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Biomedical subjects

J B Reid

Publications and source records attributed to J B Reid.

At least 37 records · Page 2Linked to original sources
PubMed1992

Use of an Acylcyclohexanedione Growth Retardant, LAB 198 999, to Determine Whether Gibberellin A(20) Has Biological Activity per se in Dark-Grown Dwarf (le) Seedlings of Pisum sativum.

Dwarf (le(5839)) seedlings of Pisum sativum respond to gibberellin A(20) (GA(20)) in the dark, although the same dosage of GA(20) applied to light-grown le(5839) seedlings elicits no growth response. The acylcyclohexanedione growth retardant, LAB 198 999, which is known to inhibit gibberellin oxidation and in particular 3beta-hydroxylation such as the conversion of GA(20) to GA(1), also inhibits the growth response of dark-grown dwarf (le(5839)) seedlings to GA(20). Thus, the biological activity of GA(20) in the dark appears to be a consequence of its conversion to GA(1), even though it is known from studies with light-grown seedlings that the le mutation reduces the conversion of GA(20) to GA(1).

Journal Article↗
PubMed1992

The Distribution of Gibberellins in Vegetative Tissues of Pisum sativum L. : I. Biological and Biochemical Consequences of the le Mutation.

The concentrations of endogenous gibberellin (GA) 1, 5, 8, 19, 20, and 29 in the component tissues of maturing tall (Le) and dwarf (le) pea (Pisum sativum) plants have been determined. The following conclusions were drawn from the data obtained: (a) GA(20) and its metabolites accumulate only in the growing regions of Le and le plants; (b) the le mutation is biochemically expressed in all immature tissues of the dwarf plants; (c) the quantitative composition of the GA metabolites in the various immature tissues is variable; (d) the total GA concentration in apical buds, unexpanded leaves, and tendrils is considerably higher than in GA(1)-responsive stem tissue; and (e) there is very little GA accumulation of the inactive 2beta-hydroxylated GAs (GA(8) and GA(29)) in either the mature vegetative tissues or the roots of pea plants.

Journal Article↗
PubMed1991

A comparative evaluation of parent-training interventions for families of chronic delinquents.

Fifty-five families of chronically offending delinquents were randomly assigned to parent-training treatment or to service traditionally provided by the juvenile court and community. The families in the parent-training group received an average of 44.8 hours of professional contact (23.3 hours of which were phone contacts), and each control group family received treatment estimated at more than 50 hours on the average. Comparisons of police contact data at baseline and subsequent years for the two groups showed that subjects in both groups demonstrated reduced rates of offending during the followup years. The finding most relevant was significant treatment-by-time effect for offense rates, with most of this effect accounted for by a greater reduction in serious crimes for the experimental group during the treatment year, and a similar reduction of the community control group occurring in the first of three followup years. These early decrements in offense rates persisted during followup for both groups. Throughout the study, boys in the experimental group spent significantly less time in institutional settings than did boys in the control group. Parent training had a significant impact, but the reduction in offending was produced at very high emotional cost to staff. Although it is clear that this population requires substantial treatment resources, this study underscores the need for more work on prevention.

Adolescent↗
PubMed1991

Mediational screening as a model for prevention research.

Examined here is Pillow, Sandler, Braver, Wolchik, and Gersten's (this issue) strategy for screening prevention trial participants. The reviewer concludes that their selection strategy should increase the statistical power of prevention outcome studies, increase intervention cost effectiveness, and help to prevent their possible iatrogenic effects. Also, their model points up inadequacies in the longitudinal data on which most prevention strategies are based, and their model could well serve as a template for future research.

Child↗
PubMed1990

Physical basis for altered stem elongation rates in internode length mutants of Pisum.

Biophysical parameters related to gibberellin (GA)-dependent stem elongation were examined in dark-grown stem-length genotypes of Pisum sativum L. The rate of internode expansion in these genotypes is altered due to recessive mutations which affect either the endogenous levels of, or response to, GA. The GA deficient dwarf L181 (ls), two GA insensitive semierectoides dwarfs NGB5865 and NGB5862 (lka and lkb, respectively) and the slender' line L197 (la crys), which is tall regardless of GA content, were compared to the wild-type tall cultivar, Torsdag. Osmotic pressure, estimated by vapor pressure osmometry, and turgor pressure, measured directly with a pressure probe, did not correlate with the differences in growth rate among the genotypes. Mechanical wall properties of frozen-thawed tissue were measured using a constant force assay. GA deficiency resulted in increased wall stiffness judged both on the basis of plastic compliance and plastic extensibility normalized for equal stem circumference. Plastic compliance was not reduced in the GA insensitive dwarfs, though lka reduced circumference-normalized plasticity. In contrast, in vivo wall relaxation, determined by the pressure-block technique, differed among genotypes in a manner which did correlate with extension rates. The wall yield threshold was 1 bar or less in the tall lines, but ranged from 3 to 6 bars in the dwarf genotypes. The results with the ls mutant indicate that GA enhances stem elongation by both decreasing the wall yield threshold and increasing the wall yield coefficient. In the GA-insensitive mutants, lka and lkb, the wall yield threshold is substantially elevated. Plants possessing lka may also possess a reduced wall yield coefficient.

