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W A Phillips

Publications and source records attributed to W A Phillips.

At least 19 recordsLinked to original sources
PubMed1992

Zymosan-triggered tyrosine phosphorylation in mouse bone-marrow-derived macrophages is enhanced by respiratory-burst priming agents.

We have investigated the relationship between tyrosine phosphorylation and respiratory-burst activity in mouse bone-marrow-derived macrophages (BMM). We demonstrate that zymosan, an agent known to trigger the macrophage respiratory burst, also triggers the activation of tyrosine kinase activity, resulting in rapid tyrosine phosphorylation on numerous proteins, and provide evidence for the role of tyrosine phosphorylation in the triggering of the BMM respiratory burst. Agents, such as tumour necrosis factor alpha (TNF alpha), interferon-gamma (IFN-gamma) or lipopolysaccharide (LPS), which prime the macrophage for an enhanced zymosan-triggered respiratory burst, increase tyrosine phosphorylation triggered by zymosan. The zymosan-triggered tyrosine phosphorylation and respiratory-burst activity were partially suppressed by the tyrosine kinase inhibitors alpha-cyano-3-ethoxy-4-hydroxy-5-phenylmethylcinnamide (ST638) and herbimycin A. In addition, pre-exposure of BMM to vanadate, a phosphotyrosine phosphatase inhibitor, greatly enhanced the ability of zymosan to induce tyrosine phosphorylation and trigger the respiratory burst. These data highlight the importance of the balance between tyrosine kinase and phosphotyrosine phosphatase activity in determining the ultimate level of tyrosine phosphorylation in BMM and suggest that zymosan-triggered tyrosine phosphorylation is an important biochemical signal for triggering of the respiratory burst.

Animals↗
PubMed1992

Priming of the respiratory burst of bone marrow-derived macrophages is associated with an increase in protein kinase C content.

The biochemical mechanism(s) underlying the priming of the macrophage for an enhanced PMA-induced respiratory burst is not understood. Because the cellular receptor for PMA is thought to be protein kinase C (PKC), we have investigated the effects of priming agents on cellular PKC levels. Sonicates from unprimed bone marrow-derived macrophages (BMM) were found to contain PKC activity (309 +/- 51 pmol 32P-incorporated/mg/min; mean +/- SE, n = 17) as measured by the phospholipid-, diacylglycerol-, and calcium-dependent phosphorylation of histone. Exposure of BMM to priming agents such as TNF-alpha, LPS, and granulocyte/macrophage-CSF resulted in a significant increase in both histone-phosphorylating activity and levels of immunoreactive PKC protein in these cells. A minimum of 6-h exposure, with an increasing effect up to 48 h, was required for a detectable increase in PKC level. The activity from primed BMM, like that of the untreated cells, was predominantly cytosolic. The kinetics and concentration dependence of the priming agent-induced increase in the PKC content of BMM closely paralleled the enhancing effects of these agents on the PMA-stimulated respiratory burst. Furthermore, CSF-1, a cytokine that does not prime BMM, failed to increase PKC activity. We propose that the exposure of BMM to priming agents leads to an increase in the expression of a stimulatory isozyme(s) of PKC, resulting in an enhanced ability to mount a respiratory burst in response to stimulation with PMA.

Animals↗
PubMed1992

The effect of interleukin-4 on the macrophage respiratory burst is species dependent.

Preexposure of human monocytes to recombinant human interleukin-4 (IL-4) suppressed the respiratory burst response to a number of different stimuli, including phorbol myristate acetate, zymosan, platelet-activating factor and the chemotactic peptide, f-met-leu-phe. Under similar conditions, the respiratory burst of murine macrophages was enhanced by preexposure to recombinant murine IL-4. By conducting our studies on cells from different species under similar conditions we have demonstrated that there is a significant disparity in the effects of IL-4 on human and murine macrophages thus providing an explanation for some apparent inconsistencies in the literature and highlighting the need for caution when extrapolating data across species barriers.

