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Biomedical subjects

M Freeman

Publications and source records attributed to M Freeman.

At least 145 records · Page 8Linked to original sources
PubMed1986

Acute renal rejection versus acute tubular necrosis in a canine model: MR evaluation.

Findings of magnetic resonance (MR) imaging in acute renal rejection and acute tubular necrosis (ATN) were studied in dogs. On T1-weighted images, corticomedullary differentiation was absent in kidneys undergoing acute rejection. The loss of corticomedullary differentiation in these kidneys was secondary to a decrease in the relative signal intensity of the cortex, indicating prolongation of the T1 relaxation time of the cortex. In contrast, corticomedullary differentiation was preserved on T1-weighted images of autotransplanted kidneys and kidneys with ATN. MR imaging findings correlated with changes in water content in these three groups of kidneys. Kidneys undergoing acute rejection showed a marked increase in water content compared with kidneys in the other two groups. No change in fat content was found in any group.

Acute Kidney Injury↗
PubMed1986

On computer-assisted analysis of biological sequences: proline punctuation, consensus sequences, and apolipoprotein repeats.

During the past several years, the use of computer programs in the analysis of protein and DNA sequences has become commonplace. In all but the simplest procedures, the ability to critically review the results obtained with computer methods requires a basic knowledge of the algorithms employed (and the assumptions upon which they are based), an awareness of the capabilities and limitations of the particular program that implements an algorithm, and some familiarity with probability and statistics. We describe a number of computer methods that have been applied to the analysis of apolipoprotein sequences. We discuss the suitability of these methods for particular problems, how the choice of initial "parameters" can affect the results, and what the results can tell us about protein or gene sequences. We also identify some outstanding problems of apolipoprotein sequence analysis where further work is needed.

Amino Acid Sequence↗
PubMed1985

Malignant "Triton" tumors. Natural history and immunohistochemistry of nine new cases with literature review.

Malignant schwannomas with rhabdomyoblastic differentiation have been termed malignant "Triton" tumors (MTT). To define the natural history of MTT, we have analyzed our experience (9 cases, the largest series reported) in combination with the 27 previously described in the literature (total 36 cases). This study was initiated due to the unusual presentation of MTT as a polypoid esophageal mass. Rhabdomyoblastic differentiation in these tumors was confirmed using myoglobin immunohistochemistry. Two groups of patients were identified: those with Von Recklinghausen's Neurofibromatosis (Group I, VRN cases); and those without (Group II, sporadic, non-VRN cases). Group I patients accounted for over 70% of cases and displayed a marked male predominance, young age, and common head and neck presentation. By contrast, Group II patients were older, had a female predominance, and tumors frequently located on the trunk. Both groups fared equally poorly: local recurrence was common and the 5-year survival rate for all cases was 12%. Our data support the view that the natural history of MTT, whether in VRN patients or not, is much more aggressive than sporadic malignant schwannoma and similar to VRN sarcomas in general. This poor outlook could not be attributed to site; rather, it appeared to reflect the high frequency of Grade III histology in this disease.

Adult↗
PubMed1985

Cerebrospinal fluid levels of angiotensin-converting enzyme in Alzheimer's disease, Parkinson's disease and progressive supranuclear palsy.

Angiotensin-converting enzyme (ACE, E.C. 3.4.15.1) has been identified as a normal constituent of human cerebrospinal fluid (CSF). ACE activity in CSF from adult subjects without known neurologic disorder correlated positively (P = 0.002) with age between 50 and 90 years. Patients with moderate degrees of senile dementia of the Alzheimer's type and comparably demented patients with Parkinson's disease or progressive supranuclear palsy exhibited mean levels of ACE activity that were decreased 41, 27 and 53% respectively, compared to the mean level in an age and sex-matched group of neurologically intact individuals. These results raise the possibility that ACE activity in CSF may be an index of neuronal dysfunction in certain central neurodegenerative disorders.

Aged↗
PubMed1985

A format for integrating the interpretation of exercise ejection fraction and wall motion and its application in identifying equivocal responses.

