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Biomedical subjects

L D Grant

Publications and source records attributed to L D Grant.

At least 19 recordsLinked to original sources
PubMed2000

Estimating separately personal exposure to ambient and nonambient particulate matter for epidemiology and risk assessment: why and how.

This paper discusses the legal and scientific reasons for separating personal exposure to PM into ambient and nonambient components. It then demonstrates by several examples how well-established models and data typically obtained in exposure field studies can be used to estimate both individual and community average exposure to ambient-generated PM (ambient PM outdoors plus ambient PM that has infiltrated indoors), indoor-generated PM, and personal activity PM. Ambient concentrations are not highly correlated with personal exposure to nonambient PM or total PM but are highly correlated with personal exposure to ambient-generated PM. Therefore, ambient concentrations may be used in epidemiology as an appropriate surrogate for personal exposure to ambient-generated PM. Suggestions are offered as to how exposure to ambient-generated PM may be obtained and used in epidemiology and risk assessment.

Air Pollution↗
PubMed1998

Spindle cell squamous carcinoma of the esophagus: analysis of ploidy and tumor proliferative activity in a series of 13 cases.

Spindle cell squamous esophageal carcinomas are distinctive polypoid "biphasic" tumors in which the sarcoma-like phenotype usually predominates over the epithelial component. To biologically assess both phenotypes, we compared the tumoral proliferative activity and DNA ploidy between the two histological components of 13 polypoid spindle cell squamous carcinomas of the esophagus. We studied the tumoral proliferative index (TPI) using MIB 1 monoclonal antibody (Ki-67) and determined the DNA histogram by image cytometry on Feulgen-stained sections. The DNA histograms were classified into four types (I to IV) according to the degree of dispersion of the DNA. The TPI of the carcinomatous regions ranged from 0.20 to 0.63 (mean, 0.44) and from 0.55 to 0.85 for the sarcoma-like areas (mean, 0.68) P < .0001. In all cases, the sarcoma-like areas were aneuploid, and 37.5% of the carcinomatous regions were diploid. Also, in all instances the carcinomatous areas were of either histogram type I or II, and the sarcoma-like areas showed histograms of type II or III. We conclude that in esophageal spindle cell squamous carcinomas the sarcoma-like phenotype differs biologically in two ways from the carcinomatous: (1) it has a higher TPI and (2) it has higher aneuploidy with a greater dispersion of the DNA content. We postulate that these characteristics could give a "growth" advantage to the sarcoma-like component of these tumors and explain its predominance over the carcinomatous component.

Aged↗
PubMed1997

Hepatic undifferentiated (embryonal) sarcoma arising in a mesenchymal hamartoma.

We report the case of a hepatic undifferentiated (embryonal) sarcoma (UES) arising within a mesenchymal hamartoma (MH) in a 15-year-old girl. Mapping of the tumor demonstrated a typical MH transforming gradually into a UES composed of anaplastic stromal cells. When evaluated by flow cytometry, the MH was diploid and the UES showed a prominent aneuploid peak. Karyotypic analysis of the UES showed structural alterations of chromosome 19, which have been implicated as a potential genetic marker of MH. The histogenesis of MH and UES is still debated, and reports of a relationship between them, although suggested on the basis of histomorphologic similarities, have never been convincing. The histologic, flow cytometric, and cytogenetic evidence reported herein suggests a link between these two hepatic tumors of the pediatric population.

Adolescent↗
PubMed1996

Effects of ageism on individual and health care providers' responses to healthy aging.

Although misconceptions about the aging process have lessened over recent years, ageism is still having a detrimental effect on healthy aging. This article reviews the literature to support this contention and to demonstrate how stereotyping can affect the shape and nature of programs for elderly people. It is argued that for long-lasting change to occur, service providers need to directly target these negative attitudes in themselves, their professional institutions, their clients, and their communities. Suggestions are made for professional development, research, and program planning.

Aged↗
PubMed1996

Unbalanced chromosomal translocation, der(17)t(13;17)(q14;p11) in a solid and cystic papillary epithelial neoplasm of the pancreas.

We report on a solid and cystic papillary epithelial neoplasm of the pancreas containing the unbalanced chromosome translocation der(17)t(13;17)(q14;p11), resulting in loss of 13q14-->qter and 17p11-->pter. Although the clinical and pathologic characteristics of this case are largely typical of this uncommon pancreatic neoplasm, the presence of cellular pleomorphism, tumor giant cells, and a DNA tetraploid tumor population suggest that this tumor may have an increased metastatic potential. The unbalanced translocation between chromosomes 13 and 17 and the genes flanking the breakpoints may prove to be markers for solid and cystic papillary epithelial neoplasm of the pancreas and provide insight into its histogenesis.

Adult↗
PubMed1996

Adenomatoid tumor of the adrenal gland: a report of four new cases and a review of the literature.

Adenomatoid tumors of the adrenal gland are rare, benign, asymptomatic neoplasms that are usually found incidentally. Previously reported cases occurred only in men and only on the left side. We report four cases, including two from the right adrenal gland, one from a woman, and one with a cystic component. The average age of our patients was 49 years, compared with the average age of 34 years in previously reported cases. Our immunohistochemical stains and electron microscopic analysis support the presumed mesothelial derivation of these tumors. The differential diagnosis of adenomatoid tumors of the adrenal gland includes a variety of solid and cystic tumors. It is important to recognize these rare tumors to avoid misclassifying them, especially as metastatic or primary malignant vascular tumors.

Adenomatoid Tumor↗
PubMed1990

Research on risk assessment and risk management: future directions.