Animals↗
PubMed1992

Protein kinase C has both stimulatory and suppressive effects on macrophage superoxide production.

Unlike resident peritoneal macrophages (RPM) or tumor necrosis factor alpha (TNF alpha)-primed bone marrow-derived macrophages (BMM), unprimed BMM do not generate superoxide in response to the protein kinase C (PKC) activator, phorbol myristate acetate (PMA). However, these cells do contain significant levels of PKC activity. In contrast to PMA, zymosan induces the generation of superoxide in unprimed BMM, as well as in TNF alpha-primed BMM and RPM. Staurosporine, a potent PKC inhibitor, failed to affect the zymosan-induced production of superoxide by unprimed and TNF alpha-primed BMM and RPM, in spite of substantial inhibition of PMA-induced superoxide production by the primed BMM and RPM. However, when PKC was depleted from unprimed BMM by prolonged (24 h) treatment with phorbol dibutyrate (PdBt) (10(-7) M) the ability of zymosan to induce the production of superoxide was greatly diminished. Such a result could be interpreted as suggesting a role for PKC in the zymosan-induced response, a conclusion which contrasts with the inhibitor data. However, PKC depletion, in this case, is achieved via the PdBt-induced activation of PKC. It is thus possible that it is the initial activation of PKC, rather than its depletion, that suppresses superoxide production. Consistent with this interpretation, the co-stimulation of unprimed BMM with both zymosan and PMA resulted in a reduced superoxide release compared to zymosan alone. The activation of PKC therefore appears to have a suppressive effect on the generation of superoxide by unprimed cells. We thus conclude that PKC is not required for zymosan-induced superoxide production by either primed or unprimed macrophages and suggest that PKC may be involved in regulatory mechanisms restricting superoxide production by macrophages. However, since PMA alone can initiate the release of superoxide from primed BMM and RPM, it would appear that PKC can mediate both stimulatory and suppressive signals for macrophage superoxide production.

Alkaloids↗
PubMed1992

Effect of initial restraint, weaning, and transport stress on baseline and ACTH-stimulated cortisol responses in beef calves of different genotypes.

The productivity and well-being of animals can be substantially affected by stress. This is particularly true in the case of beef calves that are subjected to a multitude of stressors over a short period during the first year of life. Perhaps the most often studied stress-responsive variable has been blood corticosteroid concentrations. Factors such as age, gender, genetics, and degree of prior experience, can influence how an animal perceives and responds to a given stressor. Few studies have tried to control these variables, and accordingly, many conflicting results have been published regarding the impact of various stressors on cortisol response. We measured baseline plasma cortisol concentration over a 44-day study in Bos indicus and Bos taurus calves. Plasma cortisol values in Bos indicus calves were higher (32.60 +/- 0.66 ng/ml) than values in calves of Bos taurus (25.81 +/- 0.76) breeding. A precipitous decrease in cortisol concentration was observed 7 days after transport stress in all calves. Baseline cortisol concentration did not provide any indication of the intensity of the various stressors. However, significant differences were readily observed after ACTH administration. On the basis of cortisol secretion, stresses of transport and weaning were similar and were the most stressful to calves, regardless of genotype.

Adrenocorticotropic Hormone↗
PubMed1992

Lipopolysaccharide- and interferon-gamma-induced expression of hck and lyn tyrosine kinases in murine bone marrow-derived macrophages.

