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Biomedical subjects

J C Lewis

Publications and source records attributed to J C Lewis.

At least 127 records · Page 7Linked to original sources
PubMed1982

Surface characteristics of adherent avian cells; extrapolation of in vitro characteristics to cells on atherosclerotic lesions.

Through the use of correlative Wright's stain and scanning electron microscopy (SEM), the distinguishing surface characteristics of adherent pigeon blood cells have been determined. The identification criteria, established by using an in vitro adhesion system, have been extrapolated to cells associated with the surface of atherosclerotic lesions. The results presented in this paper clearly distinguish erythrocytes, thrombocytes and lymphocytes from monocytes and granulocytes. Erythrocytes are fusiform in shape and have a distinctively smooth plasma membrane. Thrombocytes, smaller than erythrocytes but also fusiform, extend numerous filipodia when surface activated. Often a delicate hyalomere connects adjacent filipodia on the substrate. In contrast to erythrocytes and thrombocytes, lymphocytes are round cells whose plasma membrane forms numerous stubby microvilli. Monocytes and granulocytes can be distinguished from the other cell types by their larger size; however, the distinction between the two is much finer than the previous three blood cell lines. When adherent, both retain a round, nuclear region often encircled by a hyalomere apposing the substrate; the discrete difference between granulocytes and monocytes lies in the convolutions of the plasma membrane. The monocyte membrane folds into ruffles covering both the nuclear area and hyalomere; whereas, the granulocyte membrane forms small microvilli and cytoplasmic ridges only over the nuclear area. The SEM descriptions of adherent pigeon blood cells were demonstrated to be potentially useful in identifying cells adherent to early atherosclerotic lesions in pigeon coronary arteries.

Animals↗
PubMed1981

Microfilament reorganization in normal and cytochalasin B treated adherent thrombocytes.

Thrombocyte adhesion following activation by a Formvar surface involves a morphologic transition resulting in a fully spread cell. Correlative SEM and whole mount TEM were used to study the cytoskeletal alterations that accompany changes in surface morphology during adhesion. Following initial adhesion, thrombocytes extend slender pseudopods containing longitudinally oriented bundles of filaments that are 13-22 nm in diameter. Concomitant with pseudopod extension, a cytoplasmic hyalomere, consisting of a dense filamentous network, extends between the pseudopods and ultimately results in a fully spread cell. Treatment of thrombocytes with cytochalasin B (10(-5) M) caused clumping of the hyalomere filament network and retraction of the hyalomere. Examination of partially retracted cells revealed that pseudopod filament bundles were continuous with the contracting filamentous network. It is concluded that pseudopod filament bundles and cytoplasmic hyalomere filaments are interconvertible and that their organizational relationship changes in accordance with gross morphologic changes.

Blood Platelets↗
PubMed1981

Neutrophil responses to platelet-activating factor.

1-O-Alkyl-2-O-acetyl-sn-glycerol-3-phosphorylcholine (i.e., platelet-activating factor) was prepared and confirmed to possess potent platelet aggregating activity. It was also potent in aggregating and degranulating rabbit and human neutrophils. When injected into rabbits, the lipid induced profound neutropenia, thrombocytopenia, and anaphylactic symptoms. The lyso derivative of this lipid, 1-O-alkyl-sn-glycerol-3-phosphorylcholine, was inactive or several orders of magnitude weaker in inducing these responses. The acetylated lipid appears to be a potent stimulator of both platelets and neutrophils. Its anaphylactic-like toxicity may be related, at least in part, to its ability to aggregate or otherwise stimulate these cells.

Animals↗
PubMed1981

Limitations of Gullino-type chambers for collection of interstitial proteins from human tumour xenografts: a histological and theoretical study.

