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PubMed1994

Teachers' perceptions of maladaptive behaviour in Lebanese refugee children.

Research on the psychological status of children who are refugees from war has led to varying results. Children from war conditions or who have been subject to evacuation have been shown to have relatively low levels of disturbed behaviour, have internalising symptoms of anxiety or depression, display behaviour with aggressive features, and suffer slight psychological disturbance, depending on their caretakers' response to the stressful experience. Based on the contrasting evidence and observations within an inner Melbourne Muslim school, this study aimed to determine whether more behaviour problems existed in Muslim children from Lebanese families. Compared with other war refugee Muslim immigrant children, Lebanese children were not found to be more aggressive, but were more anxious. Lebanese males displayed more inattentive behaviour at school than non-Lebanese males. Sex differences were found in adaptive functioning within Lebanese and non-Lebanese groups. Differences in school performance and adaptive functioning were found between Lebanese and normative samples when males and females were analysed separately. These results are discussed in the context of teacher expectations and perceptions of culturally acceptable behaviour.

Adaptation, Psychological↗
PubMed2004

Site and extent of digestion and amino acid flow to the small intestine in beef cattle consuming limited amounts of forage.

Eight Angus x Gelbvieh heifers (445 +/- 74.5 kg) fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square double double-crossover designed experiment to assess the effect of restricted forage intake on site and extent of digestion and flow of essential AA amino acids to the small intestine. Heifers were fed chopped (2.54 cm) bromegrass hay (9.2% CP, 64% NDF on an OM basis) at one of four percentages of maintenance (30, 60, 90, and 120%). Experimental periods were 21 d in length, with 17 d of adaptation followed by 4 d of intensive sample collection, after which maintenance requirements and subsequent level of intake were adjusted for BW change. True ruminal OM, NDF, and N digestion (g/d) decreased linearly (P < 0.001) with decreasing forage intake. When expressed as a percentage of OM intake, true ruminal OM and N digestibility were not affected (P = 0.23 to 0.87), whereas ruminal NDF digestibility tended to increase (P = 0.09) as forage intake decreased. Total and microbial essential amino acid flow to the duodenum decreased linearly (P = 0.001) from 496.1 to 132.1 g/d and 329.1 to 96.0 g/d, as intake decreased from 120 to 30% of maintenance intake, respectively. Although the profile of individual essential amino acids in duodenal digesta (P = 0.001 to 0.07) and isolated ruminal microbes differed (P = 0.001 to 0.09) across treatment, the greatest difference noted for total and microbial essential amino acid profile was only 0.3 percentage units. Because total and microbial flow of essential amino acids to the small intestine decreased as OM intake decreased, but true ruminal degradability of individual essential amino acids (P = 0.17 to 0.99) and digesta essential amino acid profile were comparable across treatments, total essential amino acid supply to the small intestine was predicted using OM intake as the independent variable. The resulting simple linear regression equation was: total essential amino acid flow = (0.055 x OM intake) + 1.546 (r2 = 0.91). The model developed in this experiment accounted for more of the variation in the data set than the current beef cattle NRC model, which under-predicted total flow of essential amino acids to the duodenum. The prediction equation developed herein can be used to estimate the supply of essential amino acids reaching the small intestine when formulating supplements to compensate for potential amino acid deficiencies resulting from restricted forage intake.

Adaptation, Physiological↗
PubMed2006

Maculopathy due to the R345W substitution in fibulin-3: distinct clinical features, disease variability, and extent of retinal dysfunction.

