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D Black

Publications and source records attributed to D Black.

At least 109 records · Page 6Linked to original sources
PubMed1996

Comparison of semiquantitative visual and quantitative morphometric assessment of prevalent and incident vertebral fractures in osteoporosis The Study of Osteoporotic Fractures Research Group.

The assessment of radiographs for vertebral fractures is important in the clinical evaluation of patients with suspected osteoporosis, in the epidemiological evaluation of elderly populations, and in clinical trials of osteotrophic drugs. The purpose of this study is to compare visual semiquantitative (SQ) approaches and quantitative morphometric approaches for assessing prevalent and incident vertebral fractures in postmenopausal osteoporosis. We analyzed lateral thoracolumbar spine radiographs (baseline and approximately 3.5 year follow-up) of 503 women (age > or = 65) randomly selected from the Study of Osteoporotic Fractures (SOF) population. SQ assessment by an experienced radiologist graded vertebral fractures from 0 (normal) to 3 (severe). Incident fractures by SQ were defined as an increase of > or = 1 grade on follow-up radiographs. Trained research assistants visually triaged women as normal, uncertain, or probably fractured and visually flagged vertebrae with moderate/severe (grade > or = 2) prevalent fractures or with any (grade > or = 1 change) incident fracture. The radiographs were also digitized by research assistants, and quantitative morphometry (QM) was used to classify vertebral deformities at several cut-offs based on standard deviation (SD) reductions in height ratios from normal means, e.g., QM > or = 3 SD. Incident fractures by QM were defined as a decrease in height of more than 15% (QM15) on follow-up radiographs. Finally, a combination of these methods was used to detect moderate/severe prevalent fractures and any grade of incident fractures. In the overall analysis, the prevalence of fractures varied from 14 to 33% and the incidence from 5 to 10% by woman, depending upon the method and cut-off criteria. In the detailed analysis, considering visually triaged uncertain as abnormal, triage by research assistants detected 97.0% (163/168) of women with SQ grade > or = 1 fractures and 100% (70/70) with SQ grade > or = 2 fractures. Visual flagging by research assistants detected 88.5% (108/122) of SQ > or = 2 prevalent fractures (kappa score, kappa = 0.82) and 85.2% (52/61) of SQ incident fractures (kappa = 0.79). QM > or = 3 SD detected 37.9% (141/372) of SQ > or = 1 prevalent fractures (kappa = 0.51) and 79.5% (97/122) of SQ > or = 2 prevalent fractures (kappa = 0.68), plus 18 vertebrae without SQ fractures. QM 15 detected 59% (36/61) of SQ incident fractures (kappa = 0.70), plus five vertebrae without SQ incident fractures. The combination assessment detected 92% (112/122) of SQ > or = 2 prevalent fractures (kappa = 0.76) and 84% (51/61) of SQ incident fractures (kappa = 0.91). The precision errors of QM vertebral height measurements (baseline versus follow-up) ranged from 2.71 to 2.92%. Nevertheless, excluding the 5719 vertebrae that were clearly normal by morphometry, i.e., within 2 SD of the normal means at both baseline and follow-up, two-thirds (358/556) of the remaining vertebrae changed classification by at least 1 SD category. Visual triage and visual flagging by research assistants appear to be highly effective methods for vertebral fracture assessment in osteoporosis, potentially reducing the number of false-positive and false-negative fractures detected by QM, at least relative to SQ by the radiologists. There is higher concordance among the visual approaches studied than between the visual SQ and quantitative morphometric approaches, with QM having limited ability to detect mild fractures but good ability to detect moderate/severe fractures, as classified by SQ. Use of a combination of sensitive qualitative and quantitative criteria, with adjudication by an experienced radiologist, is feasible and draws upon the relative strengths of each of the methods. Quantitative morphometry should not be performed in isolation, particularly when applying highly sensitive morphometric criteria at low threshold levels, without visual assessment to confirm the detected prevalent or incident vertebral defor

Aged↗
PubMed1996

Normal ranges for vertebral height ratios and prevalence of vertebral fracture in Hong Kong Chinese: a comparison with American Caucasians.

