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Biomedical subjects

J Shields

Publications and source records attributed to J Shields.

At least 37 records · Page 2Linked to original sources
PubMed1989

Population ecology of preimaginal Culex tarsalis (Diptera: Culicidae) in Kern County, California.

The effects of abiotic and biotic mortality factors on preimaginal survivorship and the production of adults were investigated for populations of Culex tarsalis Coquillett at a stable foothill breeding site during 1985 and at seven ephemeral breeding sites during 1986. Female abundance was correlated temporally with larval abundance and spatially with first instar to adult survivorship. Catastrophic events, such as fluctuations in water level and pollution, drastically reduced larval and pupal abundance. Under relatively stable conditions, the effect of natural mortality factors was estimated by comparing preimaginal survivorship rates, estimated horizontally for fed and unfed cohorts in predator exclusion cages, with survivorship, estimated vertically from the age structure of the natural population using a life table approach. Mortality for fed cohorts ranged from 8.5 to 90.0% and was attributed to abiotic factors, including temperature and water quality. Mortality caused by lack of food was comparatively low (less than 15%); however, the low nutrient level at three of six sites lengthened the duration of the fourth stadium, delayed pupation, and resulted in the emergence of small-sized adults with a reduced expression of autogeny. Predation mortality ranged from 3.7 to 84.5% and was the most important cause of larval death at five of six study sites. Based on relative abundance and correlation over time and space, zygopteran naiads were the most important predator at a stable foothill breeding site during 1985, and coleopteran larvae were the most important predator at ephemeral breeding sites sampled during 1986.

Animals↗
PubMed1989

Cross-institutional stability of behavioral criteria desirable for success in radiology residency.

Certain dimensions of job performance are critical to radiology residents, and several of these dimensions are noncognitive in nature (eg, interpersonal skills, conscientiousness, recognition of limits). Our initial study examined these factors in only one residency program, so the general nature of these dimensions must be documented. The current study was a cross institutional analysis involving 31 faculty radiologists at three separate academic institutions (82% of total faculty) who participated in a critical incident interview to obtain data on important resident behaviors and attitudes. The resultant 172 incidents were sorted by two physicians into the six categories (knowledge, technical skills, attitudes toward self and [both recognitions of limits and confidence in abilities], conscientiousness, curiosity, and interpersonal skills); inter-rater reliability was 92%, kappa = .89. A Chi square analysis revealed similar distributions of incidents across categories (x2 12 = 17.22) among the three institutions, supporting the general reliability of these dimensions across the institutions studied. Further, the distributions of these incidents demonstrated that the noncognitive dimensions again were given considerable importance by faculty radiologists. For example, more than 40% of the critical incidents pertained to the conscientiousness dimension. These findings documented the generalization of these behavioral dimensions across several sites and support their importance in selection and evaluation of residents.

Attitude of Health Personnel↗
PubMed1987

Retinoblastoma. Immunohistochemistry and cell differentiation.

Tumor from eight enucleated eyes was analyzed by immunohistochemistry, using a panel of specific antibodies including interphotoreceptor retinoid-binding protein (IRBP), S-antigen (S-Ag), opsin, neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), laminin, and vimentin. In addition, immunoelectron microscopy and enzyme-linked immunosorbent assay (ELISA) for IRBP were performed. Immunohistochemical staining disclosed the most pronounced labeling of tumor cells with NSE and IRBP antibodies. A correlation was found between the degree of tumor differentiation and amount of IRBP, a protein specifically synthesized by photoreceptor cells. Moderate labeling of the better differentiated tumors was also observed with antibodies against S-Ag and focal labeling in a few tumors with opsin antibodies. Anti-GFAP labeling was limited to a smaller number of reactive glial cells and perivascular glial cells. These data indicate the essential neuronal nature of retinoblastoma tumor cells in situ as well as at least partial photoreceptor-like features, as shown by the presence of recognized photoreceptor cell markers (IRBP, S-Ag, opsin). Tissue culture studies using the human Y-79 retinoblastoma cell line also demonstrate that the tumor cells are primitive multipotential retinoblasts capable of at least partial differentiation along neuronal, glial, or pigment epithelial cell lines.

Antibodies, Anti-Idiotypic↗
PubMed1986

B cell growth and differentiation induced by supernatants of transformed epithelial cell lines.

