Biomedical subjects

G L Robinson

Publications and source records attributed to G L Robinson.

At least 19 recordsLinked to original sources

PubMed2003

Plasma cholesterol levels and Irlen syndrome: preliminary study of 10- to 17-yr.-old students.

The preliminary study investigated metabolic anomalies in children and teenagers with Irlen Syndrome, particularly in relation to the levels of n-3 and n-6 essential fatty acids, plasma cholesterol levels, and the relative abundance of plasma saturated fatty acids. The experimental group involved 13 subjects with Irlen Syndrome (M=13.3 yr., SD=2.5 yr.), with a comparison group of 16 age- and sex-matched controls (M=13.8 yr., SD=2.4 yr.). The Irlen Syndrome group were selected from people referred for help with reading and writing problems. The control group were primarily recruited from the general public. All subjects were screened for symptoms of the syndrome using the Scotopic Sensitivity Syndrome Screening Manual. Samples of whole blood were collected and plasma extracted. Metabolites were compared using the Student t test. There were no differences in n-3 and n-6 essential fatty acids between Irlen Syndrome and control groups, although the former group had lower mean levels in most of these essential fatty acids. Total plasma cholesterol level was significantly decreased for the Irlen Syndrome group, and there was a significant increase in the relative abundance of the odd-chain fatty acid, heptadecanoic acid. The differences in heptadecanoic acid may have implications for altered membrane function and neurotransmission. The differences in plasma cholesterol levels, as well as heptadecanoic acid, may also point to the presence of viral or bacterial infection.

Adolescent↗

PubMed2001

A biochemical analysis of people with chronic fatigue who have Irlen Syndrome: speculation concerning immune system dysfunction.

This study investigated the biological basis of visual processing disabilities in adults with Chronic Fatigue Syndrome. The study involved 61 adults with symptoms of Chronic Fatigue Syndrome who were screened for visual processing problems (Irlen Syndrome) and divided into two groups according to the severity of symptoms of Irlen Syndrome. Significant variations were identified in blood lipids and urine amino and organic acids of the two groups, which may be indicative of activation of the immune system due to some infective agent. It was suggested that metabolic profiling may help the development of more valid diagnostic categories and allow more investigation of immune system dysfunction as a possible causal factor in a range of learning and behaviour disorders.

Adult↗

PubMed2000

The familial incidence of symptoms of scotopic sensitivity/Irlen syndrome: comparison of referred and mass-screened groups.

The familial incidence of Scotopic Sensitivity/Irlen Syndrome was investigated in two samples. One sample involved parents and siblings of 126 children identified with symptoms who had been referred for screening. The other sample involved parents and siblings of 33 children who had been identified with symptoms through mass screening of all children in Grades 3 to 6 at two local schools. Two different samples were taken to investigate the possibility of parental referral bias. Familial incidence may be inflated in a referred sample because some parents may be aware of their own symptoms and actively seek assistance. For the sample of children referred for screening, there was an 81% chance of either one or both parents showing similar symptoms and a 76% chance of siblings being similarly affected. For the sample of children identified through school screening, there was an 85%, chance of either one or both parents showing similar symptoms and a 54% chance of siblings being similarly affected. The data confirm previous estimates of incidence and suggest that Scotopic Sensitivity/Irlen Syndrome may be a genetically-based deficit in visual processing.

Adult↗

PubMed1999

Scotopic sensitivity/Irlen syndrome and the use of coloured filters: a long-term placebo-controlled study of reading strategies using analysis of miscue.

This study investigated the long-term effects of using coloured filters on the frequency and type of errors in oral reading. A double-masked, placebo-controlled crossover experimental design was used, with subjects being assessed over a period of 20 months. There were three experimental groups (Placebo tints, Blue tints, and Diagnosed tints) involving 113 subjects with reading difficulties, ranging in age from 9.2 yr. to 13.1 yr. The 35 controls (ranging in age from 9.4 yr. to 12.9 yr.) had reading difficulties but did not require coloured filters. There was a significant improvement for all groups in the accuracy of miscues over the period, although experimental groups over-all did not improve at a significantly different rate than the control group. The failure to find significantly greater improvement for the experimental groups over the control group for the total period, despite subjects' reports of improved print clarity, may be partly related to the lack of effective letter-sound analysis and synthesis skills and to the use of a word-identification strategy of guessing based on partial visual analysis.

