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N E Dunlap

Publications and source records attributed to N E Dunlap.

34 records · Page 2Linked to original sources
PubMed1992

A 'safe-site' for Salmonella typhimurium is within splenic polymorphonuclear cells.

Following oral or systemic infection with Salmonella typhimurium, the focus of infection is in the liver and spleen. The majority of Salmonella surviving in the liver and spleen by 4 h post infection are already in an environment where they are largely protected from subsequent killing. Previous studies have shown that the majority of surviving Salmonella are intracellular. In the present study we sought to determine the cell type containing most of the cell-associated Salmonella liberated from the spleen. We enriched for Salmonella-containing cells by Ficoll-Hypaque separation followed by fluorescence-activated cell sorting. Approximately 85% of the total intracellular Salmonella were found in Mac-1+/J-11d+ cell fractions of the Ficoll-Hypaque band and pellet. By microscopic examination of stained cells from the sorted cell populations, it was evident that virtually all of the Salmonella were in polymorphonuclear cells (PMN). The numbers of Salmonella observed microscopically were similar in numbers to Salmonella colony forming units detected by plating. Salmonella containing PMN in the Ficoll band generally contained a single bacterium, while those from the probably less healthy cells in the Ficoll pellet generally contained several Salmonella.

Animals↗
PubMed1991

T helper/inducer (CD4+) cells prestimulated with PPD induce monocytes to produce interleukin-1 beta.

We obtained peripheral blood mononuclear cells (PBMC) from four healthy, tuberculin purified protein derivative (PPD) reactive donors and cultured these cells in media containing PPD (low dose = 200 ng/ml or high dose = 1 micrograms/ml). Five days after the addition of PPD, T cells were isolated, washed, and added to autologous adherent cell cultures at a 1:1 ratio. Adherent cells were then cultured for 24 h in media only (baseline), media plus lipopolysaccharide (LPS, 2 micrograms/ml; positive control), or media containing the prestimulated T cells. After 24 h, supernatants were harvested and interleukin 1 beta (IL-beta) levels were assayed by radioimmunoassay (RIA) or enzyme-linked immunosorbent assay (ELISA). The results show that T cells prestimulated with low dose PPD (200 micrograms/ml) did not induce IL-1 production by adherent cells (mean increase over baseline 0.2 +/- 1.3 standard deviation [SD] ng/ml, P = 0.61). However, T cells prestimulated with high dose PPD (1 microgram/ml) did induce adherent cells to secrete IL-1 beta (mean increase over baseline 1.7 +/- 0.62 [SD] ng/ml, P = 0.01), but this induction was abolished when cell-to-cell contact was prevented by use of double well chambers (mean increase over baseline 0.1 +/- 0.36 [SD] ng/ml, P = 0.69). Prestimulated T helper (CD4+) cells were able to induce monocytes to secrete IL-1 beta but prestimulated CD8+ T cells were not. These data suggest that when T helper (CD4+) cells are sufficiently activated they acquire the ability to induce monocytes to secrete IL-1 beta. Cell-to-cell contact between monocytes and T cells is required. This function of activated T cells may be important in the normal cellular immune response.

CD4-Positive T-Lymphocytes↗
PubMed1991

A 'safe-site' for Salmonella typhimurium is within splenic cells during the early phase of infection in mice.

Salmonella typhimurium infection in mice is focused on the spleen and liver, and prolonged infection can lead to sepsis and death. After intravenous infection with a moderate dose of S. typhimurium, the few bacteria that survive in the spleen and liver grow in a 'safe-site' where they are protected from immune destruction. In this study, we demonstrated that the lack of killing of resident salmonella in the spleen and liver was not because the salmonella were transformed within the host and became resistant to killing, or because the infected mice lost the ability to kill salmonella. We showed that the salmonella were within an intracellular 'safe-site' that protected them from killing. Brief treatment of salmonella-infected mice with gentamicin reduced the numbers of salmonella in the blood but had no effect on the numbers in the liver and spleen, suggesting an intracellular location of the salmonella. After dissociation of spleen cells from recently infected mice, 60% of the salmonella remained cell associated. These cell-associated salmonella, unlike cell-free salmonella, were resistant to killing by gentamicin. The cell-associated salmonella were rendered susceptible to gentamicin after sonication, providing confirmation of their previous intracellular location.

