Search PubMed⌕ Search

Biomedical subjects

K Schroeder

Publications and source records attributed to K Schroeder.

At least 55 records · Page 3Linked to original sources
PubMed1995

Congenital leukemia: report of two cases.

Congenital leukemia is a rare disease in which a leukemic process is present at birth or immediately thereafter. The majority of cases presented in the literature were reported prior to the availability of contemporary immunophenotyping methods, and lineage assignment was often made on the basis of morphology alone. Congenital leukemias may be of various lineages, although, historically, monocytic and myelomonocytic congenital leukemias appear to be the most prevalent. We present two cases of congenital leukemia with detailed immunophenotypic and cytochemical characterization. One case is of the lymphoid lineage, and the second is of myelomonocytic lineage. Neither patient displayed trisomy 21.

Female↗
PubMed1994

Specific interaction of 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid with human cellular CD4.

We recently demonstrated that 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) prevented the infection of T cells by human immunodeficiency virus type-1 (Cardin et al., J. Biol. Chem. 266, 13355, 1991). In the present study we have used a panel of monoclonal antibodies (mabs) against a variety of human leukocyte antigens to characterize the interaction of DIDS by flow cytometry with various T cell surface molecules. DIDS blocked the specific immunoreactivity of mabs OKT4A and Leu 3A with CD4 on human leukemic T cells (JM) and human mononuclear lymphocytes with an IC50 approximately 30 microM. The membrane distal (D1) and proximal (D3 and D4) domains of CD4 remained blocked for up to 5 hr of culture and returned to control levels of expression after 24 hr, reflecting the rate of membrane turnover of the CD4-DIDS complex. The binding frequencies (% positive) for anti-CD2, -CD3, -CD5, -CD6, -CD7, -CD8, -CD11a, -CD14, -CD18, -CD19, -CD45, -T cell receptor, and -HLA-DR were not significantly affected. However, there was a partial reduction in the antigen density of CD2, CD5, CD8, and CD11b. The selective interaction of DIDS with CD4 suggests that antagonism of the virus receptor may account in part for the antiviral properties of the stilbene disulfonate.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1994

Dose comparison of tropisetron (Navoban) 5 mg and 10 mg orally in the prophylaxis of dacarbazine-induced nausea and emesis.

In this double-blind, randomized trial performed at five study centers, the prophylactic, antiemetic effect of two different dosages of tropisetron (Navoban; Sandoz Pharma Ltd, Basel, Switzerland) was investigated in dacarbazine-treated patients with melanoma. Patients received tropisetron 5 mg or 10 mg orally (as one capsule) once daily (minimum 3 days) on each day of chemotherapy. No significant differences were found in the effects of tropisetron 5 mg and 10 mg. During the first 24 hours, total control of vomiting was seen in 93% and 98% of patients receiving tropisetron 5 mg and 10 mg, respectively. Total control of nausea was achieved in 84% and 80% of patients receiving tropisetron at these dosages. Over days 2 to 7 of chemotherapy, total control of vomiting and nausea remained high. Patients reported that quality of life remained good throughout chemotherapy, as did mood; only a small decrease in food intake occurred. Tropisetron was well tolerated. Constipation was the most common adverse event, occurring in 13% of patients. Headache (4%), diarrhea (4%), and anorexia (2%) also were observed.

Administration, Oral↗
PubMed1992

Computer-assisted identification of mycobacteria using code lists--results of a multi-centric study. German Working Group on Mycobacteria.

The frequency of isolation of environmental mycobacteria from clinical specimens has increased significantly in the course of the last years. Assessment of the medical importance of such isolates always depends on a correct identification of any of these strains. In a multicentric study, the efficacy of a standardized, computer-aided system for identification has been evaluated. 13 Laboratories received 24 strains of mycobacteria each and were asked to test all these strains for 16 different features. The results were coded in a standardized way. For the evaluation of these tests, the laboratories were supplied with a list containing all possible codes, which might be indicative of one or another identification. The results proved the logic of the approach. However, the application of the system lead to a correct identification in only 74% of all attempts. It is concluded that such a standardized approach is not useful for mycobacteria, because it requires too much working time and material. It will be more practical to concentrate on a smaller number of tests in the peripheral laboratories, which might allow the identification of M. tuberculosis and a few other species and to leave the definitive identification to reference laboratories. The development of faster, simpler and more reliable methods remains highly desirable.

