Localization of chlorotetracycline fluorescence in human polymorphonuclear neutrophils

Chlorotetracycline (CTC) has been used in many cells as a probe for membranous calcium. In polymorphonuclear neutrophils (PMN), the changes in CTC fluorescence upon stimulation are considered to monitor an early event in the activation process. Using quantitative video-enhanced microscopy, we report that in resting cells about 80% of the CTC signal emanates from the perinuclear region of the cell, indicating that internal structures are labeled with CTC. Approximately 20% of the total CTC fluorescence is taken up in a compartment sensitive to mitochondrial inhibitors, which is not present in neutrophils depleted of nucleus and granules or cytoplasts. Upon stimulation PMN loaded with CTC exhibit a rapid, biphasic decrease in fluorescence that is dose dependent. The second phase of the response is not seen in neutrophil cytoplasts. These results suggest that internal stores of CTC are responsive upon stimulation and could account for the later decrease in CTC fluorescence, whereas the early phase of CTC changes represents the plasma membrane response.     

Genetic Variation in the Peroxisome Proliferator‐Activated Receptor (PPAR) and Peroxisome Proliferator‐Activated Receptor Gamma Co‐activator 1 (PGC1) Gene Families and Type 2 Diabetes

We used a two‐stage study design to evaluate whether variations in the peroxisome proliferator‐activated receptors (PPAR) and the PPAR gamma co‐activator 1 (PGC1) gene families (PPARA, PPARG, PPARD, PPARGC1A, and PPARGC1B) are associated with type 2 diabetes (T2D) risk. Stage I used data from a genome‐wide association study (GWAS) from Shanghai, China (1019 T2D cases and 1709 controls) and from a meta‐analysis of data from the Asian Genetic Epidemiology Network for T2D (AGEN‐T2D). Criteria for selection of single nucleotide polymorphisms (SNPs) for stage II were: (1) P < 0.05 in single marker analysis in Shanghai GWAS and P < 0.05 in the meta‐analysis or (2) P < 10^?3 in the meta‐analysis alone and (3) minor allele frequency ≥ 0.10. Nine SNPs from the PGC1 family were assessed in stage II (an independent set of middle‐aged men and women from Shanghai with 1700 T2D cases and 1647 controls). One SNP in PPARGC1B, rs251464, was replicated in stage II (OR = 0.87; 95% CI: 0.77–0.99). Gene‐body mass index (BMI) and gene–exercise interactions and T2D risk were evaluated in a combined dataset (Shanghai GWAS and stage II data: 2719 cases and 3356 controls). One SNP in PPARGC1A, rs12640088, had a significant interaction with BMI. No interactions between the PPARGC1B gene and BMI or exercise were observed.     

Glycoprotein-180 deficiency: genetics and abnormal neutrophil activation

Neutrophil function was studied in a patient with polymorphonuclear leukocyte (PMN) glycoprotein-180 deficiency and in her parents. PMNs of the patient had abnormal chemotaxis, phagocytosis, adherence, surface charge, and membrane-associated events of activation. Selective defects to C3b, immunoglobulin G (IgG), phorbol myristate acetate (PMA) and N- formyl-methionyl-leucyl-phenylalanine (FMLP) are described, although C3b receptor density was normal. The parents were found to have abnormal adherence to nylon-wool fibers, abnormal transmembrane potential depolarization with PMA, and reduced amounts of glycoprotein- 180 in their PMNs. These studies provide further evidence that the oxidative burst has several different pathways for activation. They demonstrate that the absence of a single PMN surface glycoprotein is associated with a broad spectrum of PMN functional abnormalities. Finally, the observations made in the parents support an autosomal recessive mode of inheritance.     

Neutrophil cytoplasts: relationships of superoxide release and calcium pools

Activation of human polymorphonuclear neutrophils (PMNs) by the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP) leads to a transient increase in intracellular level of ionized calcium and an alteration of the plasma membrane permeability. Calcium has been proposed as a second messenger for activation of the PMN. Modulation of intracellular pools of calcium is of importance in the regulation of PMN activation. We have studied the changes in membrane-bound and cytoplasmic calcium in PMN and PMN devoid of granules and nucleus by quantifying changes in chlorotetracycline (CTC) and Quin 2 fluorescence and comparing their relation to O(2) release. Similar to PMN, PMN cytoplasts (PMN-CPs) produce equivalent amounts of O(2) in response to 10(-7) mol/L fMLP. The decrease in CTC fluorescence following fMLP stimulation is not significantly different in PMN-CP (-9.9% +/- 3.7%) from that observed in PMN (-12.7% +/- 2.33%), suggesting that the trigger pool of Ca++ is present in PMN-CPs. Although PMNs show a net increase in free Ca++ as measured by Quin 2, PMN-CPs display a lower sustained rise, which is totally abolished in the absence of external Ca++. PMN-CPs release O(2) efficiently in the absence of external Ca++ when stimulated with 10(-7) mol/L fMLP, whereas PMNs release significantly less O(2) under the same conditions. Our results suggest that a rapid rise in free Ca++, as monitored by Quin 2 fluorescence, is not required for expression of full activation of the oxidase system and release of O(2) from PMN-CPs.     

