Obstacles to translating the promise of nanoparticles into viable amyloid disease therapeutics.

Nanoparticles (NPs) constitute a powerful therapeutic platform with exciting prospects as potential inhibitors of amyloid-[Formula: see text] (Aß) aggregation, a process associated with Alzheimer's disease (AD). Researchers have synthesized and tested a large collection of NPs with disparate sizes, shapes, electrostatic properties and surface ligands that evoke a variety of responses on Aß aggregation. In spite of a decade of research on the NP-Aß system and many promising experimental results, NPs have failed to progress to any level of clinical trials for AD. A theoretical framework with which to approach this physical system is presented featuring two simple metrics, (1) the extent to which NPs adsorb Aß, and (2) the degree to which interaction with a NP alters Aß conformation relative to aggregation propensity. Most of our current understanding of these two interactions has been gained through experimentation, and many of these studies are reviewed herein. We also provide a potential roadmap for studies that we believe could produce viable NPs as an effective AD therapeutic platform.

Impact of phospholipid bilayer saturation on amyloid-beta protein aggregation intermediate growth: a quartz crystal microbalance analysis.

Evidence that membrane-associated amyloid aggregate growth can impart membrane damage represents one possible mechanism for the neurodegeneration associated with deposited amyloid-beta protein (Abeta) aggregates in the brains of Alzheimer's disease (AD) patients. This potential pathogenic event necessitates an understanding of the impact that cellular membrane composition may have on Abeta aggregate growth. In the current study, a quartz crystal microbalance (QCM) was employed to examine the growth of Abeta(1-40) aggregation intermediates on supported phospholipid bilayers (SPBs) assembled at the crystal surface. These surface-specific measurements illustrate that zwitterionic SPBs selectively bind aggregated but not monomeric protein, and these bound aggregates are capable of supporting nonsaturable reversible growth via monomer addition. Growth-capable Abeta(1-40) aggregation intermediates more readily bind SPBs composed of phospholipids with a greater degree of carbon saturation. Furthermore, kinetic analysis afforded by the quantitative real-time QCM measurements reveals that SPBs with greater saturation also better support the growth of bound Abeta(1-40) aggregation intermediates as a result of the slower dissociation of bound monomer rather than more efficient recognition between aggregate and monomeric protein. These findings correlate with epidemiological and experimental evidence that links increased dietary intake of polyunsaturated fatty acids to a reduced risk of AD.

Static and dynamic loading effects on temporomandibular joint disc tractional forces.

UNLABELLED: Mechanical fatigue-related degeneration of the temporomandibular joint (TMJ) disc may be promoted by tractional forces. This study tested the hypotheses that tractional forces following static loading of the TMJ disc: (1) increase with compressive strain at the start of movement, and (2) are velocity-dependent during movement. Sixty-four porcine discs received a 10-N static load via an acrylic indenter for 1 or 30 sec before cyclic movement. Physical data were recorded and analyzed by ANOVA. The results showed that compressive strain and tractional forces were largest for the start of movement following 30 sec of static loading (p

Exposure to carbon monoxide and nitrogen dioxide in enclosed ice arenas.

This article summarises the latest information on the adverse cardiorespiratory effects of exposure to carbon monoxide (CO) and nitrogen dioxide (NO(2)) in enclosed ice rinks. Sources of CO and NO(2) emissions are identified, current standards for these agents, as well as methods of controlling the emissions, dispersion, and evacuation of these toxic gases are presented. A detailed literature search involving 72 references in English and French from research conducted in North America and Europe was used. Material was from peer reviewed journals and other appropriate sources. Air pollutants such as carbon monoxide (CO), and nitrogen dioxide (NO(2)) which are present in enclosed skating facilities, may exacerbate a pre-existing pathogenic condition in those people who spend considerable time in these environments. Considering the popularity of ice hockey, short track speed skating, and figure skating, and the hundreds of hours that a sensitive person may spend each year in these environments, it would seem appropriate to seek more definitive answers to this important health problem. From the findings and conclusions of the research reviewed in this paper, 10 recommendations are listed.