GULLINO-type diffusion chambers, made entirely from polytetrafluoroethylene (P.T.F.E.) were implanted subcutaneously into athymic nude mice either alone or with tumour mince from a human colonic tumour xenograft. Those implanted with mince became incorporated into the resulting tumours. Chambers were removed at various times following implantation and histological sections prepared from surrounding tissues. A consistent histological picture was seen adjacent to all parts of the implants comprised of a foreign body giant cell reaction with fibrosis, irrespective of the presence of tumour. We argue that in the absence of any reaction, such chambers may collect specific proteins and allow estimation of total interstitial protein content, but are unsuitable for determining the effective in vivo concentration of any particular interstitial protein. It is further suggested that the presence of reactive tissue around the chambers could introduce further sources of error, adequate controls for which are essential for interpretation of data relating of interstitial proteins collected in this manner.

Animals↗
PubMed1981

A human choriocarcinoma xenograft in nude mice; a model for the study of antibody localization.

The successful development of the concept of linking cell-killing agents to tumour-specific antibodies will be largely determined by the extent to which the antibodies are preferentially localized in the malignant tissue. A xenograft of human choriocarcinoma (CC3) has been established in nude mice, and the relative distribution of affinity-purified specific antibodies to human chorionic gonadotrophin has been compared with that of nonspecific antibodies from the same species. Treatment of the nonspecific antibodies with ammonium thiocyanate appeared to be important to ensure that the distributions in normal nude mice were equivalent. Specificity indices, derived from the comparative distributions of isotope activity in the tumour and lung of labelled specific and nonspecific antibodies, ranged between 1.3 and 2.0.

Animals↗
PubMed1981

Relationship of serum CEA levels to tumour size and CEA content in nude mice bearing colonic-tumour xenografts.

The relationship of serum carcinoembryonic antigen (CEA) levels to tumour size and antigen content was studied in nude mice bearing well differentiated, mucinous human colonic-tumour xenografts. Blood samples were taken from normal nude mice and others bearing xenografts, whose size had been calculated from in vivo measurements; saline and KCl extracts were made of a proportion of these tumours. Sera and tissue extracts were assayed for CEA activity by double-antibody radioimmunoassay. Extracts were also made from the livers and spleens of tumour-bearing and normal nude mice. All normal sera and 78% of sera from tumour-bearing animals had CEA values less than 11.4 ng/ml. No clear correlation was found between serum CEA levels greater than 11.4 ng/ml and tumour size or weight, or between serum CEA and tumour CEA concentrations or total CEA burden. The concentration of CEA in those tumours tested varied from 1 to 22 microgram/g. Our results confirm and extend the conclusions reached by others (Stragand et al., 1980) studying the significance of serum CEA levels with xenograft model systems. The complexity of factors contributing to circulating CEA is discussed in the light of our findings.

Animals↗
PubMed1981

Activation of lysosomal acid phosphatase of eosinophil leukocytes.

Acid phosphatase (AP) within the specific granules of eosinophils is held in a latent, inactive form prior to degranulation. Eosinophils responded to membrane stimuli with activation of AP throughout the granules of the cell, prior to degranulation. Activation occurred within the time required for fixation of the cells by glutaraldehyde. Whereas resting normal eosinophils demonstrated AP activity in 7.8 +/- 1.2 per cent of the granules, cells stimulated with opsonized staphylococci demonstrated activity in 78.9 +/- 5.0 per cent of the granules, and the amount of lead phosphate reactant deposited per active granule was considerably more intense in the stimulated than in the unstimulated cells. A similar stimulation of AP activity in eosinophils occurred with exposure to the surface-active agent phorbol myristate acetate or the calcium ionophore A23187. Activation was not altered by 5 microgram. per ml. of cytochalasin B or 4 x 10(-6) M colchicine. These aspects of the response closely parallel the stimulation of oxidative metabolism of eosinophils; however, the two were separable. Eosinophils obtained from a patient with chronic granulomatous disease, although unable to activate the normal oxidative metabolic burst, demonstrated a normal activation of AP.

Acid Phosphatase↗
PubMed1981

1-O-Alkyl-sn-glyceryl-3-phosphorylcholines: a novel class of neutrophil stimulants.