Adolescent↗

PubMed1999

Scotopic sensitivity/Irlen syndrome and the use of coloured filters: a long-term placebo controlled and masked study of reading achievement and perception of ability.

This study investigated the effects of using coloured filters on reading speed, accuracy, and comprehension as well as on perception of academic ability. A double-masked, placebo-controlled crossover design was used, with subjects being assessed over a period of 20 mo. There were three treatment groups (Placebo filters, Blue filters, and Optimal filters) involving 113 subjects with "reading difficulties", ranging in age from 9.2 yr. to 13.1 yr. and with an average discrepancy between chronological age and reading age of 1.8 yr. The 35 controls (who did not use coloured filters) ranged in age from 9.4 yr. to 12.9 yr., with an average discrepancy between chronological age and reading age of 2.1 yr. The treatment groups increased at a significantly greater rate than the control group in reading accuracy and reading comprehension but not for speed of reading. For self-reported perception of academic ability, two of the three treatment groups showed significantly greater increases than the control group. The larger improvements for treatment groups in reading comprehension may be related to a reduction in print and background distortions allowing attention to be directed to the processing of continuous text rather than to the identification of individual words. A reduction in print distortion, however, may not be sufficient to generate improved word-identification skills without additional remedial support, and this may be indicated by the nonsignificant increase in rate of reading.

Achievement↗

PubMed1998

Patients' perceptions of chamba (marijuana) use in Malawi.

This study examines the perceptions of the social aspects, triggers, and effects of chamba (marijuana) use among psychiatric patients at Zomba Mental Hospital in Malawi. Focus groups were used to elicit responses from 44 male and 10 female psychiatric patients about their perceptions of chamba use in Malawi. This study provides insight into these patients' perceptions of the triggers and effects of their chamba use, and it has implications for the development of treatment and prevention programs for chamba users in Malawi.

Adult↗

PubMed1996

3-Benzisothiazolylpiperazine derivatives as potential atypical antipsychotic agents.

A series of substituted phenethyl derivatives of 3-benzisothiazolylpiperazine incorporating potent D2 and 5-HT2A antagonist activity was investigated as an approach to a novel atypical antipsychotic agent. The in vitro profile of 8e from this series is a combination of D2 receptor affinity comparable to the typical antipsychotic agent haloperidol and a 5-HT2A/D2 ratio comparable to the atypical agent clozapine. In vivo 8e possesses activity consistent with an efficacious antipsychotic agent with less tendency to induce extrapyramidal side effects in man.

Amphetamine↗

PubMed1996

The familial incidence of symptoms of Scotopic Sensitivity/Irlen syndrome.

The familial incidence of Scotopic Sensitivity/Irlen Syndrome was investigated using parents of 751 children identified with symptoms. Children were identified by methods independent of their parents' symptoms or lack of symptoms. For these children, there was an 84% chance of either one or both parents showing similar symptoms, with similar numbers of mothers identified with symptoms as fathers. The data suggest that Scotopic Sensitivity/Irlen Syndrome may be a genetically based deficit in visual processing, but the simplest genetic models do not appear to fit.

Adolescent↗

PubMed1995

c-jun inhibits insulin control element-mediated transcription by affecting the transactivation potential of the E2A gene products.

Pancreatic beta-cell-type-specific transcription of the insulin gene is principally controlled by trans-acting factors which influence insulin control element (ICE)-mediated expression. The ICE activator is composed, in part, of the basic helix-loop-helix proteins E12, E47, and E2-5 encoded by the E2A gene. Previous experiments showed that ICE activation in beta cells was repressed in vivo by the c-jun proto-oncogene (E. Henderson and R. Stein, Mol. Cell. Biol. 14:655-662, 1994). Here we focus on the mechanism by which c-Jun inhibits ICE-mediated activation. c-Jun was shown to specifically repress the transactivation potential of the E2A proteins. Thus, we found that the activity of GAL4:E2A fusion constructs was inhibited by c-Jun. The transrepression capabilities of c-Jun were detected only in pancreatic islet cell lines that contained a functional ICE activator. Repression of GAL4:E2A was mediated by the basic leucine zipper regions of c-Jun, which are also the essential regions of this protein necessary for controlling ICE activator-stimulated expression in vivo. The specific target of c-Jun repression was the transactivation domain (located between amino acids 345 and 408 in E12 and E47) conserved in E12, E47, and E2-5. In contrast, the activation domain unique to the E12 and E47 proteins (located between amino acids 1 and 99) was unresponsive to c-Jun. Our results indicate that c-Jun inhibits insulin gene transcription in beta cells by reducing the transactivation potential of the E2A proteins present in the ICE activator complex.

