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Biomedical subjects

H L Stewart

Publications and source records attributed to H L Stewart.

At least 19 recordsLinked to original sources
PubMed1993

Angiofollicular lymphoid hyperplasia (Castleman's disease) in two mice treated with polyoma virus or urethane.

Localized angiofollicular hyperplasia, otherwise known as Castleman's disease, is described in the lymph nodes of 2 mice of different strains, one inoculated with polyoma virus at birth and the other given urethane within 24 hr of birth. A plasma cell component in the lesion, suggestive of bone marrow stem cell involvement, was present in the mouse treated with polyoma virus but absent in the mouse given intraperitoneal urethane. Dysregulated interleukin 6 has recently been reported to produce the systemic variety of angiofollicular hyperplasia in mice, but the role of this cytokine in the localized variety described in this report is not known. This lesion appears to be rare in mice, but when present it could easily be missed or overlooked because the typical layering of follicle cells and the relatively large germinal centers seen in humans do not appear prominent in mice. Although there is, obviously, no proof of a causal relationship between the lesion and polyoma virus or urethane, it is suggested that this lesion be searched for in order to estimate its frequency and possible etiologic associations.

Animals↗
PubMed1986

Symptom correlates of blood pressure: a replication and reanalysis.

Although normative studies have traditionally found that blood pressure (BP) fluctuations are asymptomatic, recent research by Pennebaker et al. [(1982). Psychophysiology 19: 201-210] has suggested that systolic blood pressure (SBP) changes are, in fact, highly correlated with idiosyncratic patterns of symptoms within individuals. The present study was designed as a conceptual replication of those findings and as an initial attempt to develop a standardized clinical procedure for assessing symptom-BP relationships. Eleven normotensive male subjects participated in a series of 16 brief tasks. The first eight tasks were "mental" stressors (e.g., WAIS-R subtests), while the second eight were "physical" stressors (e.g., breath-holding, running in place). Following each task or baseline, blood pressure was measured and subjects rated the degree to which they were experiencing each of nine symptoms (e.g., racing heart, sweaty hands). For each subject, simple symptom-BP correlations were computed across the 16 measurement periods. High symptom-SBP correlations were obtained only for the physical task period. It is argued that the magnitudes of the correlations reported by Pennebaker et al. (1982) were spuriously inflated by the inclusion of strenuous physical exercise, and a reanalysis of the data from that study supports this contention. The clinical value of assessing idiosyncratic symptom-blood pressure relationships seems doubtful.

Adolescent↗
PubMed1986

Mammary gland tumors in irradiated and untreated guinea pigs.

This is a report of mammary gland tumors from 62 guinea pigs. The tumors arose in the terminal ductal-lobular units as either lobular acinar carcinoma or cystadenocarcinoma or as papillary carcinomas within large ducts near the mammilla. About half the number of the males had terminal ductal-lobular carcinomas and all but 2 of the papillary duct carcinomas also arose in males. Large tumors frequently exhibited squamous, chondromatous, osseous, fatty and myoepitheliomatous types of tissues. In 2 irradiated males and 1 female the tumors metastasized. Whole-body irradiation did not produce significant changes in the number or sex distribution or in the morphology of mammary gland tumors in inbred or outbred guinea pigs. All females had cystic ovaries without increase in granulosa cells, 24 (66.6%) had uterine tumors and 13 (34.2%) had adrenal gland tumors; all males had atrophic testes, 5 (16.5%) had testicular and 6 (22.2%) had adrenal gland tumors.

Animals↗
PubMed1986

Comparative pathology of cardiac neoplasms in humans and in laboratory rodents: a review.

This review deals with the frequency, heredity, and morphology of 19 different histologic types of cardiac tumors that may affect humans, rat, mouse, guinea pig, and mastomys. Chemicals, durable fibrous materials, viruses, and probably irradiation have induced cardiac tumors in rodents. Apart from the involvement of asbestos in the induction of pericardial mesothelioma, no carcinogens have been identified in induction or promotion of cardiac tumors in humans. A hereditary tendency for the occurrence of myxoma and aortic paraganglioma has been indicated in humans as well as strain-specific heredity for rhabdomyoma in the guinea pig and for atriocaval node tumor in the rat.

Animals↗
PubMed1985

Tumor induction in Praomys (Mastomys) natalensis by N,N'-2,7-fluorenylenebisacetamide.

Feeding N,N'-2,7-fluorenylenebisacetamide (CAS:304-28-9) at 0.025% to 15 male and 15 female mastomys considerably shortened their life-span. At death every treated mastomys had several primary tumors; untreated animals at comparable ages had none. Several mastomys with hepatoblastomas and 1 with giant cell hepatitis and a metastasizing pancreatic carcinoma are first reported here. The tumor load per animal averaged 4.0 for treated females, 2.6 for treated males, 1.5 for untreated females, and 0.6 for untreated males. Of 24 hepatic tumors in treated mastomys, 11 metastasized, compared to none of the incipient tumors in 8 of 26 untreated animals. Pancreatic adenomas developed in 27 treated and 1 untreated mastomys, and a metastasizing adenocarcinoma developed in 1 treated animal. All treated females, 3 treated males, and 1 untreated female developed multiple villous adenomas in the small intestine. One untreated female and 8 treated females developed mammary cancers, 4 of which metastasized. Primary tumors of other sites occurred infrequently.

2-Acetylaminofluorene↗
PubMed1984

Cardiac tumors of mice.

