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Biomedical subjects

S Mayer

Publications and source records attributed to S Mayer.

At least 109 records · Page 6Linked to original sources
PubMed1989

Penetration of antibiotics into bovine neutrophils and their activity against intracellular Staphylococcus aureus.

The penetration of three antibiotics, penicillin, chloramphenicol and erythromycin into bovine neutrophils, either alone or containing previously ingested Staphylococcus aureus, was determined, and their intracellular activity against these bacteria was measured. Uptake of radiolabelled antibiotics was assessed by rapidly separating neutrophils from extracellular antibiotic by centrifugation through silicone oil. Intracellular activity was estimated by comparing the numbers of bacteria surviving intracellularly in neutrophils exposed to antibiotic for 3 h at ten times the MBC, with those surviving intracellularly in untreated neutrophils. Penicillin was slightly concentrated within the neutrophils, reaching a maximum intracellular concentration 1.75 times that of the extracellular concentration; this is the C/E ratio. Chloramphenicol entered to a greater extent with a maximum C/E ratio of 7.08. Erythromycin became highly concentrated within the neutrophils with a C/E ratio of 11.46 after 90 min incubation. The presence of ingested staphylococci significantly reduced the uptake of chloramphenicol, but had no significant effect on the penetration of the other antibiotics. Intracellular activity studies indicated that, at ten times MBC, only penicillin had any significant activity against intracellular staphylococci, reducing survival by 28%. This work demonstrates that penetration of certain antibiotics can be altered by the presence of ingested staphylococci and that high intracellular levels of antibiotics do not necessarily ensure good intracellular activity against pathogenic micro-organisms.

Animals↗
PubMed1989

Wholly life: a new perspective on death.

When caring for the dying, the holistic nurse must be cognizant of many factors involved in this extraordinary process. Many of these factors, including the phenomena of the fear of death, the influences that cause it, and the behavior associated with it, have been discussed in this article. This article presented a new perspective of death in the light of recent discoveries in quantum physics. The concepts of one-ness, self-awareness, and love, together with their relevance to the nurse, have been explored. Grounded in this new paradigm, the holistic nurse serves as a bridge between an old way of seeing and a new way of being.

Attitude of Health Personnel↗
PubMed1989

Class II alloantigen expression on leukemic cells.

Class II antigen expression on leukemic cells has been mainly studied using monoclonal antibodies (Mabs). On the other hand, class II polymorphism has been mainly studied using alloantisera. The present study shows that the reactivity of leukemic cells from different lineages with class II Mabs was not always the same as that obtained with alloantisera and that the reactivity varied depending on the leukemic cell-type studied.

Antibodies, Monoclonal↗
PubMed1988

HLA and Down syndrome (DS): parents at the origin of the nondisjunction share no more HLA-A and -B antigens with their DS child than controls.

Fifty couples and their children with Down syndrome (D.S.) were typed for HLA-A and HLA-B antigens and compared to 50 control families and 464 blood donors. The parental origin of the extra chromosome 21 was determined by cytogenetic methods. All individuals were caucasians and there was no history of consanguinity. No excessive HLA sharing was present in D.S. parents. The mothers of D.S. shared no more HLA antigens with their D.S. children than the control mothers with their normal children (14% vs. 18%). Thirteen of the fifty pairs (26%) (parent in whom the nondisjunction occurred and D.S. child) shared three HLA antigens at the A and/or B locus. This was not significantly higher than the proportion in the control group (12/50 or 24%). These data suggest that it is not the sharing of HLA-A and HLA-B antigens between the parents or between the parent who was the origin of the nondisjunction and the D.S. child that is related either to the occurrence of trisomy 21 zygotes or to prenatal survival of affected embryos and fetuses.

Adult↗
PubMed1988

The effect of pretreatment with pentobarbital on the extent of [14C] incorporation from [U-14C]glucose into various rat brain glycolytic intermediates: relevance to regulation at hexokinase and phosphofructokinase.