We have established the normal ranges for vertebral height ratios and studied the prevalence of vertebral fracture in 481 Chinese women aged 70-79. Our results were compared with those of an American study with a similar methodology. Lateral spine radiographs centered at T8 and L3 were taken, and the anterior, middle, and posterior vertebral heights of each vertebra from T5 to L4 were measured. The means and standard deviations (SDs) of the anterior to posterior, middle to posterior, and posterior to posterior vertebral height ratios were derived after trimming the extreme values from the distribution. The Chinese had smaller vertebral size than the American Caucasians at all levels. Moreover, the anterior to posterior vertebral height ratios were consistently smaller in the Chinese than in the Americans from T10 onward. The means of other vertebral height ratios in the Chinese were similar to the American Caucasians, but the SDs were greater in the Chinese. The prevalence of vertebral fracture was 29% in the Chinese and 25% in the American Caucasians if a cut-off of 3 SD below the mean for vertebral height ratios was used. We conclude that population-specific means and SD should be used for defining vertebral fracture and that the prevalence of vertebral fracture is similar in Hong Kong Chinese and American Caucasians.

Aged↗
PubMed1996

Characterization of virus-specific and cross-reactive monoclonal antibodies to Herpesvirus simiae (B virus).

A panel of 13 monoclonal antibodies (MAbs) was produced that detect B virus (BV) proteins. Several of these MAbs were highly specific for BV, while the remainder cross-reacted in varying degrees with the other primate alphaherpesviruses. Utilizing western blot and radioimmunoprecipitation analysis, the MAbs were found to detect at least four distinct BV-infected cell antigens, several of which were composed of multiple polypeptides. One target antigen has been identified as the BV glycoprotein B (gB) homologue and was recognized by both virus-specific and cross-reactive MAbs. Although gB is an essential protein, none of the anti-gB MAbs neutralized infectious virus.

Animals↗
PubMed1996

Attitudes and knowledge about case mix reform among hospital staff in Australia.

This paper reports some of the findings of a national survey of staff in acute care hospitals about their knowledge of case mix and their attitudes towards it. Our findings suggest that, despite the range and scope of activities that have been pursued under the Australian Casemix Development Program (ACDP), knowledge of case mix among acute care hospital staff remains patchy. The evidence also shows that significant aspects of the DRG classification system and the uses to which it can be put are not accepted by many hospital staff, particularly medical staff. The paper concludes with a discussion of what some of these findings imply for future activity on case mix reform.

Allied Health Personnel↗
PubMed1996

Effect of acute feeding of diets of varying fatty acid composition on intestinal apolipoprotein expression in the newborn swine.

The purpose of this study was to determine the effects of dietary fatty acids of varying chain lengths and degrees of saturation on intestinal apolipoprotein (apo) B and A-I expression in the newborn piglet. Two-day-old female piglets received one of three isocaloric formulas containing 48% of total calories (120 kcal/kg/24 h) as medium-chain triglycerides (MCT) from MCT oil, intermediate-chain saturated triglycerides (ICST) from coconut oil, or long-chain polyunsaturated triglycerides (LCPUT) from safflower oil by continuous duodenal infusion for 24 h. After in situ radiolabeling, jejunal and ileal mucosal apo B-48 and A-I were immunoprecipitated, and synthesis was expressed as percentage of total protein synthesis. Mucosal apo B and A-I mass was measured by ELISA as nanograms of apoprotein/microgram of total protein. Fifty percent less apo B jejunal synthesis was present in the ICST group versus the MCT and LCPUT groups (0.67 +/- 0.07, 1.19 +/- 0.20, and 1.25 +/- 0.15, respectively, mean +/- SEM, p < 0.05). Jejunal apo B mass was lower in the MCT group versus the ICST and LCPUT groups (0.10 +/- 0.02, 0.21 +/- 0.03, and 0.16 +/- 0.03, respectively, p < 0.05). Ileal apo B synthesis was lowest in the ICST group. No differences were found in ileal apo B mass. Two-fold higher jejunal apo A-I synthesis was found in the LCPUT group versus the MCT and ICST groups (14.18 +/- 1.69, 7.56 +/- 2.63, and 6.36 +/- 0.58, respectively, p < 0.01). No differences were found for jejunal apo A-I mass. In the ileum, the only difference was a higher apo A-I mass in the LCPUT group (p < 0.05). We conclude that in the newborn piglet intestinal apo B and A-I expression is acutely and differentially regulated by dietary lipid varying in fatty acid chain length and saturation. The patterns of regulation are complex and vary among specific apolipoproteins and regions of the small intestine and include co- and posttranslational mechanisms.