Bacterial Typing Techniques↗
PubMed1991

Stilbene disulfonic acids. CD4 antagonists that block human immunodeficiency virus type-1 growth at multiple stages of the virus life cycle.

The stilbene disulfonic acids 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), 4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonic acid and, 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid bound the variable-1 immunoglobulin-like domain of CD4 on JM cells. The interaction blocked the binding of the anti-CD4 monoclonal antibody OKT4A and the envelope glycoprotein gp120 of the human immunodeficiency virus type-1 (HIV-1). DIDS inhibited the acute infection of CD4+ cells by HIV-1 with a potency (IC50 approximately 30 microM) similar to that which blocked gp120 binding (IC50 approximately 20 microM) to the cellular antigen. Pretreating uninfected CD4+ C8166 cells with DIDS blocked their fusion with chronically infected gp120+ cells. DIDS covalently and selectively modified lysine 90 of soluble CD4 and abolished the gp120-binding and antiviral properties of the recombinant protein. When added to cells productively infected with HIV-1, DIDS blocked virus growth and cleared cultures of syncytia without inhibiting cellular proliferation. The stilbene disulfonic acids are a novel class of site-specific CD4 antagonists that block multiple CD4-dependent events associated with acute and established HIV-1 infections.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1991

A highly selected panel of anti-CD4 antibodies fails to induce anti-idiotypic antisera mediating human immunodeficiency virus neutralization.

Anti-CD4 antibodies directed to the N terminus of CD4 can inhibit human immunodeficiency virus (HIV) infection. Therefore, it has been proposed that some of these reagents may contain idiotypic determinants which conformationally model the binding site expressed on gp120. In this report, we have selected a panel of anti-CD4 monoclonal antibodies as idiotypic mimics of gp120 by employing cross-blocking techniques, and CD4 epitope mapping using site-directed mutagenesis. These studies suggest that only 4 out of the original panel of 12 would be expected to represent suitable candidates for modelling the gp120 binding site. Nevertheless, anti-idiotypic antisera raised against these antibodies failed to inhibit gp120 binding to CD4. This negative result may reflect the incomplete modelling of the virus binding site by anti-CD4, or the lack of internal image antibody in the anti-idiotypic preparations. Alternatively, the binding site on gp120 may not be accessible to antibody neutralization, excluding the possibility of an idiotypic vaccine to HIV based on anti-CD4 antibody as surrogate antigen.

Animals↗
PubMed1991

Color consistency, plaque accumulation, and external marginal surface characteristics of the collarless metal-ceramic restoration.

Four techniques for making collarless metal-ceramic restorations were investigated in this study to examine the final color consistency, the bacterial plaque accumulation, and the surface characteristics of the porcelain margin. Twenty crowns were constructed and data revealed the superiority of the platinum foil technique in producing consistent color, whereas the shoulder porcelain technique resulted in the most significant color deviation. Metal surfaces exhibited the greatest in vitro bacterial plaque accumulation (42.43%), and the margins of the platinum foil technique accumulated the least plaque (7.23%). In addition, the wax binder and the platinum foil techniques produced the smoothest surfaces, whereas again the shoulder porcelain technique exhibited pronounced surface roughness. From the obtained results, and with the limitations of this in vitro study, one can speculate that surface roughness is not a predominant factor in the initial process of bacterial plaque accumulation.

Analysis of Variance↗
PubMed1991

Suppression of interleukin-1 beta and LDL scavenger receptor expression in macrophages by a selective protein kinase C inhibitor.