Biophysical Phenomena↗
PubMed1990

Genetic analysis of the role of gibberellin in the red light inhibition of stem elongation in etiolated seedlings.

Red light causes a reduction in the extension growth of dark-grown seedlings. The involvement of gibberellin in this process was tested by screening a number of gibberellin synthesis and gibberellin response mutants of Pisum sativum L. for the kinetic response of stem growth inhibition by red light. Gibberellin deficient dwarfs, produced by mutant alleles at the Le, Na, and Ls loci, and gibberellin response mutants produced by mutant alleles at the La and Cry(2), Lka, and Lkb loci were tested. Extension growth of expanding third internodes of dark-grown seedlings was recorded with high resolution using angular position transducers. Seedlings were treated with red light at a fluence rate of 4 micromoles per square meter per second either continuously or for 75 seconds, and the response was measured over 9 hours. With certain small exceptions, the response to the red light treatments was similar in all the mutants and wild types examined. The lag time for the response was approximately 1 hour and a minimum in growth rate was reached by 3 to 4 hours after the onset of the light treatment. Growth rate depression at this point was about 80%. Seedlings treated with 75 seconds red light recovered growth to a certain extent. Red/far-red treatments indicated that the response was mediated largely by phytochrome. The similar responses to red light among these wild-type and mutant genotypes suggest that the short-term (i.e. 9 hour) response to red light is not mediated by either a reduction in the level of gibberellin or a reduction in the level or affinity of a gibberellin receptor.

Journal Article↗
PubMed1987

Abusive parents' perceptions of child problem behaviors: an example of parental bias.

The behavior of children in 21 child abusive and 21 nonabusive matched comparison families were compared using home observations performed by professional independent observers and parental report measures (Becker Bipolar Adjective Checklist, Child Behavior Checklist, Parent Daily Report). Parental report measures of child conduct problems differed significantly between the two groups, independent observations showed few significant differences in rates of either child or parental behaviors. Results are discussed in terms of the validity of parental perceptions and reports of child problem behaviors, the informativeness of differing reports for diagnosis and clinical treatment, and the need to gather corroboration across various sources and settings before clinical decisions are made that may irrevocably alter a child's future development.

Child↗
PubMed1987

Internode Length in Pisum: Gene na May Block Gibberellin Synthesis between ent-7alpha-Hydroxykaurenoic Acid and Gibberellin A(12)-Aldehyde.

The elongation response of the gibberellin (GA) deficient genotypes na, ls, and lh of peas (Pisum sativum L.) to a range of GA-precursors was examined. Plants possessing gene na did not respond to precursors in the GA biosynthetic pathway prior to GA(12)-aldehyde. In contrast, plants possessing lh and ls responded as well as wild-type plants (dwarfed with AMO-1618) to these compounds. The results suggest that GA biosynthesis is blocked prior to ent-kaurene in the lh and ls mutants and between ent-7alpha-hydroxykaurenoic acid and GA(12)-aldehyde in the na mutant. Feeds of ent-[(3)H]kaurenoic acid and [(2)H]GA(12)-aldehyde to a range of genotypes supported the above conclusions. The na line WL1766 was shown by gas chromatography-mass spectrometry (GC-MS) to metabolize [(2)H]GA(12)-aldehyde to a number of[(2)H]C(19)-GAs including GA(1). However, there was no indication in na genotypes for the metabolism of ent-[(3)H]kaurenoic acid to these GAs. In contrast, the expanding shoot tissue of all Na genotypes examined metabolised ent-[(3)H]kaurenoic acid to radioactive compounds that co-chromatographed with GA(1), GA(8), GA(20), and GA(29). However, insufficient material was present for unequivocal identification of the metabolites. The radioactive profiles from HPLC of extracts of the node treated with ent-[(3)H]kaurenoic acid were similar for both Na and na plants and contained ent-16alpha,17-dihydroxykaurenoic acid and ent-6alpha,7alpha,16beta,17-tetrahydroxykaurenoic acid (both characterized by GC-MS), suggesting that the metabolites arose from side branches of the main GA-biosynthetic pathway. Thus, both Na and na plants appear capable of ent-7alpha-hydroxylation.

Journal Article↗
PubMed1986

Influence of housing conditions for mice on the results of a dermal oncogenicity bioassay.

