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Biomedical subjects

D Pinkel

Publications and source records attributed to D Pinkel.

13 recordsLinked to original sources
PubMed1979

Flow cytometry of mammalian sperm: progress in DNA and morphology measurement.

Variability in DNA content and head shape of mammalian sperm are potentially useful markers for flow cytometric monitoring of genetic damage in spermatogenic cells. The high refractive index and extreme flatness of the sperm heads produce an optical effect which interferes with DNA measurements in flow cytometers which have dye excitation and fluorescence light collection normal to the axis of flow. Orientation of sperm in flow controls this effect and results in coefficients of variation of 2.5% and 4.2%, respectively, for DNA measurements of mouse and human sperm. Alternatively, the optical effect can be used to generate shape-related information. Measurements on randomly oriented sperm from three mammalian species using a pair of fluorescence detectors indicate that large shape differences are detectable. Acriflavine-Feulgen stained sperm nuclei are significantly bleached during flow cytometric measurements at power levels routinely used in many flow cytometers. Dual beam studies of this phenomenon indicate it may be useful in detecting abnormally shaped sperm.

Animals↗
PubMed1978

Hydrodynamic orientation of sperm heads for flow cytometry.

Two specially shaped sample injection tubes orient flat-shaped mature sperm heads in a flow cytometer. Orientation allows control of a photometric difficulty experienced with some flow cytometers in the measurement of fluorescent and scattered light from sperm and other flat cells. Both relative DNA-stain content and a measure of cell flatness can now be determined simultaneously for each cell at the high rates possible with flow instruments.

Animals↗
PubMed1978

High resolution dual laser flow cytometry.

Flow cytometers based on optical sensing utilize external light sources and fluorescent dyes to measure one or more specific components or properties of individual cells or subcellular particles in liquid suspension. To provide for independent excitation of two dyes used in double staining experiments we have constructed a high resolution flow cytometer that uses two laser beams to provide two wavelengths of excitation. These beams are separated spatially so that cells flow through them sequentially, with a time separation of about 20 musec. Since the dyes are excited sequentially their emission occurs at different times and their emission spectra may overlap without causing any difficulty in analysis. We have developed new light collection optics that permit up to four measurements to be made on each cell. This approach greatly increases the number of dye combinations that can be used in flow cytometry, thus removing a significant limitation of single illumination instruments.

Animals↗
PubMed1977

Radiotherapy in leukemia and lymphoma of children.

Radiotherapy is important in the treatment of leukemia and lymphoma of children. In acute lymphocytic leukemia administration of cranial irradiation early during chemotherapy-induced remission prevents initial meningeal relapse. When cranial irradiation is combined with a 3-year course of multiple drug systemic chemotherapy approximately one-half of the children remain in complete remission for 5 years or more and are at little risk of relapse. Preventive cranial irradiation is effective in children with acute myelocytic leukemia, also, but this does not affect survival because of the inadequacy of chemotherapy in controlling bone marrow disease. Low dose palliative irradiation can be helpful in caring for some children with obstructive, painful or disabling leukemic lesions. In Hodgkin's disease of children radiotherapy is effective in curing stages IA, IIA, and IIIA disease and contributes to chemotherapy control of stages IIIB and IV disease. The role of radiotherapy in non-Hodgkin's lymphoma is less clear. Children with T-lymphoblastic lymphoma tend to have rapid dissemination to bone marrow and meninges and appear to benefit more from multiple agent chemotherapy and preventive meningeal irradiation. Children with B-lymphoblastic lymphoma usually benefit from cyclophosphamide therapy; the value of irradiation is yet to be established. However, radiotherapy is frequently curative in stage I B-lymphocytic nodular and histiocytic lymphomas. The indications for radiotherapy in children with leukemia and lymphoma are constantly changing. Before each child is treated the multi disciplinary evaluation and treatment team must consider the rationale in relation to the specific child and current knowledge.

Antineoplastic Agents↗
PubMed1977

Flow system fluorescence polarization measurements on fluorescein diacetate-stained EL4 cells.

We have adapted a multiparameter cell sorter to measure the distribution of fluorescence polarization in cell populations. Measurements carried out on EL4 cells show that the percent polarization of fluorescein fluorescence decreases with increasing fluorescence intensity. This inverse relationship between polarization and intensity is shown both within the cell population and by the average values of the two quantities during both the increase and decrease of fluorescence intensity. The quantitative relation between intensity and polarization is different in hypertonic than in isotonic media. These results suggest that polarization measurements carried out at a fixed time after incubation of cells with fluorescein diacetate, which is converted to fluorescein within the cells, may depend in part on the rate of fluorescein accumulation, and that agents that have been reported to change the polarization of fluorescein in living cells may do so by changing the kinetics of fluorescein accumulation.

Cell Line↗
PubMed1975

Capsular and vascular invasion: important prognostic factors in Wilms' tumor.

The influence of capsular and vascular invasion on prognosis was determined retrospectively in 52 children with Wilms' tumor. Local recurrence was more prevalent (0.26) in patients with rupture or capsular invasion than in any other group. Inadequate postnephrectomy irradiation or infiltration of the liver by nephroblastoma cells appeared to be predisposing factors in the development of these reccurrences. Of the 26 patients with gross or microscopic vascular invasion, 13 developed metastasis. This proportion was significantly higher than in patients without vascular involvement (p less than 0.05). These observations emphasize the importance of microscopic detection of capsular and vascular invasion in staging of Wilm's tumor.

Child↗
PubMed1975

Preoperative therapy for unresectable malignant tumors in children.

Thirty-six children with initially unresectable malignant tumors were managed with pre- and postoperative therapy combined with reduction of primary tumor burden by total or subtotal resection. The proportion of patients achieving long-term tumor-free survival after surgery was 0.48 in the Wilms' tumor group and 0.60 among patients with other regionally unresectable malignant neoplasms. These results are encouraging in an otherwise high mortality situation.

Adolescent↗