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Biomedical subjects

D L Taylor

Publications and source records attributed to D L Taylor.

At least 109 records · Page 6Linked to original sources
PubMed1990

A multicellular tumor spheroid model of cellular immunity against head and neck cancer.

A multicellular tumor spheroid (MTS) model for head and neck cancers has been used to examine the immune function of fresh and 6-day interleukin-2(IL-2)-activated peripheral blood lymphocytes (PBL). MTS are individually cultured in the presence of effector cells, and the spheroids' growth is monitored by sizing them under an inverted microscope. Dose/response studies for IL-2 (0-100 U/ml) alone and for fresh unstimulated PBL (0-10(5) cells/MTS) showed no effects on MTS growth. IL-2-activated PBL (0-10(5) cells/MTS), in contrast, modulated MTS growth in a multiphasic pattern: MTS growth was unperturbed for the first 3 days and then growth inhibition occurred, followed by MTS disintegration. Histological analysis showed that intact MTS histoarchitecture correlated with unperturbed growth, and increasing cell sloughing and MTS dissolution and replacement by activated PBL correlated with growth inhibition and disintegration. Flow-cytometric sorting of lymphocyte subset populations indicated that it was the Leu19+CD3- cells that produced these growth-modulatory effects. In contrast to the initial LAK cell resistance of MTS, single-cell suspensions demonstrated significant lysis in standard 4-h chromium-release assays. Differences between single cells and MTS suggest a potential for tissue-like organization as a factor in lymphokine-activated killing.

Carcinoma, Squamous Cell↗
PubMed1990

Continuous or interrupted fascial closure: a prospective evaluation of No. 1 Maxon suture in 402 gynecologic procedures.

During a 14-month period of using a long-term absorbable suture (No. 1 Maxon), 402 patients were entered into a prospective, randomized trial of fascial closure. Patients were randomized between a continuous closure (201 patients) and an interrupted en bloc (201 patients) technique. Each patient was subjected to a preoperative and intraoperative protocol for wound management. There were no acute wound failures. Wound infection rates and risk of hernia were not apparently affected by closure technique.

Adult↗
PubMed1990

Single-dose antibiotic prophylaxis for patients undergoing extended pelvic surgery for gynecologic malignancy.

The comparative efficacy of single-dose antibiotic prophylaxis was retrospectively evaluated in 116 patients undergoing extended pelvic surgical procedures with curative intent. During the 24-month period, other important variables such as surgeon's experience, duration of preoperative hospitalization, preoperative preparation, method of hair removal, suture type, suture size, use of drains, use of cautery, and abdominal closure were controlled. The overall surgical site infection rate was 4.3% after radical hysterectomy with lymphadenectomy and 4.5% after total hysterectomy with lymphadenectomy. In this clinical situation the use of a single dose of antibiotic prophylaxis theoretically decreases cost and patient exposure and appears to be as efficacious as a multiple-dose regimen.

Anti-Bacterial Agents↗
PubMed1990

Differential sensitivity of head and neck cancers to non-major histocompatibility-restricted killer cell activity.

Cell lines derived from squamous cell carcinoma of the upper aerodigestive tract (head and neck cancer) were phenotypically characterized with regard to differential sensitivity to nonmajor histocompatibility restricted (non-MHCr) killer cell activity. Requirements for detectable lysis of the cell lines in a standard chromium release assay included either isolation of fresh enriched Leu 19+ large granular lymphocytes (both Leu 19+CD3+ and Leu 19+CD3- populations) or interleukin-2 (IL-2) stimulation of peripheral blood lymphocytes (PBL). In neither circumstance could lytic activity be identified among Leu 19- populations. With PBL IL-2 stimulation significant differential sensitivity to lysis expressed by the head and neck cancer cell lines (P less than 0.001 by analysis of variance) was identified and maintained regardless of PBL source, i.e., PBL from healthy controls and three differing populations of head and neck cancer patients categorized by disease status and treatment. One factor associated with a cell line's increased sensitivity was degree of tumor differentiation, poorly differentiated tumors (as defined by intermediate filament cytochemical staining [decreased keratin and increased vimentin]) being more sensitive. Furthermore, as tumor cell lytic sensitivity increased, major histocompatibility complex (MHC)-class I antigen expression diminished concurrently. In 1 of 4 cell lines tested, however, pretreatment of tumor cells with interferon-gamma induced diminished lytic sensitivity independent of changes in MHC-class I expression, indicating factors not related to MHC-class I expression are likewise relevant. In previous studies we defined the in vivo prognostic significance of non-MHCr killer cell cytotoxicity activity against K562 targets, diminished activity being principally predictive of metastatic disease development in persons with poorly differentiated head and neck cancers. This report extends these observations by demonstrating in vitro that poorly differentiated head and neck cancer target cells are highly sensitive to changes in lytic function expressed by Leu 19+ non-MHCr effector cells.