Role of metastatic potential in the adhesion of human breast cancer cells to endothelial monolayers.

To gain further insight into the process of metastasis, adhesion to endothelial monolayers was compared for a nonmetastatic and a highly metastatic human breast cancer cell line. The parallel plate flow chamber was employed to quantify adhesion using an attachment assay. This assay was carried out at several physiological shear stresses both with and without endothelial TNF-alpha stimulation. At a venular shear stress of 1 dyne cm-2, the nonmetastatic cell line was more adhesive to stimulated endothelial monolayers, while no differences could be noted for resting monolayers. At a lower shear stress of 0.25 dynes cm-2, the highly metastatic cell line was more adhesive to stimulated endothelial monolayers, while the nonmetastatic cell line was more adhesive to resting monolayers. Thus, metastatic potential correlated with attachment only at low shear stresses and following endothelial stimulation. These results emphasize the importance of studying cancer cell adhesion under multiple physiological flow conditions. Furthermore, these results indicate that adhesion of these two cell lines may be controlled by two different mechanisms. Antibody blocking experiments of adhesion molecules on the endothelial cells confirmed that adhesion of the nonmetastatic cell line was mediated by E-selectin expressed on the endothelial cells and adhesion of the highly metastatic cell line was mediated by both E-selectin and VCAM-1 expressed on the endothelial cells.

Chronic ingestion of uranium in drinking water: a study of kidney bioeffects in humans.

A study was conducted of the chemical effects on the human kidney induced by the chronic ingestion of uranium in drinking water. Subjects were divided into two groups: The low-exposure group, whose drinking water was obtained from a municipal water system and contained < 1 microgram uranium/L, and the high-exposure group, whose drinking water was obtained from private drilled wells and contained uranium levels that varied from 2 to 781 micrograms/L. Years of residence varied from 1 to 33 years in the low-exposure group and from 3 to 59 years in the high-exposure group. The indicators of kidney function measured in this study included glucose, creatinine, protein, and beta 2-microglobulin (BMG). The markers for cell toxicity studied were alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), lactate dehydrogenase (LDH), and N-acetyl-beta-D-glucosaminidase (NAG). Urinary glucose was found to be significantly different and positively correlated with uranium intake for males, females, and pooled data. Increases in ALP and BMG were also observed to be correlated with uranium intake for pooled data. In contrast, the indicators for glomerular injury, creatinine and protein, were not significantly different between the two groups nor was their urinary excretion correlated to uranium intake. These results suggest that at the intakes observed in this study (0.004 microgram/kg to 9 micrograms/kg body wt), the chronic ingestion of uranium in drinking water affects kidney function and that the proximal tubule, rather than the glomerulus, is the site for this interference.

Uranyl nitrate: 28-day and 91-day toxicity studies in the Sprague-Dawley rat.

Although uranium (U) is a classic experimental nephrotoxin, there are few data on its potential long-term chemical toxicity. These studies were undertaken to derive a no-observed-adverse-effect level (NOAEL) in male and female Sprague-Dawley rats following 91-day exposure to uranium (as uranyl nitrate hexahydrate, UN) in drinking water. Following a 28-day range-finding study, five groups of 15 male and 15 female weanling rats were exposed for 91 days to UN in drinking water (0.96, 4.8, 24, 120, or 600 mg UN/L). A control group was given tap water (< 0.001 mg U/L). Daily clinical observations were recorded. Following the study, animals were euthanized and exsanguinated, and multiple hematological and biochemical parameters were determined. Necropsies were conducted, and multiple tissues were sampled for histopathological examination. The hematological and biochemical parameters were not affected in a significant exposure-related manner. Although there were qualitative and slight quantitative differences between males and females, histopathological lesions were observed in the kidney and liver, in both males and females, in all groups including the lowest exposure groups. Renal lesions of tubules (apical nuclear displacement and vesiculation, cytoplasmic vacuolation, and dilation), glomeruli (capsular sclerosis), and interstitium (reticulin sclerosis and lymphoid cuffing) were observed in the lowest exposure groups. A NOAEL was not achieved in this study, since adverse renal lesions were seen in the lowest exposed groups. A lowest-observed-adverse-effect level of 0.96 mg UN/L drinking water can be reported for both the male and the female rats (average dose equivalent 0.06 and 0.09 mg U/kg body wt/day, respectively).