We have examined the role of tyrosine phosphorylation during the course of macrophage activation. Initial experiments indicated that vanadate, a known phosphotyrosine phosphatase inhibitor, enhanced the phorbol 12-myristate 13-acetate (PMA)-triggered respiratory burst and potentiated the priming effects of bacterial lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma), suggesting that tyrosine phosphorylation may be important in these end cell functions. As src-related kinases have been implicated in the activation of cells of other haemopoietic lineages, we examined the relationship between the activity of two such kinases, hck and lyn, and priming of the respiratory burst. We found that the level of hck and lyn is increased following exposure of bone marrow-derived macrophages (BMM) to LPS or IFN-gamma. The induction of both of these kinases follows similar kinetics with maximal activity occurring at 24-48 h. Interestingly, the kinetics of induction of hck and lyn kinase activity in BMM demonstrated a close temporal relationship with the priming effects of LPS and IFN-gamma on the macrophage respiratory burst. Collectively, these observations raise the possibility that modulation of expression of hck and lyn is involved in the regulation of the respiratory burst.

Animals↗
PubMed1991

Protein kinase C isotypes and signaling in neutrophils. Differential substrate specificities of a translocatable calcium- and phospholipid-dependent beta-protein kinase C and a phospholipid-dependent protein kinase which is inhibited by long chain fatty acyl coenzyme A.

Neutrophils possess a classical Ca2+, phosphatidyl serine (PS) and diglyceride (DG)-dependent protein kinase C (beta-PKC) which was translocatable from cytosol to membrane in response to elevated Ca2+ in the physiologic range or to pretreatment with phorbol myristate acetate (PMA). The translocatable beta-PKC was purified from neutrophil membranes prepared in the presence of Ca2+, eluted with EGTA and subjected to hydroxyapatite chromatography. An 80-kDa protein possessing Ca/DG/PS-dependent histone phosphorylating activity was recognized by a monoclonal antibody to beta-PKC but not to alpha-PKC or gamma-PKC. A cytosolic kinase activity remaining after Ca(2+)-induced translocation of beta-PKC was dependent on PS and DG but did not require Ca2+. This novel Ca(2+)-independent, PS/DG-dependent kinase, termed nPKC, eluted from hydroxyapatite between alpha-PKC and beta-PKC, ran as a 76-kDa band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and was reactive to a polyclonal consensus antibody but not to monoclonal antibodies to alpha-PKC, beta-PKC, or gamma-PKC. Long chain fatty acyl-CoA, but not the corresponding free fatty acids, inhibited nPKC in the 1-10 microM range. The chemotactic peptide fMet-Leu-Phe triggered prompt but transient increases in neutrophil long chain fatty acid acyl-CoA, suggesting that nPKC is regulated by fatty acyl-CoA as well as DG during neutrophil activation. Purified beta-PKC phosphorylated a number of cytosolic proteins in a Ca(2+)-dependent manner, including a major 47-kDa cytosolic protein, which may be implicated in superoxide anion generation. In contrast, nPKC did not phosphorylate the 47-kDa protein, but phosphorylated numerous cytosolic proteins in a Ca(2+)-independent manner, including a 66-kDa protein which was not phosphorylated by beta-PKC. Differences in location, substrate specificity, and cofactor dependence between nPKC and beta-PKC suggest these kinases may play selective roles in the activation sequence of the neutrophil.

Acyl Coenzyme A↗
PubMed1991

Fusion of the upper cervical spine in children and adolescents. An analysis of 17 patients.

A retrospective review of 17 immature patients who underwent posterior spinal fusion of C1-C2 or C1-C3 was performed to establish the efficacy of the procedure, to determine the incidence of complications, and to identify those at high risk for complications. All had radiographic C1-C2 instability or dislocation. Etiologies included os odontoideum, fixed rotatory subluxation, atlantoaxial subluxation, type II dens fracture nonunion, and nonunion of a Hangman's fracture. Before surgery, 10 patients were neurologically intact, and seven had neurologic findings. Associated diagnosis included Down's syndrome in three and Ehler-Danhlos in one. Follow-up averaged 25 months. One neurologically intact patient had a C2 radiculopathy that resolved by 1 year. Three patients with Down's syndrome had complications: one with a preoperative Brown-Sequard syndrome had transient worsening in the immediate postoperative period, one with a preoperative myelopathy developed a late recurrence of a severe myelopathy that required odontectomy, and another sustained an intraoperative spinal cord contusion followed by postoperative quadriplegia and death due to respiratory failure. Of seven reporting neurologic symptoms before surgery, two had residual deficit in the late postoperative period. These two represented preventable technical errors. There were two nonunions, one of which required occiput to C2 fusion. In general, posterior spinal fusion of the upper cervical spine was found to be a reliable, safe, and predictable procedure, but extra caution should be employed when considering arthrodesis in patients with ongoing spinal cord compression, fixed dislocations, and inherited ligamentous laxity.