PURPOSE: To determine (1) clinical features that distinguish maculopathy due to the R345W substitution in fibulin-3 from other forms of inherited or early-onset drusen, (2) the phenotypic variability, and (3) the extent of retinal disease in those with a positive molecular diagnosis. METHODS: Affected individuals underwent ophthalmic examination, digital color fundus photography, fundus autofluorescence (AF) imaging, and psychophysical testing with automated photopic and dark-adapted perimetry and fine matrix mapping. Blood samples were taken for DNA extraction and screening for the R345W mutation in fibulin-3. Patients were subsequently divided into mutation-positive and -negative groups, to compare the identified phenotypic findings in these two sets of subjects. RESULTS: Twenty-nine subjects from 19 families were ascertained with inherited or early-onset drusen. Twenty-four (83%) subjects from 15 families were found to harbor the R345W fibulin-3 mutation. Peripapillary deposition and a radial distribution of macular drusen were consistent, distinguishing signs in the mutation-positive group. Subretinal neovascular membrane (SRNVM) was a rare occurrence, affecting only 1 of 48 eyes, whereas hyperpigmentation and atrophy of the retinal pigment epithelium (RPE) were common in older mutation-positive patients. Increased AF corresponding to the drusen was detected in both the mutation-positive and -negative groups. The phenotype in the group of patients positive for the R345W mutation was extremely variable, with evidence of interocular, intrafamilial, and interfamilial variability in visual loss, natural history, ophthalmoscopic findings, autofluorescence imaging, and psychophysical data. The novel finding of nonpenetrance was observed in a 62-year-old asymptomatic, mutation-positive man. The findings from detailed perimetry performed on a subset of subjects were consistent with the presence of widespread retinal dysfunction not isolated to the macula. CONCLUSIONS: Marked inter- and intrafamilial variation associated with the fibulin-3 R345W mutation in terms of retinal appearance, severity, progression, and nonpenetrance were identified. It was noted that SRNVM is a rare occurrence in R345W fibulin-3 maculopathy. These findings are helpful for advice regarding prognosis and for genetic counseling. The findings established that the presence of peripapillary deposit is highly likely to indicate that a patient carries the R345W mutation.

Adult↗
PubMedDate not supplied

Rapid, sensitive micro blood lead analysis: a mass screening technique for lead poisoning.

A rapid micro blood lead method is described. Analyses were performed on 20-microL blood samples spotted on filter paper, collected in graduated heparinized capillary glass tubes following finger pricks. The samples were air dried on filter paper and mailed to the laboratory in glassine envelopes. These samples stored on filter paper are stable for at least six months. The blood spots were punched out with a 1/4-in. diameter hole punch and placed in Delves cups for insertion into the flame atomic absorption spectrometer. The innovation of this method is that an ashing step precedes sample introduction into the flame. In phase 1, the Delves cup with the blood sample is pushed 1 cm from the flame. The heat is sufficient for the filter paper to ignite and burn to completion in seconds. After the smoke dissipates, the samples are introduced into the flame for lead analysis, reading the signal at 283.3 nm. The entire analysis time is 15 s per sample. The limit of quantitation is 4 micrograms/dL of lead. Standard curves were linear from 4-42 micrograms/dL. The average CV for this range is 8.2%. The comparative study between the MIBK extraction method and this method yielded a correlation coefficient r = .99 (n = 55). The method is fast, practical, economical, and easily adaptable to screen large numbers of micro lead samples.

Humans↗
PubMed2003

Adaptation in the env gene of HIV-1 and evolutionary theories of disease progression.

The exact mechanisms by which HIV overwhelms the immune system remain poorly understood. Among the several explanations of HIV disease progression, most include adaptation of the viral genome to the host environment as a causal factor. Therefore, quantifying the rate and pattern of adaptive evolution within infected patients is critical to understanding the development of AIDS. Using sequence data from infected individuals sampled at multiple time points, I estimate the within-host adaptation rate of the HIV-1 env gene for viral populations from 50 different patients. I find that, averaging across patients, one adaptive substitution occurs every 3.3 months. Also, one adaptive mutation is driven to a high frequency (>50% but <100%) every 2.5 months. Taken together, such adaptive events occur once every 25 viral generations, which is the fastest adaptation rate ever recorded for a single protein-coding gene. Within the entire env gene, I estimate that a majority ( approximately 55%) of both nonsynonymous substitutions and high-frequency polymorphisms are adaptive. Further, in the C2-V5 region of env, I find that patients with longer asymptomatic periods have virus populations with higher adaptation rates, corroborating the notion that a broad, strong immune response against epitopes in the env gene product leads to longer asymptomatic periods. I conclude by discussing the distribution of nonsynonymous changes over the env gene.

Adult↗
PubMed2002

T-cell subset counting and the fight against AIDS: reflections over a 20-year struggle.