Animals↗
PubMed1990

In vitro natural killer and lymphokine-activated killer activity in patients with bronchogenic carcinoma.

The authors examined peripheral blood mononuclear cells from 45 patients with bronchogenic carcinoma to determine natural killer (NK) and lymphokine-activated killer (LAK) activity after in vitro incubation with media alone or media plus interferon gamma (IFN, 200 U/ml) and/or interleukin-2 (IL-2, 100 U/ml). Our results show that lymphocytes from patients with bronchogenic carcinoma can acquire LAK activity, but the level of activity acquired was significantly lower compared with lymphocytes from 25 control subjects when IL-2 cultures were supplemented with 10% autologous human serum (AHS) (15.6% +/- 2.1% specific release versus 26.0% +/- 2.9% specific release, P = 0.004). The LAK activity, defined as cytotoxicity of an NK-resistant cell line, of the patients' lymphocytes was augmented when cells were cultured with both IL-2 and IFN compared with IL-2 alone (P = 0.0001, paired t-test). Control subjects were unchanged (P = 0.09). There was no significant difference between groups of patients with different histologic types of tumor or different stages of disease. The NK activity, defined as killing of NK-sensitive K-562 target cells, of the patients' lymphocytes was not significantly different from that of the controls' lymphocytes (42.8% +/- 3.0% specific release versus 49.3% +/- 3.3% specific release, P = 0.16). These studies indicate the feasibility of IL-2 and IFN therapy in patients with bronchogenic carcinoma.

Aged↗
PubMed1990

Corticosteroids in asthma.

The use of corticosteroids in the treatment of asthma has significantly decreased the morbidity and mortality from this disease. However, corticosteroids have devastating side effects when given frequently or for prolonged periods. High doses of systemic corticosteroid preparations should be used only during bouts of acute bronchospasm, whereas the lowest possible dose needed to control symptoms is recommended for the treatment of chronic asthma. Aerosolized steroids offer an alternative to systemic preparations and have less associated morbidity. Various corticosteroid preparations have various potencies and durations of action that need to be considered. Patients with coexisting liver disease require preparations that do not need hepatic hydroxylation, whereas patients with congestive heart failure require preparations that minimize salt retention. When asthma and pregnancy coexist, it is vital that symptoms of bronchospasm are controlled to protect the fetus. During stressful situations, such as surgery, it is important to consider the possibility of hypothalamic-pituitary-adrenal axis suppression if the asthmatic patient has been previously treated with corticosteroids.

Acute Disease↗
PubMed1989

Interleukin-2 augmentation of interleukin-1 and prostaglandin E2 production.

Some of the major side effects of interleukin-2 (IL-2) therapy in the treatment of malignancies may be related to increased interleukin-1 (IL-1) and/or prostaglandin E2 (PGE2) production. We examined the effect of recombinant (rIL-2) on the in vitro production of IL-1 beta and PGE2 by unstimulated and LPS-activated human blood mononuclear cells (PBMC). We also compared the effect of rIL-2 on IL-1 beta production by adherent and nonadherent blood mononuclear cell populations. Cultures of PBMC (5 x 10(6)/ml) were incubated for 24 hr in media only (control, 1,000 U/ml rIL-2, 2 micrograms/ml LPS, or both LPS and rIL-2. Supernatants obtained from these cultures were analyzed for levels of IL-1 beta and PGE2 by radioimmunoassays. The addition of rIL-2 caused an increase in IL-1 beta production in 13 of 13 control PBMC cultures and in 11 of 13 LPS-stimulated cultures, which were significant increases as determined by paired t tests. When PBMC were fractionated into plastic adherent and nonadherent populations, the rIL-2 induced increases in IL-1 beta production were more consistent in control (six of seven cases) and LPS (seven of seven cases) cultures of plastic nonadherent cells than in control (three of seven cases) and LPS (four of seven cases) cultures of plastic adherent cells. Recombinant IL-2 did not increase PGE2 production in control PBMC cultures (none of four cases), but did so in LPS-stimulated PBMC cultures (three of four cases]. These results suggest that rIL-2 may increase IL-1 production in vivo and thus possibly account for some of the side effects of this therapy.