Uranyl nitrate: 91-day toxicity studies in the New Zealand white rabbit.

These studies were undertaken to derive a lowest-observed-adverse-effect level (LOAEL) in the New Zealand White rabbit following a 91-day exposure to uranium (U, as uranyl nitrate hexahydrate, UN) in drinking water. Males were exposed for 91 days to UN in their drinking water (0.96, 4.8, 24, 120, or 600 mg UN/L). Subsequently, females were similarly exposed for 91 days (4.8, 24, or 600 mg UN/L). Control groups were given tap water (< 0.001 mg U/L). Regular observations were recorded, and urine was collected periodically. Four males showed evidence of Pasteurella multocida infection and were excluded from the study. Following the study, all animals were euthanized, and multiple hematological and biochemical parameters were determined. Necropsies were conducted, and histopathological examination was performed. The hematological and biochemical parameters were not affected in a significant exposure-related manner. Dose-dependent differences consisted of histopathological changes limited primarily to kidney. Changes in renal tubules were characteristic of uranium toxicity. Based on changes in the tubular nuclei, the 91-day LOAEL for males in this study is 0.96 mg UN/L drinking water. The females drank 65% more water than the males, yet appeared to be less affected by the exposure regimen, although they also developed significant tubular nuclear changes in their lowest exposure group, deriving a LOAEL of 4.8 mg UN/L. Tissue uranium residue studies suggested that pharmacokinetic parameters for the males and females differ, possibly accounting for the difference in observed sensitivity to UN. An adverse effect of P. multocida infection cannot be excluded.

Uranyl nitrate: 91-day exposure and recovery studies in the male New Zealand white rabbit.

This study was undertaken to examine the reversibility of renal injury in the male New Zealand White rabbit subsequent to a 91-day exposure to uranyl nitrate (UN) in drinking water, followed by various recovery periods. Specific pathogen-free (SPF) animals were exposed for 91 days to UN in their drinking water (24 or 600 mg UN/L). Control groups were given municipal tap water (< 0.001 mg U/L). Regular clinical observations were recorded, and urine was collected periodically. Recovery periods between the last UN exposure and termination were 0, 8, 14, 45, or 91 days. Following the study, all animals were anesthetized and terminated by exsanguination, and multiple hematological and biochemical parameters were determined. Necropsies were conducted, and histopathological examination was performed. Exposure-related histopathological changes were observed only at much higher doses than in our previous male rabbit study where non-SPF-free animals had been used. Minor increases in kidney to body weight ratios were observed in the high-dose groups following exposure and early recovery. Renal tubular injury with degenerative nuclear changes, cytoplasmic vacuolation, and tubular dilation was seen in the high-dose group, without consistent resolution even after 91 days recovery. Animals ingested approximately 33% more uranium per day in this study than did males in a comparable dose group in the previous study, yet their kidney tissue uranium residues were 30% lower. These results suggest that SPF rabbits are less sensitive to uranyl injury than the non-SPF animals. The lowest-observed-adverse-effect level is estimated to lie at or below 24 mg UN/L.

Immediate impact of thirty-two drug use prevention activities among students at continuation high schools.

Those teenagers who are unable to remain in the regular school system for reasons including substance use are transferred to a continuation high school. Generic comprehensive social-influence-drug-use-prevention-activities are less likely to be effective for use with these at risk youth. Thus, both classroom and self-instruction (main mode of instruction at continuation high schools) versions of 16 activities derived from different theoretical sources were tested and ranked on immediate outcome variables. 388 students from six continuation high schools were provided with a pretest-activity-posttest "component study" protocol. The scores on perceived quality ratings were standardized and averaged to permit easy comparisons across lessons. While yielding similar knowledge changes, students who received the health educator led activity consistently reported higher scores on perceived quality. Social influence-oriented lessons, in general, were rated of relatively low perceived quality. The present approach assisted in selection of the lessons with the greatest overall immediate impact.

