Biomedical subjects

J Blom

Publications and source records attributed to J Blom.

At least 73 records · Page 4Linked to original sources

PubMed1989

Comparison of antigen uptake by peritoneal macrophages and veiled cells from the thoracic duct using isotope-, FITC-, or gold-labelled antigen.

Veiled cells (VC), isolated from the thoracic duct of irradiated lymphadenectomized mice (MLNX) or peritoneal macrophages (PM phi were incubated with isotope-labelled hen egg lysozyme (HEL), purified protein derivative (PPD) or keyhole limpet haemocyanin (KLH) in vitro. About 2-10 times less antigen was associated with VC than with PM phi when measured in a Philips well-type scintillation counter. Autoradiographs of these cells indicated that 3-10% veiled cells had silver grains associated with them in contrast to 20-95% of the PM phi, depending on the type of antigen studied. It was also shown, from the distribution curves for grains in individual cells, that VC contained smaller numbers of grains than PM phi. Transmission electron microscopy using KLH conjugated with colloidal gold and immunofluorescence microscopy using KLH-FITC confirmed the results obtained from autoradiographs. However, measurements of the uptake of KLH-FITC by individual VC and PM phi using flow cytometry indicated that antigen was associated with nearly all VC in vitro but in much smaller amounts than with PM phi. Both VC and PM phi were capable of presenting HEL to primed T lymphocytes in vitro. These results are discussed in relation to the function of VC as accessory cells compared with PM phi.

Animals↗

PubMed1989

Engulfment of the Philadelphia strain of Legionella pneumophila within pseudopod coils in human phagocytes. Comparison with other Legionella strains and species.

In this paper we report our ultrastructural studies of the early phagocytosis of two different strains of L. pneumophila serogroup (SG) 1 (Philadelphia 1 and Knoxville 1) and of L. micdadei. These bacteria replicate, in vivo as well as in vitro, in eukaryotic cells e.g. in monocytes and macrophages. Whether or not the mode of entry of these organisms in phagocytes contributes to their intracellular survival is presently unknown. Whilst internalization of bacteria of the Philadelphia 1 strain occurred within a pseudopod coil, organisms of the Knoxville 1 strain and L. micdadei were phagocytized in the classical manner, i.e. between pseudopods. No ultrastructural differences were observed between the two strains of L. pneumophila SG 1 whereas L. micdadei appeared as shorter rods with an extracellular layer of relatively low electron density. The phenomenon of coiling phagocytosis was not affected by heat-killing the bacteria or preopsonization with specific antibody. Formation of phagolysosomes was seen when cells of the Knoxville strain and L. micdadei were used but not with the Philadelphia strain. In our experiments, the occurrence of coiling phagocytosis was specific for the Philadelphia 1 strain of L. pneumophila and independent of bacterial virulence. Thus, it seems most unlikely that the coiling phenomenon plays any important role in the resistance of Legionella to the killing abilities of phagocytic cells.

Humans↗

PubMed1988

The construction of a simultaneous functional order in nervous systems. IV. The influence of physical constraints on the resulting functional order.

The signal activity in a neural net will be constrained both by its physical structure and by environmental constraints. By monitoring its signal activity a neural system can build up a simultaneous functional order that encodes these constraints. We have previously (Part I) presented two models that construct a simultaneous functional order in a collection of neural elements using either signal-covariances or signal-coincides. In this paper we present the results of simulation experiments that were performed to study the influence of the physical constraints of a neural system on the simultaneous functional order produced by both models. In the simulation experiments we used a one-dimensional detector array. We delineate the physical constraints such an array has to satisfy in order to induce a functional order relation that allows an isomorphism with a geometrical order. We show that for an appropriate choice of the system parameters both models can produce a simultaneous functional order with sufficient internal coherence to allow isomorphisms with a triangulation. In this case the dimensionality and the coherence of the detector array are objectively available to the system itself.

Environment↗

PubMed1988

Attempts to demonstrate a polysaccharide capsule in Neisseria gonorrhoeae.

