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Biomedical subjects

C Powell

Publications and source records attributed to C Powell.

At least 37 records · Page 2Linked to original sources
PubMed1989

Home visiting of varying frequency and child development.

Two studies were made of home visiting and psychosocial stimulation with deprived urban children in Jamaica. The aim was to determine the relative effectiveness of different frequencies of visiting on the children's developmental levels and the feasibility of integrating the model into government primary health care services. Health paraprofessionals supervised by a nurse from a local health center conducted the intervention. In the first study, 152 children aged 6 to 30 months were assigned to groups visited biweekly, monthly, or not at all by area of residence. The biweekly group showed small but significant increases in scores on the Griffiths Mental Development Scales (developmental quotient) and performance subscale compared with the monthly and control groups, whereas no benefit was shown in the Griffiths scores of the monthly group. In the second study, 58 children aged 16 to 30 months from the same neighborhoods were randomly assigned to weekly visited and control groups. The group visited weekly showed marked improvements in the performance and hearing and speech subscales as well as the developmental quotient scores. The results indicate that as the frequency of visiting increases from none through monthly and biweekly to weekly, the benefits increase as well.

Child Development↗
PubMed1989

Stunting, severe malnutrition and mental development in young children.

The association was examined between an episode of severe malnutrition, stunting in length and children's developmental levels. Twenty-nine children aged between 6 and 24 months, who had recently recovered from severe malnutrition, were compared with 29 children matched for age and height who had never had an acute episode, and who came from similar social backgrounds. Both groups were given developmental assessments on the Griffiths Test, and their developmental quotients (DQs) were not significantly different. Both groups' DQs were significantly lower than a third group of 15 non-stunted children. It was concluded that the poor developmental levels usually found in severely malnourished children may be largely explained by factors associated with stunting, rather than the acute episode.

Child Development↗
PubMed1988

Botulinum toxin therapy for squint.

Four hundred and five patients have been treated with injections of Botulinum neurotoxin A to extraocular muscles in the Botulinum Toxin Clinic at Moorfields Eye Hospital from November 1982 until the present. The indications and outcome of therapy are described and discussed.

Adolescent↗
PubMed1987

Oligodeoxyribonucleoside methylphosphonates. NMR and UV spectroscopic studies of Rp-Rp and Sp-Sp methylphosphonate (Me) modified duplexes of (d[GGAATTCC])2.

1H NMR chemical shift assignments for the title compounds were made for most of the 1H signals using two-dimensional nuclear Overhauser effect (2D-NOE) data, which were also used to establish the absolute configuration at the modified phosphorus. The chemical shifts were similar to those reported [Broido, M.S., et al. (1985) Eur. J. Biochem. 150, 117-128] for the unmodified, parent, B-type duplex [d(GGAATTCC)]2. Differences in chemical shifts were mostly localized to the nucleotides on the 5'- and 3'-sides of the modified phosphorus. The Rp-Rp isomers exhibited UV-derived Tm values similar to that of the parent duplex. On the other hand, the Sp-Sp isomers generally exhibited lower Tm values which correlated with P-CH3--H3' (n-1 nucleotide) cross peak intensities and 31P spectral parameters. The combined data argue for increased steric interactions with the Sp-P-Me methyl group as the modification position is moved toward the center of the oligomer. All of the Tm results can be explained in terms of three factors which result from replacement of a phosphate by a methylphosphonate group: reduction of oligomer charge; electronic and other substituent effects; steric interactions.

Deoxyribonucleosides↗
PubMed1987

Introduction of Shigella flexneri 2a type and group antigen genes into oral typhoid vaccine strain Salmonella typhi Ty21a.

For protection against dysentery caused by Shigella flexneri 2a, an in vivo-constructed recombinant plasmid with genes specifying the S. flexneri type and group antigens located near the pro (min 6) and his (min 44) chromosomal markers, respectively, was made and transferred to the galE Salmonella typhi strain Ty21a. Strain Ty21a carrying this recombinant plasmid was shown by immunological and biochemical analyses to express the S. flexneri 2a type and group antigens. Mice immunized with this vaccine strain were found to be protected against challenge with virulent S. flexneri 2a, but not significantly against S. typhi challenge, presumably because synthesis of the Shigella antigens interfered with expression of the typhoid antigens. Elimination of the recombinant plasmid from Ty21a allowed this strain to again express typical S. typhi O antigens. Mouse protection against both S. typhi and S. flexneri 2a challenges was achieved with a whole-cell vaccine mixture composed of equal parts of Ty21a and the Ty21a-S. flexneri 2a hybrid strain.

