Contractile proteins in leukocytes.
Explore the source record for details and available documents.
Actin Cytoskeleton↗
Biomedical subjects
F S Southwick
Publications and source records attributed to F S Southwick.
Neutrophil actin dysfunction is a genetic disorder associated with partial impairment of neutrophil actin assembly in three family members.
A male infant with a severe neutrophil motility disorder and poorly polymerizable actin in PMN extracts was reported over a decade ago to have neutrophil actin dysfunction (NAD) (1974. N. Engl. J. Med. 291:1093-1099). Polymerized actin (F-actin) content of fixed and permeabilized intact neutrophils from the father, mother, and sister of the NAD index case have been measured using nitrobenzoxadiazole-phallacidin, a fluorescent compound which binds specifically to actin filaments. F-actin content of unstimulated PMN from all three family members was significantly lower than unstimulated control PMN (mean 23.6 +/- 0.4 SEM fluorescent units vs. 32.6 +/- 0.6 for controls). After stimulation with the chemotactic peptide FMLP, maximal F-actin content of NAD family member PMN was below that of controls (52.7 +/- 1.3 vs. 72.6 +/- 1.8). F-actin content of detergent insoluble cytoskeletons after stimulation with FMLP was also significantly lower in PMN from NAD family members as compared with controls (21 +/- 6% vs. 73 +/- 8%). PMN extracts from the father and mother, when treated with 0.6 M KCl, polymerized half as much actin as controls. Whereas diisopropylfluorophosphate treatment of normal PMN decreased actin polymerizability in cell extracts, this treatment increased the assembly of actin in parental PMN extract. Addition of purified actin to NAD extracts failed to reveal an abnormal actin polymerization inhibitory activity, and no obvious structural defect in actin purified from the father's PMNs was noted by HPLC and two dimensional thin layer chromatography of tryptic digests. The present studies of actin assembly in intact PMNs confirm that NAD is associated with a true defect in PMN actin assembly and is a genetic disorder that is recessively inherited.
Actins↗
Platelet-activating factor both stimulates and "primes" human polymorphonuclear leukocyte actin filament assembly.
The phospholipid inflammatory mediator, platelet-activating factor (PAF), can stimulate polymorphonuclear leukocyte (PMN) chemotaxis. Conversion of cytoplasmic actin from monomers to filaments is associated with PMN motile functions. Using the fluorescent actin filament stain nitrobenzodiaxole phallicidin, we have investigated PAF's effects on human PMN actin polymerization. Concentrations of PAF between 1 x 10(-11) to 1 x 10(-6) mol/L induced actin filament (F-actin) assembly. An optimal concentration of PAF (1-5 x 10(-8) mol/L) induced a significantly lower rise in relative F-actin content (1.72 +/- 0.07 SEM) than an optimal concentration (5 x 10(-7) mol/L) of the chemotactic peptide FMLP (2.21 +/- 0.06). Unlike FMLP (F-actin content: 1.25 +/- 0.04 at five seconds), PAF stimulation was associated with a delay of more than five seconds (1.04 +/- 0.01 at five seconds) before an increase in F-actin could be detected. F-actin concentration reached maximum levels by 30 to 60 seconds. Prolonged stimulation (20 minutes) with PAF was associated with two phases of polymerization and depolymerization. Like FMLP, the initiation of actin filament assembly by PAF required receptor occupancy, this reaction being totally blocked by the PAF receptor inhibitor, SKI 63-441. As evidenced by the lack of inhibition by nordihydroguaiaretic acid (5 to 20 mumol/L), the production of leukotriene B4 was not required for the PAF-induced changes in F-actin. Like FMLP, PAF's ability to stimulate PMN actin polymerization was inhibited by pertussis toxin (.05 to 2.5 micrograms/mL) but not impaired by the addition of EGTA and/or the calcium ionophore A23187. Preincubation with 1 x 10(-11) to 1 x 10(-8) mol/L PAF for 2 to 60 minutes enhanced the rise in F-actin content induced by low concentrations of FMLP (5 x 10(-12) to 1 x 10(-10) mol/L) indicating that this phospholipid was capable of "priming" the PMN actin polymerization response.
Actin Cytoskeleton↗
Rabbit alveolar macrophages contain a Ca2+-sensitive, 41,000-dalton protein which reversibly blocks the "barbed" ends of actin filaments but does not sever them.