The presence or absence of a polysaccharide capsule on the human pathogen Neisseria (N.) gonorrhoeae is still a topic of controversy. For this reason we compared the results obtained by light microscopy (dry India ink-Fuchsin stain) and electron microscopy (Alcian blue-lanthanum nitrate stain) of encapsulated strains of N. meningitidis and Streptococcus (S.) pneumoniae and of non-encapsulated strains of S. pneumoniae and Escherichia (E.) coli with those obtained using the same methods on strains of pilliated and non-pilliated N. gonorrhoeae. After staining with India ink-Fuchsin no capsules could be demonstrated on any of the N. gonorrhoeae strains studied. If present the capsules on these cells are too delicate to be identified by light microscopy. After treatment with Alcian blue-lanthanum nitrate sections of cells of N. meningitidis and S. pneumoniae generally showed the presence of a capsular layer. Sections of cells of the non-encapsulated strain of S. pneumoniae which possess C (common)-polysaccharide also showed surface associated capsule-like material. Similarly the surface of the cells of the E. coli strain showed material which appeared to be tufts of pili and/or M (mucoid)-antigen. In experiments where the N. gonorrhoeae cells were harvested as early as after six hours of growth a capsule-like material was demonstrated on cells of all strains studied.

Culture Media↗

PubMed1988

Ultrastructural localization of capsules, cell wall polysaccharide, cell wall proteins, and F antigen in pneumococci.

The localization of pneumococcal capsular and cell wall antigens was examined by immunoelectron microscopy. C polysaccharide (C-Ps), a common component of all pneumococci, was uniformly distributed on both the inside and outside of the cell walls. The thickness of the C-Ps varied with the strain. Encapsulated strains were covered by varied amounts of capsular polysaccharide concealing the C-Ps of the bacteria so as to render it inaccessible to anti-C-Ps antibodies. In addition to C-Ps, protein antigens were demonstrable on the surface of nonencapsulated pneumococci. The proteins were not masked by the C-Ps layer. An extra layer on the cell walls was conspicuous on electron micrographs of both rough and encapsulated pneumococci. The nature of this extra layer has not been disclosed. F antigen, another common antigen of pneumococci, was uniformly distributed on the surface of the plasma membranes. During the course of the experimental work a reproducible method of gold labeling immunoglobulins was developed.

Antibody Specificity↗

PubMed1987

The construction of a simultaneous functional order in nervous systems. I. Relevance of signal covariances and signal coincidences in the construction of a functional order.

We have developed two algorithms that construct a simultaneous functional order in a collection of neural elements using purely functional relations. The input of the first algorithm is a matrix describing the total of covariances of signals carried by the members of the neural collection. The second algorithm proceeds from a matrix describing a primitive inclusion relation among the members of the neural collection that can be determined from coincidences in their signal activity. From this information both algorithms compute a partial functional order in the collection of neural elements. Such an order has an objective existence for the system itself and not only for an external observer. By either merging individual neurons or recruiting previously unspecified ones the partial order is locally transformed into a lattice order. Thus, the simultaneous functional order in a nervous net may become isomorphic with a geometrical order if the system has enough internal coherence. Simulation experiments were done, both for the neuron-merging and the neuron-recruitment routines, to study the number of individuals in the resulting lattice order as a function of the number of individuals in the underlying partially ordered set.

Algorithms↗

PubMed1987

The construction of a simultaneous functional order in nervous systems. II. Computing geometrical structures.

The functional order of a collection of nervous elements is available to the system itself, as opposed to the anatomical geometrical order which exists only for external observers. It has been shown before (Part I) that covariances or coincidences in the signal activity of a neural net can be used in the construction of a simultaneous functional order in which a modality is represented as a concatenation of districts with a lattice structure. In this paper we will show how the resulting functional order in a nervous net can be related to the geometry of the underlying detector array. In particular, we will present an algorithm to construct an abstract geometrical complex from this functional order. The algebraic structure of this complex reflects the topological and geometrical structure of the underlying detector array. We will show how the activated subcomplexes of a complex can be related to segments of the detector array that are activated by the projection of a stimulus pattern. The homology of an abstract complex (and therefore of all of its subcomplexes) can be obtained from simple combinatorial operations on its coincidence scheme. Thus, both the geometry of a detector array and the topology of projections of stimulus patterns may have an objective existence for the neural system itself.

Animals↗

PubMed1987

The construction of a simultaneous functional order in nervous systems. III. The influence of environmental constraints on the resulting functional order.

