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Biomedical subjects

J E Roberts

Publications and source records attributed to J E Roberts.

At least 73 records · Page 4Linked to original sources
PubMed1995

FM amplification for enhancement of conversational discourse skills: case study.

The purpose of this single-subject pilot study was to examine the efficacy of FM amplification for enhancing the discourse skills of a 4-year-old girl with a history of speech-language impairments, otitis media with effusion (OME), and motoric delays. Over a period of several weeks, language treatment sessions were conducted with and without FM amplification, in a classroom setting. Sessions were videotaped and analyzed for the appropriateness and effectiveness of the subject's conversational turns during sessions with amplification and with no amplification. Although the number of sessions was small, more appropriate and effective conversational turns occurred during sessions with amplification.

Amplifiers, Electronic↗
PubMed1995

Photoreactivity of biologically active compounds. VIII. Photosensitized polymerization of lens proteins by antimalarial drugs in vitro.

The drugs commonly used in the treatment of malaria are photochemically unstable. Several of these compounds cause dermal and ocular toxic reactions that may be light induced. The in vitro photopolymerization of calf lens proteins in the presence of antimalarial drugs was studied as part of a screening of the photochemical properties and phototoxic capabilities of these compounds. The pseudo-first-order rate constant for the reaction was calculated, and related to the amount of light absorbed by the compounds in order to determine the relative photosensitizing effect of each drug. The reaction mechanisms were evaluated by adding a variety of quenchers to the reaction medium during irradiation. Based on the results obtained in this study and previous knowledge about the pharmacokinetic behavior of these compounds, several of the drugs investigated have to be considered as potential photosensitizers in the human lens, the retina and the skin.

Animals↗
PubMed1994

Otitis media in early childhood and patterns of intellectual development and later academic performance.

Examined long-term associations between otitis media with effusion (OME) during the first 5 years of life and patterns of intellectual development from 3-8 years and academic performance after 3 years in elementary school. Fifty-five socioeconomically disadvantaged children were studied prospectively between birth and 8 years. OME history was routinely documented from birth through 5 years during well and illness periods. Two aspects of children's OME experience were examined in relation to developmental outcomes: timing (whether the OME occurred during infancy vs. preschool years) and nature (whether the OME tended to be recurrent or persistent). Although OME during the first 5 years of life was not related to patterns of overall intellectual development between ages 3 and 8 years, recurrent OME during infancy was a negative predictor of teachers' ratings of children's task orientation/distractibility in the classroom. Results are interpreted in the context of the growing OME literature.

Achievement↗
PubMed1994

A double-blind study of cysteine photoprotection in erythropoietic protoporphyria.

In an open trial in 9 patients, we found that the ingestion of 500 mg of cysteine twice a day could prevent or lessen the photosensitivity associated with erythropoietic protoporphyria (EPP). We report here the results of a double-blind cross-over design trial in 16 patients. Patients with EPP were randomized into two groups, one that received 500 mg twice daily of cysteine during the first period and then placebo during the second period, and the second that received placebo first and then cysteine. Each drug ingestion period lasted 8 weeks, and there was a 1 week wash-out period between them. Patients were seen before the first period, at the end of the first period and at the end of the second period for phototesting, an objective method of assessing treatment efficacy, and for blood tests to monitor cysteine safety. The subjects also were asked to keep light-exposure diaries, a subjective method of assessing efficacy. We found that cysteine significantly prolonged the time it took to develop erythema by phototest, objectively demonstrating efficacy. In addition, analysis of patients' diaries showed that cysteine ingestion significantly increased the length of sun exposure it took to develop symptoms of photosensitivity. We conclude that cysteine ingestion may be an effective therapy in the prevention of photosensitivity associated with EPP.

Adolescent↗
PubMed1994

Communication among preschoolers with and without disabilities in same-age and mixed-age classes.

