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Biomedical subjects

G Blake

Publications and source records attributed to G Blake.

At least 19 recordsLinked to original sources
PubMed1998

Insulin-like growth factor-I and bone mineral density.

To assess the relationship between insulin-like growth factor-I (IGF-I) and bone mineral density (BMD) 201 healthy postmenopausal women (age 41-68 years) within 10 years of menopause were studied. In all subjects, BMD at the lumbar spine and left hip were measured using dual-energy X-ray absorptiometry and blood samples were obtained. In all subjects, serum IGF-I and parathyroid hormone (PTH) were measured. In a subgroup of these subjects serum concentrations of IGF-binding protein-3 (IGFBP-3), osteocalcin (OC), bone-specific alkaline phosphatase (BALP), tartrate-resistant acid phosphatase (TRAP), and carboxyterminal propeptide of type I procollagen (PICP) were also measured. Serum IGF-I correlated significantly with age (r = -0.159, p = 0.0241), serum OC (r = 0.226, p = 0.0131), BALP (r = 0.259, p < 0.0001), and TRAP (r = 0.261, p < 0.0015), but not with PICP, PTH, or BMD at any site. Although there was a strong correlation between IGF-I and IGFBP-3 (r = 0.559, p < 0.0001), there was no correlation between IGFBP-3 and any of the markers of bone turnover (OC, BALP, TRAP, or PICP) nor with PTH or BMD at any site. We conclude that IGF-I and markers of bone turnover are related, but there is no relationship between IGF-I and BMD.

Absorptiometry, Photon↗
PubMed1998

Angiomyofibroblastoma--a rare but distinct entity.

A case of angiomyofibroblastoma of the vulva in a 23-year-old woman is presented. Clinical, histological and immunohistochemical features as well as the differential diagnosis and prognosis of this rare but distinct entity are discussed. Only about 65 cases are documented in the literature and to our knowledge this is the first case to be reported from the Caribbean.

Adult↗
PubMed1997

Bone mineral density in professional female dancers.

OBJECTIVES: To measure the long term effects of dance training and the contribution of the timing and duration of any menstrual disruption on bone mineral density (BMD). DESIGN: Measurement of BMD in 57 premenopausal, previously professionally dance trained women and the relationship to menstrual and training history. MAIN OUTCOME MEASURES: Bone density measurements at lumbar spine and femoral neck by dual energy x-ray absorptiometry. RESULTS: The average Z score for BMD at the lumbar spine in the amenorrhoeic dancers was significantly below that for the normal population. The average Z score for BMD at the femoral neck in the eumenorrhoeic dancers was significantly above that for the normal population. There was a significant difference between the average Z score for BMD at both the lumbar spine and femoral neck between the amenorrhoeic and eumenorrhoeic dancers. Significant negative relationships were found between BMD at the lumbar spine and (1) age at menarche, (2) duration of amenorrhoea, (3) BMD at the femoral neck, and (4) the variable of ideal minus lowest weight, which was independent of amenorrhoea. No significant relationships were found between duration of oral contraceptive pill usage and BMD at either the lumbar spine or the femoral neck in eumenorrhoeic or amenorrhoeic dancers. In order to quantify the effect of a combination of these significant factors, a model of BMD was constructed using multiple regression incorporating the variables duration of amenorrhoea, age at menarche, and ideal minus lowest body weight. In this model R2 was 33.6%, in other words 33.6% of the total variation in the Z score for BMD at the lumbar spine could be accounted for by these factors. CONCLUSION: Professional female dancers with a history of delayed menarche and amenorrhoea have been identified as another group of premenopausal women potentially at risk of developing osteoporosis because of a decrease in BMD at the lumbar spine. The femoral neck in dancers with a history of amenorrhoea was partially protected from loss of BMD by virtue of being the major weight bearing site in previous dance training, and in eumenorrhoeic dancers BMD was significantly increased at this site.

Absorptiometry, Photon↗
PubMed1996

Reduced bone density and osteoporosis associated with a polymorphic Sp1 binding site in the collagen type I alpha 1 gene.

Osteoporosis is a common disease with a strong genetic component, characterized by reduced bone mass and increased fracture risk. Current evidence suggests that the inheritance of bone mass is under polygenic control but the genes responsible are poorly defined. Type I collagen is the major protein of bone encoded by the COLIA1 and COLIA2 genes. While these are strong candidates for the genetic regulation of bone mass, no abnormality of either gene has so far been defined in osteoporosis. In this study, we describe a novel G-->T polymorphism in a regulatory region of COLIA1 at a recognition site for the transcription factor Sp1(7) that is significantly related to bone mass and osteoporotic fracture. G/T heterozygotes at the polymorphic Sp1 site (Ss) had significantly lower bone mineral density (BMD) than G/G homozygotes (SS) in two populations of British women and BMD was lower still in T/T homozygotes (ss). The unfavourable Ss and ss genotypes were over-represented in patients with severe osteoporosis and vertebral fractures (54%), as compared with controls (27%), equivalent to a relative risk of 2.97 (95% confidence interval 1.63-9.56) for vertebral fracture in individuals who carry the 's' allele. While the mechanisms that underlie this association remain to be defined, the COLIA1 Sp1 polymorphism appears to be an important marker for low bone mass and vertebral fracture, raising the possibility that genotyping at this site may be of value in identifying women who are at risk of osteoporosis.

