Biomedical subjects

J K Jackson

Publications and source records attributed to J K Jackson.

At least 37 records · Page 2Linked to original sources

PubMed1997

Calcium pyrophosphate dihydrate crystals activate MAP kinase in human neutrophils: inhibition of MAP kinase, oxidase activation and degranulation responses of neutrophils by taxol.

The activation of MAP kinase in human neutrophils stimulated by both uncoated and plasma-opsonized crystals of triclinic calcium pyrophosphate dihydrate (CPPD) was investigated. The effect of taxol on MAP kinase activation and on the responses of neutrophils stimulated by plasma-opsonized crystals was determined. MAP kinase activation was identified and quantified in Mono Q chromatography separated fractions of neutrophils that had been incubated with CPPD crystals by measuring [gamma-32P]adenosine triphosphate (ATP) phosphorylation of myelin basic protein and using immunoblotting techniques. Human neutrophils were incubated with taxol (0-50 microM), added to plasma-opsonized CPPD (50 mg/ml) and MAP kinase activation, chemiluminescence, superoxide anion generation, lysozyme and myeloperoxidase release were monitored. Both uncoated and plasma coated CPPD crystals induced a large increase in MAP kinase activity in neutrophils over control levels within 1 min of incubation. Pretreatment of neutrophils with taxol was able to suppress this activation of MAP kinase. Taxol produced a concentration-dependent inhibition of opsonized CPPD-induced neutrophil chemiluminescence, superoxide anion production and myeloperoxide release. Taxol at 28 microM also significantly inhibited chemiluminescence, superoxide anion production and myeloperoxidase release from neutrophils stimulated by opsonized zymosan. This is the first report of crystal-induced activation of MAP kinase in neutrophils. Microtubule-associated processes, such as signal transduction, secretion and phagocytosis are involved in particulate-induced neutrophil responses. We have suggested that the inhibitory effect of taxol observed in this work is due to its stabilizing effect on microtubules and disruption of MAP kinase activation associated with microtubules.

Antineoplastic Agents, Phytogenic↗

PubMed1997

Evidence that mortality from Vibrio vulnificus infection results from single strains among heterogeneous populations in shellfish.

Vibrio vulnificus is the leading cause of food-related mortality reported in the state of Florida. It is normal microflora in marine environments, where seawater and molluscan shellfish are the primary vectors of V. vulnificus disease. Risk correlates with seasonally high numbers of V. vulnificus bacteria during the summer months. Currently, the infectious dose for humans, as well as whether the disease is caused by single or multiple strains found in molluscan shellfish, is unknown. In this work, we studied pulsed-field gel electrophoresis profiles of V. vulnificus strains isolated from blood and oysters associated with V. vulnificus disease. Results showed that ca. 10(3) V. vulnificus bacteria/gram of oyster and higher concentrations were associated with human infections and that a single V. vulnificus strain, evidenced by pulsed-field gel electrophoresis profiles, was isolated from human tissues.

Adult↗

PubMed1997

Efficacy of prophylactic antibiotics in arthroscopic surgery.

A prospective, randomized, double-blind study of 437 patients undergoing arthroscopic diagnostic and operative procedures found that no deep infections occurred in any patient and only one superficial infection occurred in a patient who did not receive prophylactic antibiotics. One patient had a mild allergic reaction to the antibiotic that resolved after treatment with Benadryl. These results suggest that the routine use of prophylactic antibiotics is not indicated for patients undergoing arthroscopic surgery and that the slight risk of infection is outweighed by the cost of the antibiotics and the slight risk of allergic reaction.

Adolescent↗

PubMed1997

The involvement of phosphatidylinositol 3-kinase in crystal induced human neutrophil activation.

