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Biomedical subjects

D E Saunders

Publications and source records attributed to D E Saunders.

At least 37 records · Page 2Linked to original sources
PubMed1995

Measurement of infarct size using MRI predicts prognosis in middle cerebral artery infarction.

BACKGROUND AND PURPOSE: An accurate measure of the severity of ischemic insult and the resulting prognosis is needed to assess the effectiveness of new treatments for acute stroke. We studied the reproducibility and accuracy of measurements of infarct volume with MRI and correlated the measurements with outcome. METHODS: Infarct volume was measured on T2-weighted images with the Analyze image analysis software. This technique was found to be highly accurate and reproducible. RESULTS: Measurements of infarct volume were found to be highly accurate and reproducible. Twenty-one patients (mean age, 66.5 years; range, 28 to 90 years) with cortical middle cerebral artery territory infarcts in whom adequate data could be obtained were studied within 72 hours from onset (mean delay to MRI, 27.5 hours; range, 5 to 72 hours). The Scandinavian Stroke Scale was used to calculate a prognostic score, and clinical outcome was assessed at 3 months. Infarct volume was found to significantly predict outcome. Mean infarct volume in the independent patients was 35.7 +/- 29.7 cm3 compared with 88.3 +/- 71.3 cm3 in dependent patients and 166.5 +/- 65.9 cm3 in dead patients (F = 10.52, P < .001). Patients with an initial infarct volume less than 80 cm3 were found to have a better outcome than those with larger infarct volumes. Secondary hemorrhage visible on MRI also predicted a poor outcome. In contrast, the Scandinavian Stroke Scale did not significantly predict outcome. CONCLUSIONS: The results demonstrate that measurement of the size of middle cerebral artery infarction with MRI is a useful tool in assessing prognosis and will have a valuable role in assessing new therapeutic agents.

Adult↗
PubMed1995

Continuing ischemic damage after acute middle cerebral artery infarction in humans demonstrated by short-echo proton spectroscopy.

BACKGROUND AND PURPOSE: Proton MR spectroscopy is a noninvasive method of monitoring in vivo metabolite concentration changes over time. The aim of this work was to study the ischemic penumbra in humans by measuring the metabolic changes that occur after a middle cerebral artery territory infarction. METHODS: Diagnostic MRI and short-echo time MR spectroscopy were performed on a 1.5-T system. Localized proton MR spectroscopy was performed within the area of cerebral infarction and in a homologous area of the contralateral hemisphere. The residual water resonance in the spectra was removed with the use of the Hankel Lanczos singular value decomposition method, after which peak area estimates were obtained by means of the variable projection time domain fitting analysis. The unsuppressed water signal was used as an internal concentration standard. Ten patients with acute middle cerebral artery infarction were studied within 28 hours of stroke onset and followed up for a period of up to 3 months. RESULTS: Significant changes were seen in the initial spectra from the infarct compared with the contralateral spectra. Lactate, a marker of anaerobic metabolism, was present within the infarct but not detected in the contralateral hemisphere. N-Acetyl aspartate, a neuronal marker, and total creatine were significantly reduced. The initial choline signal, arising from choline-containing compounds within the cell and cell membrane, remained unchanged in the infarct core compared with the contralateral hemisphere. Further reductions in N-acetyl aspartate and total creatine concentrations occurred within the first week. A fall in the lactate concentration was seen within the infarct core during the first 7 to 10 days. Similar reductions in the choline concentration were observed during this period. CONCLUSIONS: The demonstration of the continuing loss of cerebral metabolites within an infarct region suggests that further cell loss occurs up to 10 days after infarction. The continuing loss of neurons may represent continued ischemic damage after middle cerebral artery infarction.

Adult↗
PubMed1994

Magnetic resonance neurography of the median nerve.

A magnetic resonance imaging sequence, combining fat and flow suppression with T2 weighting, has been used to produce high conspicuity images of the median nerve within the carpal tunnel. Standard maximum intensity projection techniques were then used to produce three-dimensional (3D) reconstructions of the nerve. Comparison of 3D projections with the wrist in a neutral position and wrist flexed at 45 degrees depicted changes in the shape and course of the median nerve through the carpal tunnel of normal volunteers. In some cases of carpal tunnel syndrome evidence of a localized compression was observed. A 3D image of a nerve may help in the diagnosis of peripheral neuropathy and be an aid to surgery of or near major nerves.

Adult↗
PubMed1994

HIV disease. Psychosocial issues for patients and doctors.

How a patient responds to a diagnosis of HIV disease depends on personality and coping skills learned throughout life. Health care professionals are seriously challenged to meet the psychosocial needs of HIV patients and their networks of partners, families, and friends. We find great satisfaction in being able to help these patients.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Gay patients. Context for care.

