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Biomedical subjects

C Allen

Publications and source records attributed to C Allen.

At least 181 records · Page 10Linked to original sources
PubMed1989

The policy forum. A panel of experts may provide the best guidelines for complex ethical decisions.

Policies on complex issues such as the termination of life-sustaining treatment can be developed and implemented through a variety of methods, but a facility's ethics committee may be the most appropriate forum. Since committee members' interests are often too diverse to deal with specifics that are organizationally useful, the facility should establish a subcommittee of experts. This committee should include physicians; nurses; one or more hospital administrators; a trustee; representatives from social services, respiratory therapy, and pastoral care; a social gerontologist; and an ethicist. The members should keep open the doors of communication to their peers to address their concerns, incorporate their input, and expand the educational process. This will alleviate the frustration sometimes encountered in policy implementation, where those who must carry it out have had no part in its formulation. Once the subcommittee has drafted a policy, the full ethics committee should discuss and refine it before forwarding it to the administration. After the administration has accepted it, the medical staff, employees, patients, and families need to be informed.

Ethics↗
PubMed1989

A blueprint for better service.

The authors review the thoughtful process that led an independent laboratory in Seattle from a mostly manual ordering/reporting system to a computer-based operation that has exceeded expectations for improved service to all of their laboratory customers.

Autoanalysis↗
PubMed1989

Behavior of human RPE cultured on Bruch's membrane and on necrotic debris.

Degeneration and necrosis of the retinal pigment epithelium (RPE) is found in several conditions associated with reactive alteration of the cell layer, and is probably involved in the formation of drusen and age-related macular degeneration. In the current study we describe a novel system for culturing human RPE. This system permits evaluation of the effect of necrotic material between the epithelium and Bruch's membrane, of drusen, and of other alterations in Bruch's membrane on the behavior of the RPE. In this system, dissociated RPE cells were seeded onto isolated Bruch's membrane. Cell behavior was assessed in areas with and without drusen, and also in areas covered with necrotic cells and fragmented debris. On both exposed Bruch's membrane and on the membrane covered with debris, the cells developed a polygonal shape, with a varying density of apical microvilli. The cultures were monolayered with some overlapping. In areas containing fragmented debris and dead cells, seeded RPE cells were found to adhere to the apical surface of necrotic cells, but were also seen to intrude between the necrotic debris and underlying Bruch's membrane, appearing to clear the membrane of such debris. Our study demonstrates the stability of epithelial histology of human RPE under not previously tested conditions. Further, it shows that the present system permits exposure of these cells to several in vivo physiological and pathological changes in a controlled in vitro environment.

Cells, Cultured↗
PubMed1988

Kikuchi's disease--apparent malignancy of a neck mass.

We report a case of Kikuchi's disease presenting as cervical lymphadenopathy in an adolescent. The original histological diagnosis in this case was a metastatic neoplasm. We wish to highlight the importance of this rare condition because of its potential for mimicking malignancy.

Adolescent↗
PubMed1988

The morphology of human cells from the choroid and retinal pigment epithelium grown in vitro on isolated Bruch's membrane.

Cells from samples of human choroidal tissue were collected and seeded onto isolated Bruch's membrane in vitro, and the morphology of the developing cultures was examined by light-, scanning electron- and transmission electron-microscopy. In early cultures, the cells showed a flattened, spread out appearance with short surface villi and a low degree of cellular overlapping. After 48 h, a shift towards a more elongated cell form was observed, and one week old cultures were composed of predominantly elongated cells with a pronounced degree of overlapping. In contrast, human retinal pigment epithelial cells seeded onto sheets of Bruch's membrane maintained a spread out epithelial morphology with a varying degree of overlapping throughout the culture period. The present system permits comparative studies on the behavior of choroidal and pigment epithelial cells under controlled conditions. It may serve as an in vitro model for disorders characterized by growth of these cells on Bruch's membrane in vivo.

Cell Membrane↗
PubMed1988

The effect of a pulsed neodymium-YAG laser on chorioretinal monolayered cell cultures.

The effect of a pulsed YAG laser on monolayers of chorioretinal cells maintained in vitro on plastic surface was examined. At the energy levels used, phase contrast microscopic visible lesions were observed at all focus distances up to 2 mm. Scanning electron microscopy demonstrated curling of detached sheets of cells, displacement of single cells, clustering of cells, and severe cell membrane damage at the edge of the lesions. The present system permits evaluation of the effect of different laser characteristics and application modes on the extent and morphology of damage in monolayers of human cells under easily controlled conditions.

