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Biomedical subjects

C F Hall

Publications and source records attributed to C F Hall.

At least 19 recordsLinked to original sources
PubMed1999

Fc gamma receptor-mediated activation of phospholipase D regulates macrophage phagocytosis of IgG-opsonized particles.

Receptors for the Fc portion of IgG (Fc gamma Rs) integrate the innate and acquired components of immunity by coupling the specific recognition of IgG Abs to the activation of phagocytic leukocytes. Knowledge of the molecular mechanisms that regulate phagocyte stimulation by Fc gamma Rs may permit therapeutic modulation to augment immunoprotective aspects and minimize damage to host tissues in diverse inflammatory diseases. Since phospholipase D (PLD) has been linked to the stimulation of cytotoxic leukocyte responses, we characterized Fc gamma R-dependent activation of PLD in human macrophages. IgG-coated SRBCs (EIgG) stimulated a 9.4-fold increase in PLD activity compared with SRBCs treated with control Ab (p < 0. 001), determined by formation of the PLD-specific product phosphatidylethanol in the presence of 0.5% ethanol. Levels of phosphatidic acid, the physiologic product of PLD-mediated catalysis, were significantly increased in the absence of ethanol (6.4-fold, p < 0.001). PLD activity was also stimulated by immune complex-coated latex beads or cross-linking of Abs specific for Fc gamma RI, Fc gamma RII, or Fc gamma RIII. Phagocytosis of EIgG was reduced by two inhibitors of PLD-mediated signaling, 2,3-diphosphoglycerate or 1-butanol. Addition of purified PLD restored control levels of phagocytosis in cells in which endogenous PLD was inhibited. The tyrosine kinase inhibitors genistein and herbimycin A caused concordant reductions in Fc gamma R-stimulated PLD activity and phagocytosis. These studies demonstrate that Fc gamma R-mediated phagocytosis is accompanied by tyrosine kinase-dependent activation of PLD and support the hypothesis that stimulation of PLD functions to regulate the ingestion of IgG-opsonized particles.

Adult↗
PubMed1996

Activation of phospholipase D is tightly coupled to the phagocytosis of Mycobacterium tuberculosis or opsonized zymosan by human macrophages.

Phagocytosis of Mycobacterium tuberculosis by human mononuclear phagocytes is mediated primarily by complement receptors (CRs) but the transmembrane signaling mechanisms that regulate phagocytosis of the bacterium are unknown. We have analyzed the activation of phospholipase D (PLD) during phagocytosis of the virulent Erdman and attenuated H37Ra strains of M. tuberculosis by human monocyte-derived macrophages (MDMs), radiolabeled with [3H]-lyso-phosphatidylcholine. Phagocytosis of either Erdman or H37Ra M. tuberculosis in the presence of autologous non-immune serum was associated with a 2.5-3-fold increase in phosphatidic acid (PA). Definitive evidence for activation of PLD by M. tuberculosis was provided by markedly increased generation of the PLD-specific product phosphatidylethanol (PEt) (9.9-fold increases in [3H]-PEt for both Erdman and H37Ra strains compared to control, P < 0.001, n = 12), in the presence of 0.5% ethanol. Phagocytosis of opsonized zymosan (OZ), which is also mediated by CRs, was similarly associated with activation of PLD (12.2-fold increase in PEt, P < 0.001, n = 12). The competitive PLD inhibitor 2,3-diphosphoglycerate (2,3-DPG) produced concentration-dependent inhibition of PLD activity stimulated by either M. tuberculosis (-78 +/- 8%) or OZ (-73 +/- 6%). Inhibition of PLD by 2,3-DPG was associated with concentration-dependent reductions in phagocytosis of M. tuberculosis (-74 +/- 4%) and OZ (-68 +/- 5%). Addition of purified PLD from Streptomyces chromofuscus to 2,3-DPG-treated macrophages restored phagocytosis of M. tuberculosis to control levels. Inhibition of M. tuberculosis- or OZ-stimulated PA generation by ethanol was associated with concentration-dependent reductions in phagocytosis of both particles. Incubation of MDMs with either Erdman or H37Ra M. tuberculosis, or OZ, resulted in rapid (onset 1 min) and sustained (60 min) increases in the tyrosine phosphorylation (Tyr-P) of multiple MDM proteins. Prominent Tyr-P was noted in proteins of 150, 95, 72, 56, and 42 kD. The protein tyrosine kinase (PTK) inhibitors genistein and herbimycin A reduced M. tuberculosis-stimulated PLD activity by 66-84%. Inhibition of PLD activity by genistein or herbimycin A was associated with inhibition of phagocytosis of M. tuberculosis and OZ. These data demonstrate that PLD is activated during macrophage phagocytosis of M. tuberculosis or OZ, that PTKs are involved in this stimulation of PLD, and that the extent of phagocytosis of these particles is tightly coupled to activation of PLD.