Gays and lesbians are a part of our society and our practices: real people with real lives, not stereotypes. Understanding their inner world and their social milieu is the first step to providing care that is holistic and appropriate. The "coming out" process and other unique health issues are described. Guidance is provided on how to identify and relate to gay and lesbian patients.

Adaptation, Psychological↗
PubMed1993

Additive inhibition of RL95-2 endometrial carcinoma cell growth by carboplatin and 1,25 dihydroxyvitamin D3.

Responses of stage III/IV endometrial adenocarcinomas to cytotoxic agents have been partial and of short duration, results which indicate a need for new agents and therapeutic strategies. This study was undertaken to determine the effects of carboplatin and the active metabolite of vitamin D, 1,25 dihydroxyvitamin D3 (calcitriol), on the growth of RL95-2 endometrial carcinoma cells. Carboplatin is a second-generation platinum-based cytotoxic agent. Calcitriol is a biologic agent that has activity against multiple solid tumors, including ovarian carcinomas. Carboplatin inhibited the growth of RL95-2 cells in a concentration-dependent manner with maximal inhibition (78%) at 200 micrograms/ml. Calcitriol also inhibited RL95-2 growth in a concentration-dependent manner. Maximal inhibition (29%) was elicited by 80 nM calcitriol. Addition of 10-50 nM calcitriol to 5-20 micrograms/ml carboplatin resulted in improved growth inhibition. The degree of interaction between carboplatin and calcitriol was assessed using isobolographic analysis and was found to be additive at all drug concentrations and ratios examined. These results suggest that carboplatin and calcitriol each inhibit the growth of RL95-2 endometrial carcinoma cells and that the combination of these two agents acts additively to inhibit the growth of RL95-2 cells. These agents merit further investigation for their utility against endometrial carcinomas.

Adenocarcinoma↗
PubMed1993

Inhibition of c-myc in breast and ovarian carcinoma cells by 1,25-dihydroxyvitamin D3, retinoic acid and dexamethasone.

The role and regulation of the c-myc protooncogene in breast and ovarian neoplasms is receiving increased attention. The downregulation of the c-myc protooncogene by 1,25-dihydroxyvitamin D3 (calcitriol), retinoic acid (RA) and dexamethasone (Dex) is closely associated with growth inhibition in leukemic cells. Calcitriol, RA and Dex have anti-proliferative activity in breast and gynecologic carcinoma cells; however, the regulation of c-myc by these agents in breast and ovarian cancers is mostly unknown. We have addressed the regulation of c-myc in these cancers using an adaptation of a novel method which employs an immunohistochemical procedure to detect c-myc protein followed by quantification of c-myc staining with computerized image analysis. This system represents an alternative to protein product assay by Western blotting and is straightforward, rapid (1 day), can be carried out on a small scale and provides a sample size that readily facilitates statistical analysis of assay data. In MCF-7 human breast cancer cells, c-myc was suppressed 29% by 0.5 nM Dex, 45% by 0.01 nM RA and 54% by 100 nM calcitriol after 24 h of drug treatment. At the same hormone concentrations, growth was inhibited 18% by Dex, 18% by RA and 39% by calcitriol after 3 days of treatment (p < 0.05 for all hormones). Similar patterns of growth and c-myc inhibition were seen in T47D human breast cancer cells and NIH:OVCAR3 human ovarian cancer cells, with the exception of Dex in T47D cells, which caused no inhibition of c-myc or growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Western↗
PubMed1993

Proton spectroscopy in vivo.

1H magnetic resonance spectroscopy (MRS) has attracted much attention in recent years. Since the proton is the most sensitive stable nucleus for MRS, and since almost all metabolites contain hydrogen atoms, it is possible to perform a noninvasive chemical analysis on tissues deep within the body of a subject. Technical solutions to the elimination of water and lipid signals as well as resolution of the large number of potential metabolite peaks have been found. Most current work is on the brain, much of it in humans. This review begins with a consideration of these technical problems and also localization, editing, quantitation, and interpretation of spectra. Two diseases are considered in detail: cerebral ischemia (including stroke and neonatal ischemic/hypoxic injury) and cancer; a further section briefly reviews studies on other diseases. In the immediate future, 1H MRS is likely to benefit from a number of technical advances: higher field magnets, better control of gradients and eddy currents, more sophisticated radiofrequency (RF) pulses, and 1H-observe/13C-edited spectroscopy all offer potential improvements. Another major improvement will come from increased user-friendliness of clinical spectrometers and use of automated objective methods for spectroscopic data analysis.

Animals↗
PubMed1992

Receptors for 1,25-dihydroxyvitamin D3 in gynecologic neoplasms.