OBJECTIVE: We investigated whether phosphatidylinositol (PI) 3-kinase is involved in the signal transduction pathway leading to neutrophil activation by inflammatory microcrystals. METHODS: Neutrophil chemiluminescence and degranulation responses to opsonized crystals were measured in the presence of selective inhibitors known to inhibit PI 3-kinase activity in neutrophils. RESULTS: Wortmannin and LY 294002, 2 selective inhibitors of PI 3-kinase, were shown to inhibit neutrophil activation induced by plasma opsonized crystals of calcium pyrophosphate dihydrate (CPPD) [both monoclinic (M) and triclinic (T) forms] and monosodium urate monohydrate (MSUM). IC50 for wortmannin or LY 294002 inhibition of crystal induced respiratory burst (measured by chemiluminescence) was about 3 nM and 0.3 microM, respectively, proving the pivotal role of PI 3-kinase in neutrophil respiratory burst activation by all 3 crystals. Degranulation responses of neutrophils to CPPD(M) and CPPD(T) crystals were also inhibited by about 50% by wortmannin in the 10 to 20 nM concentration range, supporting the direct involvement of PI 3-kinase in signal transduction pathways leading to crystal induced neutrophil degranulation. All 3 crystals induced the activation of PI 3-kinase in neutrophils as measured by the increased PI 3-kinase activity associated with immunoprecipitated tyrosine phosphorylated proteins from 1 min crystal-neutrophil incubations. Neutrophils pretreated with wortmannin at 10 nM showed sub-basal levels of PI 3-kinase activity at all time points measured. CONCLUSION: PI 3-kinase plays a central role in the signal transduction pathways leading to respiratory burst and degranulation responses in neutrophils activated by inflammatory microcrystals.

Androstadienes↗

PubMed1996

Mechanism of hemolysis of human erythrocytes exposed to monosodium urate monohydrate crystals. Preliminary characterization of membrane pores.

Microcrystals of monosodium urate monohydrate (MSUM) have the ability to cause rapid hemolysis of erythrocytes. The nature of the initial MSUM crystal-erythrocyte membrane binding interaction was investigated over a range of different ionic strength media. There was negligible binding of MSUM to erythrocyte ghost membranes in low ionic strength media such as isotonic mannitol but binding was dramatically increased in isotonic NaCl/mannitol solutions or isotonic mannitol containing 1 mM Ca2+. Hemolysis induced by MSUM crystals was preceded by the leakage of K+ from the cells suggesting a colloid-osmotic mechanism of hemolysis. The inclusion of large (oligosaccharide) molecules in the extracellular media or the modulation of the extracellular solution tonicity inhibited both the rate and extent of hemolysis supporting the concept of MSUM-induced pores followed by colloid osmotic hemolysis.

Buffers↗

PubMed1996

Determination of surfactant critical micelle concentration by a novel fluorescence depolarization technique.

A novel method using fluorescence depolarization to determine the critical micelle concentrations (CMC) of surfactants was developed. Fluorescence anisotropies of Triton X-100, sodium dodecyl sulfate, and sodium cholate were measured using 1,6-diphenyl-1,3, 5-hexatriene as a fluorescence probe. Fluorescence anisotropy decreased with increasing surfactant concentrations below the CMC and leveled off above the CMC. The depolarization method does not depend on the concentration of DPH and is largely immune to light-scattering problems encountered in turbid aqueous systems.

Cholic Acid↗

PubMed1996

The interaction of monoclinic calcium pyrophosphate dihydrate crystals with neutrophils.

Monoclinic calcium pyrophosphate dihydrate (m-CPPD) crystals were synthesized and characterized using physical methods, IgG binding to m-CPPD crystals was quantitated, and the effect of IgG or plasma opsonization on m-CPPD-induced neutrophil activation was determined. Adsorption of IgG to crystals was measured using fluorescent-labelled FITC-IgG. Neutrophil activation by uncoated m-CPPD and crystals precoated with IgG or plasma was measured using luminol-enhanced chemiluminescence, superoxide anion generation, and myeloperoxidase release. m-CPPD bound small (compared to triclinic CPPD) but significant amounts of IgG and induced a strong activation of neutrophils at low concentrations of crystals. The rate and extent of chemiluminescence, superoxide anion production, and degranulation was not affected by precoating m-CPPD crystals with IgG during the early phase of neutrophil responses, but was inhibited by the precoating of crystals with plasma.

Adsorption↗

PubMed1996

Development of a polymeric surgical paste formulation for taxol.