Communicative interactions of preschool children with and without disabilities in classrooms of same or mixed ages were compared. Sixteen children with developmental disabilities (most with mild or moderate mental retardation) and 32 children without disabilities between 1.5 and 4.5 years of age were randomly assigned at the beginning of the school year to either a same- or mixed-age grouping of 6 children. They were observed 6 months later interacting with classmates in a standard free-play environment. Results showed that children in mixed-age classes took more turns in conversations with partners with disabilities than did children in same-age classrooms. They also received more turns from their partners with disabilities, which were more often responses than initiations in the mixed-age as compared to same-age classes. In contrast, during communicative interactions with partners without disabilities, children in both types of classes did not significantly differ in number or types of turns. Children of a similar developmental level also had similar communicative interaction styles.

Age Factors↗
PubMed1993

Improved peribulbar anaesthesia with alkalinization and hyaluronidase.

A prospective double-blind randomized study was carried out to determine the effect of pH and the addition of hyaluronidase to a mixture of lidocaine and bupivacaine on the efficacy of peribulbar anaesthesia. One hundred patients were assigned to one of five groups. All groups received a solution of two parts bupivacaine (0.75%) and one part lidocaine (2%) (with 1:100,000 adrenaline) as the base components of their anaesthesia. Group 1 received only the bupivacaine-lidocaine mixture, pH 3.9. Group 2 received a solution supplemented with hyaluronidase (ten units.ml-1), pH of 5.1. Group 3 received the bupivacaine-lidocaine mixture alkalinized with sodium bicarbonate to a pH of 5.1, the same as solution 2. Group 4 received the mixture with hyaluronidase alkalinized to pH of 6.7. Group 5 received the bupivacaine-lidocaine mixture alkalinized to a pH of 6.7. Efficacy of each block was graded according to the degree of residual movement 30 min following injection, as described by House et al. The solution containing hyaluronidase and pH adjusted to 6.7 was found to be the most effective (P < 0.025). The presence of hyaluronidase without alkalinization did not improve the efficacy of the mixture; and similarly, alkalinization in the absence of hyaluronidase was ineffective. These results reflected the pH- and temperature-dependent thermodynamic properties of local anaesthetics, and the pH-dependent activity of hyaluronidase.

Aged↗
PubMed1993

Acoustical analysis of maternal sounds during the second stage of labor.

Experienced obstetric nurse and midwives indicate they can differentiate among sounds indicating that a woman is (a) beginning to manifest the effort to bear down, (b) experiencing pain, or (c) frightened. This study examined the acoustical properties of work/effort, childlike, and out-of-control utterances to determine whether their acoustical properties differed. Out-of-control utterances are more tense but contain similar levels of shimmer and pitch as childlike utterances. Work/effort utterances are higher pitched and more tense than childlike utterances. Work/effort utterances contain more shimmer but have similar levels of pitch and tenseness as out-of-control utterances.

Adult↗
PubMed1992

Characterization of very young mineral phases of bone by solid state 31phosphorus magic angle sample spinning nuclear magnetic resonance and X-ray diffraction.

The properties of bone mineral change with age and maturation. Several investigators have suggested the presence of an initial or "precursor" calcium phosphate phase to help explain these differences. We have used solid state 31P magic angle sample spinning (MASS) nuclear magnetic resonance (NMR) and X-ray radial distribution function (RDF) analyses to characterize 11- and 17-day-old embryonic chick bone and fractions obtained from them by density fractionation. Density fractionation provides samples of bone containing Ca-P solid-phase deposits even younger and more homogeneous with respect to the age of mineral than the calcium phosphate (Ca-P) deposits in the whole bone samples. The analytical techniques yield no evidence for any distinct phase other than the poorly crystalline hydroxyapatite phase characteristic of mature bone mineral. In particular, there is no detectable crystalline brushite [DCPD, CaHPO4 2H2O less than 1%] or amorphous calcium phosphate (less than 8-10%) in the most recently formed bone mineral. A sizeable portion of the phosphate groups exist as HPO4(2-) in a brushite (DCPD)-like configuration. These acid phosphate moieties are apparently incorporated into the apatitic lattice. The most likely site for the brushite-like configuration is probably on the surface of the crystals.

Animals↗
PubMed1992

Vulnerable self-esteem and depressive symptoms: prospective findings comparing three alternative conceptualizations.

