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Biomedical subjects

J M Gibson

Publications and source records attributed to J M Gibson.

At least 19 recordsLinked to original sources
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↗
PubMed1991

Plasma viscosity or erythrocyte sedimentation rate in the diagnosis of giant cell arteritis?

Plasma viscosity (PV) has replaced the erythrocyte sedimentation rate (ESR) as a routine laboratory test in many hospitals. The finding of a normal PV but raised ESR in a case of biopsy proved giant cell arteritis (GCA) cast doubt on this substitution in cases of suspected GCA. To assess the equivalence of PV and ESR in the diagnosis of this disease 40 suspected cases were prospectively investigated with both tests. The correlation between the two tests was good (r = 0.742, p less than 0.0001). The substitution of one test for the other would appear to be justified in most cases of suspected GCA. In the presence of biopsy proved disease, however, the PV and ESR each produced 13.3% false negatives. These occurred both in combination with and independently of the other test showing that, when in error, the two tests may not be equivalent. In cases of doubt the performing of both PV and ESR tests together improves but does not achieve complete diagnostic accuracy. Clinical judgment based on careful assessment of all available symptoms and signs must remain the foundation of diagnosis.

Aged↗
PubMed1991

An auditory cue-depreciation effect.

An experiment is reported in which subjects first heard a list of words and then tried to identify these same words from degraded utterances. Paralleling previous findings in the visual modality, the probability of identifying a given utterance was reduced when the utterance was immediately preceded by other, more degraded, utterances of the same word. A second experiment replicated this "cue-depreciation effect" and in addition found the effect to be weakened, if not eliminated, when the target word was not included in the initial list or when the test was delayed by two days.

Acoustic Stimulation↗
PubMed1990

Infective conjunctivitis and corneal scarring in three brothers with sex linked hypogammaglobulinaemia (Bruton's disease).

The ocular findings in three brothers with Bruton's disease are reported. All three boys had purulent conjunctivitis, but the two older brothers also developed marked corneal scarring with visual impairment. Haemophilus influenzae was cultured from conjunctival swabs; it was resistant to neomycin but sensitive to chloramphenicol. Tear analysis showed that the three subjects had normal levels of lysozyme but no detectable IgA.

Agammaglobulinemia↗
PubMed1990

Excretion of a toxic dose of thallium.

We report a successfully treated case of severe thallium intoxication that required 95 days of assisted ventilation and 224 days of hospitalization. Monitoring of the patient for 500 days by measuring thallium in whole blood, serum, and urine is documented, and the role of the laboratory and utility of the measurements are considered.

Adult↗
PubMed1989

Usefulness of ophthalmoscopy in mild to moderate hypertension.

A panel of two physicians and two ophthalmologists examined 25 patients with untreated essential hypertension by direct ophthalmoscopy and assessment of fundal photographs; daytime ambulatory sphygmomanometric blood pressure monitoring, estimation of left ventricular mass by electrocardiography and two-dimensional echocardiography, and measurement of urinary microalbumin excretion were also carried out. No relation was found between blood pressure determined by clinic or ambulatory sphygmomanometry and retinopathy. The retinal features sought on fundal photographs were the percentages of arteriovenous crossings with venule nipping, venule deviation, or attenuation of venular light reflex. The ratio of arteriolar to venular diameter was measured. Only focal narrowing of arterioles was associated with higher blood pressure. There was no independent relation between retinal features and age, measures of left ventricular mass, or urinary microalbumin excretion. Assessment of arteriovenous crossing abnormalities by direct ophthalmoscopy was subject to wide variability among the panel members. Direct ophthalmoscopy was not clinically useful in the assessment of mild to moderate hypertension, whereas urinary microalbumin excretion correlated strongly with clinic blood pressure.

Adult↗