Mechanisms of anti-influenza activity of surfactant proteins A and D: comparison with serum collectins

The present study provides the first direct comparison of anti-influenza A virus (IAV) activities of the collectins surfactant protein (SP) A and SP-D, mannose-binding lectin (MBL), and conglutinin. SP-D, MBL, and conglutinin inhibited IAV hemagglutination activity with a greater potency than and by a distinct mechanism from SP-A. Although isolated trimeric SP-D carbohydrate recognition domains inhibited hemagglutination activity, preparations of SP-D also containing the collagen domain and NH2 terminus caused greater inhibition. In contrast to SP-A (or nonmultimerized SP-D), absence of the N-linked attachment did not effect interactions of multimerized SP-D with IAV. SP-D, SP-A, and conglutinin caused viral precipitation through formation of massive viral aggregates, whereas MBL formed aggregates of smaller size that did not precipitate. All of the collectins enhanced IAV binding to neutrophils; however, in the case of MBL, this effect was modest compared with the binding enhancement induced by SP-D or conglutinin. These studies clarify the structural requirements for viral inhibition by SP-D and reveal significant differences in the mechanisms of anti-IAV activity among the collectins.

Effects of glucocorticoid therapy on urine protein-to-creatinine ratios and renal morphology in dogs

Glomerulonephritis has been associated with exogenous glucocorticoid administration and spontaneous hyperadrenocorticism in the dog. The purpose of this study was to determine the effects of long-term glucocorticoid therapy on urine protein:creatinine ratios (UP/Cs) and renal morphology. Nine young-adult male dogs were determined to be healthy and have normal renal function as assessed by physical examination, CBC, serum biochemistry analysis, Knott's test for Dirofilaria immitis, urinalysis, urine culture, urine protein electrophoresis, endogenous creatinine clearance, 24-hour urinary protein excretion, and UP/C. Prednisone was administered to each dog at a dosage of 2.2 mg/kg PO bid for 42 days. Urinalysis and UP/C were performed on days 0, 7, 14, 21, 28, and 42 of treatment. Mean UP/C on day 0 was 0.29 +/- 0.10. Mean UP/C increased progressively to a maximum of 1.27 +/- 1.02 on day 28. Mean UP/C on day 42 decreased slightly (0.92 +/- 0.56) but remained significantly increased above baseline. The most consistent renal light microscopic finding on necropsy examination was generalized hypercellular glomerular tufts, suggestive of mesangial cell proliferation. Four dogs also had occasional adhesions of glomerular tufts to Bowman's capsule, accompanied by thickening of the capsule. Direct immunofluorescence for immunoglobulin deposition was negative in all dogs. Electron microscopy, evaluated in 7 dogs, was characterized by occasional mild segmental thickening of basement membranes, fusion of visceral cell foot processes, and glomerular adhesions. The results of this study indicate that long-term administration of glucocorticoids results in significant proteinuria and glomerular changes in the dog.

Malignant mast cell tumor in an African hedgehog (Atelerix albiventris)

In November 1995, a malignant mast cell tumor (mastocytoma) was diagnosed in an adult African hedgehog (Atelerix albiventris) from a zoological park (West Lafayette, Indiana, USA). The primary mast cell tumor presented as a firm subcutaneous mass along the ventrum of the neck. Metastasis to the right submandibular lymph node occurred.

Nephrotoxicity of amphotericin B administered to dogs in a fat emulsion versus five percent dextrose solution

OBJECTIVE

To determine whether administration of amphotericin B in a fat emulsion solution would reduce the nephrotoxicity of amphotericin B, compared with that associated with administration of amphotericin B in 5% dextrose solution.

DESIGN

Prospective controlled study.

ANIMALS

2 groups of 5 adult male Beagles.

PROCEDURE

Dogs received amphotericin B (1 mg/kg of body weight/d) prepared in 5% dextrose solution or in 20% fat emulsion daily for 6 doses. Serum biochemical analysis, CBC, urinalysis, and endogenous creatinine clearance was performed on days 0 and 8, 2 days after the last dose of amphotericin B. On day 8, dogs were euthanatized and gross necropsies were performed. Unbiased semiquantitative scoring of the kidneys for the degree of injury was performed by use of light microscopy.