A 41,000-dalton Ca2+-sensitive actin-modulating protein has been purified from rabbit alveolar macrophages using ion exchange and gel filtration chromatography. On sodium dodecyl-polyacrylamide gel electrophoresis, this macrophage protein migrates more rapidly than actin and fails to cross-react with polyclonal anti-actin antibody. It has a Stokes radius of 3.0 nm and an isoelectric point of 6.6. In the presence of micromolar Ca2+ this 41,000-Da protein: reduces the viscosity of polymerized actin, nucleates actin filament assembly, causes a nearly instantaneous increase in fluorescence intensity of subcritical concentrations of pyrenyl-actin (estimated KD of the pyrene actin-macrophage protein complex, 5 X 10(-8) M), increases the critical concentration of actin by 0.65 microM (molar ratios of protein/actin, 1/100-1/10), blocks actin monomer depolymerization from the "barbed" filament ends, and does not sever preformed actin filaments. The ability of this protein to block filament ends is rapidly and completely inhibited by lowering free calcium ion concentration below the micromolar range.
Actins↗
Septic thrombosis of the dural venous sinuses.
From 1940 to 1984, 19 cases of septic dural-sinus thrombosis have been diagnosed at the Massachusetts General Hospital, and some 136 cases have been reported from other institutions. Septic thrombosis most frequently involves the cavernous sinuses (96 cases). Facial or sphenoid air sinus infection often precede cavernous-sinus disease. In addition to the classical signs of proptosis, chemosis, and oculomotor paralysis, isolated sixth-nerve palsy and hypo- or hyperesthesia of the fifth nerve may be found. The major pathogens associated with cavernous-sinus infection include Staphylococcus aureus, other gram-positive organisms, and anaerobes. Septic lateral-sinus thrombosis (64 cases) is almost exclusively a complication of otitis media and/or mastoid infection. Organisms causing this infection include Proteus species, Escherichia coli, S. aureus, and anaerobes. Septic thrombosis of the superior sagittal sinus (23 cases) most frequently accompanies bacterial meningitis or air sinus infection. Causative organisms include Streptococcus pneumoniae, S. aureus, other streptococci, and Klebsiella species. Because septic dural-sinus thrombosis is rare, this disease is frequently misdiagnosed. Evaluation should include lumbar puncture, air sinus films, and computed tomographic scan with contrast. Other helpful diagnostic tests may include carotid angiography, and dynamic brain scan. Orbital venography is the most definitive study in cases of chronic cavernous-sinus thrombosis. Therapy should include intravenous antibiotics and early surgical drainage of purulent exudate in the air sinuses or mastoid regions. Retrospective analysis suggests that treatment with heparin may reduce mortality in carefully selected cases of septic cavernous-sinus thrombosis. Anticoagulation is not recommended in other forms of septic dural-sinus thrombosis. Mortality in the antibiotic-era remains high, particularly in patients with septic thrombosis of the cavernous (30%) and superior sagittal (78%) sinuses.
Adolescent↗
Effects of macrophage profilin on actin in the presence and absence of acumentin and gelsolin.
We purified profilin from rabbit alveolar macrophages and documented its structural and functional similarity to profilins isolated from other cells. The KD for formation of the macrophage profilin-actin complex was 3.0 +/- 0.8 microM (mean +/- S.D.). The affinity of this protein for actin did not change significantly in the presence of various concentrations of KCl and MgCl2, profilin-actin complex concentration being strictly dependent on the critical actin monomer concentration and free profilin concentration. We also examined profilin's interactions with actin in the presence of acumentin, a macrophage protein which inhibits actin monomer exchange at the "pointed" ends of actin filaments. Low concentrations of this protein caused substantial decreases in estimated profilin-actin complex concentration. The macrophage gelsolincalcium ion complex which blocks exchange at the "barbed" end of actin filaments, when added to profilin and actin solutions in substoichiometric concentrations, caused large increases in estimated profilin-actin complex concentration. The changes in calculated profilin-actin complex concentration induced by these two actin-modulating proteins were too large to be explained solely by their effects on critical actin monomer concentration.
Actins↗
Nonmuscle actin-binding proteins.
Explore the source record for details and available documents.
Actin Cytoskeleton↗
An analogue of the erythroid membrane skeletal protein 4.1 in nonerythroid cells.