Animals↗
PubMed1995

A comparison of conservative and aggressive transfusion regimens in the perioperative management of sickle cell disease. The Preoperative Transfusion in Sickle Cell Disease Study Group.

BACKGROUND: Preoperative transfusions are frequently given to prevent perioperative morbidity in patients with sickle cell anemia. There is no consensus, however, on the best regimen of transfusions for this purpose. METHODS: We conducted a multicenter study to compare the rates of perioperative complications among patients randomly assigned to receive either an aggressive transfusion regimen designed to decrease the hemoglobin S level to less than 30 percent (group 1) or a conservative regimen designed to increase the hemoglobin level to 10 g per deciliter (group 2). RESULTS: Patients undergoing a total of 604 operations were randomly assigned to group 1 or group 2. The severity of the disease, compliance with the protocol, and the types of operations were similar in the two groups. The preoperative hemoglobin level was 11 g per deciliter in group 1 and 10.6 g per deciliter in group 2. The preoperative value for hemoglobin S was 31 percent in group 1 and 59 percent in group 2. The most frequent operations were cholecystectomies (232), head and neck surgery (156), and orthopedic surgery (72). With the exception of transfusion-related complications, which occurred in 14 percent of the operations in group 1 and in 7 percent of those in group 2, the frequency of serious complications was similar in the two groups (31 percent in group 1 and 35 percent in group 2). The acute chest syndrome developed in 10 percent of both groups and resulted in two deaths in group 1. A history of pulmonary disease and a higher risk associated with surgery were significant predictors of the acute chest syndrome. CONCLUSIONS: A conservative transfusion regimen was as effective as an aggressive regimen in preventing perioperative complications in patients with sickle cell anemia, and the conservative approach resulted in only half as many transfusion-associated complications.

Adolescent↗
PubMed1995

Physical mapping, cloning, and identification of genes within a 500-kb region containing BRCA1.

BRCA1 is a breast/ovarian cancer susceptibility gene on human chromosome 17q21. We describe a complete and detailed physical map of a 500-kb region of genomic DNA containing the BRCA1 gene and the partial cloning in phage P1 artificial chromosomes. Approximately 70 exons were isolated from this region, 11 of which were components of the BRCA1 gene. Analysis of the other exons revealed a rho-related G protein and the interferon-induced leucine-zipper protein IFP-35.

Amino Acid Sequence↗
PubMed1995

Risk factors for hip fracture in white women. Study of Osteoporotic Fractures Research Group.

BACKGROUND: Many risk factors for hip fractures have been suggested but have not been evaluated in a comprehensive prospective study. METHODS: We assessed potential risk factors, including bone mass, in 9516 white women 65 years of age or older who had had no previous hip fracture. We then followed these women at 4-month intervals for an average of 4.1 years to determine the frequency of hip fracture. All reports of hip fractures were validated by review of x-ray films. RESULTS: During the follow-up period, 192 women had first hip fractures not due to motor vehicle accidents. In multivariable age-adjusted analyses, a maternal history of hip fracture doubled the risk of hip fracture (relative risk, 2.0; 95 percent confidence interval, 1.4 to 2.9), and the increase in risk remained significant after adjustment for bone density. Women who had gained weight since the age of 25 had a lower risk. The risk was higher among women who had previous fractures of any type after the age of 50, were tall at the age of 25, rated their own health as fair or poor, had previous hyperthyroidism, had been treated with long-acting benzodiazepines or anticonvulsant drugs, ingested greater amounts of caffeine, or spent four hours a day or less on their feet. Examination findings associated with an increased risk included the inability to rise from a chair without using one's arms, poor depth perception, poor contrast sensitivity, and tachycardia at rest. Low calcaneal bone density was also an independent risk factor. The incidence of hip fracture ranged from 1.1 (95 percent confidence interval, 0.5 to 1.6) per 1,000 woman-years among women with no more than two risk factors and normal calcaneal bone density for their age to 27 (95 percent confidence interval, 20 to 34) per 1,000 woman-years among those with five or more risk factors and bone density in the lowest third for their age. CONCLUSIONS: Women with multiple risk factors and low bone density have an especially high risk of hip fracture. Maintaining body weight, walking for exercise, avoiding long-acting benzodiazepines, minimizing caffeine intake, and treating impaired visual function are among the steps that may decrease the risk.