The story of T-lymphocyte subset immunophenotyping technology is reviewed on the occasion of the 20th anniversary of CD4 T-cell enumeration. Over time, immunophenotyping has evolved into precise, reliable, but complicated and expensive technology requiring fresh blood samples. The gating technologies that were universally adapted for clinical flow cytometry for the past decade relied on rapidly deteriorating morphological scatter characteristics of leukocytes. This special issue dedicated to CD4 T-cell enumeration features most of the available new options that will have a significant impact on how this technology will be implemented within the first decade of the 21st century. In a series of original publications, including the new NIH guideline for T-cell subset enumeration, contemporary gating protocols that use immunologically logical parameters are presented as part of the more reliable and affordable immunophenotyping alternative. Some of the improvements addressed here include the costs of the assays and the capacity to monitor interlaboratory and intralaboratory performances. It is clear that an effective attack on the human immunodeficiency virus (HIV) epidemic has to embrace resource-poor regions. Reducing the cost of the assay while improving reliability and durability is a move in the right direction.

Acquired Immunodeficiency Syndrome↗
PubMed2002

Efficiency of DNA pooling to estimate joint allele frequencies and measure linkage disequilibrium.

Pooling DNA samples can yield efficient estimates of the prevalence of genetic variants. We extend methods of analyzing pooled DNA samples to estimate the joint prevalence of variants at two or more loci. If one has a sample from the general population, one can adapt the method for joint prevalence estimation to estimate allele frequencies and D, the measure of linkage disequilibrium. The parameter D is fundamental in population genetics and in determining the power of association studies. In addition, joint allelic prevalences can be used in case-control studies to estimate the relative risks of disease from joint exposures to the genetic variants. Our methods allow for imperfect assay sensitivity and specificity. The expected savings in numbers of assays required when pooling is utilized compared to individual testing are quantified.

Alleles↗
PubMed2000

Omega-space adaptive acquisition technique for magnetic resonance imaging from projections.

An omega-space adaptive acquisition technique for MRI from projections is presented. It is based on the evaluation of the information content of a set composed of four initial projections, measured at angles 0 degrees, 45 degrees, 90 degrees, and 135 degrees, followed by the selection of new angles where the information content is maximum. An entropy function is defined on the power spectrum of the projections that is useful for evaluating the information content of each projection. The method makes it possible to reduce the total acquisition time with little degradation of the reconstructed image and it adapts to the arbitrary shape of the sample. For this reason, it can be particularly useful in those applications where acquisition from projections is strongly recommended to save acquisition time, such as functional MRI, imaging of species having very short T(2), or angiography. The method has been tested both on simulated data and on experimental data collected by a commercial MRI apparatus. The method has also been compared to the regular acquisition method, that is, the standard acquisition method in MRI from projections.

Image Processing, Computer-Assisted↗
PubMed2002

A new in vitro model to study endothelial injury.

BACKGROUND: Endothelial dysfunction or "endothelialitis" is a prominent feature in several disease states ranging from atherosclerosis to transplant rejection. This dysfunction is also caused by drugs such as cyclosporin A (CyA) and leads to allograft vasculopathy and eventual graft loss. Despite the frequency and importance of this injury, there is no model to study the morphological effects of endothelial injury and dysfunction in vitro. METHODS: We utilized a model in which mouse endothelial cells (SVEC 4-10) can be induced to form capillary tubes by culturing on a laminin-rich matrix (Matrigel). In this morphological model of endothelial cell function, we studied the effect of varying doses of CyA on two parameters of tube formation: initiation of tube formation and disruption of mature capillary tubes. As a positive control we used IFN-gamma, which inhibited capillary tube formation. We developed this assay in 96-well culture plates to test several samples simultaneously. RESULTS: The assay could be adapted to a 96-well format by optimizing the cell density. Endothelial dysfunction was seen when the endothelial cells were incubated with cyclosporin A, which affected both morphological parameters of tube formation. At higher doses (2-20 microg/ml) CyA both inhibited capillary tube formation and disrupted mature capillary tubes. At lower doses CyA only inhibited the initiation of tube formation; it did not disrupt mature capillary tubes. IL-2 (400-1000 pg/ml) and IFN-gamma (10-400 pg/ml) inhibited initiation of tube formation but did not disrupt mature capillary tubes. None of these agents, including high doses of CyA, impaired endothelial cell viability. CONCLUSION: CyA-induced endothelial dysfunction can be modeled in vitro by this novel morphological assay of capillary tube formation. This assay can discern mild and severe degrees of endothelial dysfunction. The different effects of low and high levels of CyA on capillary tube formation imply that similar dysfunction in vivo may be responsible for allograft vasculopathy caused by CyA. This novel model can also be utilized to study other forms of vasculitis.