Implementation and process evaluation of a student "school-as-community" group. A component of a school-based drug abuse prevention program.

Little documentation exists regarding the functioning of formalized adolescent groups as drug abuse prevention agents. Two studies are described that were conducted at high schools whose students are at high risk for drug abuse. Twenty-one schools were randomly assigned to one of three conditions: (a) standard care, (b) classroom drug abuse education only, or (c) classroom plus school-as-community. Results of the first study indicated that the school-as-community component--which involved weekly meetings and periodic events at seven schools--was implemented as planned, drug abused focused, and perceived as productive in discouraging drug abuse. In the second study, staff in the classroom plus school-as-community condition self-reported involvement in the greatest number of community activities across the school year, compared with staff from the other two conditions. These two studies support the feasibility of formalized groups of high-risk youth to promote drug-free events.

Detection of a R173W mutation in the porphobilinogen deaminase gene in the Nova Scotian "foreign Protestant" population with acute intermittent porphyria: a founder effect.

OBJECTIVES: Acute intermittent porphyria (AIP) is caused by mutations in the porphobilinogen deaminase (PBGD) gene that disrupt the function of the enzyme. Many mutations that lead to decreased PBGD activity have been described. An Arg to Trp substitution at codon 173 (CGG-->TGG in exon 10) and designated R173W, which leads to a CRIM-negative phenotype, has been reported in Swedish, Finnish, Scottish, and South African kindreds, and in a Nova Scotian proband with fatal AIP. In this work, we investigated the presence of this mutation in a Nova Scotian patient population presenting with AIP. DESIGN AND METHODS: Single-strand conformation polymorphism analysis and DNA sequencing by TA cloning and Sanger's dideoxy chain termination method, were used to confirm the maternal transmission of this mutation to the proband. The mutation also eliminates an Ncil (also Mspl) endonuclease restriction site, which allows for detection of the mutant allele by polymerase chain reaction amplification and restriction enzyme digestion. RESULTS: The family of the Nova Scotian proband and four other AIP kindreds showed the presence of the same mutation. These five families are descendants of German, Swiss, and French immigrants historically known as the "Foreign Protestants," who were recruited to Nova Scotia in the 1750s. CONCLUSION: In all these families, descent from one couple that settled in Nova Scotia in 1751 has been identified by genealogy research, consistent with a founder effect within this population. This is the first identified mutation in PBGD causing AIP that has been linked to a founder effect in descendants of an immigrant population to North America, and which could be traced to such a distant background, similar to the South African variegate porphyria mutation.

Continuation high schools: youth at risk for drug abuse.

Students at alternative high schools may be at substantial risk for drug abuse. The present article provides a general overview of the drug use-related context of continuation high schools in southern California. A total of 144 students and ninety-six staff were interviewed from twenty continuation high schools. The interview data revealed that continuation school students show high levels of substance use. However, only 20 percent of the students report that they received any drug abuse prevention programming. Also, students at continuation high schools aspired to a productive life after high school including continued education. Thus, these youth may still be amenable to preventive educational interventions which deter them from drug use and help them to fulfill their future goals.

Relief of the photosensitivity of erythropoietic protoporphyria by pyridoxine.

Twenty-five years ago the use of pyridoxine was described for the treatment of photosensitivity eruptions. We report two cases of erythropoietic protoporphyria, which were only moderately responsive to beta-carotene and sunscreens, whereas the use of pyridoxine has been associated with a marked reduction in photosensitivity without evidence of adverse effects. Regarding the mechanism of action, we can only speculate that pyridoxine could be mediated by increased endogenous nicotinamide production. We believe that our results warrant therapeutic trial of oral pyridoxine in patients with unrelieved photosensitivity as a result of erythropoietic protoporphyria.

Comparison of serum sodium and chloride results for Flame IV-Auto Analyzer II, SMAC, Ektachem 400, and Nova 4 clinical analyzer systems.