Growth and differentiation of B cells is thought to be regulated by soluble factors derived from T cells. However, human T cell lines and hybridomas have proved to be notoriously unreliable and unstable sources of such factors. We report here that three stable human bladder carcinoma cell lines T24, RT4 and 5637 produce, in a constitutive fashion, factors which promote growth and differentiation of human B cells.

Antigens, Differentiation, B-Lymphocyte↗
PubMed1985

Large cell lymphoma of the orbit with microvillous projections ('porcupine lymphoma').

A 57-year-old man had a diffuse mass in the lacrimal gland area associated with extensive bony destruction. A malignant epithelial tumor of the lacrimal gland was suspected clinically, and a biopsy specimen disclosed an undifferentiated malignant neoplasm of uncertain origin. Ultrastructural studies, however, revealed features of a lymphoid tumor with myriad cytoplasmic microvillous projections. The patient has had no evidence of systemic lymphoma after more than three years of follow-up. To our knowledge, this is the first report of orbital involvement of a large cell lymphoma with microvillous projections ("porcupine lymphoma"). The role of electron microscopy in the differential diagnosis of this orbital tumor was important, since epithelial tumors of the lacrimal gland are best managed by surgical excision, whereas lymphoid tumors usually respond satisfactorily to radiotherapy.

Biopsy↗
PubMed1983

Treatment of advanced malignancy with plasma perfused over staphylococcal protein A.

A total of 14 extensively pretreated patients with advanced and progressive malignancy were given 140 infusions of autologous plasma that had been perfused over staphylococcal protein A bound to an agarose gel (Sepharose). Infusions ranged in volume from 35 ml to 260 ml (mean, 70 ml), and the quantity of protein A used ranged from 1 to 30 mg per 100 ml of plasma (mean, 10 mg). Acute toxic reactions included fever (21%), chills (18%), nausea (17%), vomiting (8%), pain (9%) and bronchospasm (2%). Four patients did not have an acute toxic reaction and no chronic or cumulative toxic effects were identified. In two patients there was objective tumor regression and in five there was stabilization of disease lasting from 4 to 12 weeks. Further study of this treatment modality is warranted.

Adult↗
PubMed1982

Abnormalities of chromosome #13 in retinoblastomas from individuals with normal constitutional karyotypes.

Constitutional chromosome abnormalities have been associated with retinoblastoma, Wilm's tumor, and a familial form of renal carcinoma. For each tumor type, the particular chromosome segment involved in the observed rearrangements is different: in retinoblastoma, that segment is band q14 on chromosome #13. We now present evidence that in retinoblastoma, structural abnormalities involving the particular chromosome segment identified in the constitutional cases can also occur in the tumors of individuals with normal constitutional karyotypes. Six cases with retinoblastoma in one or both eyes were analyzed; deletions/rearrangements involving 13q14 were found in the tumor cell karyotypes of five of the six. These observations suggest that changes in a gene or genes at a common site (13q14) play a role in tumorigenesis in all forms of retinoblastoma, sporadic as well as heritable.

Child, Preschool↗
PubMed1981

A deleted chromosome no. 13 in human retinoblastoma cells: relevance to tumorigenesis.

In this report of banded karyotypes prepared after short-term culture (72 hr) from human retinoblastoma tumor tissue, on del(13)(pter leads to q14:) chromosome and one normal chromosome #13 were found in all of the metaphases examined. Similar deletions (always involving 13q14) have previously been described in the somatic cells of individuals with one form of retinoblastoma. In the present case, however, the constitutional karyotype is normal. The presence of tumors in both eyes suggests that this is the genetic form of retinoblastoma, even though the patient's family history is negative for this tumor. The normal constitutional karyotype argues that the chromosome deletion occurred as a postzygotic event. The modal chromosome number of the tumor cells is 47 and rearrangements involving chromosomes #2, #17, and #20 were also identified.

Child, Preschool↗
PubMed1976

Pelvic lipomatosis.

Three cases of pelvic lipomatosis are presented. Excretory urogram revealed characteristic elevation and elongation of urinary bladder base and relative hyperlucency of pelvic cavity. Associated varying degrees of hydronephrosis and hydroureters are seen secondary to distal ureteral obstruction. Barium enema showed elongation and elevation of rectosigmoid colon.

Female↗