RESULTS

There were no significant differences in serum creatinine, urea nitrogen, or potassium concentrations, urine specific gravity, endogenous creatinine clearance, or degree of tubulo-interstitial injury between the 2 groups.

CONCLUSION

In this model, the degree of nephrotoxicity of amphotericin B was not significantly different for dogs receiving the drug in a fat emulsion versus its administration in 5% dextrose.

Neutrophil deactivation by influenza A viruses: mechanisms of protection after viral opsonization with collectins and hemagglutination-inhibiting antibodies

Bacterial superinfections are a major cause of morbidity and mortality during influenza A virus (IAV) epidemics. Depression of phagocyte functions resulting from attachment of the IAV hemagglutinin (HA) to cell surface sialo-glycoproteins is a likely contributory cause of these infections. We have proposed that the group of collagenous lectins (termed collectins) present in blood and pulmonary surfactant play a role in initial host defense against IAV. We used here several recombinant human surfactant protein D (RhSP-D) preparations to determine the mechanism through which opsonization of IAV with collectins protects neutrophils against the deactivating effects of IAV on cellular respiratory burst responses in vitro. RhSP-D was markedly more potent than antibodies that inhibited viral hemagglutination activity (anti-HA antibodies) at protecting neutrophils in this assay. Unlike the anti-HA antibodies, RhSP-D was protective at concentrations that minimally inhibited viral hemagglutination activity. Two related features of SP-D--the degree of multimerization and the ability to cause aggregation of IAV particles--were critical determinants of the ability of SP-D to protect neutrophils against deactivation. Similarly SP-D-induced viral aggregate formation resulted in enhanced IAV binding to neutrophils and potentiated the ability of the virus itself to trigger neutrophil respiratory burst responses. In contrast to the case of IAV-antibody complexes, SP-D-IAV complexes attached to and activated neutrophils through a neuraminidase-sensitive mechanism (ie, similar to unopsonized IAV). These results indicate that collectin-mediated viral aggregation per se may be an important host defense mechanism not only by virtue of reducing the number of infectious viral particles, but also by promoting phagocyte responsiveness.

Visceral mycosis in Chinook salmon (Oncorhynchus tschawytscha) due to Sporobolomyces salmonicolor

One-month-old Chinook salmon fry from a cold-water hatchery were presented live for euthanasia and necropsy. Gross lesions were emaciation in 90% of the fry and ascites and increased cutaneous pigmentation in the remaining 10%. A cause for the emaciation was not determined. Histologically, the fry with ascites and increased pigmentation had visceral mycosis with aerocystitis, myositis, peritonitis, and dermatitis. Sporobolomyces salmonicolor, a rare human pathogen, was isolated and identified in tissue sections from affected fry.

Comparison of diagnostic tests for bacterial kidney disease in juvenile steelhead trout (Oncorhynchus mykiss)

In order to accurately diagnose bacterial kidney disease caused by Renibacterium salmoninarum in steelhead trout, kidney tissue from experimentally infected fish was evaluated using a commercially available enzyme-linked immunosorbent assay (ELISA) test kit, fluorescent antibody (FA) testing, bacteriologic culture, and histopathology. Seventy-five steelhead trout were randomly assigned to 1 of 4 groups and intraperitoneally inoculated with 0.15 ml saline (n = 20), 1 x 10(10) organisms/ml (n = 18), 1 x 10(8) organisms/ml (n = 18), or 1 x 10(6) organisms/ml (n = 19) of R. salmoninarum. ELISA, FA and bacteriologic culture were positive for R. salmoninarum from the kidney tissue of the 2 groups infected with the highest doses. Although the ELISA and FA tests were accurate when compared to the bacteriologic culture from the 2 groups infected with higher doses of the organism, they were less sensitive at the lowest level of inoculum. Histopathology was not specific for this disease; however, all infected fish had a marked proliferative histiocytic interstitial nephritis, characterized by marked expansion of the renal hematopoietic tissue by histiocytes without tissue necrosis. Other microscopic findings included splenitis and myositis (at the injection site) of some fish.