Protein 4.1 is a crucial component of the erythrocyte membrane skeleton. Responsible for the amplification of the spectrin-actin interaction, its presence is required for the maintenance of erythrocyte integrity. We have demonstrated a 4.1-like protein in nonerythroid cells. An antibody was raised to erythrocyte protein 4.1 purified by KCl extraction (Tyler, J. M., W. R. Hargreaves, and D. Branton, 1979, Proc. Natl. Acad. Sci. USA, 76:5192-5196), and used to identify a serologically cross-reactive protein in polymorphonuclear leukocytes, platelets, and lymphoid cells. The cross-reactive protein(s) were localized to various regions of the cells by immunofluorescence microscopy. Quantitative adsorption studies indicated that at least 30-60% of the anti-4.1 antibodies reacted with this protein, demonstrating significant homology between the erythroid and nonerythroid species. A homologous peptide doublet was observed on immunopeptide maps, although there was not complete identity between the two proteins. When compared with erythrocyte protein 4.1, the nonerythroid protein(s) displayed a lower molecular weight--68,000 as compared with 78,000-and did not bind spectrin or the nonerythroid actin-binding protein filamin. There was no detectable cross-reactivity between human acumentin or human tropomyosin-binding protein, which are similarly sized actin-associated proteins, and erythrocyte protein 4.1. The possible origin and significance of 4.1-related protein(s) in nonerythroid cells are discussed.
Antigen-Antibody Complex↗
The motor of leukocytes.
The movements of leukocytes involve extension, flow, and contraction of a margin of organelle-excluding cytoplasm. Actin is the principal structural component of this region. This paper reviews evidence that the expansion of cortical cytoplasm can result from the growth of actin polymers into an orthogonal network in which actin fibers branch perpendicularly under the influence of actin-binding protein. Flow occurs when actin filaments are disassembled and severed. The assembly and fragmentation of actin are regulated by actin-modulating proteins such as profilin, which sequesters actin monomers, acumentin, which binds to the slow-growing end of actin fibers, and gelsolin, a calcium-regulated protein that binds to the fast-growing end of actin polymers and severs actin filaments. Contraction of the actin network is caused by myosin, the assembly and activity of which are regulated by its state of phosphorylation, which is in turn controlled by phosphorylating and dephosphorylating enzymes and by calmodulin and calcium. Present information leads to the prediction that intracellular calcium gradients guide cytoplasmic movement and that the direction of actin assembly and therefore of cytoplasmic extension is toward regions of low cytoplasmic free calcium.
Actins↗
Sphenoid sinusitis. A review of 30 cases.
We studied 30 patients with infectious sphenoid sinusitis (15 acute cases and 15 chronic cases) in an effort to characterize the clinical presentation, bacteriology, and associated complications of this frequently misdiagnosed infection. Severe frontal, temporal, or retro-orbital headache that radiated to the occipital regions or pain in the trigeminal (V1 to V3) distribution or both were the most prominent presenting symptoms. In acute cases, purulent exudate was frequently seen in the middle and superior nasal turbinates. Computerized axial tomography or sinus tomography and cannulation of the sphenoid sinus proved to be the most useful diagnostic studies. Organisms detected in acute cases included streptococci other than Streptococcus pneumoniae (41 per cent), Staphylococcus aureus (29 per cent), and Str. pneumoniae (17 per cent). In chronic infections, gram-negative bacilli (43 per cent) and staphylococcal species (24 per cent) were the predominant organisms. In acute disease, early diagnosis and aggressive therapy, including surgical drainage, were important. Delay in treatment was always associated with serious morbidity or mortality. Fatal complications included cavernous sinus thrombosis and bacterial meningitis.
Anti-Bacterial Agents↗
Contractile proteins in leukocyte function.
Explore the source record for details and available documents.
Actins↗
Acumentin, an actin-modulating protein of rabbit pulmonary macrophages.
An actin-modulating protein has been purified from rabbit alveolar macrophages utilizing DEAE-Sepharose and gel filtration chromatography. The purified protein which we have named acumentin is similar in structure and function to a protein found in human granulocytes [Southwick, F.S., & Stossel, T.P. (1981) J. Biol. Chem. 256, 3030-3036] and has a Stokes radius of 34 A and s20,w of 4.02 S, consistent with a globular protein with a native molecular weight of 63 500. Acumentin has a molecular weight of 65 000 as determined by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. This protein is present in high concentrations in macrophages, representing about 6% of the total protein in cytoplasmic extracts. Acumentin caps the pointed end of actin filaments labeled with heavy meromyosin [Southwick, F.S., & Hartwig, J.H. (1982) Nature (London) 297, 303-307], thereby decreasing the final viscosity of monomeric actin polymerized in its presence without detectably increasing the critical monomer concentration. The activity of this protein is inhibited by KCl concentrations above 0.1 M and is completely inactive at a KCl concentration of 0.3 M. Acumentin's function is equivalent in the presence or absence of CaCl2. The presence of such a calcium-insensitive capping protein in both the human granulocyte and rabbit alveolar macrophage suggests acumentin may be of general importance in constitutively maintaining a shortened actin filament length distribution in the cytoplasm of the nonmuscle cell.
Actins↗
Acumentin, a protein in macrophages which caps the "pointed" end of action filaments.