Adolescent↗
PubMed1991

Complications of fusion to the upper cervical spine.

Forty-seven operations for posterior fusion of the upper cervical spine were reviewed for complications. Alarmingly, only 11 patients had an entirely uncomplicated course. Most complications were minor, but there were four nonunions, one requiring reoperation. Although seven patients had increased neurologic deficits after surgery, only one was permanent. There was one death due to technical error. Patients with significant instability, myelopathy, prior failed fusions, or unreducible dislocations are at high risk for perioperative neurologic complications.

Adult↗
PubMed1991

Energy and protein supplementation of ammoniated wheat straw diets for growing steers.

Eighty-eight yearling beef steers (308 +/- 1.4 kg) were used in two separate trials to determine the protein-sparing value of the N added to wheat straw during the ammoniation process and to determine the effects of supplementing ammoniated straw diets with energy and ruminal escape protein. In Exp. 1, steers were fed untreated straw (US) with either 0, 150, or 500 g of soybean meal (SBM) for 88 d. The addition of SBM to US diets increased (P less than .01) straw intake and average daily gains (ADG), indicating that N was limiting. When ammoniated straw (AS) was substituted for US, the N in the AS was used as efficiently as 500 g of SBM for growth. In Exp. 2, steers had ad libitum access to AS with three levels of supplemental corn (0, 1.23, or 2.45 kg DM.animal-1.d-1) either with or without .41 kg DM of corn gluten meal (CGM) added. Straw intake decreased (P less than .01) as the amount of corn in the diet was increased, but ADG increased (P less than .01) with the addition of corn. Straw consumption was not altered by the addition of CGM, but ADG was increased (P less than .01) by an average .35 kg by CGM. Rumen and blood N components indicated that the N from AS was contributing to the ruminal N pool and that CGM was compensating for microbial protein deficiencies postruminally.

Ammonia↗
PubMed1991

The effect of fasting, transit plus fasting, and administration of adrenocorticotropic hormone on the source and amount of weight lost by feeder steers of different ages.

Two trials (winter and summer) were conducted to determine effects of fasting and transportation and adrenocorticotropic hormone (ACTH) administration on the amount and source of weight lost by feeder steers. Sixteen steers, in each of two experiments, were adapted to metabolism stalls for 10 d, were fed medium-quality hay at 2.1% of BW for 3 d, and then were subjected to either fasting alone or fasting plus transit for 48 h. In Exp. 1 steers were randomly assigned to treatments. In Exp. 2 steers were blocked by age (OLD or YOUNG) and assigned to treatments. Fecal and urinary excretions accounted for 65 and 38% of the total weight lost in Exp. 1 and 2, respectively. Fasting plus transit did not consistently increase the amount of weight lost compared with fasting alone but increased (P less than .01) plasma glucose concentrations. Injection of ACTH before either fasting alone or fasting plus transit increased (P less than .05) the amount of weight lost as feces. Steers in the OLD group lost more weight during transit and fasting but regained the lost weight faster (P less than .01) during the recovery period than did steers in the YOUNG group. Injecting YOUNG steers with ACTH before fasting alone or fasting plus transit increased plasma fibrinogen (P less than .10) and serum glucose (P less than .05) concentrations more than ACTH injections in OLD steers. Although fasting and transit elicit mobilization of body nutrients and resulted in a loss of BW, these effects were quickly reversed during the poststress period.

