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Biomedical subjects

J M Gibson

Publications and source records attributed to J M Gibson.

At least 91 records · Page 5Linked to original sources
PubMed1994

The phosphorylation pattern of insulin-like growth factor-binding protein-1 in normal plasma is different from that in amniotic fluid and changes during pregnancy.

We have determined the phosphorylation pattern of circulating insulin-like growth factor-binding protein-1 (IGFBP-1) in normal subjects and assessed how this changes in pregnancy. Two RIAs employing different monoclonal antibodies (MAbs 6303 or 6305) were used to measure IGFBP-1. In normal subjects, RIA 6303 measured 11-fold higher levels than RIA 6305 (72.8 vs. 6.6 micrograms/L; P < 0.008). However, in amniotic fluid (AF), the two assays gave similar results. Immunoprecipitation of plasma and AF with MAb 6303 and 6305 before nonsodium dodecyl sulfate-electrophoresis and Western ligand blotting revealed different IGFBP-1 isoforms and differential antibody recognition as the cause of this discrepancy. In AF, both MAbs precipitated nonphosphorylated and phosphorylated isoforms, whereas in plasma, only a single highly phosphorylated species, not seen in AF, was observed. This form of IGFBP-1 was precipitated by MAb 6303 only. During pregnancy, the phosphorylation state of IGFBP-1 in the maternal circulation was altered, as nonphosphorylated IGFBP-1 and three lesser phosphoforms were also observed. The appearance of these other variants resulted in a significant increase in IGFBP-1 measured by RIA 6305 (37, 51, and 83 micrograms/L in first, second, and third trimesters, respectively; P < 0.0005 vs. controls). The changes in IGFBP-1 phosphorylation induced by pregnancy may influence the modulatory effects of IGFBP-1 on IGF bioavailability and, hence, fetal growth.

Adult↗
PubMed1993

Cataract and survival in an elderly nondiabetic population.

Follow-up ranging between 6 and 8 years of the survival of a cohort of 473 elderly nondiabetic subjects randomly selected from a small English town showed an age- and sex-adjusted association between nuclear cataract at the time of baseline examination and decreased survival (P = .002). Comparing those with and without nuclear cataract, the adjusted relative hazard for death was 1.52 (95% confidence interval, 1.15 to 1.99). This effect remained virtually unchanged when also adjusted for whether the subject reported ever having been a smoker.

Aged↗
PubMed1993

Population recovery capabilities of 35 cluster analysis methods.

Comparative evaluation of population recovery capabilities of 35 cluster analysis methods defined by different combinations of 5 profile similarity measures and 7 agglomeration rules was undertaken using artificial data that represented duplicate mixture samples from 4 latent populations. The latent population mean profiles differed primarily in elevation or in pattern parameters. Latent population sampling variances were controlled to provide two different levels of realistic overlap. The within-population distributions were multivariate normal with diagonal covariance structure. Across all conditions examined, complete linkage and Ward's minimum variance methods, used with Euclidian or city block interprofile distance measures, performed best. Single linkage, median, and centroid methods were substantially inferior for clustering individuals in accordance with true population memberships.

Analysis of Variance↗
PubMed1993

Typography manipulations can affect priming of word stem completion in older and younger adults.

The experiments reported here investigated whether changes of typography affected priming of word stem completion performance in older and younger adults. Across all experiments, the typeface in which a word appeared at presentation either did or did not match that of its 3-letter stem at test. In Experiment 1, no significant evidence of a typography effect was found when words were presented with a sentence judgment or letter judgment task. However, subsequent experiments revealed that, in both older and younger adults, only words presented with a syllable judgment task gave rise to the typography effect (Experiments 2-4). Specifically, performance was greater, when the presentation and test typeface matched than when they did not. Experiment 5, which used stem-cued recall, did not reveal a difference between syllable and letter judgment tasks. These findings highlight the complex nature of word stem completion performance.

Age Factors↗
PubMed1993

Spontaneous mnemonic strategies used by older and younger adults to remember proper names.

Little attention has been focused on the spontaneous mnemonic strategies that people use to remember proper names. In the experiment reported here, groups of younger (< 25 years old) and older subjects (> or = 55 years old) were shown a series of 12 name-face pairs and instructed to remember them. In a subsequent test, they were shown the same faces and asked to recall the corresponding names. After the recall task, subjects completed a questionnaire about the mnemonic strategies they used. Our analyses revealed not only that the younger subjects recalled more names than did the older subjects, but also that older and younger subjects reported using certain strategies more frequently than other strategies. Moreover, regression analyses indicated that use of certain mnemonic strategies accounted for a significant proportion of recall performance beyond that accounted for by age alone. Older-old subjects (> or = 70 years old) recalled fewer names than did younger-old subjects (> or = 55 and < 70 years old), but they did not differ in the extent to which they used specific mnemonic strategies. Our results suggest that the use of spontaneous mnemonic strategies may play a role in the difference in proper name recall between younger and older adults.