Administration, Oral↗
PubMed1987

Behavioral treatment of adherence to therapeutic exercise by children with hemophilia.

Behavioral treatment of adherence to therapeutic exercise by ten children (aged 8 to 15) with hemophilia was investigated during a one-year period. During a one-week baseline phase, adherence to exercise performance was 55%. A 12-session behavioral physical therapy program was then implemented emphasizing individualized instruction in progressive strengthening exercises with weights. Endurance activities such as stationary bicycling and swimming, as well as noncontact sports (which provide optimal musculoskeletal conditioning without potentiating a joint or muscle bleed), were also included. Within a contingency contract format, designated points were given for adherence and exchanged for reinforcers. Adherence parameters included the percentage of prescribed therapeutic exercises performed, the percentages of exercise record forms returned, and the percentage of sessions attended. During the treatment phase, therapeutic adherence averaged 94% across the three parameters. Adherence declined during the follow-up phases from 84% to 66% across these parameters, as explicit reinforcement decreased.

Adolescent↗
PubMed1987

Development of severely malnourished children who received psychosocial stimulation: six-year follow-up.

The development of 16 children who were hospitalized for severe malnutrition and participated in a home-visiting program of psychosocial stimulation was compared with that of two other groups who were also hospitalized but received standard medical care only: severely malnourished group (n = 18) and an adequately nourished one (n = 20). All groups were assessed regularly on the Griffiths Mental Development Scales and the Stanford-Binet test. Both groups of malnourished children were markedly behind the adequately nourished group on admission to the hospital and the group that received no intervention showed little sign of catching up. The intervention group caught up to the adequately nourished group in 2 years. This report covers the third year of home-visiting and the 3 years following its cessation. The intervention group showed a decline in three of the five Griffiths subscales. However, they retained a marked advantage over the nonintervention group of malnourished children on the Stanford-Binet test until the end of follow-up, showing no further decline in the last year. For height, both malnourished groups failed to catch up to the adequately nourished group. It was concluded that a relatively simple intervention can benefit the development of severely malnourished children.

Child Development↗
PubMed1986

Phosphorothioate-modified oligodeoxyribonucleotides. III. NMR and UV spectroscopic studies of the Rp-Rp, Sp-Sp, and Rp-Sp duplexes, [d(GGSAATTCC)]2, derived from diastereomeric O-ethyl phosphorothioates.

2D-NOE and 1H NMR chemical shift data obtained for the title oligonucleotides were compared with similar data previously reported [Broido et al. (1985) Eur. J. Biochem. 150, 117-128] for the unmodified "parent" structure, [d(GGAATTCC)]2. The spectroscopically detectable structural perturbations caused by replacement of phosphate oxygen with sulfur were mostly localized within the GsA moiety, and were greater for the Rp configuration wherein sulfur is oriented into the major groove of the B-helix. UV-derived Tm measurements gave the following order of stability for the duplexes in 0.4 M NaCl: unmodified (33.9 +/- 0.1 degrees C) approximately Sp-Sp (34.1 degrees C) greater than Rp-Rp (31.7 degrees C). The title compounds were prepared by a new and convenient synthetic route which utilized HPLC to separate the diastereomeric O-ethyl phosphorothioate precursors, (Rp)- and (Sp)-d[GG(S,Et)AATTCC], for subsequent de-ethylation by ammonia in water.

Indicators and Reagents↗
PubMed1986

Alkyl phosphotriester modified oligodeoxyribonucleotides. VI. NMR and UV spectroscopic studies of ethyl phosphotriester (Et) modified Rp-Rp and Sp-Sp duplexes, (d[GGAA(Et)TTCC])2.

1H NMR chemical shift assignments for the title compounds were made for all but a few H5' and H5" signals using two-dimensional nuclear Overhauser effect (2D-NOE) data, which was also used for the first time to assign absolute configuration at phosphorus. The chemical shifts were, in general, similar to those reported [Broido, M.S., et al. (1985) Eur. J. Biochem. 150, 117-128] for the B-like conformation of the unmodified, parent duplex, [d(GGAATTCC)]2. Differences in chemical shifts for corresponding protons were mostly localized to the AA(Et)TT region, and showed some stereochemical dependence. Unambiguous assignment of the phosphotriester 31P signals was achieved in a novel way using selective insensitive nucleus enhancement by polarization transfer (selective INEPT) NMR. The Rp-Rp duplex melted ca. 11 degrees C lower than either the Sp-Sp or parent duplexes, as evidenced by Tm and variable temperature 1H/31P NMR measurements. The 2D-NOE data for the Rp-Rp duplex suggested possible steric interactions between the ethyl group and the H3' of the flanking A residue. At low ionic strength, the Sp-Sp and parent duplexes had similar stability but at high ionic strength the Sp-Sp duplex was less stable.