Dinoprostone↗
PubMed1989

Human B cell differentiation by Fc fragment. III. Effect of IL-1 and IL-2 on differentiation of human B lymphocytes induced by Fc fragments of human IgG.

The human Fc fragment of IgG, when added to blood mononuclear cells in vitro, induces B cell differentiation after 6 days of culture. This activity requires the presence of T cells and monocytes. This work explores the roles of interleukin 1 (IL-1) and interleukin 2 (IL-2) in B cell differentiation induced by Fc fragments. Peripheral blood mononuclear cells (PBMC) from normal donors were examined for plasma cell differentiation following stimulation with Fc fragment (15 and 30 micrograms/ml) with or without IL-1 (6 U/ml) or IL-2 (2 U/ml). Results indicate that both IL-1 and IL-2 accelerated B cell differentiation by the Fc fragment to 3 days of culture, compared to 6 days required with the Fc fragment alone. The time required for differentiation was not further shortened when both IL-1 and IL-2 were present in culture; both IL-1 and IL-2 were able to partially induce B differentiation alone at 6 days of culture. The importance of IL-2 in B cell differentiation was further supported by the finding that antibodies specific for the IL-2 receptor blocked B cell differentiation induced by Fc fragments, with or without additional IL-1 or IL-2. The depletion of monocytes also blocked B cell differentiation and the requirement for monocytes could not be replaced by exogenous IL-1; however, Fc fragments were shown to induce monocytes to secrete IL-1 beta after 24 hr in culture. These results suggest that accelerated differentiation of B cells into plasma cells requires a double signal provided by Fc fragments and IL-1 or IL-2. Monocytes are necessary for Fc fragment-induced differentiation and cannot be replaced by either IL-1 or IL-2.

Adult↗
PubMed1987

Expression of myelomonocytic antigens on chronic lymphocytic leukemia B cells correlates with their ability to produce interleukin 1.

We analyzed the expression of myelomonocytic-associated antigens on lymphocytes from B cell chronic lymphocytic leukemia (B-CLL) patients. Blood mononuclear cells were depleted of monocytes by one-step Percoll density gradient centrifugation and tested for antigen expression by fluorescent microscopy and flow cytometry. The reactivity of patient lymphocytes was as follows: 26 of 31 were positive for CD14 (Myr), 22 of 31 for a monocyte Fc receptor (MFC-1), 22 of 31 for CD11b (C3bi receptor), eight of 31 for CD15 (Leu-M1), five of 18 for CD13 (My 7), seven of 18 for My 9, and five of 30 for Mo 2. The B lymphocytes of B-CLL patients were also tested for the ability to produce interleukin 1 (IL-1) after depletion of monocytes and T lymphocytes. In 13 of 17 cases, B lymphocytes of patients produced IL-1 as detected in a mouse thymocyte proliferation assay and, in selected cases, a radioimmunoassay specific for IL-1 beta. The 13 cases that produced IL-1 were also positive for the expression of one or more myelomonocytic-associated antigens, whereas the four cases that did not produce IL-1 lacked expression of these antigens. In conclusion, the malignant B cells of B-CLL patients frequently express a variety of antigens generally considered specific for myelomonocytic cells, and expression of these antigens is associated with the ability to produce IL-1.

Antibodies, Monoclonal↗
PubMed1985

Cushing's syndrome. Screening methods in hospitalized patients.