Aged↗
PubMed1995

Bone mass measurements and risk of fracture in Caucasian women: a review of findings from prospective studies.

Prospective studies have shown that bone mass, measured by any method and at any site, is inversely related to a woman's risk of fracture. Most types of fractures are more frequent in women with low bone mass. Bone mineral density measured in the proximal femur appears to have a stronger relationship to risk of hip fracture than bone density measured in other sites. On the other hand, measurement of bone mass in the spine does not appear to be substantially superior to measurements of bone mass in other sites. Even after age 80, bone mass measurements have a strong predictive value for most types of fracture. A woman's lifetime risk of hip fracture can be estimated from bone mass measurements made in the perimenopausal period. Although an individual's level of bone mass may vary from site to site, the incremental value of measuring bone mass in more than one site is not certain. Bone mass measurements, perhaps in combination with other risk factors for fracture, help define individuals with a high risk of fracture who stand to benefit most from efforts to prevent fractures.

Absorptiometry, Photon↗
PubMed1995

Estrogen replacement therapy and fractures in older women. Study of Osteoporotic Fractures Research Group.

OBJECTIVE: To determine the relation between estrogen replacement therapy and fractures. DESIGN: Prospective cohort study. SETTING: Four clinical centers in Baltimore County, Maryland; Minneapolis, Minnesota; Portland, Oregon; and the Monongahela Valley, Pennsylvania. PARTICIPANTS: 9704 ambulatory, nonblack women 65 years of age or older. MEASUREMENTS: Estrogen use, medical history, and anthropometric data were obtained by questionnaire, interview, and examination. Appendicular bone mass was measured by single-photon absorptiometry. Incident fractures were validated by radiographic report. RESULTS: After adjustment for potential confounders, current estrogen use was associated with a decrease in the risk for wrist fractures (relative risk [RR], 0.39; 95% CI, 0.24 to 0.64) and for all nonspinal fractures (RR, 0.66; CI, 0.54 to 0.80) when compared with no estrogen use. Results were similar for women using unopposed estrogen or estrogen plus progestin, for women younger or older than 75 years of age, and for current smokers or nonsmokers. The effect of estrogen remained after adjustment was made for appendicular bone mass. The relative risk for hip fracture tended to be lower among current users (RR, 0.60; CI, 0.36 to 1.02) than among never-users. Estrogen was most effective in preventing hip fracture among those older than 75 years. Current users who started estrogen within 5 years of menopause had a decreased risk for hip fractures (RR, 0.29; CI, 0.09 to 0.92), wrist fractures (RR, 0.29; CI, 0.13 to 0.68), and all nonspinal fractures (RR, 0.50; CI, 0.36 to 0.70) when compared with women who had never used estrogen. Previous use of estrogen for more than 10 years or use begun soon after menopause had no substantial effect on the risk for fractures. CONCLUSIONS: Current use of estrogen appears to decrease the risk for fracture in older women. These results suggest that for protection against fractures, estrogen should be initiated soon after menopause and continued indefinitely.

Age Factors↗
PubMed1995

Body composition and bone mineral density in premenopausal and early perimenopausal women.