Adrenocorticotropic Hormone↗
PubMed1991

Effect of pre- and postweaning management system on the performance on Brahman crossbred feeder calves.

During a 3-yr period (1986 through 1988), 117 calves (57 steers and 60 heifers) from the same genetic base and reared under four distinct preweaning management systems were weaned in the fall and transported from Uvalde, TX to El Reno, OK (800 km). Weaning weight and transportation shrink varied more from year to year than among preweaning treatments. Postweaning performance was not affected by preweaning treatment. After a 28- to 32-d receiving period the calves were blocked by sex and previous preweaning treatment, then randomly assigned within block to graze winter wheat forage (WHEAT) or dormant tall-grass native range (GRASS). The WHEAT group gained more (P less than .01) weight than the GRASS group during the winter (November to March), but when both groups were allowed to graze spring wheat pasture (March to June) the GRASS group gained more (P less than .01) weight than the WHEAT calves. During the subsequent finishing phase the GRASS calves were more (P less than .01) efficient than the WHEAT calves in converting DM to gain. Because cattle were slaughtered at the same degree of finish, no differences were noted in carcass characteristics among the pre- or postweaning treatments. Feeder calves exposed to a restrictive period of growth during the postweaning period gained weight more rapidly in a subsequent forage-based stockering system and were more efficient in a grain-based finishing system than nonrestricted calves.

Animal Feed↗
PubMed1991

Familial cervical dysplasia.

Nine of twelve family members from three generations were affected by an inherited form of cervical vertebral dysplasia. All of the affected people had an abnormality of the first cervical vertebra. Some also had defects of the axis and caudad to it. The mode of transmission of the disorder is autosomal dominant, with apparently complete penetrance and variable expressivity. Two patients had symptoms. One had a passively correctable tilt of the head, with an associated audible clunk and hypoplasia of the left superior facet of the second cervical vertebra. This patient had no local symptoms, neurological involvement, or muscle spasm. In the other patient, suboccipital pain developed. Radiographs revealed an anterior atlanto-occipital dislocation. The symptoms resolved after reduction and arthrodesis. Because of the apparently complete penetrance of this disorder, physicians caring for patients who have this type of congenital malformation of the cervical spine should consider examination of closely related members of the family. Clinical findings such as tilting of the head, torticollis, or limitation of cervical motion suggest that additional evaluation should be done. The examination should include lateral radiographs of the cervical spine in flexion and extension. Three-dimensional computed-tomography reformatting was helpful in demonstrating the complex cervical anatomy in our patients. Patients who have recognized abnormalities should be followed and should be re-examined whenever local or neurological symptoms develop. A magnetic resonance image of the spine in flexion and extension was valuable for identification of the potentially disastrous situation of impending damage to the cord in patients who had instability and evolving symptoms.

Adult↗
PubMed1990

Colony stimulating factor-1 is a negative regulator of the macrophage respiratory burst.

Several cytokines have previously been shown to prime macrophages for enhanced release of oxygen radicals in response to subsequent stimulation. We now demonstrate that the presence of the macrophage-specific colony stimulating factor-1 (CSF-1) inhibits the priming of murine macrophages by a variety of agents including tumor necrosis factor alpha, granulocyte/macrophage colony stimulating factor, interferon-gamma, and bacterial lipopolysaccharide. CSF-1 is also able to reduce the respiratory burst in the absence of priming. Our results indicate that CSF-1 is a potent negative regulator of the macrophage respiratory burst which acts to oppose the priming (enhancing) action of macrophage activating agents. We propose that CSF-1 may have a potentially important and previously unrecognized, role as a physiological regulator which restricts or terminates the activation of macrophages in order to prevent an uncontrolled inflammatory reaction.

Animals↗
PubMed1990

Priming the macrophage respiratory burst with IL-4: enhancement with TNF-alpha but inhibition by IFN-gamma.