We studied 18 patients with Cushing's syndrome and 25 patients in which Cushing's syndrome was excluded on follow-up to evaluate screening tests for Cushing's syndrome in hospitalized patients. Plasma cortisol values (at 8 AM) were found least helpful yielding 29% false-positive and 60% false-negative values. Diurnal variation of cortisol was present in 30% of patients with Cushing's syndrome and absent in 18% of patients without Cushing's syndrome. When corrected for total urinary creatinine, 24-hour urinary 17-hydroxycorticosteroids were specific (all patients without Cushing's syndrome had normal values) but not very sensitive (two of 12 patients with Cushing's syndrome had normal values). Similarly, 24-hour 17-ketosteroids were of little help with 17% false-positive and 35% false-negative values. Twenty-four-hour urinary free cortisol was both a sensitive and specific screening test for Cushing's syndrome (no false-positive and no false-negative results). We conclude that urinary free cortisol is the most efficient screening method for Cushing's syndrome in hospitalized patients.

Alabama↗
PubMed1985

Analysis of the monocyte Fc receptors and antibody-mediated cellular interactions required for the induction of T cell proliferation by anti-T3 antibodies.

The induction of human T cell proliferation by antibodies that cross-link T3 antigens is dependent on functional interactions of anti-T3 antibodies with monocyte Fc receptors. In this report, we used a panel of anti-T3 antibodies of differing heavy chain isotype and a variety of other monoclonal antibodies to analyze several features of the antibody-mediated interactions between T cells and monocytes that are required for mitogenesis. Whereas three IgG2a anti-T3 antibodies were mitogenic for cells from all individuals, IgM and IgG2b anti-T3 antibodies did not induce T cell proliferation in any donor and could block the proliferative responses induced by other mitogenic anti-T3 antibodies. Dose-response analyses with four IgG1 anti-T3 antibodies demonstrated donor heterogeneity as reported by other investigators. However, in contrast to these previous reports, high concentrations of IgG1 anti-T3 antibodies were found to be mitogenic for all donors, indicating that this heterogeneity is based on relative rather than absolute defects in low responder monocytes. Cell mixing experiments in which monocytes from two different low responder donors were co-cultured with T cells and IgG1 anti-T3 antibodies did not identify any complementary defects, suggesting that the low responder phenotype results from a relatively restricted polymorphism. To assess the nature of the signals required for inducing T cell proliferation, nonmitogenic anti-T3 antibodies were co-cultured with other pan-T cell antibodies having the IgG2a isotype. The combination of signals from T3 antigen cross-linkage and those independently generated by other IgG2a antibodies bound to monocyte Fc receptors did not induce T cell proliferation. Hence, it appears that the T3 antigen or closely associated structures must be clustered at the monocyte membrane for mitogenesis. Finally, in competitive inhibition experiments, the isotype specificity of monocyte Fc receptors involved in the induction of T cell proliferation was examined. Two distinct Fc receptor sites, one that binds murine IgG2a and IgG3 antibodies and a second that binds murine IgG1 antibodies, were identified. Murine IgM or IgG2b did not appear to bind either of these receptor sites. Taken together, these data indicate that human monocytes have two distinct Fc receptor sites, which must specifically and directly interact with T cell-bound anti-T3 antibodies for mitogenesis.

Adult↗
PubMed1985

A commercially available assay kit for determining aldosterone concentration in non-extracted rat serum.

A commercially available assay for aldosterone that requires no extraction was found to be valid without modification for rat serum. The assay was performed in duplicate on as little as 0.5 cc of rat serum and gave linear results from 5 ng/dl to 500 ng/dl, (i.e., the physiological range of the rat). Samples above 150 ng/dl had to be diluted in this assay. The cost per sample if performed in duplicate and in batches was approximately one dollar. We found that this assay, which was developed for and is marketed for determining aldosterone concentration in human samples, offered a cost effective assay for aldosterone determination in the rat.