Animals↗
PubMed1986

Specific detection and determination of azide in wine.

In view of false-positive results obtained with the azide-detection method based on complex-formation with ferric ions, a specific liquid-chromatographic azide determination was adapted for the analyses of wine. The samples are distilled free of alcohol under alkaline conditions and acidified, and a new distillate is collected. The distillate is buffered (pH 4.7) and treated with 3,5-dinitrobenzoylchloride and the derivative thus formed is detected and determined by HPLC.

Azides↗
PubMed1975

Adaptation of the mandible in children with adenoids.

In a sample of lateral x-ray cephalograms of children with obstructing adenoids, a dorsal rotation of the mandibular ramus was found to characterize the facial skeleton. The mandibular body and the condylar process were not correspondingly rotated. The findings suggest that dorsal rotation of the mandible occurring in association with various pathologic processes could always be primarily a response to an encroachment of the pharyngeal space. A possible involvement of the clivus region, to a minor degree, was also indicated. The need for "tailormade" cephalometric methods in studies of specific problems is stressed.

Adenoidectomy↗
PubMed1983

High sensitivity method for fluorofore detection in gradient polyacrylamide slab gels through excitation by laser light: application to glycoproteins stained with concanavalin A-fluorescein isothiocyanate.

An easy-to-assemble apparatus for the laser-light excitation of fluorofores in polyacrylamide gels is described. The assemblage is made up of a continuous-wave ion-argon laser with adjustable power output, a beam diffuser, appropriate filters to block excitation light, and a photographic camera. With this setup a minimum 20-fold increase of sensitivity was obtained for fluorofore detection in polyacrylamide gels as compared to the more conventional uv-light excitation using a commercial preparation of Con A-FITC (concanavalin A-fluorescein isothiocyanate) as reference molecule in the gel. The same apparatus, used to analyze the Con A-positive glycoproteins contained in serum Cohn fraction IV separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, showed a number of fluorescent components in a wide range of relative intensities while uv-light excitation showed none. Acrylamide concentration in the gel is critical, since a working limit of between 10 and 12% has been found, above which the diffusion of Con A-FITC in the gel, necessary to label glycoprotein bands, is hampered. The system described here also permits the optimization of detection of minor components not otherwise observable by conventional light excitation, because light power, angle of incidence, and beam divergence can be adapted to analyze specific areas of the sample gel.

Concanavalin A↗
PubMed1988

Bioflavonoid effects on in vitro cultures of Plasmodium falciparum. Inhibition of permeation pathways induced in the host cell membrane by the intraerythrocytic parasite.

A series of polyhydroxyphenol glycosides including bioflavonoid-glycosides structurally-related to phlorizin (phloretin-2-beta-glucoside) have been tested for their capacity to inhibit permeation pathways induced in red cell membranes by intraerythrocytic Plasmodium falciparum parasites. The permeation through these pathways has been assessed on trophozoites by sorbitol-mediated hemolysis based on a novel technique of high sensitivity and time resolution which has been adapted for handling relatively large number of samples in microtitration plates. Changes in the number of phenolic groups and to a lesser extent changes in the relative position of these groups had a substantial effect on the inhibitory efficacy of the phlorizin derivatives. Diglycoside derivatives were completely ineffective while various monoglycoside derivatives had comparable effects. Structure-activity relationship (SAR) studies of 3-monosubstituted phlorizin derivatives indicate that the inhibitory potency varied considerably with the chemical nature of the group substituted in the 3 position. Inhibition correlated best (r = 0.90) with Hammett's constant, underscoring the role of the electron withdrawing capacity of the chemical groups substituted on the hydroxydihydrochalcone moiety. On the other hand, substitution with lipophilic groups had either minimal effects or reduced the inhibitory power of the derivatives. Inhibition of transport correlated with the inhibition of intraerythrocytic parasite growth and provides a basis for new therapeutic approaches of malaria. Based on the SAR studies, a 3-isothiocyano analog of phlorizin was synthesized and shown to block irreversibly the above permeation pathways (20 microM, 10 min reaction at ambient temperature) as well as the intraerythrocytic growth of the parasite. The present study provides proof for the involvement of amino groups in red cell membrane components as controlling elements of the permeation pathways induced by the intraerythrocytic parasite. The putative groups could serve as targets for affinity labeling of the membrane components associated with the permeation function.