Binding Sites↗
PubMed1995

Accurate assessment of precision errors: how to measure the reproducibility of bone densitometry techniques.

Assessment of precision errors in bone mineral densitometry is important for characterization of a technique's ability to detect longitudinal skeletal changes. Short-term and long-term precision errors should be calculated as root-mean-square (RMS) averages of standard deviations of repeated measurements (SD) and standard errors of the estimate of changes in bone density with time (SEE), respectively. Inadequate adjustment for degrees of freedom and use of arithmetic means instead of RMS averages may cause underestimation of true imprecision by up to 41% and 25% (for duplicate measurements), respectively. Calculation of confidence intervals of precision errors based on the number of repeated measurements and the number of subjects assessed serves to characterize limitations of precision error assessments. Provided that precision error are comparable across subjects, examinations with a total of 27 degrees of freedom result in an upper 90% confidence limit of +30% of the mean precision error, a level considered sufficient for characterizing technique imprecision. We recommend three (or four) repeated measurements per individual in a subject group of at least 14 individuals to characterize short-term (or long-term) precision of a technique.

Absorptiometry, Photon↗
PubMed1995

Residents' formal knowledge acquisition and preferred learning styles.

BACKGROUND: Many family practice residency programs use the Myers-Briggs Type Indicator (MBTI) in their educational programs. Our purpose was to study the relationship between learning style, as determined by MBTI personality preferences, and residents' cognitive knowledge acquisition, measured by in-service training examination (ISTE) scores during the first and third years of residency. METHODS: We evaluated 36 residents using both their first- and third-year ISTE composite scores and their MBTI scores. ISTE scores were analyzed according to the MBTI personality factors. We used the Wilcoxon Rank-Sum Test to determine the association between the improvement in residents' ISTE scores between the first- and third-year examinations and preferred learning styles. RESULTS: Significant differences were found on the composite ISTE scores for the thinking/feeling and judgment/perception scales. Feelers increased ISTE scores more than thinkers (P = .031); judgers increased ISTE scores more than perceivers (P = .04). CONCLUSIONS: Results do not support the literature or current MBTI learning theory. Intuitive residents demonstrated no advantage over sensing residents. Residents using feeling/judgment as their preferred learning style acquired more knowledge over 3 years than their thinking/perceiving counterparts, as measured by ISTE scores.

Adult↗
PubMed1994

Fate of a volatile chlorinated solvent in indoor aquatic microcosms: sublethal and static exposure to [14C]dichloromethane. Groupe pour l'Etude du Devenir de Xénobiotiques dans l'Environnement (GEDEXE).

The goal of this work was to study the fate of dichloromethane in indoor aquatic microcosms after a sublethal and static exposure to simulate the accidental contamination of a lenitic ecosystem such as littoral lake zone or a pond. This kind of ecosystem is characterized by high productive capacity and rich biocoenose, and are usually first affected by acute or chronic pollution. Microcosms containing immersed bryophytes (Fontinalis antipyretica), macrophytes (Lemna minor, Groenlendia densa, Elodea canadensis), molluscs (Physa fontinalis), crustaceans (Daphnia magna), and unicellular green algae (Scenedesmus subspicatus) were contaminated with sublethal concentrations of dichloromethane or [14C]dichloromethane. The initial mean concentration was 9.9 +/- 3.7 microM. The mean concentration exposure for organisms was 4.5 +/- 1.5 microM. The fate of 14C radioactivity was monitored by measuring the radioactivity of the sediment, water, macro- and microorganism, and atmospheric compartments. Radioactivity in the water disappeared quickly from the microcosms, most likely as [14C]dichloromethane (t1/2 = 5.31 +/- 0.41 days). At the end of the experiments, radioactivity was mainly located in the atmosphere, with traces remaining in the biomass. Under static conditions, the bioaccumulation of 14C radioactivity from the radiolabeled dichloromethane was negligible.

Animals↗
PubMed1994

Age-associated risks of prophylactic anticoagulation in the setting of hip fracture.

