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Biomedical subjects

D Pinkel

Publications and source records attributed to D Pinkel.

At least 163 records · Page 9Linked to original sources
PubMed1982

Simple methods to determine and compare the sensitivity of flow cytometers.

Knowledge of the sensitivity of a flow cytometer is important both in choosing an instrument for a particular application and in determining whether the resolution obtained on real samples is limited by instrumental factors or sample variability. The coefficient of variation (CV) obtained for measurement is given by CV2 = CVS2 + CVI2 + 1/n + K(delta VB2)/n2, where CVS is the variability due to the sample, CVI that due to variations in illumination of the sample particles, n the number of photoelectrons emitted from the photomultiplier photo cathode per sample particle (which is the signal intensity), delta VB2 the mean square background noise voltage (usually due to background illumination), and K a constant. Measurement of the CV of light flashes from a light emitting diode as a function of their intensity allows development of standard curves which can be used to directly determine the degree to which the resolution obtained on actual samples is limited by signal intensity and background light. The use of standard particles allows relative calibration of the curves for different instruments and which also ranks their sensitivities.

Flow Cytometry↗
PubMed1982

Doxorubicin-vincristine therapy for Wilms' tumor: a pilot study.

Doxorubicin plus vincristine chemotherapy was given to 31 children following nephrectomy for Wilms' tumor. Radiation therapy was used as indicated. Disease-free survival by stage is: eight of nine patients (stage I), eight of nine (stage II), nine of ten (stage III), and two of three (stage IV). Median follow-up of survivors is 28 months (range, 2-67); for all but four patients, follow-up is greater than 12 months. Two of the three stage I-III failures occurred in children with unfavorable histologies; the third failure was due to fatal anthracycline cardiomyopathy. Lowering the maximal cumulative doxorubicin dose from 450 to 240 mg/m2 did not increase failures. Doxorubicin-vincristine appears to be effective chemotherapy for Wilms' tumor.

Adolescent↗
PubMed1982

Doxorubicin cardiomyopathy in children with left-sided Wilms tumor.

Two children with Wilms tumor of the left kidney experienced severe anthracycline cardiomyopathy after irradiation to the tumor bed and conventional dosage of doxorubicin. The cardiomyopathy is attributed 1) to the fact that radiation fields for left Wilms tumor include the lower portion of the heart and 2) to the interaction of doxorubicin and irradiation on cardiac muscle. It is recommended that doxorubicin dosage be sharply restricted in children with Wilms tumor of the left kidney who receive postoperative irradiation.

Cardiomyopathies↗
PubMed1981

A flow system for partial automation of plating efficiency tests.

A flow system that sterilely deposits a known number of cells into a collection vessel has been constructed and evaluated. In this device, the cells from a single-cell suspension flow through a nozzle that constrains them to the center of the emerging jet. The cells in the jet are illuminated by a 0.5-mW helium-neon laser; they are detected, sized and counted on the basis of the light scattered as they pass through the laser beam. The device has been used for plating efficiency tests in a tissue culture laboratory. We found that it saved considerable labor by eliminating the dilution step from the standard plating efficiency procedure. The biologic effect of machine plating was determined by comparing plating efficiencies of KHT, CHO-T5, and CHO-AA8 cells established by hand plating with those established by machine plating. Results indicate that machine plating reduces the plating efficiency of the CHO-T5 cells while the plating efficiencies of the CHO-AA8 and KHT cells are unaffected.

Animals↗
PubMed1981

On the possibility of automated scoring of pollen mutants.

Both flow cytometry and automated image analysis techniques may be useful in relieving the drudgery, increasing the speed, and adding quantitation to the scoring of pollen mutants, but practical problems related to the detection of very rare events have to be overcome. The features of flow and image cytometry instrumentation that may be useful for pollen measurements are discussed and a qualitative framework is presented from which to view the rare event problem.

Cell Count↗
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↗
PubMed1976

Urinary-bladder toxicity following pelvic irradiation and simultaneous cyclophosphamide therapy.

The frequency and severity of urinary-bladder toxicity were determined retrospectively in a large series of childhood cancer patients treated with either pelvic irradiation and simultaneous cyclophosphamide or cylclophosphamide with extrapelvic irradiation. Of 50 patients who received the first combination, 17 (34%) developed urinary-bladder toxicity. Eight of the 17 had transient hematuria and dysuria with complete clearing clinically after cessation of treatment; nine had chronic or intermittent hematuria which persisted after treatment was stopped and often resulted in demonstrable fibrosis and telangiectasia of the bladder. By contrast, of 60 children who received cyclophosphamide and radiotherapy outside the pelvic region, only five (8%) developed hematuria and in all instances it was transient. This comparative study demonstrates a significantly increased frequency and severity of urinary-bladder toxicity in cancer patients receiving pelvic irradiation with simultaneous cyclophosphamide.

Adolescent↗