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Biomedical subjects

E Epstein

Publications and source records attributed to E Epstein.

At least 91 records · Page 5Linked to original sources
PubMed1990

Use of soft lenses.

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Biocompatible Materials↗
PubMed1990

Selective accumulation of lymphocyte precursor cells mediated by stromal cells of hemopoietic origin.

Thymocytes were propagated in long-term cultures supported by stromal cells of both bone marrow and thymus origin. Interleukin 2 (IL-2) supplementation augmented the cell yield and allowed detailed phenotype analysis. Within 2-3 months of culture a cell population was selected in which the expression of Thy-1 antigen persisted, CD4 and CD8 antigens gradually declined, and Pgp-1 antigen, found on less than 5% of fresh thymocytes, was strongly increased. This cultured cell population (Thy-1.2 origin) contained no detectable spleen colony-forming units (CFU-S) but efficiently repopulated the thymus of Thy-1.1-irradiated congenic mice, indicating the precursor T-cell nature of the population. Upon removal from the stroma, the T cells exhibited poor cytotoxicity towards syngeneic tumor cells. Further propagation with IL-2 in the absence of stroma resulted in the acquisition of cytotoxic ability. Replacement of the horse serum used in the above experiments with fetal calf serum resulted in accumulation of cells expressing B220 antigen. This experimental model provides the means to maintain lymphocyte precursor cells in long-term culture and to further study their differentiation in the absence of stroma, both in vitro and in vivo.

Animals↗
PubMed1990

Laboratory measurement of bilirubin.

Several methods for determination of total bilirubin and its fractions have been critically discussed. Methods for serum determinations are summarized in Table 1. Because results of direct bilirubin cannot necessarily be equated with conjugated bilirubin, care must be taken in interpreting results from different laboratories, and clinicians are encouraged to become familiar with methods in use at their own institutions. Despite problems reported in the literature, bilirubin determinations, together with a reference range established for one's own patient population, should provide valuable information for patient management.

Amniotic Fluid↗
PubMed1990

Primula contact dermatitis: an easily overlooked diagnosis.

Contact dermatitis to Primula obconica is not uncommon in the United States, yet it is scarcely mentioned in current North American dermatologic textbooks and literature. Affecting mainly women, primula contact dermatitis is often misdiagnosed since its nondescript pattern suggests an endogenous dermatitis. The author summarizes his experience with nine patients encountered in his practice during two years. Patch testing is important since a positive patch test reaction confirms the diagnosis and helps to convince the patient to discard the offending plant(s). A simple technique of patch testing with the primula leaf is described.

Adult↗
PubMed1989

Allosensitization in IL-2-containing limiting dilution cultures generates cytotoxic T lymphocytes (CTL) rather than LAK cells reactive with a syngeneic nonimmunogenic murine tumor.

We have previously demonstrated that high frequency (1/20) of potent cytotoxic cells reactive with the nonimmunogenic lymphoma PIR-2 of C57BL/6 (B6, H-2b) origin, can be obtained by allosensitization of syngeneic B6 splenocytes against BALB/c (H-2d) splenocytes in limiting dilution cultures (LDC). Since a high concentration (250 U/ml) of exogenous interleukin 2 (IL-2), sufficient for the elicitation of lymphokine-activated killer (LAK) cells, was used in the LDC, and because the LDC-derived cytotoxic cells were active against a wide spectrum of target cells, we investigated whether the anti PIR-2 effector cells are LAK cells or cytotoxic T lymphocytes (CTL). We found that depletion from the B6 responder cell population of Lyt2+ (CTL precursors), but not of asialo GM1+ (LAK cell precursors), prior to LDC, results in the ablation of anti PIR-2 activity. When B6 splenocytes were plated in LDC with IL-2, in the absence of allogeneic stimulating cells, the resulting anti PIR-2 activity was greater than 10- to 500-fold lower than that obtained in LDC in the presence of allogeneic stimulating cells and IL-2. These and other observations suggest that the cytotoxic response against syngeneic tumors elicited by alloantigens in LDC is mediated by CTL rather than LAK cells, and that allogeneic sensitization in LDC can provide a means for the generation of CTL against syngeneic, nonimmunogenic tumors.

Animals↗
PubMed1989

Chemo-immunotherapy of murine tumors using interleukin-2 (IL-2) and cyclophosphamide. IL-2 can facilitate or inhibit tumor growth depending on the sequence of treatment and the tumor type.

