Search PubMed⌕ Search

Biomedical subjects

C Allen

Publications and source records attributed to C Allen.

At least 163 records · Page 9Linked to original sources
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↗
PubMed1986

Incidence and differences in urban-rural seasonal variation of type 1 (insulin-dependent) diabetes in Wisconsin.

In a hospital-based records study of Type 1 (insulin-dependent) diabetes mellitus among persons aged 0 to 29 years in two Wisconsin, USA counties (1970-79), the age-adjusted yearly incidence rate for white males (16.4/100,000) was significantly higher than for white females (11.6/100,000) (p = 0.006). Overall age-adjusted rates are similar to rates previously reported for the United States and the northern European countries of Denmark and Norway. Seasonal variation in diagnosis was found for total cases and males aged 10 to 19 years. A striking difference also was found in seasonal diagnosis between urban and rural cases. A diagnosis peak in the third and fourth quarter among rural cases contrasted with even quarterly distribution among urban cases. In addition, 52% of rural male cases aged 10 to 19 years were diagnosed during the fourth quarter while no seasonal pattern occurred among urban males the same ages. These findings identify subgroups for focus of future etiologic investigations.

Adolescent↗
PubMed1986

Breast cancer in the elderly. Current patterns of care.

To evaluate age-related differences in the current patterns of presentation and clinical management of breast cancer patients, the authors reviewed 1795 patients referred to a university hospital for their initial treatment. No age-related differences were found with respect to laterality and anatomic site. Age-related differences were seen with respect to histology, with mucinous (colloid) carcinoma being relatively more common with increasing age and medullary and inflammatory carcinoma being more common among young patients. Patients over age 55 presented with more advanced extent of disease, but the proportion did not further increase above age 65. Patients age 75 and older were nearly twice as likely to have surgery as their sole treatment as patients under age 45. The difference in treatment was specifically associated with the differential use of adjuvant chemotherapy between age groups. Sixty percent of patients under 45 with regional node involvement received adjuvant chemotherapy compared with only 27% of those 65 and older. Despite their similar characteristics in regard to laterality, anatomic site, and histology, elderly patients are less frequently given adjuvant chemotherapy in stage II breast cancer.

Adolescent↗
PubMed1986

Human retinal pigment epithelium in long term explant culture.

Explants of human retinal pigment epithelium were maintained in culture in various types of media, and examined by light and transmission electron microscopy. After one month in vitro, the central areas showed a monolayered configuration with distinct polarity and presence of ruthenium red stainable material on the apical surface. On the peripheral areas of Bruch's membrane, multilayered lesions were observed to develop and to extend from the monolayered epithelium and past the cut edge in Bruch's membrane. Cells in these lesions contained little melanin and generally lacked an apico-basal polarity. Ruthenium red staining revealed the presence of electron dense material on the apical surface of the lesions as well as in the extracellular space between cells in the various layers. Development of multilayered lesions with deposition of extracellular material are seen in various chorio-retinal disorders, including senile macular degenerations and also subsequent to laser and cryo-therapy. The findings in the present study point to the explant culture system as a valuable tool in the study of important aspects of chorio-retinal pathology.

Aged↗
PubMed1986

Requirement for two or more Erwinia carotovora subsp. carotovora pectolytic gene products for maceration of potato tuber tissue by Escherichia coli.

Several genes encoding enzymes capable of degrading plant cell wall components have been cloned from Erwinia carotovora subsp. carotovora EC14. Plasmids containing cloned EC14 DNA mediate the production of endo-pectate lyases, exo-pectate lyase, endo-polygalacturonase, and cellulase(s). Escherichia coli strains containing one of these plasmids or combinations of two plasmids were tested for their ability to macerate potato tuber slices. Only one E. coli strain, containing two plasmids that encode endo-pectate lyases, exo-pectate lyase, and endo-polygalacturonase, caused limited maceration. The pectolytic proteins associated with one of these plasmids, pDR1, have been described previously (D. P. Roberts, P. M. Berman, C. Allen, V. K. Stromberg, G. H. Lacy, and M. S. Mount, Can. J. Plant Pathol. 8:17-27, 1986) and include two secreted endo-pectate lyases. The second plasmid, pDR30, contains a 2.1-kilobase EC14 DNA insert that mediates the production of an exo-pectate lyase and an endo-polygalacturonase. These enzymes are similar in physicochemical properties to those produced by EC14. Our results suggest that the concerted activities of endo-pectate lyases with endo-polygalacturonase or exo-pectate lyase or both cause maceration.

Cell Wall↗
PubMed1985

The interaction between Pseudomonas aeruginosa and the corneal epithelium. An electron microscopic study.

The interaction between Pseudomonas aeruginosa and the rabbit corneal epithelium during the first hour after inoculation was studied using scanning and transmission electron microscopy. Fifteen minutes after inoculation, adherent bacteria were found on damaged or exposed basal epithelial cells at the edge of an epithelial defect, and this adherence was the result of an interaction between the bacterial and epithelial cell membranes. Thirty minutes after inoculation, the adherent bacteria began to penetrate the epithelial cells by the formation of "pockets" surrounding the organisms, and after an additional 15 minutes the bacteria further penetrated the cells as the pockets began to fill in with cellular material. One hour after inoculation, only rare bacteria were seen on the cell surfaces or within the margins of the epithelial defect. Transmission electron microscopy, however, revealed many intracellular bacteria or bacteria that had migrated between the basal epithelium and corneal stroma. Therefore, it appears that the initiating events in Pseudomonas corneal ulceration involve adherence to the damaged or exposed basal epithelial cells by an interaction between the bacterial and cellular membranes, after which the organisms are engulfed by the epithelial cell and reach the corneal stroma by a process of transcellular migration.

Adhesiveness↗
PubMed1985

Prevalence and clinical associations of intraocular pressure changes in Graves' disease.

We investigated an unselected series of 55 patients with treated or untreated hyperthyroid Graves' disease, assessing their clinical and laboratory status and ophthalmological findings, including the difference in intraocular pressure (dIOP) between upgaze and straight gaze using applanation tonometry. An increased dIOP (greater than 2 mm Hg) was detected in only 22% of Graves' patients [who had a mean dIOP of 3.5 +/- 1.6 (+/- SEM) mm Hg]. dIOP did not correlate with age, sex, age at disease onset, duration of disease, mode of antithyroid treatment, or thyroid function testing at the time of examination. Mean Hertel exophthalmometry measurements in patients with a dIOP greater than 2 mm Hg were 22.0 +/- 2.9 mm compared with 18.4 +/- 3.7 mm in those with a dIOP less than 2 mm Hg (P less than 0.027, by Wilcoxon rank sum test). Only 58% of patients with increased dIOP had clinical exophthalmos, but all had other evidence of Graves' eye disease. Computed tomographic scanning revealed significant proptosis and/or orbital muscle involvement in all of the patients with increased dIOP.

Adult↗