Involvement of MAP kinase in insulin signalling revealed by non-invasive imaging of luciferase gene expression in single living cells

BACKGROUND

Studies of the mechanisms by which signals are transmitted from receptor tyrosine kinases would be facilitated by a way of monitoring events at the single-cell level. We have explored how luciferase imaging can be used to examine the role of specific signalling pathways in insulin-stimulated gene expression. The analysis of luciferase expression in single cells has previously been hampered by the insensitivity of existing methodologies and the lack of a way of monitoring quantitatively, and independently, more than one promoter within the same cell. We have developed a technique for examining the dynamics of insulin-stimulated AP-1-dependent transcription in single living cells, and have explored the signalling pathway involved.

RESULTS

Luciferase and aequorin gene expression were examined in single living cells with a high-sensitivity photon-counting camera. The technique involved the comicroinjection of luciferase- and aequorin-based reporter plasmids directly into the cell nucleus, and the subsequent analysis of luminescence in the presence of luciferin and coelenterazine, respectively. The method is quantitative and allows insulin-stimulated gene expression to be monitored in real time. We found that insulin promoted a substantial increase in the expression of a luciferase gene under the control of the AP-1-binding site from the collagenase gene promoter. Aequorin expression, under the control of a cytomegalovirus promoter, was unaffected by insulin. The effect of insulin on luciferase expression was specifically blocked by overexpression of either the mitogen-activated protein (MAP) kinase phosphatase CL100, or the dominant-negative mutant MAP kinase kinase, MEKS217/221A.

CONCLUSIONS

Microinjection coupled with luciferase imaging allows hormone-regulated gene expression from relatively weak promoters to be monitored in single living cells. We have used this method to demonstrate that MAP kinase plays a central role in the ability of insulin to stimulate AP-1-dependent gene transcription.

Needs of hospice and clinic patients with cancer

The purposes of this descriptive study were: (1) to compare the self-selected needs of 69 patients with cancer, 31 from a nonprofit hospice, and 38 from a university cancer center located in the mid-south; and (2) to establish the reliability of the Cancer Patient Need Survey for hospice patients. Patients completed the Cancer Patient Need Survey and a demographic data form. Hospice and clinic patients rated the category of coping needs most important. Clinic patients also ranked the category of information needs as a priority, but did not find these needs as well met. Both groups ranked as their top individual needs support from family and friends, and a patient caregiver. Reliabilities of the instrument for the groups range from 0.91 to 0.93. The Cancer Patient Need Survey is a useful instrument for assessing and testing the needs of clinic patients, but additional work needs to be done in modifying the instrument for use with hospice patients.

Neutrophil deactivation by influenza A virus. Role of hemagglutinin binding to specific sialic acid-bearing cellular proteins

Bacterial superinfections are the most common cause of mortality during influenza epidemics. Depression of phagocyte functions by influenza A viruses (IAVs) is a likely contributory cause of such infections. We used an in vitro model of viral depression of neutrophil respiratory burst responses to FMLP and PMA to examine the mechanism of IAV-induced phagocyte deactivation. Respiratory burst responses or intracellular calcium mobilization were triggered by the virus itself, but these were not causally related to deactivation. By treating neutrophils with neuraminidase, and by use of purified IAV hemagglutinin (HA) preparations, cross-linking of sialic acid-bearing neutrophil surface components by the IAV HA was shown to be responsible for deactivation. IAV competed for binding to neutrophils with Abs directed against CD43, sialyl-Le(x), CD45, and gangliosides. Deactivation could be reproduced by treating neutrophils with anti-CD43 or -sialyl-Le(x) Abs in the absence of IAV. However, treatment of neutrophils with elastase markedly reduced CD43 expression, without affecting overall IAV binding or the ability of IAV to cause deactivation. Hence, although IAV binding to CD43 can account for deactivation, other IAV-binding proteins exist (e.g., those bearing sialyl-Le(x)) that can independently mediate functional depression.

Neutrophil deactivation by influenza A virus. Role of hemagglutinin binding to specific sialic acid-bearing cellular proteins