Of the 7 primary tumors of the mouse heart, accessed at the Registry of Experimental Cancers, 3 were mesenchymal cell sarcomas, 3 were hemangioendotheliomas, and 1 was a mesenchymoma. The mesenchymal cell sarcomas metastasized via the bloodstream to lungs, kidneys, and spleen. Five of the tumors arose in mice treated with ionizing radiation. Previously, only 3 primary cardiac tumors of mice have been reported. Tumors of the heart as part of multifocal neoplasms of a single histologic type were observed in 3 mice; 2 of these tumors were type B reticulum cell sarcomas, and 1 was a reticulum cell sarcoma not otherwise specified. Of the metastatic tumors of the heart, 12 were from alveologenic carcinoma, squamous cell carcinoma, or carcinosarcoma of the lung, 4 were from sarcoma of the subcutaneous soft tissue, and 1 each was from a subcutaneous transplant of a malignant schwannoma and from an alveologenic tumor of the lung.

Animals↗
PubMed1984

Pure yolk sac carcinoma of the mouse uterus: report of 8 cases.

This report covered the pathologic features, behavior, metastases, and results of transplantation of pure yolk sac carcinomas that were primary in the uterine horn of 8 mice; 6 mice were strain C3H and 2 were strain HR, and they varied from 10 to 23 months of age. Three of the mice had never been treated. Of the 5 that had, the treatment was different for each mouse. Therefore, treatment could not be correlated with tumor development. At least 5 mice were nulliparous; in fact they had never been mated, so in these some mechanism involving parthenogenesis must have been operative to account for the tumor. The tumors were identified as being primary in the uterus and occupied and distended the cavity of one uterine horn where they were polypoid or plaquelike. The neoplastic yolk cells replaced the endometrial stroma forming a support for the original endometrial glands. In time the tumor cells destroyed many of the endometrial glands. That the glands present in the primary uterine horn tumors were the original glands of the endometrium and not neoplastic glands was attested by their absence from the secondary neoplastic deposits in 4 mice in which the tumor had spread to areas outside the cavity of the uterus and from the neoplastic tissue of the tumor transplants in the recipient mice.

Aging↗
PubMed1983

Endocardial tumors induced by carbamate or fluorenylacetamide derivatives in rats.

Endocardial tumors were induced in 18 rats treated with derivatives of carbamates and in 4 rats treated with derivatives of fluorenylacetamide. The endocardial tumor of 1 rat treated with N,N'-2,7-fluorenylenebisacetamide metastasized to the lung. This is the first report of metastasis of an endocardial tumor. Among the more than 60,000 accessions at the Registry of Experimental Cancers, Division of Cancer Cause and Prevention, National Cancer Institute, there are 4 untreated rats with endocardial tumors. On the basis of the light microscopic morphology, we have classified these endocardial tumors as mesenchymal.

2-Acetylaminofluorene↗
PubMed1983

Endocardial tumors in rats exposed to durable fibrous materials.

Endocardial tumors in the rat found in association with intrathoracic implantation of durable fibrous materials are reported here for the first time. In Osborne-Mendel female rats, endocardial tumors occurred in 3 of 50 rats associated with the implantation of fiberglass greater than 5 micron in length and 1-3 micron in diameter, in 1 of 15 rats associated with fiberglass of 0.03 X 3 micron, and in 1 of 15 rats associated with pulverized glass fiber. The intrathoracic administrations of pulverized chrysotile, of cigarette smoke condensate and crocidolite, and of coarse cotton lint, and of intravenous injections of air particulate extract were associated with endocardial tumor in 1 of 15 rats each. The dimensions of the durable fibers associated with endocardial tumors were similar to those of carcinogenic asbestos. Endocardial tumors were not observed in concurrently studied control rats.

Age Factors↗
PubMed1979

Adenocarcinoma of the gallbladder in guinea pigs.

Adenocarcinoma of the gallbladder developed in 17 of 68 untreated and in 26 of 83 irradiated guinea pigs of inbred strains 2 and 13. The carcinomas spread widely by direct extension and through lymphatic and blood vessels to lymph nodes, mesenteries, omenta, abdominal wall, liver, lungs, bones, and spleen. Whole-body exposure to gamma or X-radiation increased both the number of tumors and metastases in male inbred guinea pigs but not in females. Significantly fewer (9 of 98) noninbred than inbred guinea pigs developed gallbladder carcinomas after irradiation. In 9 untreated noninbred guinea pigs gallbladder carcinomas were not found. Inasmuch as the effect of irradiation was not dose-dependent, an indirect systemic effect of irradiation was postulated. This is the first report on the occurrence of spontaneous gallbladder adenocarcinomas in guinea pigs.

Adenocarcinoma↗
PubMed1979

Hemoccult test as a routine screening procedure for colorectal disease in the private clinic setting.

Increased attention is being focused on the earlier detection of malignant and premalignant colorectal lesions in an attempt to increase the survival rate of patients with these diseases. This study evaluates the use of the Hemoccult test as a screening procedure in a private clinic. A protocol for its implementation is presented. Of the 631 patients entered into the study, 514 (81.5%) returned completed slides. In 14 (2.7%) of these 514 patients, the slides gave positive results, and 10 of the 14 patients underwent thorough investigation. No malignant tumours were found as a result of the test. Six (1.2%) of the 514 patients had one or more benign polyps.

Adult↗
PubMed1978

Modified suturing contact lens for penetrating keratoplasty.

The authors have previously described a suturing contact lens that protects the corneal endothelium by aiding in the maintenance of the anterior chamber during penetrating keratoplasty. This report describes structural modifications of the suturing contact lens, which improve its stability and effectiveness. An additional configuration for use in corneal lacerations is presented.

Contact Lenses, Hydrophilic↗