To determine if gynecologic malignancies are candidates for 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) therapy we measured vitamin D receptor (VDR) levels in 11 tumor specimens using a radiolabeled ligand-binding assay. VDR was demonstrated in 3 of 6 ovarian tumors and 1 of 1 uterine sarcomas, but not in endometrial tumors (2), cervical tumors (1), or Krukenberg tumors (1). Scatchard plots revealed that [3H]1,25(OH)2D3 was bound to a single class of high-affinity (Kd = 0.3 to 0.6 nM), saturable sites characteristic of authentic 1,25(OH)2D3 receptors. Specificity of binding activity for 1,25(OH)2D3, the active vitamin D3 metabolite, was demonstrated by failure of 25-hydroxy- and 24,25-dihydroxyvitamin D3 to compete effectively against 1,25(OH)2D3 binding in total cellular tumor extracts. The ovarian carcinoma cell line NIH:OVCAR3 was shown to possess VDR (binding capacity = 137 fmol/mg protein, Kd = 0.48 nM). A 3-day incubation of NIH:OVCAR3 cells with 100 nM 1,25(OH)2D3 resulted in 49% inhibition of cell growth. The growth inhibition of an ovarian carcinoma line and the observation that 36% of gynecologic tumors assayed were shown to be VDR-positive suggest that further study is warranted to delineate the mechanism and possible therapeutic aspects of 1,25(OH)2D3 action in gynecologic tumors.

Calcitriol↗
PubMed1992

Are race differences in the prevalence of hypertension explained by body mass and fat distribution? A survey in a biracial population.

Body mass and body fat distribution are important considerations in the study of hypertension. However, few studies have investigated the relationships with regards to race differences in elevated arterial pressure. A population-based sample of black and white adults was assessed by interview and physical measurement. The prevalence of hypertension (defined as 140/90 mmHg and/or medically treated) was disproportionately higher among blacks than whites. In addition, blacks had a higher prevalence of the more severe hypertension (160/95 mmHg) and hypertension with higher prevalence at earlier ages than whites. Black females had a significantly higher distribution of body mass index (BMI) than white females, while no difference was found in the distributions of males. White males had a higher distribution of waist to hip ratio (WHR) than black males, while black females had the higher values compared to white females. The prevalence of hypertension increased with BMI and WHR. Blacks maintained higher rates of hypertension after controlling for BMI and WHR, however, the margin of difference diminished when BMI and WHR was considered together. The black-white difference in hypertension was not completely explained by BMI and WHR. In addition, the strength of the association of hypertension and body size was different for blacks and whites which suggests possible differences in the mechanisms regulating blood pressure.

Adipose Tissue↗
PubMed1992

Medical burnout.

Explore the source record for details and available documents.

Burnout, Professional↗
PubMed1991

Combined effects of 1,25-dihydroxyvitamin D3 and platinum drugs on the growth of MCF-7 cells.

The effects of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and platinum treatments (both singly and combined) on the growth inhibition of MCF-7 cells, an epithelial cell line shown to possess specific receptors for 1,25(OH)2D3, were evaluated. The inhibitory effects of 1,25(OH)2D3 and platinum on MCF-7 cell proliferation in vitro were time and dose related. The data showed that 10 nM and 100 nM 1,25(OH)2D3 inhibited MCF-7 cell growth by 10.8 +/- 2.4% and 34.9 +/- 0.5% (mean +/- SE), respectively. The degrees of growth inhibition induced by 0.2 to 200 micrograms/ml of cis-diammine-1,1-cyclobutane dicarboxylatoplatinum(II) (carboplatin) were slightly less than those induced by 0.02 to 20 micrograms/ml of cis-diamminedichloroplatinum(II) (cisplatin). The combined administration of 10 nM and 100 nM 1,25(OH)2D3 with either carboplatin (200 to 0.2 micrograms/ml) or cisplatin (20 to 0.02 micrograms/ml) was evaluated. Addition of 1,25(OH)2D3 to the platinum resulted in marginal to marked enhancement of growth inhibition over that observed with either platinum alone. The strength of these interactions varied inversely with the dose of the platinum drugs. Evaluation of drug interactions with isobolograms showed that at near-serum levels, carboplatin or cisplatin interacted synergistically with 1,25(OH)2D3 to inhibit MCF-7 cell growth. Our findings suggest potential usefulness in combining 1,25(OH)2D3, a biological modifier, with cytotoxic agents for the treatment of malignant disease.

Ascites↗
PubMed1990

Involvement of vitamin D3 with cardiovascular function. III. Effects on physical and morphological properties.