In the present investigation we monitored the incorporation of [14C] from [U-14C]glucose into various rat brain glycolytic intermediates of conscious and pentobarbital-anesthetized animals. Labeled glucose was delivered to brain by single bolus intracarotid injection and brain tissue was subsequently prepared at 15, 30, and 45 sec by freeze-blowing. Glycolytic intermediates were then separated by column chromatography. Our results showed a gradual decrease with time of 14C-labeled glucose which gave a calculated rate for glucose metabolism of 0.86 mumol/min/g and 0.56 mumol/min/g in conscious and anesthetized animals, respectively. Compared to the results obtained using conscious animals the administration of pentobarbital not only resulted in a significant attenuation of the rate of glucose metabolism but also caused a similar reduction in the amount of 14C incorporated into several glycolytic intermediates. These intermediates included: glucose 6-phosphate, fructose 6-phosphate, fructose 1,6 diphosphate, dihydroxyacetone phosphate and post glycolytic compounds. In addition, pretreatment with pentobarbital resulted in a 75% increase in the endogenous concentration of glucose, 10% increase in glucose 6-phosphate, no change in fructose 6-phosphate and 42% decrease in lactate compared to levels in brains obtained from conscious animals. These results are discussed in relation to control of glycolysis through coupled regulation at hexokinase-phosphofructokinase.

Animals↗
PubMed1988

[Polymorphism of C4 and factor B in type I diabetes].

The haplotypic frequencies of the fourth component of complement (C4) and factor B (Bf) have been determined in 44 Alsatian type 1 diabetics. An increased frequency of the rare allele Bf F1 (9.1% vs 1.5%) and of the silent alleles of C4 (C4 AQO: 21.6% vers 15.5% -C4 BQO: 29.6% vs 16.0%) was observed in diabetics in comparison to the general population of the same geographic area. A complete HLA haplotype determination has been obtained in 24 type 1 French diabetics. Three haplotypes were associated with the diabetic susceptibility: HLA-A30 CW5 B18 BfF1 C4A3BQO DR3 (18.75% vs 0.86%), HLA-A1 CW7 B8 BfS C4AQOB1 DR3 (15.58% vs 4.17%), HLA-A2 CW3 BW62 BfS C4A3B3 DR4 (6.25% vs 0.45%). The authors suggest that the silent alleles of C4 could modulate the expression of the diabetic susceptibility genes by lowering of the serum C4 hemolytic activity.

Alleles↗
PubMed1987

The structure of cell adhesion molecule uvomorulin. Insights into the molecular mechanism of Ca2+-dependent cell adhesion.

We have determined the amino acid sequence of the Ca2+-dependent cell adhesion molecule uvomorulin as it appears on the cell surface. The extracellular part of the molecule exhibits three internally repeated domains of 112 residues which are most likely generated by gene duplication. Each of the repeated domains contains two highly conserved units which could represent putative Ca2+-binding sites. Secondary structure predictions suggest that the putative Ca2+-binding units are located in external loops at the surface of the protein. The protein sequence exhibits a single membrane-spanning region and a cytoplasmic domain. Sequence comparison reveals extensive homology to the chicken L-CAM. Both uvomorulin and L-CAM are identical in 65% of their entire amino acid sequence suggesting a common origin for both CAMs.

Amino Acid Sequence↗
PubMed1987

Cyclic AMP and cyclic GMP phosphodiesterase activities in Hodgkin's disease lymphocytes.

Cyclic nucleotide phosphodiesterase (PDE) activities were studied in peripheral blood monocyte-depleted lymphocytes and enriched T-lymphocyte suspensions from thirteen patients with previously untreated Hodgkin's disease (HD) and fourteen age and sex matched healthy volunteers. Monocyte-depleted lymphocytes from HD patients showed PDE-activities which were two times higher than in their normal counterpart cells. The mean cAMP-PDE activity present in enriched HD T-lymphocyte suspensions was four times higher than in control T-lymphocytes, and the mean cGMP-PDE associated with HD T-lymphocytes was three times higher than in the controls. The hydrolytic activities present in both monocyte-depleted and T-lymphocyte enriched cells suspensions remained unchanged in absence or in the presence of calmodulin and calcium. Since depressed cAMP and cGMP resting levels have been observed in HD lymphocytes and lymphocyte subpopulations, our results suggest that the elevated PDE activities are, at least in part, responsible for the alterations in lymphocyte cyclic nucleotide levels.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1987

[Anti-HLA immunization following transfusions of leukocyte-poor blood].

We have followed the evolution of leucocyte antibodies in patients receiving multiple blood transfusions of leucocyte-poor blood. The number of leucocytes present in one unit of transfused blood was always less than 1 X 10(8). We observed that such preparations were able to re-stimulate antibodies which had disappeared, but especially they were able to provoke a first immunisation in some patients never immunized in the past. The specificities of these antibodies corresponded to one or several antigens present in the donor of the transfused unit. This study shows that leucocyte immunisation cannot always be avoided in spite of the selection of blood products containing very few white cells.