Cells, Cultured↗
PubMed1988

Gonadotropin-producing pituitary adenoma in a man with long-standing primary hypogonadism.

Pituitary adenomas that secrete gonadotropins are generally believed to arise spontaneously rather than as a response to chronic primary gonadal failure. However, two women who were found to have gonadotroph adenomas several years after ovarian ablation have been reported. We describe a middle-aged man who developed bitemporal hemianopia and was found to have a large pituitary tumor 35 yr after castration. He had never received any replacement therapy. The tumor was considered to be a primary gonadotroph adenoma, rather than secondary gonadotroph hyperplasia, on the basis of its secretory capabilities, its reticulin patterns, and its specific immunostaining for human FSH beta, human LH beta, and alpha-subunit. Furthermore, the tumor did not decrease appreciably in size after 12 months of testosterone treatment, although plasma gonadotropin levels decreased. Unless the association of primary gonadal failure with a gonadotroph adenoma was coincidental, it suggests that some human gonadotroph adenomas may be secondary to failure of the gonads.

Adenoma↗
PubMed1987

The use of monoclonal antibodies UCH beta and UCH gamma for the antenatal diagnosis of beta-thalassaemia.

Monoclonal antibodies for the beta-globin chain of human HbA (UCH beta) and the gamma-globin chain of human HbF (UCH gamma) have been made. UCH beta indirectly labelled with rhodamine-labelled goat anti-mouse Ig and directly flouresceinated UCH gamma have been used, via double labelling immunofluorescence microscopy, to assay for the presence of beta-chains in fetal erythrocytes obtained at fetoscopy from fetuses at risk for beta-thalassaemia major. The results from 111 cases demonstrate that beta-chain synthesis of as low as 1.8% can be detected in fetal erythrocytes. The immunochemical labelling can be rendered more sensitive by the use of biotinylated UCH beta and avidin-FITC conjugates. This method is rapid and can be used for a sample that is highly contaminated with maternal erythrocytes.

Antibodies, Monoclonal↗
PubMed1987

The China diary. AMRA delegation's visit to China. Part I.

In May, 22 AMRA representatives toured the People's Republic of China at the invitation of the Chinese government. Designated delegates kept a diary of the informational exchange between the AMRA delegates and their hosts, as well as a commentary on places seen during their travels. Their diary entries have been compiled into a two-part article. The first part appears in this issue, and the second part will appear in the September issue.

Abstracting and Indexing↗
PubMed1987

Malignant hyperthermia: a dilemma for the cardiac surgeon.

Malignant hyperthermia is an inherited disease of skeletal muscle characterized by acute elevations of body temperature. The hyperthermic crisis is triggered by a variety of drugs and by volatile anesthetics or it may occur in response to stress. In this report the authors describe the case of a patient with malignant hyperthermia who underwent emergency aortocoronary bypass surgery for unstable angina. They outline the anesthetic and surgical management for individuals susceptible to hyperthermic crises who require open-heart surgery.

Aged↗
PubMed1987

Elevation of infiltrating mononuclear phagocytes in human colorectal tumors.

The distribution of infiltrating monocytes-macrophages and T-lymphocytes in 45 primary colorectal tumors and 8 metastatic lymph nodes has been investigated by immunoperoxidase labeling with monoclonal antibodies (MoAbs). The number of lymphoreticular cells observed in tumor tissue, staged according to Dukes classification, was compared with paired normal tissue and between staged groups by statistical analysis. T-lymphocytes were not significantly elevated above the normal in either Dukes B or C stage tumors, although the IL-2 receptor (MoAb Tac) was expressed by varying numbers of T-cells in both groups. Mononuclear phagocytes increased numerically in both Dukes B (1.5-fold, P-value less than .01) and Dukes C tumors (2.5-fold, P-value less than .001) as compared to those in the uninvolved gut. In addition, the number of both total (MoAbs 3.9, 24) and stimulated mononuclear phagocytes expressing the C3b receptor (MoAb E11) was greater in metastasizing than in nonmetastasizing tumors (P-value less than .01). Thus the T-cell-to-monocyte ratio was altered from 2:1 in normal tissue to 1:1 in advanced tumors. The stromal environment around tumor cells in lymph nodes was similar to that of the primary tumor, but there was a reduction in the proportion of cells expressing the C3b receptor; unlike the primary tumor, there was virtually no infiltration of the tumor epithelium. Although there is a significant alteration in the mononuclear phagocyte population within colorectal tumors, there is no histologic evidence for a cytotoxic role for these cells.