Across diverse theoretical orientations, vulnerable self-esteem (SE) is thought to act as a diathesis for depression after life stress. In the present study, the roles of trait-level SE, low SE primed by depressed mood, and labile SE in prospectively predicting changes in depressive symptoms in a nonclinical sample (n = 192) were examined. Results indicated that labile SE predicted increases in symptoms. Furthermore, a 3-way interaction (Labile SE x Academic Stress x Initial Depression) suggested that in Ss who were initially asymptomatic, lability made Ss differentially vulnerable to increases in depressive symptoms after stress. In contrast to labile SE, trait-level SE and priming of low SE were relatively weak predictors of changes in depressive symptoms and did not interact with stress.

Achievement↗
PubMed1992

The potential ocular phototoxicity of antidepressant drugs.

Light Therapy is a new treatment for patients with Seasonal Affective Disorder (SAD), a depressive state occurring during the winter as a result of decreased sunlight. The treatment involves placing the patient in front of a light box (2-10,000 lux) for approximately 30 min to 1 hour per day during the winter months. Although there have been no reports of damage to the eye from this treatment with light alone there is increased risk in light damage to the lens and retina if these depressed patients are being treated with antidepressant/neuroleptic drugs concurrently with their light therapy. As we have been previously reported certain drugs, having absorptions longer than 295 nm can act as photosensitizers resulting in enhanced light damage to the eye. Using a screening method developed by Roberts, we examined the potential phototoxicity of a variety of antidepressant and neuroleptic drugs.

Animals↗
PubMed1991

Photooxidation of specific residues in alpha-crystallin polypeptides.

Singlet oxygen is a biologically important, photochemically generated species that preferentially oxidizes His, Trp, and Met residues of protein molecules. Calf alpha-crystallin was photooxidized with use of meso-tetra(p-sulfonatophenyl)porphyrin (TPPS) and uroporphyrin (UP) as singlet oxygen generators. The effects of photooxidation were monitored by analyzing the changes in alpha-crystallin peptide maps obtained by reversed-phase HPLC using a photodiode array absorbance detector. The reaction led to the loss of six specific peptides, five of which contained photooxidizable residues. Peptides containing His-97 and His-154 from the A chain and Met-68 from the B chain are preferentially photooxidized, suggesting that those residues have access to singlet oxygen. Trp residues in the N-terminal region are converted to NFK, whereas Trp-60 in the B chain is not photooxidized strongly suggesting that the former are close to the surface of alpha-crystallin while the latter Trp residue is buried. Only one peptide that is lost from the peptide maps does not contain a photooxidizable group; however, this peptide does contain an apparently undigested Lys residue. It is suggested that it forms a cross-link with a photooxidized His residue.

Amino Acid Sequence↗
PubMed1991

Structural and composition studies on the mineral of newly formed dental enamel: a chemical, x-ray diffraction, and 31P and proton nuclear magnetic resonance study.

The present report describes a study of the development and maturation of the mineral component of dental enamel. We prepared porcine enamel of different stages of maturation, from the very immature enamel of unerupted teeth, with a mineral content of 45%, to fully mature enamel, with a mineral content of approximately 99%. We fractionated the less mature enamel by density centrifugation and examined the enamel density fractions and unfractionated enamel by a variety of chemical and physical techniques, including conventional and radial distribution function x-ray diffraction analysis, conventional and Fourier transform infrared spectroscopy, 31P and 1H nuclear magnetic resonance spectroscopy, and chemical analysis. The three most immature preparations, from unerupted teeth, had mineral contents of 45, 67, and 91 and Ca/P molar ratios of 1.41, 1.44, and 1.47. Density distribution histograms of the three fractions show that the early maturation of dental enamel mineral is accompanied by an increase in tissue density, reflecting the increase in mineral content. The density distribution in each sample is relatively narrow, indicating that the maturation process occurs at a fairly homogeneous rate, with all enamel in an anatomically defined zone mineralizing to about the same extent. X-ray diffraction studies indicate that even the least mature, least mineralized of these immature samples is considerably more crystalline than the most mature bone mineral studied and that crystalline perfection of the enamel crystals crystals increases further with maturation. Both the a and c axes of the mineral unit cell expand significantly during early stages of maturation. Solid-state 31P nuclear magnetic resonance spectroscopy studies indicate that dental enamel contains a DCPD-like HPO4 component in an apatitic lattice, similar to the component previously observed in bone and some synthetic calcium phosphates. The proportion of this DCPD-like component decreases with maturation but is readily detectable even in fully mature enamel. The infrared spectroscopic studies indicate that the 3570 cm-1 band ascribed to the OH- group of the hydroxyapatite crystals is absent in the least mature enamel but can be detected and becomes progressively stronger as the enamel becomes more mature. The increase in the content of the OH- groups of the apatite crystals is concomitant with the observed increase in unit cell parameters. Similar studies on very young and very old mature bone of four different species failed to detect the presence of OH- groups.