Macrophages have a calcium-insensitive protein which binds to and inhibits monomer addition at the "pointed" end of actin filaments labelled with heavy meromyosin. This protein, in concert with calcium-sensitive proteins already shown to bind the "barbed" end of filaments, can lead to complete control of actin filament length in the cytoplasm. The blocking of actin filament ends in low as well as high calcium concentrations would prevent treadmilling in living cells.
Actins↗
A variant of chronic granulomatous disease: deficient oxidative metabolism due to a low-affinity NADPH oxidase.
Explore the source record for details and available documents.
Adult↗
Isolation of an inhibitor of actin polymerization from human polymorphonuclear leukocytes.
A large proportion of actin in extracts of human polymorphonuclear leukocytes is unpolymerized in the presence of 0.1 M KCl, a condition expected to promote maximal assembly of purified actin. Raising of the KCl concentration increases the extent of actin polymerization in leukocyte extracts, and, at KCl concentrations greater than or equal to 0.3 M, the polymer concentration is maximal and approaches that of purified muscle actin in 0.1 M KCl solution. After removal of the actin polymers from leukocyte extracts made 0.6 M in KCl, the supernatant fluid contains an activity which inhibits the extent of assembly of purified skeletal muscle actin in 0.1 M KCl solution. We have purified this activity by ion exchange and gel filtration chromatography. The purified inhibitor contains polypeptides of 65,000 and 62,000 daltons in a molar ratio of 1:2 as determined by polyacrylamide gel electrophoresis in dodecyl sulfate. The Stokes radius of 32 A, and S20,w of 4.8 of the native inhibitor suggest that the purified protein is a mixture of monomers of slightly different molecular weight. Substoichiometric concentrations of the inhibitor rapidly prevent the assembly of purified actin in 0.1 m KCl solution in a concentration-dependent manner, and the reduction in final viscosity remains constant over time. Raising the KCl concentration reverses the inhibition, as observed for actin polymerization in unfractionated extracts. The findings are consistent with the conclusion that this inhibitor protein is responsible for the large proportion of unpolymerized actin in extracts of polymorphonuclear leukocytes.
Actin Depolymerizing Factors↗
An inherited abnormality of neutrophil adhesion. Its genetic transmission and its association with a missing protein.
Neutrophils from a five-year-old boy with recurrent bacterial infections failed to spread on surfaces, leading to a severe defect in chemotaxis and a mild impairment in phagocytosis. Failure to spread was also seen in a fraction of the neutrophils from the patient's mother and sister, but cells from his father and brother were normal. Gel electrophoresis revealed that a protein with a molecular weight of 110,000 daltons (designated gp 110) present in the particulate fraction of normal neutrophils was absent from the patient's cells, and that its levels were below normal in cells from his mother and sister but normal in neutrophils from his father and brother. These findings suggest that gp 110 is necessary for the spreading of neutrophils onto surfaces, that the functional abnormality in the patient's cells is caused by its absence, and that deficiency of gp 110 is an X-linked congenital disease.
Blood Proteins↗
Recovery after prolonged asystolic cardiac arrest in profound hypothermia. A case report and literature review.
Asystole can be the presenting ECG finding of accidental hypothermia when the core temperature is less than 28 degrees C. Even two hours of persistent asystole does not represent irreversible cardiac compromise. With cardiopulmonary support and active rewarming, resuscitation and survival without serious sequelae can be achieved. Case reports and electrophysiology studies suggest that asystole is a primary manifestation of hypothermia potentiated by carbon dioxide retention. However, ventricular fibrillation in this setting is probably a secondary complication of resuscitation efforts, being precipitated by hypocapnic alkalosis, physical manipulation of the heart, and rewarming.
Accidents, Home↗
Hemophilus influenzae in hospitalized adults: current perspectives.
In an eight year period 16 cases of serious extrapulmonary Hemophilus influenzae infection in adults were identified, including cases of meningitis, pericarditis, epiglottitis, empyema, cellulitis, osteomyelitis, endometritis, urinary tract infection, orbital cellulitis, primary peritonitis, mesenteric lymphadenitis and aortic graft infection. An 18 month prospective study of H. influenzae infection in hospitalized adults identified 10 cases of bronchitis, 25 of pneumonia and 65 of respiratory tract colonization, but there were no extrapulmonary infections. In 29 percent of the respiratory tract infections, H. influenzae appeared to be a nosocomial pathogen; in 71 percent, the infection was mixed. Finally, 110 clinical isolates of H. influenzae were studied for antimicrobial susceptibility. Eight percent were ampicillin resistant, two strains were resistant to tetracycline and one to chloramphenicol, but all were susceptible to trimethoprim-sulfamethoxazole and cefamandole.
Adolescent↗