Bacterial superinfections are the most common cause of mortality during influenza epidemics. Depression of phagocyte functions by influenza A viruses (IAVs) is a likely contributory cause of such infections. We used an in vitro model of viral depression of neutrophil respiratory burst responses to FMLP and PMA to examine the mechanism of IAV-induced phagocyte deactivation. Respiratory burst responses or intracellular calcium mobilization were triggered by the virus itself, but these were not causally related to deactivation. By treating neutrophils with neuraminidase, and by use of purified IAV hemagglutinin (HA) preparations, cross-linking of sialic acid-bearing neutrophil surface components by the IAV HA was shown to be responsible for deactivation. IAV competed for binding to neutrophils with Abs directed against CD43, sialyl-Le(x), CD45, and gangliosides. Deactivation could be reproduced by treating neutrophils with anti-CD43 or -sialyl-Le(x) Abs in the absence of IAV. However, treatment of neutrophils with elastase markedly reduced CD43 expression, without affecting overall IAV binding or the ability of IAV to cause deactivation. Hence, although IAV binding to CD43 can account for deactivation, other IAV-binding proteins exist (e.g., those bearing sialyl-Le(x)) that can independently mediate functional depression.

Search for life on Mars: evaluation of techniques

An important question for exobiology is, did life evolve on Mars? To answer this question, experiments must be conducted on the martian surface. Given current mission constraints on mass, power, and volume, these experiments can only be performed using proposed analytical techniques such as: electron microscopy, X-ray fluorescence, X-ray diffraction, alpha-proton backscatter, gamma-ray spectrometry, differential thermal analysis, differential scanning calorimetry, pyrolysis gas chromatography, mass spectrometry, and specific element detectors. Using prepared test samples consisting of 1% organic matter (bovine serum albumin) in palagonite and a mixture of palagonite, clays, iron oxides, and evaporites, it was determined that a combination of X-ray diffraction and differential thermal analysis coupled with gas chromatography provides the best insight into the chemistry, mineralogy, and geological history of the samples.

Real-time analysis of the transcriptional regulation of HIV and hCMV promoters in single mammalian cells

The regulation of human cytomegalovirus (hCMV) and human immunodeficiency virus (HIV) gene expression has been studied in single intact mammalian cells. Viral promoters were placed upstream of the firefly luciferase reporter gene and the resulting hybrid reporter constructs were stably integrated into the HeLa cell genome. A highly sensitive photon-counting camera system was used to study the level of gene expression in single intact cells. Luciferase expression was studied in the absence of activators of viral gene expression, in the presence of the HIV-1 TAT transactivator protein, or in the presence of sodium butyrate, a non-viral activator of gene expression. In the absence of any activator of gene expression, while expression was undetectable in most cells, significant levels of basal luciferase activity were observed in a few cells, indicating heterogeneity in gene expression in the cell population. In the presence of the general activator of viral gene expression, sodium butyrate, transcriptional activation from the viral promoters gave rise to significant and relatively homogeneous levels of luciferase expression in a majority of cells. The luciferase imaging technology was used for the real-time analysis of changes of gene expression within a single cell. This non-invasive reporter assay should become important for studies of the temporal regulation of gene expression in single cells.

Intron-less RNA injected into the nucleus of Xenopus oocytes accesses a regulated translation control pathway

The translation of a capped, polyadenylated RNA after injection into the nucleus of Xenopus oocytes occurs only if the RNA contains an intron. A single point mutation in the splice donor site prevents translation. Intron-less RNA is exported efficiently to the cytoplasm and is held, undegraded, in a translationally inert state for several days. Translation can be activated by treating the oocytes with progesterone or by injecting antibodies that bind the FRGY2 class of messenger RNA binding proteins, p56 and p60, but these antibodies are only effective if delivered to the nucleus. Inhibitors of casein kinase II also activate translation whereas phosphatase inhibitors block progesterone-mediated activation of translation. These data suggest the presence of an RNA handling pathway in the nucleus of Xenopus oocytes which is regulated by casein kinase type II phosphorylation and which directs transcripts to be sequestered by p56/p60 or by closely related proteins. This pathway can be bypassed if the RNA contains an intron and it can be reversed by progesterone treatment. These data may have implications for understanding translational control during early development.