Base Sequence↗
PubMed1985

Plasma tryptophan, age and depression.

Plasma, obtained from 131 nondepressed, otherwise healthy subjects aged from 17 to 102 years, and 22 depressed subjects aged over 70 years, was analysed for total and free tryptophan. Variation with age was found in total tryptophan. This association has not been described hitherto. There was a significant increase in total tryptophan and a non-significant increase in free tryptophan with depression. This is in contrast to some studies in younger people showing a decline in plasma tryptophan in depressed subjects.

Adolescent↗
PubMed1985

Partial purification and characterization of somatomedin from sheep serum.

A rapid, high yield preparative technique for the isolation of sheep somatomedin is reported. Purification of biologically active somatomedin from the 60% ammonium sulfate precipitate of sheep serum was accomplished using three gentle fractionation steps. Biological activity during purification was monitored using the rat adipocyte nonsuppressible insulin-like activity (NSILA) assay. A stepwise pH elution (pH 2.85, 3.5, 4.5, and 6.0) from SP-Sephadex resulted in the elimination of more than 99% of the serum proteins and a 500-fold enhancement of biological activity. The active fraction eluted at pH 6.0 and was further fractionated on Sephadex G-50 (fine) chromatography at pH 2.85. This resulted in about a 10,000-fold enhancement of activity over serum activity. The most active fractions from Sephadex chromatography were further separated on reverse phase HPLC in 0.1% trifluoroacetic acid using a linear gradient of 24-60% acetonitrile. The biological activity of the final preparation was enhanced 61,000- to 182,000-fold over that of serum (mean, 93,000-fold) when assayed in the NSILA assay. Protein yield was estimated to be 467 micrograms/liter serum. In addition to the NSILA activity, the final preparation demonstrated dose-dependent sulfation factor activity in the embryonic chick pelvic leaflet bioassay. Sheep somatomedin was active at physiological levels in both bioassays. Analysis of the somatomedin preparation by sodium dodecyl sulfate-electrophoresis at pH 8.8 showed that it was homogeneous by this criterion. The activity eluted from Sephadex G-50 was estimated to have a molecular size of 6900. Two Coomassie blue-stained bands were present in the final sheep somatomedin preparation after polyacrylamide gel electrophoresis at pH 3.2. Our purification process is a rapid, high yield technique which yields a polypeptide fraction enriched in NSILA and somatomedin-like activity. The molecular size and biological activity in the NSILA and sulfation factor assays suggest that our sheep NSILA is analogous to somatomedins purified from other species of animals.

Animals↗
PubMed1985

Creativity and the boundaries of the self: separation and engulfment anxiety in Keats and Poe.

Creativity is considered as a vicissitude of the cohesiveness or fragmentation of the self. The emergence of a self, separate from the mothering figure, requires the mother's empathic fuelling and the child's capacity to contain his gradual disillusionment with her. The process is never fully completed, allowing a potential for anxiety over threatened disintegration, along a continuum from separation anxiety (loss of the object), in a relatively cohesive self, to engulfment anxiety (loss of the self) in the less cohesive. The creative artist is uniquely sensitive to these anxieties, through his own difficulties in separating from the infantile union with the mother, or in mourning an object that dies during his childhood. The artist draws on his unconscious experience to speak to the unconscious of the audience. For the audience, it is having one's own deepest longings and deepest anxieties spoken to and spoken for that constitutes the power of creative art.

Anxiety↗
PubMed1979

The induction of acute psychosis in a group setting.

The case histories of two patients are described, each of whom suffered a severe psychotic decompensation, one apparently schizophreniform and the other affective, after attending a seven day marathon group conducted by a charismatic, aggressive leader. The work of Yalom and Lieberman is reviewed, with regard to leader and participant characteristics in encounter group casualties. Drawing upon the work of Bion and Kernberg, a specific means for the induction of psychosis is suggested, involving primitive splitting and the projection of "all bad" self-object constellations within a group setting.

Adult↗