Body composition appears to be an important determinant of bone mineral density (BMD). BMD at the femoral neck, lumbar spine, and whole-body and the whole-body soft-tissue composition were measured cross-sectionally in 334 healthy premenopausal and early perimenopausal women, aged 44-50 years, using a Hologic QDR densitometer. Correlations between lean mass and BMD at the hip, spine, and whole-body were greater (r = 0.40, r = 0.44, and r = 0.45, respectively, p < 0.0001) than those for fat mass (r = 0.19, r = 0.16, and r = 0.16, respectively, p < 0.01). There was a significant linear trend in femoral BMD from the lowest to highest category of lean mass (0.75 +/- 0.10 g/cm2, 0.80 +/- 0.10 g/cm2, and 0.86 +/- 0.09 g/cm2, p < 0.0001). Similar trends were demonstrated for spinal and whole-body density. For categories of fat mass, there was a significant linear trend at the hip (0.78 +/- 0.10 g/cm2, 0.79 +/- 0.10 g/cm2, and 0.83 +/- 0.10 g/cm2, p = 0.0106), but not at the spine or whole body. There was a 5.00% (3.62, 6.38; 95% confidence limits) difference in hip BMD per unit (standard deviation) of lean mass, while only a 0.73% (-0.66, 2.11) difference in hiP BMD per unit (SD) of fat mass. Differences in BMD were examined by categories of lean and fat mass (low, medium, high) for a total of nine possible combinations of lean and fat measures. BMD at the hip, spine, and whole-body were significantly higher in those with high lean mass than in those with low lean mass, irrespective of fat mass. Women with high lean/low fat had similar hip, spinal, and whole-body BMD as those with high lean/high fat, despite their significantly lower body weight (62.5 +/- 3.3 kg vs 85.7 +/- 5.4 kg, respectively, p < 0.0001). In premenopausal and early perimenopausal women, body weight alone may not be associated with increased bone mass unless a significant proportion of that weight is comprised of lean mass. The stronger association between lean mass and BMD than that for fat mass may be attributed to differences in determinants of lean mass, such as exercise, lifestyle factors, estrogen levels, or a combination of these factors.

Adult↗
PubMed1995

Which vertebrae should be assessed using lateral dual-energy X-ray absorptiometry of the lumbar spine.

The purpose of this study was to determine precision and diagnostic capability of bone mineral density measurements using lateral dual-energy X-ray absorptiometry (DXA) of the lumbar spine in supine position. Duplicate postero-anterior (PA) and lateral DXA measurements were performed in 60 women. Precision errors of the single vertebral levels using lateral DXA ranged from 3.3% to 4.9%. The combination of all levels improved the precision errors to 2.0%. Paired PA and lateral DXA measurements (Hologic QDR 2000) including the vertebral levels L2 to L4 were performed in 331 postmenopausal women. In 42 women an overlap of L4 by the pelvis was suspected on the lateral DXA images. Vertebral fractures were assessed as a fracture/non-fracture dichotomy. L4 and combinations of vertebrae including L4 showed the best discriminatory capabilities with respect to vertebral fractures in receiver operating characteristic (ROC) analyses, t-tests and Z-scores, with smaller variability of the results when multiple vertebral levels were used. The areas under the ROC curves were 0.662 and 0.639 for lateral and PA measurements of L2 to L4, respectively when all women were included. Excluding the women with pelvic overlap on lateral DXA scans improved the ROC area for lateral scans to 0.686 while that for PA scans remained almost constant (0.641). The differences between PA and lateral measurements were not statistically significant. In 162 women of our study cohort an additional quantitative computed tomography (QCT) measurement of the vertebral levels L2 to L4 was performed and overlapping bony structures at the three levels were studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1995

Myoclonic-like finger microdisplacements in patients with cerebellar deficits.

BACKGROUND: Here we assess the ability of patients with cerebellar disease to execute a simple visually-guided movement task involving tracking of a target with the index finger. METHODS: Spontaneous microdisplacements in index finger position are compared in patients with cerebellar deficits (ischemia [n = 3], multiple sclerosis [n = 3], degenerative cerebellar disease [n = 3]) and age-matched healthy subjects. Subjects were required to maintain a constant finger position relative to a stationary baseline displayed on an oscilloscope. RESULTS: Unusual transient abrupt movements (saccadic or myoclonic-like) directed with or against gravity were seen in patients whose neurological deficits were the most severe (7/9 patients). These abrupt myoclonic-like movements occurred independently of visual input, were not associated with clinically observable myoclonus, and were not detected previously in patients with Parkinson's disease. These abrupt myoclonic-like movements were not associated with abnormalities in either physiological tremor, or oscillations in finger microdisplacements induced by insertion of a delay (300-1400 ms) into the visual feedback of this finger "holding" experiment. An unexpected finding is that the results obtained for patients with cerebellar deficits by insertion of an experimental delay are not significantly different from those obtained with their age-matched controls. CONCLUSIONS: These observations suggest that abrupt myoclonic-like movements are a characteristic abnormality of patients with a variety of cerebellar deficits and emphasize the value of this simple motor tracking task for characterizing movement disorders.