Metabolic, membrane, and functional responses of human polymorphonuclear leukocytes to platelet-activating factor

The phospholipid mediator of anaphylaxis, platelet-activating factor (PAF) is chemotactic for polymorphonuclear leukocytes (PMN). We have examined this agent's effects on several other PMN functions. Human PMN were prepared from heparinized venous blood by Ficoll gradient. Metabolic burst was examined by measurement of O2 use and O2.- production in the presence or absence of PAF (10(-6)--10(-9) M). Unless cells were treated with cytochalasin-B (5 micrograms/ml), no significant respiratory burst was demonstrated. However, pretreatment with PAF (10(-7) M) enhanced approximately threefold the O2 utilization found when cells were subsequently stimulated with 10(-7) M FMLP. PAF also stimulated arachidonic acid metabolism in 14C-arachidonic acid- labeled PMN. Thin-layer chromatography analysis of chloroform-methanol extracts showed substances that comigrated with authentic 5- hydroxyeicosatetraenoic acid had a marked increase in radioactivity following PAF stimulation at 10(-7) M. PAF failed to stimulate release of granule enzymes, B-glucuronidase, lysozyme, or myeloperoxidase unless cytochalasin-B were added. PAF from 10(-6) M to 10(-10) M affected PMN surface responses. PMN labeled with the fluorescent dye, chlorotetracycline, showed decreased fluorescence upon addition of PAF, suggesting translocation of membrane-bound cations. Further, the rate of migration of PMN in an electric field was decreased following PAF exposure, a change consistent with reduced cell surface charge. PMN self-aggregation and adherence to endothelial cells were both influenced by PAF (10(-6) M--10(-9) M). Aggregation was markedly stimulated by the compound, and the percent PMN adhering to endothelial cell monolayers increased almost twofold in the presence of 10(-8) M PAF. Thus, PAF promotes a variety of PMN responses: enhances respiratory burst, stimulates arachidonic acid turnover, alters cell membrane cation content and surface charge, and promotes PMN self- aggregation as well as adherence to endothelial cells.     

Clearance kinetics of parasites and pigment-containing leukocytes in severe malaria

In tropical areas, where unsupervised use of antimalarial drugs is common, patients with an illness consistent clinically with severe malaria but with negative blood smears pose a management dilemma. Malaria pigment is evident in peripheral blood leukocytes in greater than 90% of patients with severe malaria. To characterize the clearance kinetics of parasitized erythrocytes and malaria pigment-containing leukocytes, sequential peripheral blood and intradermal smears were assessed in 27 adult Vietnamese patients with severe falciparum malaria. The clearance of parasitized erythrocytes and pigment- containing monocytes (PCMs) followed first order kinetics. The elimination of pigment-containing neutrophils (PCNs) was first order initially, but deviated from this when counts were low. Clearance of peripheral blood PCMs (median clearance time, 216 hours; range, 84 to 492 hours) was significantly slower than that of parasitized erythrocytes (median, 96 hours; range, 36 to 168 hours) or PCNs (median, 72 hours; range, 0 to 168 hours; P < .0001). Intradermal PCM clearance times were the longest of all (median, 12 days; range, 6 to 23 days; significantly longer than peripheral blood PCM clearance, P < .001). Twenty-one (88%) patients still had signs, symptoms, or laboratory features of severe malaria after parasite clearance but before phagocyte pigment clearance. Sixteen of the 23 surviving patients (70%; 95% confidence interval, 50% to 87%) still had intraleukocytic malaria pigment on peripheral blood films 72 hours after parasite clearance. Thus, by determining the distribution of malaria pigment in peripheral blood and intradermal phagocytes, the time since effective antimalarial treatment started can be estimated. Microscopy for intraleukocytic pigment is valuable in the differential diagnosis of severe febrile illnesses in malarious areas where uncontrolled use of antimalarial drugs is widespread.     

‘How do we get the managers we need and the leaders we want?’ A personal view

For most patients and the general public, their most significant interface within the hospital setting occurs at the ward level. Here, the professional abilities of the Ward Sister/Charge Nurse – as well as the ward environment – will have a major impact on the experience and outcome of the patient’s stay in hospital. It will also strongly influence the opinion of relatives and friends about the standards of care being delivered in that hospital. Ward managers are expected to demonstrate not only clinical leadership, but also be competent at dealing with the plethora of organisational issues which arise on their ward on a daily basis. As part of a professional response to the public’s concerns around the environment of care within our hospitals and the perception that nursing leadership is not what it was, Welsh Assembly Government have launched a new strategy to re‐empower Ward Sisters/Charge Nurses and develop and support the nurse managers/leaders of the future.