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Biomedical subjects

B Ong

Publications and source records attributed to B Ong.

At least 19 recordsLinked to original sources
PubMed2001

LAD-1, the Caenorhabditis elegans L1CAM homologue, participates in embryonic and gonadal morphogenesis and is a substrate for fibroblast growth factor receptor pathway-dependent phosphotyrosine-based signaling.

This study shows that L1-like adhesion (LAD-1), the sole Caenorhabditis elegans homologue of the L1 family of neuronal adhesion molecules, is required for proper development of the germline and the early embryo and embryonic and gonadal morphogenesis. In addition, the ubiquitously expressed LAD-1, which binds to ankyrin-G, colocalizes with the C. elegans ankyrin, UNC-44, in multiple tissues at sites of cell-cell contact. Finally, we show that LAD-1 is phosphorylated in a fibroblast growth factor receptor (FGFR) pathway-dependent manner on a tyrosine residue in the highly conserved ankyrin-binding motif, FIGQY, which was shown previously to abolish the L1 family of cell adhesion molecule (L1CAM) binding to ankyrin in cultured cells. Immunofluorescence studies revealed that FIGQY-tyrosine-phosphorylated LAD-1 does not colocalize with nonphosphorylated LAD-1 or UNC-44 ankyrin but instead is localized to sites that undergo mechanical stress in polarized epithelia and axon-body wall muscle junctions. These findings suggest a novel ankyrin-independent role for LAD-1 related to FGFR signaling. Taken together, these results indicate that L1CAMs constitute a family of ubiquitous adhesion molecules, which participate in tissue morphogenesis and maintaining tissue integrity in metazoans.

Amino Acid Motifs↗
PubMed2001

Synovial chondromatosis of the elbow.

Synovial chondromatosis is an uncommon disorder with rare occurrence in the elbow. Case reports in the literature for elbow synovial chondromatosis have described presenting symptoms secondary to peripheral nerve compressions or localized bursitis. We discuss a case of synovial chondromatosis of the elbow that presented as an isolated soft-tissue mass over the radial head-more suggestive of a soft-tissue tumor than of synovial chondromatosis.

Chondromatosis, Synovial↗
PubMed2001

Importance of correlating static and dynamic imaging studies in diagnosing degenerative lumbar spondylolisthesis.

Degenerative spondylolisthesis in the lumbar spine is due to long-standing segmental instability. A standing plain radiograph is commonly the only imaging study needed to establish the diagnosis. Translatory motion in spondylolisthesis is traditionally assessed with lateral flexion and extension radiographs. These dynamic studies often demonstrate a decrease in the slip percentage between the vertebral segments with extension and an increase with forward flexion. Some low-grade spondylolisthetic deformities reduce anatomically on the operating table after the administration of an anesthetic. We encountered one case in which there was complete reduction of an L4-5 grade I degenerative spondylolisthesis with positioning of a non-anesthetized patient in the supine position during a lumbosacral magnetic resonance imaging (MRI) scan. The patient's condition was originally misdiagnosed, as the spondylolisthesis was not identified on recumbent plain radiographs or on lumbosacral MRI. This case stresses the importance of correlating static and dynamic imaging studies in developing a treatment plan for patients with degenerative spondylolisthesis.

Female↗
PubMed2000

A neuropsychological investigation of dementia in motor neurone disease (MND).

Different clinical criteria for diagnosing dementia were compared in a sample of 69 patients with motor neurone disease (MND). Participants' performances on a computerised battery of neuropsychological tests were evaluated to assess the usefulness of these tests in predicting dementia in MND. The results indicated that when diagnostic criteria for frontotemporal (FTD) were used as part of a questionnaire method of diagnosing dementia the incidence of dementia in MND was considerably greater than traditional estimates suggest. Through a series of logistic and multiple regressions the results demonstrated that neuropsychological test performance related well to diagnostic classifications of dementia. MND patients with a clinical diagnosis of dementia were likely to demonstrate impaired new learning; poor working memory and planning; slowness in information processing and rigidity in thinking. These features, which are typical of cases of FTD, suggest that the dementia of MND is usefully characterised as a form of FTD. The finding that neuropsychological impairment correlated with behavioural features of dysexecutive impairment in daily living, indicates that the management focus in MND must be broadened to include cognitive/behavioural issues.

Adult↗
PubMed2000

Photosynthesis and antioxidant enzymes of phyllodes of Acacia mangium.