This paper has been reviewed by the Office of Health and Environmental Assessment, U.S. Environmental Protection Agency, and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. The U.S. EPA has increasingly relied upon quantitative health risk assessments as the basis for management decisions about public health protection. Full utilization of risk assessment in management applications, however, is limited by uncertainties in the resultant accuracy of the risk estimates. This paper will discuss a research strategy to address the uncertainties in the risk assessment process and describe parallel issues to address in the risk management area. An attendant need for effective communication of complex scientific concepts is also identified.

Dose-Response Relationship, Drug↗
PubMed1989

Prenatal and postnatal effects of low-level lead exposure: integrated summary of a report to the U.S. Congress on childhood lead poisoning.

This article provides an integrated summary of a report to Congress from the Federal government (ATSDR) on childhood lead poisoning in the United States, with particular reference to low-level lead exposure and its effects on the fetus and the preschool child. As mandated by Section 118(f)(1)(C) of the 1986 Superfund Amendments and Reauthorization Act (SARA), ATSDR has examined the full spectrum of human in utero and postnatal lead toxicity, with emphasis on low-level neurotoxicity and adverse impacts on growth indices in risk populations. Especially important has been assessment of the relative persistence of these effects in later life as discernible from a number of longitudinal studies now under way around the world. Included in the Congressional report were discussions of dose-effect and dose-response relationships using blood lead levels as the indicator of lead dose.

Child, Preschool↗
PubMed1981

(3-H)-dihydrotestosterone in catecholamine neurons of rat brain stem: combined localization by autoradiography and formaldehyde-induced fluorescence.

A combined formaldehyde-induced fluorescence (FIF)-autoradiography procedure was used to determine how and where the androgen, dihydrotestosterone (DHT), is associated with catecholamine systems in the rat brain. With this dual localization method, (3H)-DHT target sites can be visualized in relation to catecholamine perikarya and terminals. In the hindbrain, catecholamine neurons adjacent to the fourth ventricle (group A4), the nucleus (n.) olivaris superior (group A5), the n. parabranchialis medialis (group A7), and in the locus coeruleus (group A6) and subcoeruleal regions, as well as in the substantia grisea centralis, concentrate (3H)-DHT in their nuclei. (3H)-DHT target neurons appear to be innervated by numerous catecholamine terminals in the following hindbrain regions: n. motorius dorsalis nervi vagi, n. tractus solitarii, n. commissuralis, n. raphe pallidus, n. olivaris inferior, the ventrolateral portion of the substantia grisea centralis, n. cuneiformis, and the ventrolateral reticular formation in the caudal mesencephalon. In the forebrain, (3H)-DHT concentrates in nuclei of catecholamine neurons located in the n. arcuatus and n. periventricularis (group A12). In addition, (3H)-DHT target neurons appear to be innervated by numerous catecholamine terminals in the following forebrain regions: n. periventricularis rotundocellularis, n. paraventricularis, n. dorsomedialis, n. periventricularis, area retrochiasmatica, n. interstititalis striae terminalis (ventral portion), and n. amygdaloideus centralis. The disclosure of a morphologic association between (3H)-DHT target sites and certain brain catecholamine systems suggests a close functional interdependence between androgens and catecholamines.

Animals↗
PubMed1981

Combined autoradiography and formaldehyde-induced fluorescence methods for localization of radioactively labeled substances in relation to monoamine neurons.

A combined technique of formaldehyde-induced fluorescence (FIF) and autoradiography is described for the localization of radioactively labeled substances in relation to monoamine neurons. This method permits the simultaneous visualization of 3H-labeled steroid hormone or drug uptake sites and fluorescing monoamine neural elements (cell bodies, fiber projections, terminals) in the same tissue section. Thin frozen sections cut in a cryostat are freeze-dried, exposed to formaldehyde vapor at 80 degrees C, and carried through dry-mount autoradiography processing steps before fluorescence microscopy screening. Subsequent histological staining of sections and light microscopy are employed for conventional autoradiogram screening. With this procedure, 3H-estradiol and 3H-dihydrotestosterone are localized in various catecholamine (CA) neurons in the diencephalon and lower brain stem of the rat. Also, catecholaminergic as well as noncatecholaminergic sex steroid target neurons are seen to be innervated by CA terminals in various rat brain regions.

Animals↗
PubMed1981

Effects of neonatal lead exposure on memory in rats.

Five groups of rats exposed to varying doses of lead by gastric intubation from Day 3 to Day 30 of life were tested to determine whether lead affects memory. A variable intertrial interval spatial alternation task was used to examine memory; it permits generation of a complete retention curve within subjects in a single session. Because of lead's putative effects on the cholinergic neuronal system, the cholinergic drugs controls to the drugs and to compare drug effects with lead effects. Orderly memory functions were obtained in all animals; however lead-exposed groups did not differ in performance from controls. Scoopolamine decreased alternation accuracy but its effects did not differ across the neonatal dose groups.

Animals↗
PubMed1980

Brainstem catecholamine neurons are target sites for sex steroid hormones.

Sex steroid hormones and catecholamines have physiological interactions in the brain. By the combined use of autoradiography and fluorescence histochemistry, steroid hormone target sites and catecholamine neurons were visualized simultaneously in the same tissue preparation. By this dual localization method, [3H]estradiol and [3H]dihydrotestosterone target sites were identified in nuclei of many catecholamine cell bodies in the brainstem, and catecholamine nerve terminals were observed near certain steroid hormone target neurons. These results suggest close anatomical interrelations between steroid hormone sites of action and catecholamine sites of production and action in the brain.

Adrenalectomy↗