In a previous paper (Part I) we introduced a model that constructs a simultaneous functional order in a set of neuronal elements by monitoring the coincidences in their signal activities (the so-called coincidence-model). The simultaneous signal activity in a neural net will be constrained both by its physical restrictions and by environmental constraints. In this paper we present the results of simulation experiments that were performed to study the influence of environmental constraints on the resulting functional order in a set of neural elements corresponding to a one-dimensional detector array. We show that the coincidence-model produces a functional order that encodes the physical constraints of the environment. Moreover, we demonstrate that the signal activity in the neural net (the "perceptions") can be related to events in the outer world. We provide some examples to demonstrate that our model may prove useful to gain insight into certain developmental disorders.

Algorithms↗

PubMed1987

Sarcoplasmatic reticulum function in the ischemic myocardium.

The effects of different periods of myocardial ischemia on sarcoplasmatic reticulum function were studied in porcine hearts in which successive occlusions of branches of the left anterior descending coronary artery yielded myocardium ischemic for 0.5, 1 or 2 h. Sarcoplasmatic reticulum vesicles were isolated from transmural biopsies of control and ischemic segments. Ca2+ pumping ATPase was already impaired after 0.5 h of ischemia (77 +/- 9% of control, n = 5) and had decreased to 44 +/- 9% of control (n = 4) after 1 h of ischemia. The functional damage caused by ischemia may be related to an altered second messenger control of the Ca2+ pump because the in vitro phosphorylation of phospholamban by catalytic subunit was also reduced.

Animals↗

PubMed1986

A comparison of two fluorescence-activated cell sorters, the FACSIV (laser) and the FACSTm (mercury lamp), as research analyzers for the quantification of T and B cell subsets in human peripheral blood.

T cell subset determinations were performed on 146 peripheral blood samples from healthy volunteers, and on 112 samples from immune deficient patients using two fluorescence-activated cell sorters (the FACSIV laser, and the FACSTm mercury lamp analyzer). The procedures necessary for the use and calibration of the FACSTm analyzer are discussed, and detailed. Using the FACSTm analyzer, counts were made of T and B cell subsets in 28 patients with multiple infections, 9 patients suffering from the acquired immune deficiency syndrome (AIDS) and 16 patients with a primary immunodeficiency disease. These results were compared with data obtained from 47 healthy volunteers, as control references. Results from the two instruments proved closely comparable, both qualitatively and quantitatively.

B-Lymphocytes↗

PubMed1986

Cytochemical localization of beta-galactosidase in resident and inflammatory peritoneal macrophages from C57BL mice.

A cytochemical method for the detection of beta-galactosidase (beta-Gase) in mouse peritoneal macrophages was used to study the ultrastructural localization of this enzyme in these cells. It was found that the reaction product for beta-Gase was localized in the perinuclear cisternae, the endoplasmic reticulum, the Golgi complex, lysosomes, vesicles and on the cell surface of peritoneal macrophages from untreated C57BL mice. When examined by X-ray microanalysis the crystalline reaction product was found to contain bromine, an element present in the indolyl substrate which was used to identify beta-Gase. Injection of Proprionibacterium acnes (P. acnes) intraperitoneally or BCG intravenously caused a visible loss in beta-Gase from all the organelles and from the cell surface of the macrophages.

Animals↗

PubMed1986

Morphological study of the in vitro cytotoxic effect of alpha-hemolytic E. coli bacteria and culture supernatants on human blood granulocytes and monocytes.

The morphological changes of human blood granulocytes and monocytes caused in vitro by alpha-hemolytic strains of E. coli and bacteria-free culture supernatants of these bacteria were studied by light- and transmission electron microscopy. The following sequence of cellular alterations were observed: Cessation of intracellular cytoplasmic streaming and cellular movements succeeded by extension of cytoplasmic pseudopodia, degranulation and development of cytoplasmic and nuclear edema. Within two hours the leukocytes appeared as empty sacks. Finally, long straight filaments were formed between the cells. The changes induced by alpha-hemolytic bacteria and culture supernatants containing free alpha-hemolysin appeared to be identical. The cytotoxic effect became more pronounced as the numbers of bacteria, the hemolytic activity of growth supernatants or the period of incubation were increased. A beta-hemolytic and a nonhemolytic E. coli strain were not cytotoxic.

Adult↗

PubMed1986

The ultrastructure of antibiotic-susceptible and multi-resistant strains of group JK diphtheroid rods isolated from clinical specimens.