Pre-exposure to bacterial lipopolysaccharide (LPS) or certain cytokines is known to enhance the ability of murine macrophages to generate a respiratory burst in response to subsequent stimulation, a phenomenon referred to as 'priming'. We report here that the cytokine interleukin-4 (IL-4) can prime murine macrophages. Pretreatment of murine bone marrow-derived macrophages (BMM) with 10 U/ml murine IL-4 for 48 hr was found to enhance the respiratory burst following subsequent stimulation with phorbol myristate acetate (PMA) (10(-6) M) or zymosan (1 mg/ml). Human tumour necrosis factor-alpha (TNF-alpha) (10(-9) M) can also prime BMM for an enhanced respiratory burst and the combination of TNF-alpha and IL-4 resulted in an enhanced (greater than additive) priming effect. In contrast, interferon-gamma (IFN-gamma) (100 U/ml), although by itself capable of priming the BMM respiratory burst, was found to antagonize the priming effects of IL-4. These results demonstrate that IL-4 can be added to the growing list of cytokines capable of modulating the respiratory burst response of macrophages, suggesting a possible role for this cytokine in inflammation and in the host response to infection. The opposing effects of TNF-alpha and IFN-gamma when interacting with IL-4 highlight the difficulties in predicting the effect of a given cytokine in vivo, where potential interactions with other cytokines must be considered.

Animals↗
PubMed1989

Influence of calcium on the subcellular distribution of protein kinase C in human neutrophils. Extraction conditions determine partitioning of histone-phosphorylating activity and immunoreactivity between cytosol and particulate fractions.

Activation of the neutrophil respiratory burst is thought to involve a translocation and activation of protein kinase C. We report that the presence of Ca2+ during the disruption of unstimulated human neutrophils and cytoplasts resulted in an increase in protein kinase C activity (histone phosphorylation) and immunoreactive protein kinase C species in the particulate (membrane) fraction and a reduction in such activities in the cytosol. This Ca2+-induced translocation of activity was concentration-dependent and occurred at physiologically relevant concentrations of Ca2+ (30-500 nM). The Ca2+-induced membrane association of protein kinase C could be reversed by removal of Ca2+. These findings indicate that the Ca2+ concentration of the extraction buffer can determine the subcellular distribution of protein kinase C in disrupted cells and suggest that the observed location of this enzyme activity in cell fractions may not necessarily reflect the localization in intact cells. These results also raise the possibility that the distribution of protein kinase C between cytosol and membrane is a dynamic equilibrium controlled by levels of free Ca2+. Thus, Ca2+ might regulate distribution as well as activation of protein kinase C.

Biological Transport↗
PubMed1989

Phorbol ester-stimulated superoxide production by murine bone marrow-derived macrophages requires preexposure to cytokines.

Murine resident peritoneal macrophages (RPM) generate superoxide (O2-) in response to stimulation with PMA or zymosan. Murine bone marrow-derived macrophages (BMM) generate O2- in response to zymosan but not PMA. However, the ability to generate O2- in response to PMA could be induced in BMM by pre-exposing the cells to certain cytokines, including granulocyte-macrophage CSF (GM-CSF), tumor necrosis factor-alpha (TNF-alpha), IFN-gamma, and, to a lesser extent, IL-1 alpha. Bacterial LPS also induced the ability to respond to PMA. These same agents were also shown to prime RPM for enhanced PMA-induced respiratory burst. In contrast to GM-CSF, CSF-1 did not enhance the ability of BMM or RPM to generate O2- in response to PMA. Pretreatment with GM-CSF or TNF-alpha did not significantly affect the zymosan-induced release of O2- by BMM. These results suggest that unprimed BMM have a deficiency in the PMA-dependent signaling pathway that is corrected by exposure to selected cytokines. The results also raise the possibility that the basal ability of tissue macrophages to generate a respiratory burst in response to PMA may be a reflection of in vivo exposure to cytokines.

Animals↗