Adolescent↗
PubMed1987

Human epidermal Langerhans cells cointernalize by receptor-mediated endocytosis "nonclassical" major histocompatibility complex class I molecules (T6 antigens) and class II molecules (HLA-DR antigens).

HLA-DR and T6 surface antigens are expressed only by Langerhans cells and indeterminate cells in normal human epidermis. We have previously demonstrated that T6 antigens are internalized in Langerhans cells and indeterminate cells by receptor-mediated endocytosis. This process is induced by the binding of BL6, a monoclonal antibody directed against T6 antigens. In the present study, using a monoclonal antibody directed against HLA-DR antigens, on human epidermal cells in suspension, we show that the surface HLA-DR antigens are also internalized by receptor-mediated endocytosis in Langerhans and indeterminate cells. Moreover, using immunogold double labeling, we demonstrate that T6 and HLA-DR antigens are internalized through common coated regions of the membrane of Langerhans or indeterminate cells. The receptor-mediated endocytosis that is induced involves coated pits and vesicles, receptosomes, lysosomes, and also, in Langerhans cells, the Birbeck granules. Thus, T6 antigens, which are considered to be "unusual" or "nonclassical" major histocompatibility complex class I molecules, and the major histocompatibility complex class II molecules, HLA-DR, are internalized in Langerhans and indeterminate cells through common receptor-mediated endocytosis organelles.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

HLA class I antigens on normal and leukemic cells (quantitative analysis).

A monomorphic anti-Class I monoclonal antibody, ST01, found in our laboratory, was used to quantify Class I antigens on normal and leukemic cells, using a "CELISA" technique. Saturation graphs were used to compare the quantity of Class I antigens on normal PBL (25 cases) with that on the following types of leukemic cells: a) common acute lymphoblastic leukemias (cALL) (11 cases), b) mature B lymphocytic proliferations (16 cases), c) T hemopathies (9 cases), d) non-lymphoid leukemias (9 cases). In most cases the quantity of HLA Class I antigens was greatly reduced. No correlation was found between the quantitative expression of Class I antigens and the stage of maturation in each cell type, nor was any correlation found between the quantitative expression of Class I antigens on the leukemic cells and the proliferation of leukemic cells in the peripheral blood.

B-Lymphocytes↗
PubMed1987

Na microelectrode study of pathways of Na entry into Amphiuma intestinal absorptive cells.

To define the pathways of Na+ entry into intestinal villus cells, intracellular Na+ activity (aiNa) was measured in Amphiuma duodenum using conventional and Na-sensitive microelectrodes. Replacement of Na+ in the luminal medium reduced aiNa rapidly; replacement of Na+ in the serosal medium caused a slow decline of aiNa. Hence, mucosal and serosal membranes are both permeable to Na+. Ouabain addition to the serosal medium caused aiNa to increase over 4 h. When Na+ was present only in the mucosal medium and Na+ transport was inhibited with ouabain, aiNa increased over 4 h. With galactose or valine (20 mM) in the mucosal medium aiNa was greater at 2 h relative to paired control tissues. The gain in aiNa was unaffected by replacement of luminal medium Cl- with gluconate or exposure to 1 mM furosemide or amiloride. Amiloride, at 1 mM, was detected by the Na-sensitive neutral carrier. Over a wide range of Na+ concentrations in the luminal medium the rate of Na+ entry across the mucosal membrane correlated strongly (r = 0.95) with the electrochemical gradient for Na+ across the luminal membrane. It is concluded that aiNa of urodele intestinal cells is maintained at a low level by the operation of a Na+-K+ pump. Na+ entry across the luminal membrane occurs by diffusion and by the cotransport with sugars and amino acids. Luminal NaCl cotransport and Na+-H+ exchange do not appear to contribute to Na entry to a measurable extent but it is possible that these transport processes operate at a slow rate, but were inhibited secondary to inhibition of the Na-K pump.

Absorption↗
PubMed1987

[Cytotoxic antibodies in multiple sclerosis].