We have previously shown that depletion of vitamin D3 in rats results in a large increase in the contractile function of isolated hearts (R. E. Weishaar, J. Clin. Invest. 79: 1706-1712, 1987). To characterize the mechanism responsible for this increase, the effect of vitamin D3 depletion on key physical and morphological properties of cardiac muscle was examined. Depletion of vitamin D3 increased the heart weight/body weight ratio. This increase could neither be blocked by limiting hypocalcemia nor reversed by restoring increasing serum calcium levels. The cardiomegaly observed 9 wk after vitamin D3 depletion was not accompanied by an increase in myocardial water content or leakage of myocardial creatine phosphokinase and was not caused by myocardial cell hypertrophy. Histological examination of ventricular muscle from vitamin D3-deficient rats revealed a significant decrease in myofibrillar area and a significant increase in extracellular space. The increase in extracellular space was accompanied by a significant increase in myocardial collagen. Prevention of hypocalcemia in the vitamin D3-deficient rats did not prevent the increase in myocardial collagen. Such alterations in the physical and morphological properties of myocardial tissue might represent the basis for the change in myocardial contractile function that accompanies lengthy periods of vitamin D3 deficiency.

Animals↗
PubMed1989

Changing patterns of acute myocardial infarction: decline in period prevalence and delay in onset.

The rural Pee Dee area of South Carolina has had the highest mortality rate in the nation for coronary heart disease. Community surveillance shows a 22.7% (p = 0.0008) decline in fatal and nonfatal acute myocardial infarction (AMI) rates during the period 1978 to 1985 in the Pee Dee area. Rates for white men decreased 32% (p = 0.001), whereas in other race-sex groups changes were not significant, although there was a downward trend (p = 0.18) among black men. Among white men decreases in the AMI rates occurred in each of the decades of age 35 to 64 years. In all race-sex groups there was a sharp increase in rates between 1978 and 1985 for those 65 to 74 years of age, suggesting that the incidence of AMI was delayed to a later age. Out-of-hospital AMI death rates declined markedly in all race-sex groups: 63% for white men, 62% for white women, 49% for black men, and 39% for black women. Overall case fatality rates declined from 14% (27 of 193) to 10% (23 of 232), but the decrease was not statistically significant.

Adult↗
PubMed1989

Role of porcine endometrial estrogen sulfotransferase in progesterone mediated downregulation of estrogen receptor.

Estrogen sulfotransferase (EST) is a progesterone (Pg) induced secretory endometrial enzyme which may effect estrogen receptor levels by esterifying estradiol-17 beta (E2) to an inactive, sulfate form. The effects of this enzyme were studied using specific inhibitors of EST that do not bind to estrogen receptor (ER): 4-nitroestrone 3-methyl ether and 4-fluoroestrone 3-methyl ether. A 1 h pulse with 4 nM E2 caused ERn (i.e. E2-bound, chromatin-bound receptor) to increase 40% in incubations of proliferative gilt endometrium (no EST activity), while the same E2 treatment of secretory endometrium (high EST activity) caused no increase in ERn. ERn accumulation was completely restored in these experiments by preincubating secretory endometrium with 4 microM 4-fluoroestrone 3-methyl ether. Gilt endometrial explants cultured 7 days with 1 nM E2 plus 1 microM Pg (which induced EST activity) possessed half the ERn as explants devoid of EST activity which were cultured in E2 alone. The addition of 10 microM 4-nitroestrone 3-methyl ester to the cultures of secretory endometrium restored ERn to the levels seen in minces cultured with E2 alone. Furthermore, ovariectomized gilts injected daily with 250 micrograms E2 plus 25 mg Pg had much lower ERn (0.06 fmol/micrograms DNA) than gilts injected with E2 only (0.21 fmol/microgram DNA). ERn was restored completely by supplementing the E2 plus Pg injections with 0.5 g 4-nitroestrone 3-methyl ether administered by vaginal suppositories.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Studies on type II progesterone receptor in MCF-7 cells.

These experiments demonstrate for the first time the existence of a Type II progesterone receptor (RpII) in MCF-7 human breast cancer cells. RpII was shown to have a lower affinity for tritiated progesterone ([3H]Pg) (Kd greater than or equal to 13 nM) than classical Rp (Kd less than or equal to 3 nM). RpII was detected by cytosolic, nuclear, and whole cell assays of MCF-7 cells. Scatchard analysis of [3H]Pg binding data revealed that classical Rp but not RpII could be recompartmentalized from the cytosolic to the nuclear pool by treating cells 1 h at 37 degrees C with 1 microM Pg. RpII levels were shown to be increased more than two-fold by growing MCF-7 cells for 4 days in 10 nM estradiol (E2) plus 100 nM Pg when compared to either untreated cells or to cells treated with only E2.

Breast Neoplasms↗