1-O-Alkyl-2-O-acetyl-sn-glyceryl-3-phosphorylcholine aggregates and degranulates platelets and polymorphonuclear neutrophils. Here, the bioactivities of this platelet-activating factor, its 2-O-ethyl, and its 2-lyso derivatives were examined further. Each phospholipid aggregated and degranulated rabbit platelets and neutrophils with relative potencies of about 10,000 1,000, and 1, respectively. For rabbit neutrophils, and 2-O-acetyl compound was active in nanomolar and lower concentrations; required extracellular calcium and magnesium in order to induce aggregation; and required extracellular calcium and cytochlasin B in order to induce optimal degranulation. Furthermore the 2-O-acetyl and 2-O-ethyl compounds, in concentrations about tenfold higher than those required for rabbit neutrophils, aggregated and degranulated human neutrophils. With reference to these human neutrophil responses, degranulation required, and aggregation was dramatically enhanced by, cytochalasin B. The lysoanalog was unable to induce these response in the human cells. Thus, these lipids represent a novel class of neutrophil stimulants that closely resemble certain chemotactic factors (eg, C5a and synthetic oligopeptides) in their ability to aggregate and degranulate neutrophils and in the influences which calcium, magnesium and cytochalasin B have on their bioactions. Because platelet-activating factor circulates in the blood of rabbits and, perhaps, humans during anaphylaxis and is suspected of being involved in other syndromes such as serum sickness, this lipid may have unique biologic significance: it may act to recruit platelets and neutrophils into the lesions of these and similar pathologic syndromes.

Animals↗
PubMed1981

Selective desensitization of neutrophils: further studies with 1-O-alkyl-sn-glycero-3-phosphocholine analogues.

Human polymorphonuclear neutrophils aggregate and degranulate in response to 2 recently described platelet-activating phospholipids: 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphocholine and 1-O-alkyl-2-O-ethyl-sn-glycero-3-phosphocholine. Here, we find that the 2 phospholipids can also desensitize neutrophils. Thus, cells incubated with either phosphocholine for 1 to 5 min in the absence of calcium and magnesium (which are required for aggregation) did not aggregate when exposed to the bivalent cations and fresh lipid stimulus. Also, cells incubated with either lipid for 5 min in the absence of cytochalasin B (which is required for degranulation) did not degranulate when exposed to cytochalasin B and fresh lipid stimulus. However, these desensitized neutrophils aggregated and degranulated fully in response to the chemotactic oligopeptide N-formyl-methionyl-leucylphenylalanine and C5a. In relation to the aggregation response, this selective desensitization was not due to lipid inactivation; it persisted after thorough cell washing; and it was not induced by a nonaggregating analogue, 1-O-alkyl-sn-glycerol-3-phosphocholine. Furthermore, cells desensitized to the formylated oligopeptide or C5a (by preincubation with either stimulus in the absence of bivalent cations) did not aggregate when challenged with the oligopeptide or C5a, respectively, but exhibited a normal or enhanced aggregation response to the 2 active phospholipids. These data support the concept that C5a, formylated oligopeptides, and phosphocholines represent 3 distinct classes of stimulants that activate and densensitize neutrophils by at least partially independent pathways. This activation and desensitization may be mediated by 3 types of cellular receptors, each of which interacts with only 1 class of stimuli.

Animals↗
PubMed1980

Ultrastructures of Reilly bodies (metachromatic granules) in the Maroteaux-Lamy syndrome (mucopolysaccharidosis VI). A histochemical study.

The leukocytes from an 8-year-old white girl having features of the Maroteaux-Lamy syndrome (mucopolysaccharidosis VI) contained large granular inclusions (Reilly granules). Light and electron microscopy showed that these granules had characteristics of those seen in several other types of mucopolysaccharidoses, including Morquio's syndrome, which are of a different structure than those of other types of mucopolysaccharidosis. Similar granules were seen in the platelets, a finding which, so far as we know, has never been reported before. The granules contained an acid mucosubstance demonstrated by cytochemical studies.