The conventional interpretation of ejection fraction change with exercise may be limited because it does not consider the rest value, define equivocal responses or integrate wall motion data reproducibly. Thus, a format was developed for combined interpretation of rest and exercise radionuclide ejection fraction and wall motion by reviewing the reported data for the exercise responses of patients without prior myocardial infarction. The ejection fraction data of 202 normal patients and of 259 patients with coronary artery disease were first fitted to beta distributions. The true positive and false positive rates for coronary disease for each combination of rest and exercise ejection fraction were then determined directly from these distributions. A given rest/exercise ejection fraction combination was "normal" if the false positive rate was greater than the true positive rate, or "abnormal" if the true positive rate was greater than the false positive rate, and "equivocal" when the rates were similar (within a 50% confidence interval). This analytic format, which predicted an inverse relation between rest ejection fraction and the change required with exercise, was then validated prospectively in 854 patients without myocardial infarction (557 with and 297 without angiographic coronary artery disease). Using the conventional criterion of an abnormal test result (less than 0.05 absolute rise in ejection fraction with exercise or a wall motion abnormality), sensitivity was 85 +/- 2% and specificity only 42 +/- 3%. The statistical format had a sensitivity of 70 +/- 2% and specificity of 70 +/- 3%, resulting in a twofold increase in information content. This format has at least two advantages over conventional interpretation: 1) it provides an explicit definition of equivocal responses; and 2) it reproducibly integrates discordant ejection fraction and wall motion responses and allows for the combined analysis of other nonscintigraphic observations, such as age and sex.

Adult↗
PubMed1985

Doughnut sign on bone scintigraphy in angioblastic meningioma.

Bone imaging was performed in a patient with a rapidly expanding parietal bone lesion. The findings on the nuclear medicine study showed a doughnut type lesion. The underlying abnormality was found to be an angioblastic meningioma causing local bone destruction.

Diphosphonates↗
PubMed1984

Alcohol and marijuana use in adolescents' daily lives: a random sample of experiences.

High school students filled out reports on their experiences at random times during their daily lives, including 48 occasions when they were using alcohol or marijuana. Alcohol use was reported primarily in the context of Friday and Saturday night social gatherings and was associated with a happy and gregarious subjective state. Marijuana use was reported across a wider range of situations and was associated with an average state that differed much less from ordinary experience.

Adolescent↗
PubMed1984

Nongranulomatous ulcerative jejunoileitis.

Nongranulomatous ulcerative jejunoileitis is a rare cause of small intestinal ulceration. Clinical features include fever, pain, steatorrhea, and protein-losing enteropathy with an unremitting downhill course. Some cases have shown similarities to gluten-sensitive enteropathy. However, the small bowel barium study of these two diseases shows markedly divergent patterns.

Acute Disease↗
PubMed1983

Women refused second-trimester abortion: correlates of pregnancy outcome.

Little is known of the outcome of pregnancy in women denied abortions in the United States. To address this question, we studied the pregnancy outcomes in 316 low-income women who were denied second-trimester abortion at a large, metropolitan teaching hospital in the Southeast between August, 1978, and July, 1979. Follow-up information was available on 82%. One in five women denied an abortion managed to obtain one elsewhere. Earlier gestational age at the initial abortion request, higher education level, and higher income were the best predictors of whether a woman subsequently obtained an abortion. For the women who continued their pregnancies, neither the rate of serious maternal complications nor the neonatal death rate was increased when compared with that of the rest of the hospital's population.

Abortion, Induced↗
PubMed1983

Clinical evaluation of seven-pinhole tomography for the detection and localization of coronary artery disease: comparison with planar imaging using quantitative analysis of myocardial thallium-201 distribution and washout after exercise.