Giant cell variant of malignant fibrous histiocytoma in dogs: 10 cases (1986-1993)

Signalment, tumor sites, clinicopathologic, radiographic, and ultrasonographic features, as well as treatment protocols and survival information, were evaluated for 10 dogs with a histologic diagnosis of giant cell variant of malignant fibrous histiocytoma. Common clinical findings included subcutaneous masses, weight loss, anorexia, and lethargy. Laboratory abnormalities included anemia, hypoalbuminemia, and high concentrations of serum hepatic enzymes. Radiography and ultrasonography were useful in staging the extent of metastasis. Seven dogs had tumor metastasis at the time of diagnosis. Two other dogs developed evidence of metastasis during the course of treatment. The most common sites of tumor involvement were subcutaneous tissues, lymph nodes, liver, and lungs. Treatment protocols included surgical resection, intraoperative radiotherapy, and chemotherapy. Median survival time of all dogs was 61 days. Median survival time of the 6 treated dogs was 161 days. Findings on necropsy revealed metastasis with multiple organ involvement. The giant cell variant of malignant fibrous histiocytoma was determined to be a highly metastatic neoplasm in dogs, which may be responsive to surgical excision, chemotherapy, or radiotherapy.

Interferon-alpha enhances neutrophil respiratory burst responses to stimulation with influenza A virus and FMLP

Despite increasing therapeutic use of interferon (IFN)-alpha, its effects on human neutrophil function are not well characterized. In vitro preincubation of neutrophils with recombinant IFN-alpha and -gamma, tumor necrosis factor (TNF), or granulocyte-macrophage colony-stimulating factor (GM-CSF) enhanced neutrophil respiratory burst responses to stimulation with influenza A virus (IAV) and FMLP. The enhancing effects of IFNs were more subtle and required more prolonged incubation than those of TNF and GM-CSF. TNF and GM-CSF enhanced neutrophil binding of IAV and neutrophil intracellular calcium and membrane depolarization responses to IAV or FMLP stimulation, while IFNs did not. Inhibitors of neutrophil tyrosine kinase activation and protein synthesis blocked IFN-alpha-induced enhancement of respiratory burst responses. In addition to its other well-characterized effects, IFN-alpha may protect against viral infection indirectly by promoting neutrophil respiratory burst responses.

Dietary choline requirement of juvenile hybrid striped bass

Two experiments were conducted to estimate the dietary choline requirement and to determine the effects of dietary choline on liver lipid deposition in juvenile hybrid striped bass (Monrone saxatilis x M. chrysops). Experimental diets contained 0.73 g total sulfur amino acids/100 g diet (0.47 g methionine + 0.26 g cyst(e)ine/100 g diet), thus meeting, but not exceeding, the requirement. Graded levels of choline bitartrate in Experiment 1 and choline chloride in Experiment 2 were added to the basal diet, resulting in eight dietary treatments in each experiment. Dietary treatments were 0, 250, 500, 1000, 2000, 4000, 6000 and 8000 mg choline/kg dry diet. Diets were fed for 12 and 10 wk in Experiments 1 and 2, respectively. Dietary choline concentrations significantly affected weight gain, feed efficiency, survival and total liver lipid concentrations in each experiment. Weight gain and feed efficiency were greatest in fish fed 500 mg choline/kg dry diet as choline bitartrate. Total liver lipid concentrations were variable but tended to be lowest in fish fed diets containing at least 2000 mg choline/kg diet. Survival was significantly lower in the group of fish fed 8000 mg choline/kg diet supplied by choline bitartrate. Weight gain and feed efficiency were greatest and total liver lipid concentration was lowest in groups of fish fed at least 500 mg choline/kg diet as choline chloride; survival was unaffected by dietary treatment. Therefore, choline chloride seems to be a better source of dietary choline than choline bitartrate and 500 mg choline/kg diet is adequate for maximum weight gain and prevention of increased liver lipid concentration in juvenile hybrid striped bass.

Human neutrophil respiratory burst response to influenza A virus occurs at an intracellular location

We have studied in detail the in vitro interactions of influenza A viruses (IAVs) with human neutrophils to clarify why these cells become dysfunctional during IAV infection. Unosponized IAV elicited a respiratory burst response in neutrophils which, like that triggered by formylmethionyl-leucyl-phenylalanine (fMLP), involved mediation of signal-transducing GTP-binding proteins and tyrosine kinase activation. The IAV-induced response differed from that provoked by fMLP in that H2O2 was produced without concomitant O2- release. IAV also did not cause extracellular release of granule enzymes in cytochalasin B-treated neutrophils. Using chemiluminescence assays, the respiratory burst response to IAV was found to occur at an intracellular location. These findings may, in part, explain the anomalous nature of the respiratory burst response elicited by IAV and suggest strategies for determining the mechanism of IAV-induced neutrophil deactivation.