2,3-Diphosphoglycerate↗
PubMed1981

Unusual disease conditions in pet and aviary birds.

Ninety percent ot 100% mortality in budgerigar (Melopsittacus undulatus) nestlings from 2 aviaries was attributed to giardiasis. Treatment with dimetridazole in drinking water was effective in controlling mortality. Aeromonas hydrophila infection incriminated in acute deaths of aviary canaries (Serinus canarius) was successfully treated with chlortetracycline. Aeromonas hydrophila also was isolated in pure culture from a toucan (ramphastos toco) with acute nephrosis and a cockatiel (Nymphicus hollandicus) with chlamydiosis (psittacosis). Coccidiosis associated with hemorrhagic enteritis, diarrhea, and mortality was diagnosed in budgerigars originating from 3 aviaries. Sporulated oocysts from 1 group of budgerigars were identified as Eimera sp. Sulfamethazine in drinking water was an effective treatment.

Aeromonas↗
PubMed1981

Bacterial coryza in turkeys in Texas.

A motile, gram-negative, short bacillus was isolated from the tracheas of turkey poults with coryza. An Escherichia coli also was isolated from the tracheas of poults. The former bacterium possessed characteristics similar or identical to those isolated from coryza outbreaks in other states. The characteristics were similar to those described for Alcaligenes fecalis. Cultures of the turkey coryza isolate produced coryza when inoculated intranasally in 1 to 3-day-old poults. The bacterium was reisolated consistently from the tracheas of the affected poults. In one experiment, poults inoculated with the coryza bacterium and the E. coli isolate had an apparent increased incidence of air sacculitis. No viruses were isolated from the tracheas of coryza-affected poults. Blood serums were negative for precipitating and hemagglutination-inhibition antibodies to avian influenza and Newcastle disease viruses, respectively. The serum neutralizing antibody titers to infectious bursal disease virus in noninoculated poults, and poults inoculated with the coryza bacterium, or E. coli or both, were undetectable or low. Serum agglutination was not a reliable method for determining infection by the coryza bacterium.

Alcaligenes↗
PubMed1975

Purification and concentration of viruses associated with transmissible (coronaviral) enteritis of turkeys (bluecomb).

Purification and concentration of viruses contained in pathogenic material was accomplished by sucrose density gradient centrifugation. Electron microscopy was also performed. Viruses recovered from intestinal preparations of both affected and unaffected turkey poults had a density of 1.16 to 1.17. The viruses resembled myxoviruses, paramyxoviruses, or oncornaviruses morphologically. In addition, preparations from bluecomb-affected poults were found to contain viruses indistinguishable from known coronaviruses. No such virus particles were seen in the control preparations. Data are presented to indicate an etiologic relationship between the coronavirus and transmissible enteritis of turkeys.

Animals↗
PubMed1972

Serologic response of turkeys to an agent associated with infectious enteritis (bluecomb).