Carcinoma, Squamous Cell↗
PubMed1989

Natural killer cell lysis of head and neck cancer.

This study analyzed the capacity of both fresh unseparated peripheral blood lymphocytes and enriched natural killer (NK) cells to lyse head and neck cancer cell lines. In a 6-hour chromium-release assay, only Leu-19+ NK cells mediated significant lysis. Furthermore, cell lines established from poorly differentiated cancers were more sensitive to lysis than were cell lines established from well-differentiated cancers. Cell lines from well-differentiated cancers also less readily inhibited K562 lysis in a cold-target inhibition assay, were not recognized by NK cells in a monolayer absorption assay (unlike poorly differentiated cancers), and failed to form conjugates with NK cells in a single-cell assay. These results indicated that deficient killing of a well-differentiated cancer cell vs a poorly differentiated cancer cell is partly a function of diminished NK cell recognition and tumor binding necessary to initiate lysis. As in previous studies regarding the prognostic implication of quantitated measures of NK cell activity within head and neck cancer patients, the results support the biologic relevance of the NK cell as a defense mechanism against metastatic disease, especially in patients with poorly differentiated, low major histocompatibility complex class I-expressing head and neck cancers.

Antibodies, Monoclonal↗
PubMed1989

Correlated distribution of actin, myosin, and microtubules at the leading edge of migrating Swiss 3T3 fibroblasts.

The formation of lamellipodia in migrating cells involves dynamic processes that occur in a cyclic manner as the leading edge of a cell slowly advances. We used video-enhanced contrast microscopy (VEC) to monitor the motile behavior of cells to classify protrusions into the temporal stages of initial and established protrusions (Fisher et al.: Cell Motility and the Cytoskeleton 11:235-247, 1988), and to monitor the fixation of cells. Multiple parameter fluorescence imaging methods (DeBiasio et al.: Journal of Cell Biology 105:1613-1622, 1987; Waggoner et al.: Methods in Cell Biology, Vol. 30, Part B, pp. 449-478, 1989) were then used to determine and to map accurately the distributions of actin, myosin and microtubules in specific types of protrusions. Initial protrusions exhibited no substructure as evidenced by VEC and actin was diffusely arranged, while myosin and microtubules were absent. Newly established protrusions contained diffuse actin as well as actin in microspikes. There was a delay in the appearance of myosin into established protrusions relative to the presence of actin. Microtubules were found in established protrusions after myosin was detected, and they were oriented parallel to the direction of migration. Actin and myosin were also localized in fibers transverse to the direction of migration at the base of initial and established protrusions. Image analysis was used to quantify the orientation of actin fibers relative to the leading edge of motile cells. The combined use of VEC, multiple parameter immunofluorescence, and image analysis should have a major impact on defining complex relationships within cells.

Actins↗
PubMed1989

Evaluation of algorithms for ratio imaging in fluorescence microscopy.

Ratio imaging in fluorescence microscopy is used in measuring parameters such as pH, pCa, cytoplasmic porosity, and the relative concentration of fluorescent analogs within single cells. The fastest method for ratio imaging is to use lookup tables on special-purpose image processors. Since lookup tables store integers in integer addresses, using a lookup table will generate rounding errors. The magnitude of the error will depend on the transformation performed and on the number of levels used in the lookup table. We examined ratio imaging by lookup table and computed the errors generated by both inversion and log subtraction methods. Both uniformly fluorescing fields and fluorescing cell images were employed to provide data for use in confirming our calculations and illustrating both the magnitude and spatial incidence of errors. It is shown that, through proper design of lookup tables, a significant reduction can be made in the errors generated in comparison with common methods available in most image processors.

Algorithms↗
PubMed1989

Heterogeneity of the changes in cytoplasmic pH upon serum stimulation of quiescent fibroblasts.

Addition of mitogens to quiescent cells results in rapid ionic changes in the cytoplasm, including pH. We studied the changes in cytoplasmic pH in single Swiss 3T3 cells upon serum stimulation using fluorescence ratio imaging microscopy. Quiescence was attained using two approaches, serum deprivation of subconfluent cells and confluence. All measurements were made in the presence of bicarbonate and the absence of other organic buffers. We also used BCECF coupled to dextran to avoid several artifacts associated with using BCECF-AM, including leakage and phototoxicity. Analysis of the changes in cytoplasmic pH demonstrated a dramatic heterogeneity in the responses of single cells. There were six basic classes of responses, 1) a fast alkalinization, reaching a maximum pH in approximately 2-5 min; 2) a slow alkalinization, reaching a maximum pH in 10-20 min; 3) a very slow alkalinization, not reaching a plateau pH within the measurement time; 4) no apparent change in pH during the measurement time; 5) an early transient acidification, followed by either a fast or slow alkalinization; and 6) an acidification, followed by alkalinization and then by a decrease to some intermediate pH. Subconfluent cells exhibited greater heterogeneity in response than confluent cells, with no single dominant class of response. The dominant (55%) response for confluent cells was a gradual alkalinization of approximately 0.01 pH units/min. A larger proportion (52%) of subconfluent cells exhibited an early transient acidification compared to confluent cells (7%). A significant proportion of both types of cells (23% subconfluent, 36% confluent) exhibited no change in cytoplasmic pH upon stimulation. In general, the kinetics of changes in cytoplasmic pH were significantly different from the published results with population averaging methods.