Adenoviridae↗

PubMed1994

Expression of the trans-active factors that stimulate insulin control element-mediated activity appear to precede insulin gene transcription.

Cell type-specific expression of the major differentiated products of alpha (glucagon) and beta (insulin) cells are regulated by sequences found within their 5'-flanking region. Specific transcription of the insulin gene appears to be principally controlled by a single cis-acting DNA element, termed the insulin control element (ICE). The ICE activator acts in combination with other positive regulatory factors that interact within this region to generate the correct, cell type-specific expression. In the present study, we show that the ICE activator is not only present but is functionally active in the islet glucagon-producing alpha cell line, alpha TC6. Analysis of the expression of various transfected insulin enhancer expression plasmids demonstrated that the insulin enhancer is active in alpha TC6 cells, although at a lower level than in beta cells. The reduced transcription from these constructs appears to be a consequence of the lack of other essential positive regulator(s). The alpha TC6 cells were also shown to display neuronal-like properties. Since islet cells appear to evolve from an alpha-like precursor cell that transiently expresses neuronal cell markers, these results would indicate that the ICE activator factor is induced before transcription of the insulin gene in the developing islet.

Animals↗

PubMed1994

Isolation and characterization of a novel transcription factor that binds to and activates insulin control element-mediated expression.

Pancreatic beta-cell-type-specific transcription of the insulin gene is principally regulated by a single cis-acting DNA sequence element, termed the insulin control element (ICE), which is found within the 5'-flanking region of the gene. The ICE activator is a heteromeric complex composed of an islet alpha/beta-cell-specific factor associated with the ubiquitously distributed E2A-encoded proteins (E12, E47, and E2-5). We describe the isolation and characterization of a cDNA for a protein present in alpha and beta cells, termed INSAF for insulin activator factor, which binds to and activates ICE-mediated expression. INSAF was isolated from a human insulinoma cDNA library. Transfection experiments demonstrated that INSAF activates ICE expression in insulin-expressing cells but not in non-insulin-expressing cells. Cotransfection experiments showed that activation by INSAF was inhibited by Id, a negative regulator of basic helix-loop-helix (bHLH) protein function. INSAF was also shown to associate in vitro with the bHLH protein E12. In addition, affinity-purified INSAF antiserum abolished the formation of the activator-specific ICE-binding complex. Immunohistochemical studies indicate that INSAF is restricted in terms of its expression pattern, in that INSAF appears to be detected only within the nuclei of islet pancreatic alpha and beta cells. All of these data are consistent with the proposal that INSAF is either part of the ICE activator or is antigenically related to the specific activator required for insulin gene transcription.

Amino Acid Sequence↗

PubMed1994

Irlen filters and reading strategies: effect of coloured filters on reading achievement, specific reading strategies, and perception of ability.

The effect of tinted nonoptical (Irlen) lenses was investigated with 29 lens-using subjects and a control group of 31 subjects. Assessment of reading four months after the initial screening showed a significant improvement in reading rate and comprehension but not in accuracy. A significant decrease in the number of pauses while reading was also noted for the lens users as well as increases in correlation between word repetition and reading rate and accuracy. The lens users also showed significantly improved scores on a scale of attitude towards school tasks.

Adolescent↗

PubMed1990

The effects of Irlen colored lenses on students' specific reading skills and their perception of ability: a 12-month validity study.

Recent evidence suggests that a specific visual-perceptual dysfunction not normally assessed by eye examination should be considered as a significant cause of reading problems. The use of tinted nonoptical (Irlen) lenses to minimize this dysfunction has been hypothesized to result in significant improvement in reading and other visual-processing skills. The present study involved 44 subjects with reading disabilities (33 males, 11 females), aged between 9 years 1 month and 15 years 11 months, who had been provided with Irlen lenses. Assessment of subjects' perception of their own ability (Student's Perception of Ability Scale) 6 and 12 months after the fitting of Irlen lenses indicated a significant improvement in attitude to school and to basic academic skills. Subjects also demonstrated significant improvements in reading comprehension and reading accuracy, but not in rate of reading, when assessed using the Neale Analysis of Reading Ability at 3-, 6-, and 12-month intervals after lens fitting. Differences in the pattern of improvement are discussed in light of previous findings.

Adolescent↗

PubMed1987