PURPOSE: To develop and characterize a biodegradable polymeric sustained release surgical paste formulation for taxol. METHODS: Taxol was incorporated into poly(epsilon-caprolactone) (PCL) or blends of PCL with methoxypolyethylene glycol, MW 350 (MePEG). The surgical pastes were characterized using gel permeation chromatography, thermal analysis, scanning electron microscopy, and a tensile strength tester. In vitro release data for taxol from the surgical paste formulations was carried out at 37 degrees C in phosphate buffered saline, pH 7.4, using an HPLC assay for taxol. Antiangiogenic activity of the formulations were assessed using a chick chorioallantoic membrane assay (CAM). RESULTS: The addition of up to 30% MePEG in PCL decreased the melting point of PCL by 5 degrees C and the tensile strength by 152.7 N/cm2 to 26.7 N/cm2 but increased the degree of PCL crystallinity from 42% to 51%. Taxol showed a biphasic in vitro release profile composed of a burst phase lasting 1 or 2 days followed by a period of slow sustained drug release. There was no significant difference in the release profiles of taxol from two different sources of PCL. The addition of MePEG increased the amount of water taken up by the polymer blends but decreased the rate of taxol release. The formulations were shown to have antiangiogenic activity by the CAM assay at levels as low as 0.1% taxol using 3 mg surgical paste pellets. CONCLUSIONS: Our surgical paste formulations for taxol give sustained release while having physical properties which can be adjusted using additives.

Allantois↗

PubMed1996

Pulsed-field gel electrophoresis and ribotype profiles of clinical and environmental Vibrio vulnificus isolates.

Vibrio vulnificus belongs to the autochthonous bacterial flora of warm estuarine waters. It can cause life-threatening extraintestinal disease in persons who have underlying illness and who consume raw shellfish or contact wounds with estuarine water. Currently, very little is known about genetic diversity within this species. In this report, we describe high-level variation in restriction fragment length polymorphism profiles among 53 clinical and 78 environmental isolates, as determined by pulsed-field gel electrophoresis. In contrast, ribotype profiles showed greater similarity. When combined ribotype profiles of clinical and environmental isolates were analyzed, four predominant clusters were observed. Interestingly, a low number (16%) of clinical isolates were found in cluster C, compared with clusters A, B, and D (range, 50 to 83%). In addition, 83% of all Hawaiian isolates were located in a single cluster, indicating a possible relationship between geography and genotype. We also report that spontaneous translucent colonial morphotypes were distinct by both restriction fragment length polymorphism and biochemical profiles, compared with opaque parent strains.

Bacterial Typing Techniques↗

PubMed1995

Controlled delivery of taxol from microspheres composed of a blend of ethylene-vinyl acetate copolymer and poly (d,l-lactic acid).

'Large' (30-100 microns) and 'small' (10-30 microns) size range taxol-loaded microspheres composed of a blend of biodegradable poly (d,l-lactic acid) (PLA) polymer and nondegradable ethylene-vinyl acetate (EVA) copolymer were prepared using the solvent evaporation method. Encapsulation efficiencies were between 95-100% for taxol in 50:50 EVA:PLA blend microspheres. Between 10-13% of the total taxol content of the microspheres (0.6% w/v taxol loading) was released in 50 days. Using the chick chorioallantoic membrane (CAM) model, the taxol microspheres released sufficient taxol to produce vascular regression and inhibition of angiogenesis. This taxol-loaded microsphere formulation may have potential for the targeted delivery of taxol to a tumor via arterial chemoembolization.

Animals↗

PubMed1995

Taxol encapsulation in poly(epsilon-caprolactone) microspheres.

Poly(epsilon-caprolactone) (PCL) microspheres containing taxol were prepared by the solvent evaporation method and tested for angiogenesis inhibition using the chick chorioallantoic membrane (CAM) model. Very high encapsulation efficiencies (95%) for taxol in PCL microspheres were obtained. In vitro release studies showed about 25% of the loaded drug was released in 6 weeks from microspheres containing 5% taxol. Studies with the CAM showed that taxol released from the microspheres induced vascular regression and inhibited angiogenesis.

Allantois↗

PubMed1995

Viability of Vibrio vulnificus in Association with Hemocytes of the American Oyster (Crassostrea virginica).