Serum cold cytotoxic activities against allocells: total lymphocytes, B lymphocytes and monocytes were detected in 12 of 21 multiple sclerosis (MS) patients at 15 degrees C using a microcytotoxicity technique. Cytotoxic activity was found at 37 degrees C in certain MS patients. This activity was weak or absent in non MS patients and in healthy controls. Tests with autocells were positive in 6 MS patients. Cerebrospinal fluid cytotoxic activity was found in MS as well as in non-MS diseases; at 37 degrees C CSF produced lysis of monocytes in the absence of complement. No correlation was found between cytotoxic activity and parameters of clinical disease. Our results suggest that there may be a wide variety of cytotoxic antibodies in MS. Their significance is unknown; it may be that they have an effect on certain lymphocyte subsets as it has been suggested in other diseases.

Adult↗
PubMed1986

Decreased membrane "fluidity" of T lymphocytes from untreated patients with Hodgkin's disease.

Plasma membrane "fluidity" of peripheral blood T lymphocytes from untreated patients with Hodgkin's disease (HD) and healthy controls was studied using the fluorescent probes 1,6-diphenyl-1,3,5-hexatriene (DPH) and 1-(4(trimethylamino)phenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH). In 13 consecutive patients a significant increase of T lymphocyte plasma membrane microviscosity was observed with both DPH and TMA-DPH. These alterations seemed unrelated to the cholesterol (Chol) and phospholipid (PL) content of HD T lymphocytes since the Chol/PL ratio was comparable in both HD and control cells. Since prostaglandin E2 (PGE2) from monocytic origin has been claimed to be responsible for the impairment of cell-mediated immunity (CMI) associated with HD, we studied the effect of exogeneously added PGE2 (0.1 microM) on control subjects T lymphocyte membrane "fluidity". Using the fluorescent probe DPH and the spin labelled fatty acid probe 16 NMS for electron paramagnetic resonance study, we observed a PGE2-induced fluidization of control T lymphocyte membranes which is specifically located in the inner part of the plasma membrane, whereas the plasma membrane surface seemed unaffected by PGE2 as judged by the TMA-DPH probe. Thus, PGE2 does not appear to be responsible for the alterations of T lymphocyte membranes observed in HD. Intrinsic alterations and/or other mediators might be involved.

Adult↗
PubMed1986

New human MHC class I antigens segregating with HLA-A antigens detected on some lymphocyte subpopulations.

Recent genetic studies of the murine chromosome 17 have demonstrated that many genes encode class I antigens, most of which are still not detected serologically; most of these genes belong to the Tla region. Five human alloantisera were selected from 383 female sera and were further studied using a panel of peripheral blood lymphocytes (PBL), B lymphocytes (BL), and PHA activated lymphocytes (PHA-L) from the same blood donors. After intensive platelet absorption, the five sera still reacted positively by a complement-dependent cytotoxicity technique with PHA-L, but negatively with PBL and BL. The antigens detected by these antibodies segregated with an HLA-A allele and were assumed to belong to the class I antigen series as they could be blocked by a turkey anti-beta 2 microglobulin serum. They were found on some lymphocyte populations: PHA-L, common acute lymphoblastic leukemia (cALL) cells, and (preliminary results) a small subpopulation of PBL cells (mostly NK cells), but were not found on chronic lymphocytic leukemia (CLL) cells, T and early T acute lymphoblastic as well as myeloblastic leukemia cells. Kinetic studies showed that several hours of culture with PHA were necessary for the antigen to be expressed. These results show that the antigens described do not belong to the classic HLA antigen series but could be considered to belong to the human Qa-like antigens or to be the human counterpart to the second murine H-2K locus antigens.

Antigen-Antibody Complex↗
PubMed1986

[Expression of class I and class II markers on populations of leukemic cells].

The study of class I and class II antigen expression on leukemic cells brought the following conclusions: most of the leukemic cells show a slower number of class I antigenic sites than normal peripheral blood lymphocytes (PBL) but, in most cases, this does not hinder HLA typing; contrarily to normal PBL, leukemic cells seem to carry "non HLA" antigens (and/or non classical HLA antigens) which are probably responsible of the false positive reactions frequently observed at the time of HLA typing; most of the leukemic cell types express DR antigens (except those belonging to the T lineage) but DQ antigen expression (and in some cases MT antigen expression) varies depending on the cell type studied: well defined on mature B hemopathies, DQ expression is often lower than DR expression on acute leukemic cell types.

HLA Antigens↗