Antibodies, Monoclonal↗
PubMed1986

Macrophage antigens and the effect of a macrophage activating factor, interferon-gamma.

Molecules characteristic of mononuclear phagocytes have been identified using monoclonal antibodies (MAb). MAb 3.9 reacts with a 150/95 000 dalton heterodimer which is found exclusively on monocytes and macrophages and appears to be the third member of the lymphocyte function-associated (LFA) family of molecules. In contrast, the reactivity of MAb 24, which bonds to a 175 000 dalton protein, is most highly expressed on the macrophages in lymphoid tissue. Both 3.9 and 24 detect the interdigitating cells in the T cell areas of these tissues, which strongly suggests that this cell type belongs to the macrophage family. A third MAb, 10.1, reacts selectively with a set of macrophages outside lymphoid tissue, particularly on Kupffer cells, alveolar macrophages and microglia. Thus subsets of tissue macrophages are proving easy to identify whereas it appears that circulating monocytes are not easily subdivided. None of the MAbs detected either Langerhans' cells, dendritic reticulum cells of B cell areas, or osteoclasts, indicating that these cells are not mononuclear phagocytes. As a first step towards identifying macrophage molecules which have a biological function, we have investigated the effect of macrophage-activating factor, interferon-gamma, on the expression of macrophage membrane molecules. There was greatly increased expression of only two out of ten molecules detected with anti-myeloid antibodies.

Antibodies, Monoclonal↗
PubMed1986

The p150,95 molecule is a marker of human mononuclear phagocytes: comparison with expression of class II molecules.

A new monoclonal antibody (mAb), named 3.9, is described that is specific for the p150,95 molecule, a member of the LFA-1, CR3, p150,95 family of human leukocyte differentiation antigens. The LFA-1 molecule participates in a variety of T cell interactions and the CR3 molecule is the receptor for the complement component iC3b, but little is known about the p150,95 molecule. Here we show that the expression of p150,95 is confined to myeloid cells. mAb 3.9 reacts variably with neutrophils, more strongly with monocytes and is most strongly expressed on tissue macrophages. Using this mAb and others, we have examined the heterogeneity of tissue macrophages. Cells such as Langerhans' cells, dendritic reticulum cells and osteoclasts failed to react with these mAb and thus, probably do not belong to the mononuclear phagocyte lineage. Using a new double-labeling technique, we investigated lymphoid tissue for dendritic cells bearing class II molecules which might function in interactions with T cells. In T cell areas macrophages expressing class II markers were seen but there was no evidence for other types of dendritic or interdigitating cells which expressed class II molecules but not macrophage epitopes. The conclusion from this survey was that the most prominent cell with dendritic morphology found in the T cell areas of lymphoid tissue was a macrophage.

Antibodies, Monoclonal↗
PubMed1986

Effects of cold stress and exercise on fat loss in females.

A Latin Square design has been used to test the responses of 24 relatively fit young women to 200 minute bouts of exercise performed over 5 day trials under each of three different ambient conditions: 15 degrees C (warm-warm; (WW)); -20 degrees C while inhaling, from a facemask, air heated to 18 degrees C (cold-warm; (CW)); and -20 degrees C (cold-cold; (CC)). In both of the cold environments, special clothing and boots were provided (insulation 0.47 degree C X watt-1 X m-2 and 0.62 degree C X watt-1 X m-2; (4 and 3 CLO units)). All three trials led to a small (0.6-0.7 degree C) rise of rectal temperature, but in the two cold environments mean body temperatures fell by over 1.0 degree C. A large increase of serum ketones occurred under all conditions, and the exercise respiratory quotient suggested some increase of fat utilization, WW (0.85) through CW (0.84) to CC (0.83). A fat loss of about 0.5 kg over the five days was confirmed by hydrostatic weighing and measurement of skinfold thicknesses. This was much less than the change previously observed in men, and moreover, it seemed to be independent of ambient conditions. Possible reasons why cold did not increase fat loss in these women include: a lower relative intensity of exercise; a greater stability of fat stores in women; avoidance of caffeine; a possible translocation of subcutaneous fat to deep fat depots; and a greater desire to "lose weight" irrespective of environmental conditions.

Adipose Tissue↗