Certain indigenous estuarine bacteria, such as Vibrio vulnificus, may cause opportunistic human infections after consumption of raw oysters or exposure of tissues to seawater. V. vulnificus is known to be closely associated with oyster (Crassostrea virginica) tissues and is not removed by controlled purification methods, such as UV light-assisted depuration. In fact, when live shellfish are subjected to controlled purification, the number of V. vulnificus cells can markedly increase. A review of previous studies showed that few workers have examined mechanisms in oysters which may influence the persistence of V. vulnificus in shellfish, such as the fate of V. vulnificus following phagocytosis by molluscan hemocytes. The objectives of this study were to define the intracellular viability and extracellular viability of V. vulnificus during the phagocytic process and to study the release of specific lysosomal enzymes. The viability of a virulent estuarine V. vulnificus isolate with opaque morphology was compared with the viability of a translucent, nonvirulent form, the viability of Vibrio cholerae, and the viability of Escherichia coli in phagocytosis experiments. Our results showed that the levels of phagocytosis and bactericidal degradation of the opaque V. vulnificus isolate were less than the levels of phagocytosis and bactericial degradation of the translucent morphotype. These findings indicate that encapsulation may contribute to resistance to ingestion and degradation by hemocytes. The rates of intracellular death of V. cholerae and E. coli exceeded the rate of intracellular death of the opaque V. vulnificus isolate, even though the ingestion or uptake rates did not differ significantly. The levels of lysozyme activity and acid phosphatase activity were not significantly different in hemocyte monolayers inoculated with V. vulnificus.

Journal Article↗

PubMed1994

Inhibition of crystal-induced neutrophil activation by a protein tyrosine kinase inhibitor.

The objective of this work was to investigate the role of tyrosine kinase in monosodium urate monohydrate (MSUM) and calcium pyrophosphate dihydrate (CPPD) crystal-induced neutrophil activation using the tyrosine kinase inhibitor lavendustin C (LVC). Human neutrophils pretreated with LVC at concentrations between 10 and 150 microM or control neutrophils were stimulated by plasma-coated CPPD or uncoated MSUM, and chemiluminescence, superoxide generation, intracellular calcium concentration, and degranulation (myeloperoxidase and lysozyme release) were monitored with time. LVC strongly inhibited chemiluminescence, superoxide anion generation, myeloperoxidase and lysozyme release, and calcium mobilization. After 1-min crystal-neutrophil incubations, neutrophil cytosolic fractions showed extensive inhibition of tyrosine kinase activity by LVC. We conclude that the inhibition of neutrophil responses to crystal stimulation, by the protein tyrosine kinase inhibitor LVC, provides evidence that supports the involvement of tyrosine kinases in crystal-induced neutrophil activation.

Calcium↗

PubMed1994

Understanding survival responses of battered women.

Battered women often endure years of physical, psychological, and/or sexual abuse at the hands of an intimate partner. To intervene effectively, health professionals need to understand both the external factors and the complex conditioning process that keep many women trapped in abusive relationships. Many of the physical and psychological symptoms shown by battered women can be understood as complex survival strategies and responses to the abuse.

Battered Women↗

PubMed1994

Cytosolic Ca2+ concentration determinations in neutrophils stimulated by monosodium urate and calcium pyrophosphate crystals: effect of protein adsorption.

OBJECTIVE: To develop methods to correct for light scattering artifacts produced by monosodium urate monohydrate (MSUM) and calcium pyrophosphate dihydrate (CPPD) crystals in the measurement of the levels of cytosolic free calcium, [Ca2+]i, in neutrophils and to quantitate the extent of association of neutrophils with crystals. METHODS: The association of neutrophils with crystals through binding of crystals onto the neutrophil plasma membrane and/or internalization was quantitated by mixing crystals with diphenyl hexatriene (DPH) loaded neutrophils and monitoring the fluorescence intensity of supernatants ("free" neutrophils) following gravity sedimentation of "free" crystals and neutrophils with bound/internalized crystals. The effects of precoating CPPD and MSUM crystals with IgG, plasma, serum and BSA on crystal-neutrophil association and [Ca2+]i were determined. RESULTS: MSUM produced a large increase in [Ca2+]i that reached maximal values in less than 1 min, whereas CPPD produced a smaller and slower increase in [Ca2+]i. IgG adsorbed onto CPPD increased the rate and extent of increase in [Ca2+]i. Heparinized plasma and serum adsorbed onto CPPD increased the extent but not the rate of increase in [Ca2+]i. CONCLUSION: [Ca2+]i increases induced by MSUM were not affected by IgG, serum or heparinized plasma precoating. IgG, serum, or heparinized plasma adsorbed into CPPD amplified neutrophil activation increasing the extent of the increase in [Ca2+]. Neither MSUM nor CPPD induced increases in [Ca2+]i were sensitive to precoating crystals with bovine serum albumin.