Two antibiotic-susceptible and two multi-resistant strains of diphtheroid rods of the group JK, obtained from clinical specimens in Denmark and from CDC in the U.S. were studied. The cells of all four strains presented an ordinary Gram-positive cell wall and an additional surface layer. Septum formation in dividing cells appeared to result in a "snapping-like" dividing mechanism, thus corroborating the relationship of the JK cells to the genus Corynebacterium. A significantly increased thickness of the surface layer of the multi-resistant strains was observed when cells were treated with ruthenium red. It is suggested that such a structural difference on the exterior of the cell-wall among JK bacteria may affect the cell-wall's permeability to antibiotics.

Anti-Bacterial Agents↗

PubMed1985

Ability of rosetting or non-rosetting individual control and inflammatory macrophages to kill Escherichia coli X43 intracellularly.

An autoradiographic method combined with a rosette technique was used to assess the bactericidal activity of individual control and inflammatory peritoneal macrophages (PM phi) in the presence or absence of expression of Fc receptor for IgG (FcR). There was a lack of FcR reactivity in a certain percentage of both categories of PM phi exposed to E. coli X43, a bacterium which is readily phagocytosed in the presence of specific antibody. Both rosetting and non-rosetting PM phi were capable of phagocytosing E. coli X43, but inflammatory PM phi showed a marked reduction in their capacity to ingest these bacteria compared with control PM phi. Once ingested the E. coli X43 were killed equally well by non-rosetting and rosetting control and inflammatory PM phi.

Animals↗

PubMed1985

Clinical evaluation of a technetium-99m bone imaging agent based on the vicinal diphosphonate 1,2-diphosphonoethyleneglycol (DPEG).

From a series of technetium-99m labelled agents based on a vicinal diphosphonic acid structure, the ligand 1,2-diphosphonoethyleneglycol (DPEG) was selected for clinical study on the basis of a biodistribution in rats which compared well with that of methylene disphonphonate (MDP). The 99Tcm-DPEG agent was assessed in ten patients in whom bone metastases had been demonstrated by 99Tcm-MDP imaging two to seven days previously. Visual comparison of the skeletal images obtained with the two agents revealed the same number of bone metastases at the same locations. Statistical analysis of the data revealed no significant differences between the two radiopharmaceuticals on the basis of lesion to soft tissue ratio and lesion to normal bone ratio, although a slightly higher lesion to soft tissue ratio was found for MDP than for DPEG (p less than 0.03). At least for the formulation tested, it is concluded that this new radiopharmaceutical based on the P-C-C-P structure does not possess diagnostic advantages over 99Tcm-MDP for the detection of bone metastases.

Aged↗

PubMed1985

The ultrastructural localization of iron in human bone marrow plasma cells.

Ferritin was demonstrated by electron microscopy in bone marrow plasma cells of four patients with multiple myeloma and in one patient with another malignant disease. The ferritin molecules were present in membrane bound vesicles and freely dispersed in the cytoplasm. The plasma cells were often localized around and in close contact with dendritic macrophages, which frequently were laden with ferritin. In some of these plasma cells ferritin was seen at specialized contact zones with macrophage extensions.

Aged↗

PubMed1984

Phagocytosis and killing of Escherichia coli X43 by individual resident mouse peritoneal macrophages assessed by an autoradiographic technique.

An autoradiographic technique for the determination of viable bacteria in individual cells is described, based on the incorporation of [3H]thymidine into the DNA of viable Escherichia coli X43, following phagocytosis by resident mouse peritoneal macrophages. The results of the autoradiographic technique were in overall agreement with viable colony counts. Investigation of the killing of E. coli X43 with the autoradiographic technique showed that the percentage viable bacteria tended to be the same irrespective of the number of bacteria ingested per macrophage, although there was a definite correlation between the numbers phagocytosed and the percentage killed in some of the experiments.

Animals↗

PubMed1984

A comparison between whole body scans made at two hours and three hours after intravenous injection of Tc-99m HDP as to image quality and lesion detectability.

Bone scans of 35 patients were evaluated as to the quality and the number of bone lesions that could be detected at studies 2 hours and 3 hours after injection of Tc-99m HDP. It was found that 2 hour bone scans are of high "cosmetic" and diagnostic quality and that all lesions present at 3 hour scans are well visualized at 2 hours. These features are among the major advantages of the use of Tc-99m HDP over other diphosphonates.

Adult↗