Adult↗
PubMed1992

Long-term orthodontic tooth movement response to short-term force in the rat.

Both the amount of force applied and the duration of the application affect tooth movement. To study the effect of duration, adult male Sprague-Dawley rats were fitted with orthodontic appliances delivering a 40-gm initial mesial tipping force to the maxillary molars. The animals were divided into two longitudinal groups (I: 1 hour and II: 24 hours; N = 15). Sham-treated control (III) and 14 day (IV) continuous cross-sectional force tooth movement data were also included for comparison (72 rats per group). Extraoral cephalometric radiographs were obtained at appliance placement and at 1, 3, 5, 7, 10, & 14 days. Tooth movement was determined with respect to palatal implants. ANOVA indicated significant differences existed over time in each group (p = 0.0001). Continuous force applied for 14 days generated a classic three-part tooth movement curve. Short-term forces were characterized by initial mesial movement, a distal relapse period (d3-d5), and a late mesial movement period (d7-d14). The results suggest short-term forces of 1 and 24 hours initiate remodeling events, which result in tooth movement 7 to 14 days later and that the minimum effective duration of a 40-gm activation is less than 1 hour in this animal model.

Activator Appliances↗
PubMed1992

Assessment of ethical decisions and values.

The development and pilot testing of the Professional Decisions and Values Test (PDV) is described. The PDV is designed to assess how ethical conflicts are dealt with by medical and law students and which moral values motivate them. Data from two consecutive classes of entering medical and law students are presented and their action tendencies and ethical values are compared. The findings support the construct validity of the test. Regarding reliability, stability over time is present for action tendencies but not for values. Perhaps the ethical values of entering medical and law students do not become stable until later. Change in ethical values can be studied with the PDV for groups, not individuals, during the first year of professional education.

Attitude↗
PubMed1991

Long-term follow-up of and underlying medical conditions in patients with diabetic exudative maculopathy.

Recent reports of risk factors for and survival of patients with diabetic retinopathy do not include exudative maculopathy as a separate entity. We therefore studied a group of hypertensive Type II diabetic subjects with exudative maculopathy (n = 26) compared to a carefully matched hypertensive diabetic comparison group without retinopathy (n = 26) over seven years. Diabetic maculopathy patients had higher mean diastolic blood pressure (101.6 +/- 14 versus 94.8 +/- 10 mmHg, p less than 0.05), serum cholesterol (6.65 +/- 2.2 versus 5.9 +/- 1.31 mmol/l), HDL2 subfraction levels (0.46 +/- 0.23 versus 0.32 +/- 0.18 mmol/l) and a higher prevalence of hyperlipidaemia (54% versus 35%) compared to the comparison group. After seven years, the maculopathy group showed a strikingly higher prevalence of renal failure and nephrotic syndrome (42% versus 8%, p less than 0.05) and of macroproteinuria (58% versus 15%, p less than 0.01) compared to the comparison group. Mortality and cardiovascular disease event rate was 12% and 38% in the maculopathy and 15% and 31% respectively in the comparison group. We conclude that although mortality is not significantly higher in diabetics with exudative maculopathy, proteinuria, renal failure and nephrotic syndrome may be associated features on long term follow-up. Hypertension and hypercholesterolaemia may also be risk factors in the development of diabetic maculopathy.

Adult↗
PubMed1991

Electroretinography as a prognostic indicator or neovascularisation in CRVO.

A prospective study was carried out to compare the efficacy of electroretinography, fundus fluorescein angiography and clinical examination in identifying those at risk of rubeotic glaucoma following central retinal vein occlusion (CRVO). Our preliminary observations are described. The findings suggest a complementary role for electroretinography in the management of CRVO. Particularly significant were interocular differences in 30 Hz flicker latency, the ability to elicit pattern ERGs and the ratio of scotopic and photopic a:b wave amplitudes. Of the clinical measures the depth of the relative afferent pupil defect was a sensitive indicator of rubeosis. Factors of lesser statistical prognostic value included poor visual acuity and the extent of deep retinal haemorrhages. Fundus fluorescein angiography in this study had limited value in predicting those patients at risk of rubeosis.

Electroretinography↗
PubMed1991

Anti-Kell in pregnancy.

A review of data on haemolytic disease of the newborn (HDN) collected in Newcastle upon Tyne over 25 years revealed 194 pregnancies in which anti-Kell was the only antibody detected. Sixteen affected babies were born. None was hydropic, three had very severe disease but all survived. There were also three stillbirths, none of which had post-mortem appearances of HDN. The highest recorded anti-Kell titres in individual patients ranged from 1/1 to 1/2048 and bore no relation to the severity of the disease. Of the eight pregnancies in which amniotic fluid examination predicted a high risk of stillbirth, half resulted in unaffected babies. We suggest that haemolytic disease caused by anti-Kell is less severe than suggested by some workers. The use of guidelines developed from the study of Rhesus disease to determine the need for intervention in women with anti-Kell may be inappropriate.

Amniotic Fluid↗