Adsorption↗

PubMed1993

Enhancement of crystal induced neutrophil responses by opsonisation of calcium pyrophosphate dihydrate crystals.

OBJECTIVES: Little is known about the effect on crystal induced neutrophil responses of the opsonisation of calcium pyrophosphate dihydrate (CPPD) (triclinic) crystals with components of serum and plasma. The purpose of this study was to determine the effects of precoating CPPD crystals with plasma, serum, complement depleted serum, and IgG on a full range of crystal induced neutrophil responses (calcium mobilisation, chemiluminescence, superoxide anion production, non-cytolytic lysosomal enzyme release, and leukotriene synthesis). METHODS: Crystals were precoated with IgG, serum, plasma, or complement depleted serum (heated at 56 degrees C), incubated with neutrophils and the responses monitored with time. Measurement of the extent of neutrophil association with crystals was based on monitoring the decrease in fluorescence intensity of supernatants when crystals and diphenylhexatriene labelled neutrophils were allowed to settle under gravity. RESULTS: Precoating CPPD crystals with IgG, plasma, and serum significantly enhanced chemiluminescence, superoxide anion generation, increases in cytosolic free calcium levels, and non-cytolytic lysosomal enzyme release by neutrophils compared with uncoated CPPD crystals. The enhancement of neutrophil responses by crystals coated with complement depleted serum was less pronounced. The increased neutrophil responses induced by CPPD crystals coated with IgG might have been due to the observed increase in the association of IgG coated crystals with neutrophils. CONCLUSIONS: These data show that there is a marked potentiation of all neutrophil responses to IgG, plasma, and serum coated CPPD crystals. It is suggested that the adsorption of synovial fluid proteins, including IgG and C3b, to CPPD crystals in vivo, results in the opsonised crystals becoming a potent neutrophil stimulant and inflammatory agent.

Animals↗

PubMed1993

Crystal-induced protein tyrosine phosphorylation in neutrophils and the effect of a tyrosine kinase inhibitor on neutrophil responses.

A specific tyrosine kinase inhibitor, methyl 2,5-dihydroxycinnamate (mDHC), has been used to investigate the role of tyrosine kinases in monosodium urate monohydrate and calcium pyrophosphate dihydrate (CPPD) crystal-induced neutrophil activation. Both uncoated and plasma protein-coated CPPD crystals increased protein tyrosine phosphorylation in human neutrophils. Neutrophils pretreated with mDHC or control neutrophils were stimulated by plasma-opsonized CPPD, uncoated CPPD, or uncoated monosodium urate monohydrate, and chemiluminescence, superoxide generation, intracellular calcium concentration, degranulation (myeloperoxidase and lysozyme release), and protein tyrosine phosphorylation were monitored. mDHC strongly inhibited all neutrophil responses and tyrosine phosphorylation was reduced to the basal levels seen in control unstimulated neutrophils. The possible role of tyrosine kinases in the regulation of crystal-induced neutrophil activation is discussed.

Calcium↗

PubMed1991

Crystal-induced inflammation: studies of the mechanism of crystal-membrane interactions.

Studies of the interactions of monosodium urate monohydrate (MSUM) crystals and calcium pyrophosphate dihydrate triclinic (CPPD) crystals with biomembranes have been reviewed. Crystal-membrane binding and crystal-induced membranolysis have been studied using human erythrocytes as a model membrane system. The extent of MSUM-membrane binding was determined by incorporating a hydrophobic, fluorescent probe into the membranes, centrifugation to separate free membranes from membranes with bound crystals and quantitation of free membranes by measuring the total fluorescence intensity. The ability of MSUM and CPPD to hemolyse red cells was used as a measure of the membranolytic potential of the crystals. Fluorescence polarization studies showed that MSUM-membrane binding resulted in fluidization of the membrane. Cross-linking of the membrane proteins of the erythrocyte or the presence of divalent cations in the incubation medium inhibited MSUM induced hemolysis. These findings were explained by hypothesizing a "pore" model mechanism for MSUM induced membranolysis as follows. Binding of crystals to membranes induces the redistribution of transmembrane proteins into clusters or aggregates leading to "pore" formation. The "pores" permit the leakage of low molecular weight soluble compounds and ions acoss the membrane which is followed by osmotic rupture of the membrane.

Arthritis↗