Aging↗
PubMed1991

Solid state 31NMR studies of the conversion of amorphous tricalcium phosphate to apatitic tricalcium phosphate.

The hydrolytic conversion of a solid amorphous calcium phosphate of empirical formula Ca9 (PO4)6 to a poorly crystalline apatitic phase, under conditions where Ca2+ and PO4(3-) were conserved, was studied by means of solid-state magic-angle sample spinning 31P-NMR (nuclear magnetic resonance). Results showed a gradual decrease in hydrated amorphous calcium phosphate and the formation of two new PO4(3-)-containing components: an apatitic component similar to poorly crystalline hydroxyapatite and a protonated PO4(3-), probably HPO4(2-) in a dicalcium phosphate dihydrate (DCPD) brushite-like configuration. This latter component resembles the brushite-like HPO4(2-) component previously observed by 31P-NMR in apatitic calcium phosphates of biological origin. Results were consistent with previous studies by Heughebaert and Montel [18] of the kinetics of the conversion of amorphous calcium phosphate to hydroxyapatite under the same conditions.

Apatites↗
PubMed1991

Otitis media in early childhood and later language.

The relationship between early otitis media with effusion (OME) experience and later language development was examined in a prospective cohort study of 30 children from middle-class families and 33 children from low-income families. Ear status was monitored using otoscopy and tympanometry during wellness and illness periods between birth and 3 years of age. Language was assessed using standardized tests and a language sample between 4 1/2 and 6 years. Findings suggested no reliable relationship between early OME experience and later language development.

Child, Preschool↗
PubMed1991

Porphyromonas gingivalis-specific serum IgG and IgA antibodies originate from immunoglobulin-secreting cells in inflamed gingiva.

Patients with adult periodontitis (AP) exhibit elevated serum antibody levels to Porphyromonas (Bacteroides) gingivalis; however, it is not known whether these antibodies originate from plasma cells in the local disease site or from peripheral lymphoid tissues. We studied the isotype and subclass levels and origin of antibodies to P. gingivalis fimbriae, since elevated serum anti-fimbriae responses were seen when compared with sera of healthy controls. IgG anti-fibriae titres were dominant and the subclass response was IgG3 much greater than IgG1 greater than IgG2 much greater than IgG4; however, some IgA anti-fimbriae antibodies were also seen. The IgA subclass fimbriae-specific response was mainly IgA1; however, significant IgA2 anti-fimbrae antibodies were seen. We also assessed numbers of anti-fimbriae antibody producing cells from peripheral blood mononuclear cells (PMBC) and from either healthy or inflamed gingiva of AP subjects. Gingival mononuclear cells (GMC) of AP patients exhibited high numbers of immunoglobulin-producing (spot-forming) cells (SFC) including fimbriae-specific antibody secreting cells in a pattern of IgG greater than IgA greater than greater than greater than IgM. However, low numbers of SFC were seen in GMC from healthy gingiva; further, no anti-fimbriae SFC responses were noted in healthy GMC. Although no fimbriae-specific immunoglobulin-producing cells were seen in PBMC, low numbers of antigen-specific SFC were found in pokeweed mitogen-triggered PBMC from AP subjects. Treatment of AP patients for plaque and surgical removal of inflamed gingiva resulted in significant reductions in serum anti-fimbriae responses. These studies show that AP patients exhibit brisk serum IgG and IgA subclass anti-fimbriae antibodies, whose origin appear to be the plasma cells present in the localized inflamed tissues.

Antibodies, Bacterial↗