Blood Platelets↗
PubMed1980

Comparison of human eosinophils from normals and patients with eosinophilia.

Previous studies of the biochemistry and physiology of eosinophils have relied upon cells obtained from patients with eosinophilia (EE). It is unknown whether such cells might have been activated or partially exhausted by the pathological state causing eosinophilia. We examined cell surface charge, membrane transport of deoxyglucose, activation of lyso-somal acid phosphatase, and oxidative metabolism to provide a profile to compare EE with purified normal eosinophils (NE) and normal neutrophils. Eosinophils or neutrophils were obtained in >95% purity from normal individuals and patients with eosinophilia of diverse etiologies. Cell surface charge was determined by electrophoretic mobility in micromoles per second per volt per centimeter. Normal eosinophils demonstrated a surface charge of 2.46+/-0.03. Stimulation of the cells by zymosan-activated serum (ZAS) reduced the surface charge to 1.82+/-0.02. In contrast, the charge of "resting" EE was already reduced (1.89+/-0.05) and was not altered by ZAS. Resting and stimulated neutrophils had a charge of 1.98+/-0.01 and 1.69+/-0.02, respectively. Uptake of [(3)H]2-deoxyglucose has been shown to reflect carrier-facilitated hexose transport in granulocytes. Deoxyglucose uptake by resting NE and NE stimulated by ZAS was 2.40+/-0.40 and 5.44+/-0.39 (cpm x 10(-3)/2 x 10(5) eosinophils), respectively. Resting and stimulated EE demonstrated deoxyglucose uptake of 7.55+/-0.58 and 15.3+/-0.6, respectively.Lysosomal acid phosphatase was determined by an electron microscopic cytochemical technique. In normal eosinophils and neutrophils, lysosomal acid phosphatase in mature cells is held in a latent form. Normal eosinophils demonstrated weakly positive acid phosphatase activity in 7.8+/-1.2% of the specific granules. Normal eosinophils, stimulated by opsonized staphylococci or the calcium ionophore A23187, develop rapid activation of acid phosphatase in approximately 80% of the granules throughout the cells. Resting EE were usually already activated and demonstrated acid phosphatase in 48.6+/-8.6% of the granules (range, 2-95% granules positive; significant activation was observed in preparations in EE from 11 of 15 patients). Oxidative metabolism was monitored by measurement of the hexose monophosphate shunt (HMPS) (metabolism of 1-[(14)C]glucose to (14)CO(2)). Previous studies demonstrated that resting EE have an HMPS activity which is nearly that of stimulated neutrophils, yet EE remain capable of further 7-10-fold increase when stimulated by opsonized zymosan. In contrast, the HMPS of NE (resting and stimulated) was not significantly different from that of neutrophils. Thus eosinophils obtained from patients with eosinophilia appear significantly activated when compared with normal eosinophils by the criteria of surface charge, activation of lysosomal acid phosphatase, membrane hexose transport, and hexose monophosphate shunt activities.

Acid Phosphatase↗
PubMed1980

The use of correlative SEM and TEM to study thrombocyte and platelet adhesion to artificial surfaces.

Platelet adhesion is a complex process involving circulating cells, the damaged vessel wall and the complex medium of plasma in which the events take place. Elucidation of several cellular changes which occur during adhesion has been enhanced through the use of conventional transmission and scanning electron microscopy; however, many question, particularly relating to cytoplasmic control of cellular reorganization have remained unanswered. This paper describes the preparative techniques and the potential for use of correlative stereo SEM and TEM in studies of platelet adhesion. Three particular techniques: (1) stereo SEM, (2) stereo SEM-TEM of digest replicas and (3) whole mount stereo TEM are described. The applicability of these techniques to areas of cytoplasmic filaments organization, granule movement, and cell to cell contact organization is suggested.

Animals↗