A human monocytic cell line, THP-1, stimulated with 40 nM phorbol myristate acetate (PMA), differentiated to macrophage-like cells, and exhibited increased expression and release of interleukin-1 beta and expression of acetylated low density lipoprotein (ac-LDL) receptors. A selective inhibitor, MDL 29,152 (4-propyl-5-(4-quinolinyl)-2(3H)-oxazolone) was used to show that this induction required activation of protein kinase C. MDL 29,152 acts in the catalytic domain of protein kinase C and is at least 200-fold selective for protein kinase C over cAMP-dependent protein kinase in THP-1 cells. MDL 29,152 (50 microM) reduced levels of interleukin-1 beta mRNA in PMA-stimulated cells by 76% and eliminated detectable interleukin-1 beta in the media. Flow cytometric analysis showed that 48 h after THP-1 activation, approximately 50% of the cells expressed ac-LDL receptors, while in the presence of 100 microM MDL 29,152, less than 5% of the cells expressed receptors. The relationship between THP-1 differentiation and protein kinase C activation was determined by following the expression of the cell surface antigen MO-1. Expression of MO-1 antigen increases as monocytes differentiate to macrophages. After 48 h of phorbol activation, 90% of the THP-1 population was MO-1-positive; less than 16% of the population was MO-1-positive when 100 microM MDL 29,152 was present. By dual analysis, it was found that within the differentiated, MO-1-positive population, only approximately 50% of the cells also expressed ac-LDL receptors. Based on these findings, we conclude that protein kinase C promotes processes important in THP-1 activation and differentiation to macrophage-like cells including interleukin-1 beta expression and secretion, ac-LDL receptor and MO-1 expression.

Cell Differentiation↗
PubMed1990

Probucol does not alter acetylated low density lipoprotein uptake by murine peritoneal macrophages.

It has been suggested that the anti-atherogenic effect of probucol (MDL 11,309) in familial hypercholesterolemic rabbits may be due in part to the inhibition of the uptake of modified low density lipoproteins by macrophages in the arterial wall. To test this hypothesis, mice were treated with dietary probucol (0.25%) for fourteen days, peritoneal macrophages were isolated and the uptake of acetylated low density lipoprotein (ALDL) was studied. In addition, peritoneal macrophages from control animals were treated with probucol (200 micrograms/ml) for 24 h in vitro prior to the ALDL uptake assay. The assay involved a fluorescent ALDL probe (dioctadecyltetramethylindocarbocyanine perchlorate-labeled ALDL), and measurement of uptake with a flow cytometer. No differences in ALDL uptake were detected between the control macrophages and macrophages treated with probucol in vitro or macrophages taken from probucol-treated mice.

Acylation↗
PubMed1987

Aging and memory for words and action events: effects of item repetition and list length.

We were concerned with the effects of item repetition, list length, and class of item on free recall in elderly as compared with young adults. In Experiment 1, samples of young and elderly adults recalled a list of 27 words and a list of 27 action events (minitasks performed by the subjects). Some items were presented once and some twice. Although the younger subjects showed better recall on both types of lists, the older sample benefited from item repetition as much as did the younger sample. This finding was replicated in Experiment 2. A second finding in Experiment 2 was a significant aging effect in the recall of long but not of short lists of both words and action events. The absence of an Age X Repetition Effect interaction was ascribed to the strength nature of the repetition manipulation. The age effects in the recall of the long lists were attributed to possible deficits in retrieval proficiency.

Adult↗
PubMed1986

Studies on the tocopherol status in blood serum of premature babies and infants.

The level of naturally occurring tocopherols in blood serum of 88 preterm infants, aged from birth to 2 years, was determined by the high performance liquid chromatographic (HPLC) method using fluorescence detection. In 11 cases, patients were assayed for their tocopherol status in longitudinal studies, receiving known amounts of vitamin E supplements orally and/or parenterally. No correlation was found between serum alpha-tocopherol level and gestational age nor birth weight. All preterm infants receiving the vitamin E preparation showed an average serum tocopherol content of more than 0.5 mg/100 ml. The highest alpha-tocopherol concentration registered during vitamin E therapy was 3.28 mg/100 ml. Infusion of Intralipid, a product derived from fractionated soybean oil, caused a significant increase of gamma- and delta-tocopherol in blood serum. The half-life of delta-tocopherol in serum was calculated to be about 24 hours.

Administration, Oral↗
PubMed1984

Scanning electron microscopy of cusp-tip pits in developing and mature human dentitions.

A variety of cusp-tip pits were observed with the scanning electron microscope (SEM) on canines and molars of both deciduous and permanent dentitions. Larger pits or craters usually were single and funnel-shaped with a narrow 100 micron base widening to 300-400 micron peripheral opening; smaller pits were in groups. As defects occur precisely in the tips of cusps, developing cusps fetal dentitions were examined for a consistent structural pattern which could explain cusp-tip pit development.

Aging↗