Animals↗
PubMed1989

Natural killer cells and metastases from pharyngeal carcinoma.

Natural killer cell activity was assessed in 100 previously untreated pharyngeal carcinoma patients. Diminished natural killer cell function in these patients was associated with an increased risk of death from uncontrolled regional and distant metastases. During the assessment, the cell line MDA686-Ln was established from a metastatic pharyngeal carcinoma of a patient with low natural killer cell cytotoxicity. The initially cytotoxicity-resistant cell line could be lysed when natural killer cell cytotoxicity was enhanced in vitro either through enrichment of a Leu 19+ natural killer cell population by fluorescent-activated cell sorting or by interleukin-2 activation. Additionally, increased circulating immune complexes were identified in these patients, subsequently isolated, and found to block natural killer cell reactivity against MDA686-Ln. In light of this negative interaction, 38 patients were randomly evaluated for both circulating immune complex levels and natural killer cell function. Both parameters examined together were complementary in defining the risk of death with disease; four of five deaths occurred in patients with both high circulating immune complex levels and low natural killer cell function. Results support the biologic modification of natural killer cell activity for controlling metastatic pharyngeal carcinoma and point to the potential confounding influence of circulating immune complex.

Adult↗
PubMed1989

Cytomegalovirus and the acquired immunodeficiency syndrome.

The acquired immunodeficiency syndrome (AIDS) is complex in nature with one major aetiological factor but with numerous other agents exploiting the immune incompetence. Cytomegaloviruses (CMV) form a little-defined group of viruses which naturally persist in man and respond readily to the relaxation in immune surveillance. A role for CMV and other herpesviruses in potentiating the underlying infection with human immune deficiency virus (HIV) cannot be totally excluded but CMV is well established as a major opportunist in AIDS. They are considered responsible for a range of diseases in AIDS patients including retinitis, gastrointestinal disease, pneumonitis and, less frequently, encephalitis. The pyrophosphate analogue foscarnet (phosphonoformate) and the deoxyguanosine analogue ganciclovir have both been used to treat CMV infections in AIDS patients. Results of uncontrolled studies have indicated efficacy with both drugs but the work with ganciclovir is particularly encouraging. This communication provides a review of CMV infections in AIDS patients with special reference to the experiences to-date in the use of ganciclovir and foscarnet.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Enolase exists in the fluid phase of cytoplasm in 3T3 cells.

We have investigated the intracellular distribution and mobility of the glycolytic enzyme enolase, using functional fluorescent analogs labeled with the succinimidyl esters of carboxyfluorescein (F1-enolase) and carboxytetramethylrhodamine (Rh-enolase) In contrast to aldolase, neither native enolase nor labeled enolase gelled filamentous actin (F-actin), as measured by falling-ball viscometry, indicating a lack of interaction between enolase and F-actin. Fluorescence redistribution after photo-bleaching (FRAP) measurements of the diffusion coefficient (D) of F1-enolase in aqueous solutions gave a value of D37,aq = 6.08 x 10(-7) cm2s-1, and no immobile fraction, consistent with a native molecular weight of 90,000. These values were not significantly different with Rh-enolase, or in the presence of F-actin, 2-phosphoglycerate or F-actin-aldolase gels, demonstrating that neither F1-enolase nor Rh-enolase binds to F-actin or aldolase in vitro. FRAP measurements of F1- and Rh-enolase microinjected into living Swiss 3T3 cells revealed spatial differences in the diffusion coefficient, but not the mobile fraction. In the perinuclear cytoplasm, we measured an apparent diffusion coefficient of 1.1 x 10(-7) cm2s-1, compared to 7.1 x 10(-8) cm2s-1 in the peripheral cytoplasm, with approximately 100% mobility of F1- or Rh-enolase in both regions. Imaging of cells co-injected with Rh-enolase and size-fractionated FITC-dextran (FD-90) revealed that Rh-enolase entered the nucleus, while FD-90 was excluded. Ratio imaging showed a relatively high nuclear ratio of Rh-enolase/FD-90, and a uniform cytoplasmic ratio, with no indication of increased concentration of enolase around stress fibers. These data demonstrate that Rh- and F1-enolase do not bind to F-actin in vitro, and are 100% mobile in vivo. Together with our recent finding that a significant fraction of aldolase binds to F-actin in vitro and is immobile in vivo, these data suggest a correlation between actin-binding activity and cytoplasmic mobility of glycolytic enzymes.

Animals↗