Adolescent↗
PubMed1995

Embarking upon a medical career: psychological morbidity in first year medical students.

This study was undertaken to measure the prevalence of psychological morbidity, and the nature and source of stress, in first year medical students. Two hundred and four first year medical students at a university in the north of England were sent a postal, self-report questionnaire. They were asked to complete the General Health Questionnaire (GHQ), the Stress Incident Record and to give details of their alcohol consumption. A total of 172 students (84.3%) replied. Thirty-six per cent of the students scored above the threshold of the GHQ, indicating probable psychological disturbance. There was no difference between men and women. Approximately half of the students described a stressful incident, the majority of which were related to medical training rather than to personal problems. Male students reported drinking significantly more alcohol than female students, but there was no relationship between levels of alcohol consumption and either psychological disturbance or reporting of stress. The findings suggest that even at the preliminary stages of medical training, many students find aspects of the medical course very stressful. The psychological well-being of medical students needs to be more carefully addressed, and closer attention paid to the styles of medical teaching that may provoke avoidable distress.

Alcohol Drinking↗
PubMed1995

Insulin-like growth factor 1 and functional status in healthy older men.

OBJECTIVE: To determine if insulin-like growth factor 1 (IGF-1) is associated with strength and functional ability in healthy older men. DESIGN: Cross-sectional study. SETTING: San Francisco Department of Veterans Affairs Medical Center. PARTICIPANTS: One hundred four ambulatory community-dwelling men. MEASUREMENTS: Serum IGF-1 levels were obtained. Measured variables included strength of the knee flexors and extensors, handgrip, score on the Physical Performance Test, body composition, and three tests of cognitive function. RESULTS: The subjects' mean age was 75.5 +/- 4.9 (SD) years (range 70-94 years), and their mean IGF-1 level was 134.7 +/- 43.6 ng/mL. The univariate association of age with the variables was much stronger than the univariate association of IGF-1 with the same variables. In multivariable models, age, but not IGF-1, was associated with the variables. CONCLUSION: In this study of healthy older men, age is the most important variable in predicting functional decline. There was no association of IGF-1 levels to functional status independent of age.

Activities of Daily Living↗
PubMed1995

Resilience to exercise detraining in healthy older adults.

OBJECTIVE: To determine the effects of stopping and restarting two types of exercise programs in older adults. DESIGN: A controlled, longitudinal study that utilized random assignment of volunteers. Treatments were exercise programs designed to improve cardiovascular or neuromuscular fitness. MEASUREMENTS: Dependent variables measured before and after implementation of treatments were: maximum oxygen consumption, oxygen pulse, treadmill and cycle training workloads, quadriceps isokinetic peak torque, quadriceps isokinetic total work, and quadriceps training workload. MAIN RESULTS: Exercise training was highly effective in improving cardiovascular endurance or muscular strength. Ten weeks of exercise detraining resulted in small losses in newly gained cardiovascular capacity but more noticeable losses in muscular strength. Exercise retraining was accomplished easily using cardiovascular or resistive exercises. The functional benefits of restarting a cardiovascular exercise program appeared additive despite a 10-week intervening period of exercise detraining. In this age group, cardiovascular exercise produced limited improvements in muscular strength, and resistive exercise training positively influenced cardiovascular exercise performance. CONCLUSIONS: Older adults are fairly resilient to 10 weeks of cardiovascular detraining and retain newly gained muscular strength for at least 5 weeks, despite an interruption of formal exercise. An occasional missed exercise session or temporary cessation of habitual exercise should not be a cause for distress in exercising older adults. Instead, they should realize the case with which they may restart their exercise program and also appreciate the generalized fitness benefits that can be ascribed to becoming more active.

Age Factors↗