The antitumor effect of interleukin-2 (IL-2), alone and in combination with cyclophosphamide was assessed in mice with established sarcoma (MCA 105, H-2b), carcinoma (M109, H-2d) and T lymphoma (PIR-2, H-2b). Whereas administration of IL-2 alone (5 x 10(4)-10 x 10(4) U, i.p. twice daily, for 4-8 consecutive days) prolonged the survival of mice with the solid neoplasms, it enhanced tumor growth and decreased survival of mice with the lymphoma. In the PIR-2 lymphoma, no IL-2 receptor (TAC) could be detected, nor could we demonstrate IL-2 tumor growth stimulation in vitro. A synergistic therapeutic effect was achieved in mice with the solid tumors, but not in mice with the lymphoma, only when IL-2 was given 1-4 days after cyclophosphamide (100-200 mg/kg). Conversely, administration of IL-2 1-4 days prior to cyclophosphamide resulted, in all three tumor systems, in enhanced tumor growth and in decreased survival as compared with mice receiving cyclophosphamide alone. Similarly, treatment with IL-2 both before and after cyclophosphamide was less efficacious than a single course of IL-2 given afterwards. It is concluded that for maximal therapeutic efficacy, IL-2 should be administered following chemotherapy, and that certain tumors may respond adversely to IL-2 treatment.

Adjuvants, Immunologic↗
PubMed1989

Suture problems.

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Humans↗
PubMed1989

In vivo 23Na and 31P NMR measurement of a tonoplast Na+/H+ exchange process and its characteristics in two barley cultivars.

A Na+ uptake-associated vacuolar alkalinization was observed in roots of two barley cultivars (Arivat and the more salt-tolerant California Mariout) by using 23Na and 31P in vivo NMR spectroscopy. A NaCl uptake-associated broadening was also noted for both vacuolar Pi and intracellular Na NMR peaks, consistent with Na+ uptake into the same compartment as the vacuolar Pi. A close coupling of Na+ with H+ transport (presumably the Na+/H+ antiport) in vivo was evidenced by qualitative and quantitative correlations between Na+ accumulation and vacuolar alkalinization for both cultivars. Prolongation of the low NaCl pretreatment (30 mM) increased the activity of the putative antiport in Arivat but reduced it in California Mariout. This putative antiport also showed a dependence on NaCl concentration for California Mariout but not for Arivat. No cytoplasmic acidification accompanied the antiporter activity for either cultivar. The response of adenosine phosphates indicated that ATP utilization exceeded the capacity for ATP synthesis in Arivat, but the two processes seemed balanced in California Mariout. These comparisons provide clues to the role of the tonoplast Na+/H+ antiport and compensatory cytoplasmic adjustments including pH, osmolytes, and energy phosphates in governing the different salt tolerance of the two cultivars.

Adenine Nucleotides↗
PubMed1989

Phosphatidylglycerol in amniotic fluid. Comparison of an "ultrasensitive" immunologic assay with TLC and enzymatic assay.

Phosphatidylglycerol (PG) in amniotic fluid is recognized as a good indicator of fetal lung maturity and is unaffected by moderate amounts of blood or meconium contamination. A rapid immunologic agglutination assay, Ultrasensitive AmnioStat-FLM (FLM), was compared with two-dimensional thin-layer chromatography (TLC) and an enzymic, colorimetric procedure (E-PG). Eighty amniotic fluid specimens were analyzed. FLM results were reported as high (H), intermediate (I), or low positive (L). TLC was compared with FLM:H (n = 27), mean 0.14 (fraction of total phospholipids); I (n = 7), mean 0.11; L (n = 9), mean 0.03; negative results had no detectable PG by TLC. In 33 cases E-PG was compared with FLM:H (n = 9), mean 7.0 mumol/L; I (n = 5), mean 8.1 mumol/L; L (n = 3), mean 3.0 mumol/L; negative (n = 16), mean 3.2 mumol/L. Records were reviewed in 70 cases. Thirty cases were excluded: sample to delivery time was greater than 72 hours; steroids were given or sepsis was documented. Fetal lung immaturity was clinically present in six cases: respiratory distress syndrome in three cases and transient tachypnea of the newborn (TTN) in three cases. One false positive result was identified (TTN, FLM:H). FLM sensitivity for fetal lung maturity was 85.3%, specificity was 83.3%, and the positive predictive value for fetal lung maturity was 96.7%. FLM is a fast, reliable indicator of fetal lung maturity.

Agglutination Tests↗
PubMed1989

Characterization and Rooting Ability of Indole-3-Butyric Acid Conjugates Formed during Rooting of Mung Bean Cuttings.

Indole-3-butyric acid (IBA) is rapidly metabolized by mung bean cuttings during rooting. Twenty-four hours after application, less than 20% of the applied IBA remained in the free form and its level decreased continuously in the later stages of rooting. Indole-3-butyrylaspartic acid (IBAsp) and at least two high molecular weight conjugates were the major metabolites in IBA-treated cuttings. In the latter conjugates, at least part of the IBA moiety is attached to a high molecular weight constituent in an amide linkage. IBAsp level peaked 24 hours after application of IBA to the cuttings and then declined. The level of the high molecular weight conjugates increased continuously throughout the rooting process. The conjugates were active in inducing rooting of cuttings, with IBAsp being superior to free IBA. It is suggested that IBA conjugates, and particularly IBAsp, serve as the source of auxin during the later stages of rooting.

Journal Article↗
PubMed1989

Marking the spot.

Tattooing with India ink is a precise and practical method for identifying biopsy sites when there is a significant delay between biopsy and definitive surgery.

Biopsy↗