Animals↗
PubMed1992

Analysis of amplified T cell receptor V beta transcripts by a non-isotopic immunoassay.

We have recently described a new colorimetric DNA enzyme immunoassay (DEIA) for detecting specific hybrids of complementary nucleic acids. This technology is based on an antibody that selectively recognizes double, but not single stranded DNA and therefore reveals the hybridization event independently from the DNA sequences. Most importantly, the test has an ELISA format and is very rapid and convenient for processing large numbers of samples. In the present report we have adapted this method to reveal the specificity of amplified T cell receptor V beta transcripts. V beta genes were amplified by polymerase chain reaction, using family specific primers and the specificity of the amplified products was determined by Southern blot and by DEIA. Our data demonstrate that DEIA had the same degree of sensitivity and specificity of conventional Southern hybridization. The possibility of analyzing amplified products with the simplicity of a conventional immunoassay should greatly facilitate the analysis of complex multigenic systems such as the T cell receptor and the immunoglobulin repertoire.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1989

Adaptive response of human lymphocytes to low-level radiation from radioisotopes or X-rays.

Human peripheral blood lymphocytes stimulated in vitro were exposed to low level irradiation ('adaptive dose') from radioisotopes ([3H]dThd, [14C]dThd, HTO and 32P). After 50 h in culture, they were irradiated with 50 rad of X-rays ('challenge dose') and fixed 3 h later. In another series, the lymphocytes received an adaptive dose of 5 rad of X-rays at 32 h after stimulation and a challenge dose of 150 rad at 48 h; the cells were fixed at 54 h. In cells that received both the adaptive and challenge doses, the frequencies of chromosomal aberrations (chromatid and isochromatid deletions) were lower than expected on the basis of additivity of the effects of the individual treatments. These results support those published from Wolff's laboratory in showing that human lymphocytes can become 'adapted' by prior exposure to low level irradiation so that they become less sensitive to the chromosome-breaking effects of X-rays delivered subsequently. The magnitude of reduction in frequencies in the 'adapted' cells, however, varied between the blood samples from different donors.

Carbon Radioisotopes↗
PubMed1983

A serological and biochemical study of new field isolates of foot-and-mouth disease virus type A in Peru, 1975 to 1981.

Three foot-and-mouth disease virus type A isolates recovered from field outbreaks in the Department of San Martin, Peru, during the period 1975 to 1981 were compared with each other, and the South American vaccine strains A24 and A27, by complement fixation (CF), virus neutralization (VN) and polyacrylamide gel electrophoresis (PAGE). Complement fixation and VN tests gave comparable results distinguishing the field isolates from each other and from the vaccine strains. Analysis of the structural polypeptides by PAGE also showed clear differences between all the viruses examined. Samples from tissue culture passaged and mouse adapted strains of one of the field isolates gave identical patterns in PAGE, but differences were observed in the polypeptide pattern of the A24/BRA/55 strain and the Peru vaccine strain, which were serologically indistinguishable. Results illustrate a continued antigenic variation in an endemic area where vaccination has been used; however, asymmetric serological reactions between the A24 vaccine strain and the most recent field isolate indicated that a vaccine incorporating A24 should still give adequate protection.

Animals↗
PubMed1993

Stopped-flow photometric determination of clavulanic acid in pharmaceutical and serum samples.

The stopped-flow mixing technique was used to develop a simple, fast kinetic method for the determination of clavulanic acid by reaction with imidazole. Whereas the conventional method requires about 12-15 min for equilibrium to be reached, kinetic measurements can be made within a few seconds. The calibration graph was linear over the range 1-40 microgram ml-1 of clavulanic acid and the detection limit achieved was 0.3 microgram ml-1. The precision and selectivity of the method are reported. The results obtained by applying the proposed method to the analysis of pharmaceutical and serum samples show how easily it can be adapted for routine analyses.

Clavulanic Acid↗