The serologic response of turkey poults to an infectious enteritis (bluecomb disease) agent was analyzed. Serum samples collected from poults on post-inoculation days 3, 7, 14, and 21 were compared to serum from normal poults by electrophoresis and immunoelectrophoresis. Albumin concentrations were decreased whereas alpha and gamma globulins were increased during the disease. Qualitative and quantitative changes occurred in all migration zones.

Alpha-Globulins↗
PubMedDate not supplied

Experience with physiologic amputation using the CryoCare Extremity Stabilization System (CESS).

Five years of experience gained with the CryoCare Extremity Stabilization System (CESS) were evaluated in this study. Twenty-one patients underwent freezing amputation. Five patients died before undergoing surgical amputation. Symptomatic relief, control of odor, decreased demand on nursing staff, and appreciation of the family make this approach valuable even when long-term survival is not anticipated. Ten patients who underwent freezing amputation subsequently underwent surgical amputation and were discharged. Six patients underwent freezing and surgical amputation but died prior to discharge. The patients selected for the freezer application were deemed to be prohibitive operative risks because they were experiencing systemic toxicity from their ischemic limb and underlying diseases. Six patients demonstrated myoglobinuria prior to freezing which cleared with CESS. The physiologic amputation allowed stabilization of medical problems including cardiac arrhythmias, congestive heart failure, sepsis, renal failure, diabetes, and respiratory failure. Freezing of an ischemic extremity allows delay in amputation enabling physicians to achieve maximal medical stabilization. It permits symptomatic relief in patients whose long-term survival is not anticipated. Physiologic freezing amputation should be included in the repertoire of all surgeons.

Adult↗
PubMedDate not supplied

Experimental induction of hemorrhagic-aplastic anemia in chickens. II. Serum protein changes.

The serologic response of chickens to infectious bursal disease virus (IBDV) and inclusion body hepatitis virus (IBHV) was analyzed. Inoculation at one day old with either IBDV or IBHV significantly (P less than 0.05) reduced levels of serum gamma-globulins at 4 weeks postinoculation. This response was not elicited by inoculation of IBDV together with IBHV. Birds with experimentally induced or naturally occurring hemorrhagic anemia syndrome (HAS) had serum proteins quantitatively and qualitatively changed from those of controls. Serum protein profiles did not coincide, however, in experimentally infected and naturally infected chickens. Among naturally infected chickens, those that were IBHV-positive upon culture had significantly (P less than 0.05) lower hematocrit values.

Adenoviridae Infections↗
PubMedDate not supplied

Immunogenicity of an oil-emulsified Escherichia coli bacterin against heterologous challenge.

Immunogenicity of an oil-emulsified Escherichia coli bacterin against heterologous challenge was investigated. In Expts. 1 and 2, chickens were vaccinated with E. coli serotype O1 bacterin and challenged with E. coli serotype O2 (Expt. 1) and O78 (Expt. 2). Positive control chickens were not vaccinated but challenged with E. coli serotype O2 or O78; unvaccinated unchallenged chickens served as negative controls. When challenged with E. coli serotype O2, unvaccinated chickens showed a higher morbidity than vaccinated chickens. There was no mortality in either group. Although average gross lesion scores were generally higher in the unvaccinated chickens, they were not significantly different (P greater than or equal to 0.05) from those in the vaccinated chickens. In Expt. 2, morbidity was slightly higher in the unvaccinated challenged chickens. No mortality occurred in either group. There was no significant difference (P greater than or equal to 0.05) between vaccinated and unvaccinated chickens in average gross lesion scores. In general, E. coli recovery was higher in the unvaccinated challenged chickens, being highest in the air sacs followed by the liver, heart blood, and pericardial sacs. There was no morbidity, mortality, or gross lesions in the unvaccinated unchallenged chickens. No E. coli was recovered from the tissues cultured. The results of these laboratory trials revealed that an oilemulsified monovalent E. coli bacterin did not protect chickens against other E. coli serotypes associated with colibacillosis.

Animals↗