The development of quantitative techniques to assist in the analysis of planar thallium-201 stress-redistribution scintigrams has led to improved abilities of this modality to detect the presence of and to localize significant coronary artery disease (CAD). This fact has encouraged the reevaluation of its capabilities relative to other types of scintigraphic data collection, including seven-pinhole tomography. We have undertaken a comparison of planar scintigraphy and seven-pinhole tomography to detect in 40 exercised patients (23 with angiographically demonstrated CAD, eight with normal coronary angiograms, and nine with less than or equal to 1% likelihood of having CAD) the presence of significant CAD and to localize it correctly to an individual coronary artery. Emphasis was placed on similar imaging conditions and on analysis of images by the same quantitative program of TI-201 distribution and washout. Both techniques were found to be highly sensitive and specific for disease detection and localization. Importantly, seven-pinhole tomography did not significantly improve results.

Coronary Disease↗
PubMed1983

Time to completed redistribution of thallium-201 in exercise myocardial scintigraphy: relationship to the degree of coronary artery stenosis.

The relationship between the severity of coronary artery stenosis and the time to completed redistribution of thallium 201 (TI-201) defects following maximal exercise was investigated in 59 patients undergoing stress-redistribution TI-201 scintigraphy, coronary angiography, and contrast ventriculography. Multiple view TI-201 scintigrams were obtained, beginning 6 minutes (immediately post stress), less than 1 hour (early), 3 to 5 hours (average), and 18 to 24 hours (late) following intravenous TI-201 injection at peak exercise. Angiographic lesions were grouped into five levels of severity by percent stenosis. In the 107 defects which were seen on the immediate post stress images, early redistribution was noted in 15 (14%) and late redistribution was found in 23 (21%). In addition, there was a correlation (r = 0.56) between the time to completed redistribution and the severity of the coronary artery stenosis (p = 0.001). In comparison to defects with early and average redistribution, the segments contralateral to those with defects showing late redistribution more often had a critical stenosis supplying that segment. The frequency of myocardial infarction on ECG and the number of segments with akinetic and dyskinetic wall motion were less in defects undergoing late rather than no redistribution. Thus the time to completed TI-201 redistribution following stress appears to be related to the severity of stenosis in the coronary artery supplying the defect. Also, late redistribution is associated with the presence and early redistribution with the absence of a significant stenosis in the coronary artery to the contralateral segment.

Adult↗
PubMed1983

Craniofacial correlates of dietary consistency in a nonhuman primate.

Forty-three squirrel monkeys were raised on either naturally tough or artificially softened foods. Significant differences were found in craniofacial and occlusal development between hard and soft diet animals: The latter exhibit maxillary arch narrowing, palatal arching, rotated and displaced teeth, crowded premolars, and retarded cranial bone mineralization. The correlates in results between soft diet squirrel monkeys and American children suggest that dietary consistency may be an important factor in human craniofacial growth.

Animals↗
PubMed1982

Measurement of visual evoked potential in the asphyctic fetus and during neonatal survival.

Visual evoked potentials were measured in eight exteriorized near-term fetal lambs prior to and during 8 minutes of asphyxia and during 1 hour of newborn survival. Four of the lambs were then extubated, and measurements were continued while the lambs were observed for behavior and gross motor function. Early in the asphyctic period, marked changes in the visual evoked potential occurred in association with a fall in Po2, whereas during the postexposure period the visual evoked potential appeared to recover independently of cardiovascular or arterial blood gas values. Moreover, early wave components of the visual evoked potentials were more resistant to asphyxia than were later components and responded more quickly to resuscitative efforts. During the survival period the visual evoked potential did not correlate with gross motor function when animals were exposed to moderate acidosis. After severe acidosis abnormal visual evoked potentials were seen during periods of clinical deterioration.

Acidosis↗
PubMed1982

A simple reproducible method for prometaphase chromosome analysis.

A method is described for the analysis of chromosomes in prophase and early metaphase. It involves culturing the lymphocytes in medium RPMI-1640, supplemented with 10% autologous plasma instead of fetal bovine serum. Living cells are treated with actinomycin D and colcemid for 1 h prior to harvest and harvested early at 65 h of incubation, using a hypotonic solution formulated by Ohnuki (1968). The method has been tested on several hundred clinical samples on a routine basis. On average, 30% of the dividing cells were in prometaphase.

Azure Stains↗