Aldosterone↗
PubMed1984

Strongyloidiasis manifested as asthma.

We have described a case of infection with Strongyloides stercoralis manifested as asthma. As a result of treatment with corticosteroids, hyperinfection developed with aggravation of symptoms. The patient's condition improved only after thiabendazole therapy was instituted and corticosteroids were discontinued.

Adult↗
PubMed1984

Aldosterone blocks adrenal compensatory hypertrophy in the rat.

We report that adrenal compensatory hypertrophy occurs in intact and hypophysectomized anesthetized rats as well as in rats in which endogenous ACTH is suppressed by administration of dexamethasone or of dexamethasone plus low-dose ACTH. However, adrenal compensatory hypertrophy is blocked in intact and hypophysectomized animals when aldosterone alone or the combination of aldosterone, dexamethasone, and ACTH is administered using Alzet pumps. These data support previous reports that questioned the validity of the hypothesis that adrenal compensatory hypertrophy is controlled by the glucocorticoid-ACTH negative feedback system. These results require modification of current hypotheses concerning the mechanism of adrenal compensatory hypertrophy to allow for a central nervous system or other effect of aldosterone.

Adrenal Glands↗
PubMed1984

Golden Syrian hamsters: a new experimental model for adrenal compensatory hypertrophy.

We report that adrenal compensatory hypertrophy occurs in the golden syrian hamster, an animal secreting cortisol as the primary adrenal glucocorticoid. This response is seen at 3, 6, 10, and 21 days after unilateral adrenalectomy. The response is present in hypophysectomized hamsters and when endogenous ACTH secretion is suppressed by administration of dexamethasone by im injection or by dexamethasone and ACTH using the Alzet osmotic pump. Administration of either aldosterone alone or in combination with dexamethasone and ACTH by Alzet pump completely blocks adrenal compensatory hypertrophy after unilateral adrenalectomy.

Adrenal Glands↗
PubMed1984

Corticosteroid therapy in asthma.

Corticosteroids are useful in the treatment of both allergic and idiosyncratic asthma. Although the mechanisms of corticosteroid action in asthma are poorly understood, several possible sites of action have been proposed. Corticosteroids alter the cellular and vascular inflammatory response to bronchial injury, affect catecholamine action on airways, and alter the production of eicosanoids, all of which aid in the resolution of bronchospasm in asthmatic patients. Corticosteroids should only be used for the treatment of asthma after therapeutic levels of methylxanthines and beta agonists have been achieved. Although the optimal doses of corticosteroids in asthma have not been defined, guidelines exist to aid in therapy. In the treatment of status asthmaticus, the intravenous route of administration is preferable. Short courses of corticosteroids may be useful in the treatment of chronic asthma. When long-term corticosteroid therapy is the only option for control of bronchospasm, alternate-day and/or aerosolized corticosteroids are preferable to daily corticosteroids and are associated with fewer side effects. Corticosteroids are useful in the pregnant asthmatic patient when bronchospasm cannot be controlled with bronchodilators. The major risk to the fetus in pregnant asthmatics is hypoxia from uncontrolled bronchospasm, and not from therapy. However, the lowest possible dose of systemic corticosteroids needed to control symptoms, with or without the use of aerosolized corticosteroids, is recommended. All asthmatics who have needed systemic or aerosolized corticosteroids within 6 months prior to surgery should receive preoperative and post-operative corticosteroid therapy. For patients not usually on systemic corticosteroids, conversion to oral prednisone, with a rapid taper is recommended. Side effects from short-term corticosteroid therapy are minimal, with hyperglycemia and psychosis being the major concerns. Long-term steroid therapy has significant side effects, however, and use should be minimized. Suppression of the HPA axis is one of the most potentially dangerous side effects of corticosteroids, and therefore any patient who has been treated with corticosteroids for longer than 4 weeks should be evaluated for possible adrenal suppression.

Adrenergic beta-Agonists↗