Physiological processes are influenced by environmental factors and plant characteristics. The distribution of photosynthetic capacity of phyllodes of Acacia mangium Willd. seedlings was studied in relation to the in vivo photosystem II (PSII) function, photosynthetic gas exchange, chlorophyll fluorescence and activities of antioxidant enzymes (superoxide dismutase (SOD) and ascorbate peroxidase (APX)) of phyllodes at different positions on seedlings. There was a vertical gradient in photosynthetic capacity of phyllodes along the shoot. Phyllode 1 (at the apex) showed negative carbon uptake at PPFD lower than 400 µmol m(-2) s(-1). High photosynthetic capacities, chlorophyll concentrations, DeltaF/F'(m), and q(P) were observed in phyllodes 4, 6 and 8. The high photosynthetic capacities of mature phyllodes could be attributed to the enhanced availability of CO(2) and the high efficiency of PSII in energy absorption and utilization. Total SOD and APX activities (on a dry weight basis) were highest at phyllode 1 and decreased as the phyllodes matured. The high photosynthetic capacity and low respiration loss in mature phyllodes could be important factors, responsible for the rapid establishment and fast growth of A. mangium in reforestation programs.

Journal Article↗
PubMed2000

A study of performance of delayed intentions in multiple sclerosis.

The ability to remember and perform delayed intentions was investigated in a sample of 40 participants with Multiple Sclerosis (MS) and compared to a group of 36 healthy, neurologically intact, control participants. Using a model of task division, performance on both the prospective memory (PM) component (a failure to remember to do something at a specific time) and the retrospective memory (RM) component (a failure to remember the content of the intention) of two "naturalistic" delayed intention experimental tasks were examined. Significantly poorer performance of the MS group in completing one of the delayed intention tasks successfully appeared to be primarily attributable to retrospective memory deficits rather than prospective memory deficits. This proposition was further supported by group differences on RAVLT measures of retrospective memory. By utilising a paradigm that enables the nature of failure in performing delayed intention tasks to be identified, specific strategies for the clinical management of MS cognitive deficits can be developed.

Adult↗
PubMed2000

Age differences in explicit and implicit memory for pictures.

In the present study, the authors examined age effects in memory for nonverbal material. A picture fragment completion task was used to test explicit and implicit memory in a younger and an older group. Explicit memory was indexed by free recall of pictures, whereas implicit memory was indexed by perceptual learning (priming). Both free recall and perceptual learning performance were found to be impaired in the older group. A measure of executive functioning was found to be predictive of both explicit and implicit memory.

Adult↗
PubMed1999

The role of the family for behavioral outcome in children and adolescents following traumatic brain injury.

This study assessed the behavioral outcome of 51 children with traumatic brain injury (TBI) up to 2 years following injury. Children with severe injuries, but not those with mild or moderate injuries, were reported by parents to have a greater incidence of behavior problems following TBI. Regression analyses indicated that the presence of a partner for the primary caregiver of the child and the acute emotional reaction of the parent to the injury were both predictive of child behavioral outcome, although not by 2-year follow-up. These findings suggest that parental coping resources may impact on the development of child behavioral sequelae following TBI, emphasizing the role of the family in the child's response and the importance of supportive intervention.

Adolescent↗
PubMed1998

Autoradiographic identification of kidney angiotensin IV binding sites and angiotensin IV-induced renal cortical blood flow changes in rats.

The present investigation initially determined that specific binding sites for the hexapeptide angiotensin IV (AngIV) are present in the rat kidney cortex and outer medulla but not in the inner medulla, using in vitro autoradiographic techniques. This binding site has been termed AT4, is distinct from the previously characterized AT1 and AT2 sites, and does not bind the specific AT1 receptor antagonist DuP753 or the AT2 receptor antagonist PD123177. Renal artery infusions of AngIV produced a dose-dependent increase in cortical blood flow without altering systemic blood pressure. In contrast, the infusion of angiotensin II (AngII) induced a dramatic decrease in cortical blood flow, accompanied by a significant elevation in systemic blood pressure. The infusion of [D-Val(1)]AngIV, an analog that does not bind at the AT4 receptor site, and the C-terminal truncated analogs AngIV (1-4) and AngIV (1-5) that possess lower affinity for this site, produced no change in cortical blood flow. The infusion of [Nle1]AngIV and [Lys1]AngIV, analogs that bind with high affinity at the AT4 receptor site, produced increases in cortical blood flow with no influence on blood pressure. Pretreatment with a specific AT4 receptor antagonist, Divalinal-AngIV, completely blocked AngIV-induced elevations in blood flow, but failed to influence AngII-induced decreases in blood flow, suggesting that these ligands are acting at different receptor sites. Pretreatment with the nitric oxide synthase inhibitor, NG-Monomethyl-L-Arginine, also blocked subsequent AngIV-induced increases in cortical blood flow. These data support the notion that AngIV exerts a unique influence upon renal hemodynamics via the AT4 receptor subtype, and suggest that AngIV-induced elevations in blood flow may be mediated by nitric oxide.

