competed by a direct repeat of the AGGTCA motif separated by 4 nucleotides, as predicted by the 3-4-5 rule. Electrophoretic mobility shift analysis experiments showed that the myogenin, growth hormone, and myosin heavy chain TREs interacted with an identical nuclear factor(s) in muscle cells that was constitutively expressed during myogenesis. Mutagenesis of the MM TRE indicated that the sequence of the direct repeats (AGGTCA) and the 4-nucleotide gap were necessary for efficient binding to the TR alpha/RXR alpha heterodimeric complex. In conclusion, our data suggest that the MM TRE is a target for direct cross-talk between two different hormonal signals (T3 and 9-cis-retinoic acid) at the receptor level.(ABSTRACT TRUNCATED AT 250 WORDS)

The nucleotidase of Boophilus microplus and its relationship to enzymes from the rat and Escherichia coli

Boophilus microplus contains a nucleotidase-like enzyme which is able to hydrolyze a range of nucleoside 5'-mono-, di- and triphosphates to the nucleoside. Its relationship to several other nucleotide hydrolyzing enzymes has been explored. Limited peptide sequencing shows similarities to both mammalian nucleotidases and the Escherichia coli uridine diphosphate sugar hydrolase. The tick enzyme also hydrolyzes UDP-glucose, though by a mechanism different to that of the bacterial enzyme. On the other hand, it resembles the mammalian nucleotidases in that there is evidence that it is attached to the cell membrane by a glycosyl-phosphatidylinositol (GPI) anchor.

Hand infections in hospitalized patients

Two hundred hospital admissions for hand infections are reviewed with regard to the causes of infection, modes of effective therapy and causes of residual impairment. Patients with human bite injuries and those who delayed seeking treatment most frequently had severe injuries. Appropriate antibiotics and prompt surgical therapy of hand abscesses are essential.

Psychological stress, ego defenses, and cortisol production in children hospitalized for elective surgery

This study was designed to investigate the relationship between the effectiveness of coping mechanisms and physiological indicators of distress in children faced with the experience of hospitalization and surgery. Twenty-five children between the ages of 7 and 11 were studied in the out-patient department, 2 weeks before surgery, and again during their hospital stay. Effectiveness of defenses and defense style was measured by a clinical interview and by the Rorschach test. Cortisol production rates were measured by the analysis of 24-hour urine collections at home and again in the hospital. Ward adjustment was also rated by a ward questionnaire. The results indicated no relationship between defense effectiveness and cortisol production rates in the out-patient department and an inverse relationship between cortisol production and defense effectiveness under the stress of hospitalization. Defense style was found to correlate with coping under stress. Four different groups of children emerged, suggesting four different types of reaction to the hospital experience.