Evidence for a protective role of pulmonary surfactant protein D (SP-D) against influenza A viruses

We tested the hypothesis that pulmonary surfactant-associated lectins--surfactant proteins A and D (SP-A, and -D)--contribute to initial protective mechanisms against influenza A viruses (IAVs). SP-D potently inhibited hemagglutination activity of several strains of IAV as well as causing viral aggregation. SP-D enhanced neutrophil binding of IAV and neutrophil respiratory burst responses to the virus. Neutrophil dysfunction resulting from IAV exposure was diminished when the virus was pre-incubated with SP-D. Each of these effects was mediated by the calcium-dependent carbohydrate-binding property of SP-D. Native SP-D preparations of both human and rat origin, as well as recombinant rat SP-D, had similar activity. SP-A also inhibited IAV hemagglutination activity. We have previously reported that related mammalian serum lectins (mannose-binding lectin [MBL] and conglutinin) have similar effects. SP-D was at least 10-fold more potent at causing hemagglutination inhibition than were SP-A or MBL. SP-D was shown to contribute to potent anti-IAV activity of human bronchoalveolar lavage fluid. These results suggest that SP-D--alone, and in conjunction with SP-A and phagocytic cells--constitutes an important component of the natural immune response to IAV infection within the respiratory tract.

Metabolic activity of microorganisms in evaporites

Crystalline salt is generally considered so hostile to most forms of life that it has been used for centuries as a preservative. Here, we present evidence that prokaryotes inhabiting a natural evaporite crust of halite and gypsum are metabolically active while inside the evaporite for at least 10 months. In situ measurements demonstrated that some of these "endoevaporitic" microorganisms (probably the cyanobacterium Synechococcus Nageli) fixed carbon and nitrogen. Denitrification was not observed. Our results quantified the slow microbial activity that can occur in salt crystals. Implications of this study include the possibility that microorganisms found in ancient evaporite deposits may have been part of an evaporite community.

Evaluation of an orally administered vaccine, using hydrogels containing bacterial exotoxins of Pasteurella haemolytica, in cattle

Poly(methacrylic acid) hydrogels were tested for oral delivery of a vaccine against Pasteurella haemolytica infection in cattle. Culture supernatants of P haemolytica, the most common bacterium associated with pneumonia in cattle, were used as the antigens in the vaccine. Hydrogels containing culture supernatants were administered orally to calves. Calves were then challenge-exposed with virulent P haemolytica. Calves were euthanatized 3 days after challenge exposure. The lungs of each calf were scored for severity and size of pneumonic lesions. Results indicated that vaccinated calves had smaller, less severe pneumonic lesions and lived longer than nonvaccinated calves. These results indicated that hydrogels can be used to deliver vaccines orally to calves to enhance resistance to pneumonia caused by P haemolytica.

Conglutinin acts as an opsonin for influenza A viruses

Since the 1940's, non-Ig inhibitors of influenza A virus (IAV) hemagglutination activity and infectivity have been recognized in mammalian sera. Recently, the heat labile (beta) inhibitor of this type was identified by indirect methods as the lectin, conglutinin. In support of this hypothesis, we found that purified conglutinin strongly inhibited hemagglutination activity and infectivity of IAV. By using IAV strains with specific variations in glycosylation of the hemagglutinin molecule, we showed these effects to be mediated by binding of conglutinin to high mannose carbohydrate attachments on the viral hemagglutinin. Through the same mechanism conglutinin caused aggregation of IAV particles. Human neutrophils produce hydrogen peroxide upon exposure to IAV. Also, after a brief period of exposure to IAV, neutrophils exhibit depressed responsiveness (deactivation) upon exposure to other stimuli (e.g., chemotactic peptides). These phenomena may be related to the in vivo inflammatory response during IAV infection, and to the propensity of IAV-infected subjects to suffer bacterial superinfection. Pre-incubation of IAV with conglutinin markedly potentiated human neutrophil hydrogen peroxide production in response to the virus. This effect correlated with the ability of conglutinin to aggregate the virus. IAV treated with conglutinin also caused significantly less neutrophil deactivation than did the unopsonized virus. These enhancements of neutrophil respiratory burst responses by conglutinin were again mediated by binding of the lectin to viral carbohydrates. The mammalian C-type lectin family includes conglutinin, mannose-binding protein, and surfactant proteins A and D. These lectins may be important constituents of the initial host response to IAV, by inhibiting IAV infectivity directly, causing viral aggregation, and acting as opsonins to enhance phagocyte responses to the virus.