We determined serum Na+ and Cl- results using Technicon's Flame IV-Auto Analyzer II (FLIV/AAII) system and Kodak's Ektachem 400 clinical analyzer. Our objective was to determine whether Na+ and Cl- results from these analyzers were sufficiently similar to report to clinicians without reference to the system used for the determination. Method precision of the two systems for Na+ results was comparable; whereas Ektachem 400 Cl- results were more imprecise than those determined using the FLIV/AAII, Ektachem Na+ results showed lower correlation with the FLIV/AAII (r = 0.890) and Cl- results were more highly correlated (r = 0.960). When Kodak's newly developed equi-transferant electrolyte reference fluid (ETRF) was used with generation 4 Na+ slides and generation 1 Cl- slides the largest difference observed was 7.0 mmol/L for both Na+ and Cl- results. Using Kodak calibrators and the manufacturer's operational conditions for the Ektachem 400, we observed that a considerable number of sample results for both Na+ and Cl- did not agree within 3.0 mmol/L of the FLIV/AAII values. To corroborate our finding, we also analyzed serum Na+ and Cl- using a Technicon Sequential Multiple Analyzer + Computer (SMAC) system and a Nova 4 + 4 Clinical Analyzer (Nova). We conclude that flame emission systems and direct ion specific electrode systems do not yield comparable Na+ and Cl- results even when total protein and triglyceride concentrations of the samples are within reference ranges.(ABSTRACT TRUNCATED AT 250 WORDS)

Pitfalls in the initial diagnosis of tyrosinemia: three case reports and a review of the literature.

The tyrosinemias are a complex and heterogeneous group of disorders in tyrosine catabolism that embrace a wide spectrum of clinical conditions, ranging from the benign neonatal variety to the severe hepatorenal form. Readily available diagnostic tests are too insensitive to distinguish between these variants, and more definitive but technically difficult tests can be performed rapidly in only a few centres. Effective management may therefore be compromised, due to the inability of obtaining a working diagnosis quickly. This report describes difficulties encountered with conventional testing in three patients. Analysis of whole blood delta-aminolevulinic acid dehydratase activity and determination of urinary inhibition activity against the enzyme were found to be rapid and reliable screening tests for hepatorenal or type I hereditary tyrosinemia. These procedures are recommended in the initial evaluation of undifferentiated tyrosinemic states.

A fatality involving clomipramine.

A fatality following ingestion of the tricyclic antidepressant clomipramine (Anafranil), alprazolam (Xanax), and ethyl alcohol is described. Clomipramine and N-desmethylclomipramine were quantitated by high performance liquid chromatography and alprazolam by gas liquid chromatography. Concentrations of clomipramine and N-desmethylclomipramine were: in blood--0.84 and 1.4 mg/L; in urine--0.56 and 0.62 mg/L. Alprazolam concentration in blood was 0.069 mg/L. Ethyl alcohol was measured by headspace gas chromatography and found to be 375, 385, and 435 mg/dL in blood, urine, and vitreous humor, respectively. These findings are compared to previous reports of clomipramine related fatalities and alprazolam toxicity combined with ethyl alcohol.

Comparison of precision for the Kodak Ektachem 400 and Technicon AutoAnalyzer II creatinine methods.

We have evaluated the precision of the Ektachem 400 thin film enzymic creatinine method and compared it to that obtained for an AutoAnalyzer II (AAII) picric acid procedure. The results of the study show that the Ektachem method yields imprecise creatinine values over the low concentration range (40-240 mumol/L). Run-to-run precision estimates at a creatinine concentration of 225 mumol/L (by AAII) yielded CV's of 9.3 and 2.6% for the Ektachem 400 and AutoAnalyzer II methods respectively. The Ektachem 400 yielded imprecise creatinine determinations even when sample ammonia concentrations were less than 150 mumol/L. Patient samples analyzed by the AAII and Ektachem 400 over the creatinine range 40-900 mumol/L were highly correlated (r = 0.994). The correlation (r = 0.779) was low for patient data over the creatinine range 40-160 mumol/L. Creatinine results determined by the Ektachem 400 showed improved precision when samples were evaluated in triplicate using Kodak's latest (No. 8.5) software revision.