PURPOSE: Controversy exists as to whether patient age, either independently or as a marker of concomitant illness or medication use, is associated with the dose or complication rate of warfarin prophylaxis. The aim of this study was to assess this relationship in patients receiving warfarin prophylaxis after hip fracture repair. PATIENTS AND METHODS: We undertook a retrospective cohort study of 215 patients 55 years of age or greater who underwent surgery for a fractured hip between January 1, 1990, and December 31, 1991, and received warfarin prophylaxis. The mean age was 78.9 (SD 9.5) years. The average daily warfarin dose, the decrease in hemoglobin in the postoperative period, and the rate of bleeding complications were assessed. RESULTS: Elderly patients required a significantly lower average daily warfarin dose than younger patients. This effect persisted even after controlling for the number of medical conditions, number of medications on admission, proportion of time the international normalized ration (INR) was in therapeutic range, and gender. Postoperative hemoglobin decrease was associated with patient age as well as with the use of antibiotics postoperatively. Factors associated with bleeding complications included a history of alcohol abuse and a smaller proportion of time spent in the targeted anticoagulant range. CONCLUSIONS: Older age itself and not as a marker for polypharmacy or increased number of medical conditions is associated with lower requirements for warfarin and a greater hemoglobin decrease postoperatively even when the proportion of time the INR fell within the therapeutic range is controlled. Advanced patient age, in this study, was not associated with an increased incidence of bleeding complications.

Age Factors↗
PubMed1993

A comparative view of the Myers-Briggs type indicator.

BACKGROUND AND OBJECTIVES: Many family practice residency programs use the Myers-Briggs Type Indicator (MBTI) in the process of resident advising. The purpose of this study was to validate the MBTI with an alternative personality evaluation instrument. METHODS: We evaluated 44 residents with both the MBTI and the Sixteen Personality Factor Questionnaire (16PF) and computed correlation coefficients. RESULTS: The highest correlations between the two tests were for the Extraversion/Introversion dimension of personality (r = -.71). The 16PF factors of Tough Poise, Independence, and Superego/Control were also significantly correlated with items on the MBTI. The Anxiety dimension of the 16PF yielded no significant correlations with the MBTI. CONCLUSIONS: The Extraversion/Introversion variables of the MBTI and 16PF are highly correlated. Other variables on the 16PF and MBTI are also correlated.

Adult↗
PubMed1990

Impact of bone mineral measurements on osteoporosis.

Dual photon absorptiometry enables measurement of bone mineral to be carried out at the clinically relevant sites of the spine and femur. Few would argue that it provides a powerful research tool, but defining its role in clinical practice has been somewhat more difficult. With the advent of X-ray based systems, studies can be rapidly carried out with improved precision, which has led to increased clinical interest. It is probable that this technology will be incorporated into routine use in the near future. In the present review we have addressed the role of dual photon absorptiometry in areas pertinent to osteoporosis and the direction in which recent developments are leading with regard to future research.

Absorptiometry, Photon↗
PubMed1989

Traumatic intracerebral hematoma--which patients should undergo surgical evacuation? CT scan features and ICP monitoring as a basis for decision making.

When a patient presents to the neurosurgeon with a traumatic intracerebral hematoma and has not deteriorated or developed new neurological deficit since the injury, the decision to remove the hematoma may be difficult. Of 244 patients with traumatic intracerebral hematomas, 85 were selected for intracranial pressure monitoring to assist in deciding whether surgical evacuation was indicated. None had deteriorated in conscious level or developed new neurological deficit since injury. Fifty-five patients (65%) demonstrated high intracranial pressure and underwent craniotomy. In 30 patients, intracranial pressure remained under 30 mm Hg, and their hematomas were not initially removed. Five of these 30 patients suddenly deteriorated or died 6 to 11 days after injury, with features of high intracranial pressure clinically or at postmortem. Intracranial pressure monitoring therefore failed to predict a late rise in intracranial pressure in 16.6% of those with low intracranial pressure initially. An analysis of computed tomography scanning and clinical features was therefore carried out to search for better predictors of the need for surgery. Our data suggest that basal cistern status, coma score, and the severity of edema surrounding the intracerebral hematoma should be used, in addition to intracranial pressure monitoring, to improve management of patients with traumatic intracerebral hematoma.

Adolescent↗
PubMed1989

Acute traumatic lateral patellar dislocation.

An unusual case of acute extra-articular patellar dislocation is described in which the patella dislocated laterally, rotated 90 degrees about its vertical axis, and wedged against the lateral femoral condyle. Closed reduction in the emergency department failed and operative intervention was required.

Adolescent↗
PubMed1988

Intracerebral hemorrhage in a primate model: effect on regional cerebral blood flow.

The dynamic changes in regional cerebral blood flow (rCBF), induced by a developing intracerebral hematoma, were studied in eight anesthetized monkeys. Hematomas were generated by allowing femoral arterial blood to enter the caudate nucleus via a stereotactically implanted needle. Intracranial pressure peaked at 51 +/- 8 mmHg at 3 minutes after the ictus, and remained high throughout the 3-hour procedure. Cerebral blood flow was significantly reduced in all brain regions for 1 hour after the ictus. The lowest rCBF values were recorded in the immediate clot penumbra and were below threshold levels for ischemic neuronal damage for 90 minutes after the hemorrhage.

Animals↗