Amino Acid Sequence↗
PubMed1998

Delayed language onset as a predictor of clinical symptoms in pervasive developmental disorders.

DSM-IV states that Asperger Disorder may be distinguished from Autistic Disorder by a lack of a delay in early language development. The aim of this study was to establish whether the presence or absence of early language delay would predict autistic symptomatology in children diagnosed with a PDD/autism spectrum disorder. Forty-six language-delayed and 62 normal language onset individuals (M age 11 years) were compared on ICD-10 research criteria and DSM-IV criteria, receptive language, and developmental history variables. Retrospective data were also obtained to determine whether language onset predicted autism symptomatology when young (< 6 years). We found that early language delay predicts more autistic symptomatology when young, but not at an older age. Early language delay is also associated with developmental motor milestone delays and lower receptive language abilities. The results question the use of early language delay as a valid discriminating variable between PDD subgroups.

Adolescent↗
PubMed1998

Are there subgroups within the autistic spectrum? A cluster analysis of a group of children with autistic spectrum disorders.

Comprehensive data on the developmental history and current behaviours of a large sample of high-functioning individuals with diagnoses of autism, Asperger's syndrome, or other related disorder were collected via parent interviews. This provided the basis for a taxonomic analysis to search for subgroups. Most participants also completed theory of mind tasks. Three clusters or subgroups were obtained; these differed on theory of mind performance and on verbal abilities. Although subgroups were identified which bore some relationship to clinical differentiation of autistic, Asperger syndrome, and Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS) cases, the nature of the differences between them appeared strongly related to ability variables. Examination of the kinds of behaviours that differentiated the groups suggested that a spectrum of autistic disorders on which children differ primarily in term of degrees of social and cognitive impairments could explain the findings.

Adolescent↗
PubMed1997

Contamination of diagnostic ophthalmic solutions in primary eye care settings.

Pharmaceutical agents and irrigating solutions are widely used in both optometric and ophthalmologic practices. Contamination of these containers or solutions could possibly pose some risk of infection to a patient. We set out to investigate the possible contamination of a representative sample of these containers in small office practices. Representative bottles of two diagnostic pharmaceutical agents and an irrigating solution were obtained from primary care optometric and ophthalmologic practices in the San Francisco-Oakland Bay area. These bottles were tested to investigate the rate of contamination and to identify the types of microorganisms in the contaminated solutions. Sixty total samples (proparacaine, tropicamide, and an irrigating solution) were randomly cultured, and 11.7% of the samples showed contamination. Pseudomonas cepacia, Staphylococcus epidermidis, Pseudomonas putida, and Streptococcus species were the predominant organisms isolated from the contaminated bottles. In addition, 17 of the original 60 containers were further cultured for investigation of the dried residue particles around the threads of the containers. Of these 17 containers, 13 (76.5%) tested positive for Staphylococcus and Micrococcus species.

Ambulatory Care Facilities↗
PubMed1997

Predictors and indicators of academic outcome in children 2 years following traumatic brain injury.

Within the context of a longitudinal study investigating outcome for children following traumatic brain injury, this paper reports on the utility of neuropsychological testing in predicting academic outcome in children 2 years following traumatic brain injury (TBI). Twenty-nine school-age children who were admitted to hospital after TBI were assessed with a battery of neuropsychological and academic measures at 3 and 24 months postinjury. The neuropsychological battery included measures of memory, learning, and speed of information processing. Academic outcome was assessed in terms of post-TBI change in school placement. According to logistic regression analysis, change in placement from regular to special education at 2 years post-TBI was predicted by injury severity and by neuropsychological performance at 3 months post-TBI. Findings suggest that neuropsychological testing is useful in identifying children with special educational needs subsequent to TBI.

Adolescent↗
PubMed1996

Comparison of clinical symptoms in autism and Asperger's disorder.

OBJECTIVE: To determine what clinical symptoms clinicians have been using to distinguish between Asperger's disorder (AsD) and autistic disorder (AD). METHOD: Parents of children and adolescents with high-functioning AD (n = 48) and AsD (n = 69) were given a structured interview based on DSM-III-R and ICD-10 diagnostic criteria. Information regarding early and current symptom presentation and family, developmental, and verbal mental age information were collected. Logistic regression analyses were conducted to determine which variables best predicted clinician's diagnosis. RESULTS: A number of clinical variables predicted diagnosis. Delayed language onset was the only variable of the family and developmental variables that predicted diagnosis. The AsD group was also significantly higher than the AD group in verbal mental age. CONCLUSION: Clinicians appear to be diagnosing AsD and AD on the basis of published research and case study accounts. The findings question whether DSM-IV and ICD-10 criteria adequately describe the AsD individual, particularly in the communication domain.

Adolescent↗