Male C3H/HeJ mice were thrice weekly given 25 microliter applications of 0.25, 0.05, or 0.01% (w/w) benzo(a)pyrene (BaP) in acetone, or acetone alone, to clipped dorsal skin from 12 to 14 weeks of age for the remainder of their life spans. There were two groups of 40 mice for each treatment regimen, one group being housed in conventional stainless-steel wire mesh cages and the other in polycarbonate cages with wood shavings held in an enclosed ventilated cabinet. Under both housing conditions, tumor incidence was directly related and latency inversely related to BaP concentration. The time-adjusted incidence of epidermal neoplasms was significantly greater for the groups housed in polycarbonate cages. Mortality rates were directly related to BaP concentration and were significantly enhanced by the polycarbonate-cage housing conditions for the high and intermediate concentrations. Survival patterns for the two acetone control groups were similar. These findings indicate that differences in housing conditions can influence both the incidence and the latency of local neoplasms produced in response to the chronic application of a carcinogen in dermal oncogenesis bioassays.

Animals↗
PubMed1985

Role of polyamines in gibberellin-induced internode growth in peas.

To determine the requirement for polyamines in gibberellin (GA) induced internode growth polyamine content was measured in internodes of peas of various internode phenotypes (slender, tall, dwarf, nana) with and without applied gibberellin (GA(3)) and polyamine synthesis inhibitors. Polyamines were assayed as dansyl derivatives which were separated by reverse phase high performance liquid chromatography and detected by fluorescence spectrophotometry. The amounts of polyamines in the different genetic lines of peas, which differed in internode lengths and extractable GA content, correlated with the extent of internode elongation. High polyamine concentrations were associated with young internodes and decreased with internode expansion. Extremely short internodes of nana plants without GA exhibited equal or higher amine concentrations relative to internodes of other lines of peas and GA-stimulated nana seedlings. The polyamine synthesis inhibitors, alpha-difluoromethylornithine and alpha-difluoromethylarginine, independently or in combination, inhibited polyamine accumulation and internode elongation of tall peas and GA-stimulated nana plants. Agmatine and putrescine restored growth and endogenous polyamine content to variable degrees. However, exogenous polyamines were not effective in promoting growth unless intracellular amines were partially depleted.These results suggest that polyamines do not have a role in cell elongation, but may be required to support cell proliferation. Polyamines do not mediate the entire action of GA in internode growth of peas since GA induction of growth involves both cell division and cell elongation, whereas polyamines appear to affect cell division only.

Journal Article↗
PubMed1983

Family interactions of assaultive adolescents, stealers, and nondelinquents.

Eleven adolescent chronic offenders apprehended for assaultive crimes in the community were observed in their family homes. This group was matched with 11 adolescents apprehended for stealing and with 11 adolescents with no court contact. Assaultive adolescents, unlike their controls, ranked significantly higher among their own family members in terms of their total aversive behavior in the family home. The results support the notion that assaultive adolescents are more involved with fighting with their siblings in the family home and consequently have had more practice in fighting than their controls, thereby preparing them for assaultive behavior in the community. Assaultive adolescents had more female siblings than male siblings, whereas nondelinquent adolescents had more male than female siblings.

Adolescent↗
PubMed1983

Internode length in pisum: do the internode length genes effect growth in dark-grown plants?

Internode length in light-grown peas (Pisum sativum L.) is controlled by the interaction of genes occupying at least five major loci, Le, La, Cry, Na, and Lm. The present work shows that the genes at all of the loci examined (Le, Cry, and Na) also exert an effect on internode length in plants grown in complete darkness. Preliminary results using pure lines were verified using either segregating progenies or near isogenic lines. The major cause of the differences was due to a change in the number of cells per internode rather than to an alteration of the cell length. Since the genes occupying at least two of these loci, Le and Na, have been shown to be directly involved with gibberellin metabolism, it appears that gibberellins are not only essential for elongation in the dark but are limiting for elongation in the nana (extremely short, na), dwarf (Na le), and tall (Na Le) phenotypes. These results are supported by the large inhibitory effects of AMO 1618 treatments on stem elongation in dwarf and tall lines grown in the dark and the fact that applied gibberellic acid could overcome this inhibition and greatly promote elongation in a gibberellin-deficient na line. It is clear that the internode length genes, and in particular the alleles at the Le locus, are not acting by simply controlling the sensitivity of the plant to light.

Journal Article↗
PubMed1981

The consistency of a class of coercive child behaviors across school settings for individual subjects.

This study addressed the problem of the intraindividual consistency of a class of coercive child behaviors across two school settings. Observational data collected on eight coercive behaviors of 53 boys in classrooms and on the playground. Previous Guttman scale analyses had shown that these eight coercive behaviors constituted a response class. The rates of the eight coercive responses in the response class were rank-ordered separately for each of the 53 subjects in each of the two settings. The intraindividual rank-order correlations were all positive, and 37 were statistically reliable. This number of significant correlations was further shown to be significantly greater than chance. It was concluded that there is a substantial amount of cross-situational consistency if intraresponse class analyses are done for individuals.

Aggression↗