Conglutinin acts as an opsonin for influenza A viruses

Since the 1940's, non-Ig inhibitors of influenza A virus (IAV) hemagglutination activity and infectivity have been recognized in mammalian sera. Recently, the heat labile (beta) inhibitor of this type was identified by indirect methods as the lectin, conglutinin. In support of this hypothesis, we found that purified conglutinin strongly inhibited hemagglutination activity and infectivity of IAV. By using IAV strains with specific variations in glycosylation of the hemagglutinin molecule, we showed these effects to be mediated by binding of conglutinin to high mannose carbohydrate attachments on the viral hemagglutinin. Through the same mechanism conglutinin caused aggregation of IAV particles. Human neutrophils produce hydrogen peroxide upon exposure to IAV. Also, after a brief period of exposure to IAV, neutrophils exhibit depressed responsiveness (deactivation) upon exposure to other stimuli (e.g., chemotactic peptides). These phenomena may be related to the in vivo inflammatory response during IAV infection, and to the propensity of IAV-infected subjects to suffer bacterial superinfection. Pre-incubation of IAV with conglutinin markedly potentiated human neutrophil hydrogen peroxide production in response to the virus. This effect correlated with the ability of conglutinin to aggregate the virus. IAV treated with conglutinin also caused significantly less neutrophil deactivation than did the unopsonized virus. These enhancements of neutrophil respiratory burst responses by conglutinin were again mediated by binding of the lectin to viral carbohydrates. The mammalian C-type lectin family includes conglutinin, mannose-binding protein, and surfactant proteins A and D. These lectins may be important constituents of the initial host response to IAV, by inhibiting IAV infectivity directly, causing viral aggregation, and acting as opsonins to enhance phagocyte responses to the virus.

Human mannose-binding protein functions as an opsonin for influenza A viruses

Influenza A viruses (IAVs) cause substantial morbidity and mortality in yearly epidemics, which result from the ability of the virus to alter the antigenicity of its envelope proteins. Despite the rapid replication of this virus and its ability to infect a wide variety of cell types, viremia is rare and the infection is generally limited to the upper respiratory tract. The preimmune host defense response against IAV is generally, therefore, successful. We have previously provided (and summarized) evidence that neutrophils contribute to defense against IAV, although neutrophil dysfunction and local tissue damage may be less salutory byproducts of this response. Here we provide evidence that the serum lectin mannose-binding protein directly inhibits hemagglutinin activity and infectivity of several strains of IAV. In addition mannose-binding protein acts as an opsonin, enhancing neutrophil reactivity against IAV. Opsonization of IAV by mannose-binding protein also protects the neutrophil from IAV-induced dysfunction. These effects are observed with physiologically relevant concentrations of mannose-binding protein. Two different allelic forms of recombinant mannose-binding protein are found to have similar effects. We believe, on the basis of these data, that mannose-binding protein alone and in conjunction with phagocytic cells is an important constituent of natural immunity (i.e., preimmune defense) against IAV.

Influenza A virus binding to human neutrophils and cross-linking requirements for activation

Although neutrophils are not viewed as a principal defense against influenza A virus (IAV) infection, their interactions are both complex and clinically relevant. Activation of the neutrophil is distinctive from that described for chemoattractants. To more fully characterize the pathway by which IAV stimulates the human neutrophil, we have examined its binding characteristics. First, inhibition studies with various sialic acid-containing and sialic-free sugars showed that IAV binds to sialic acid residues and activates receptors distinct from those used by Concanavalin-A (Con-A) and formyl-methionyl-leucyl-phenylalanine (FMLP) and that overlap those bound by wheat germ agglutinin (WGA). That viral hemagglutinin (HA) mediates viral binding and activation was shown by preincubating neutrophils with purified monovalent bromelain-released HA (BHA) and showing that IAV-induced membrane depolarization and hydrogen peroxide (H2O2) production were inhibited approximately 95%. However, binding inhibition required significantly higher concentrations of purified HA, suggesting that binding and cell activation have different interactive requirements. Desialation of the neutrophil surface membrane by neuraminidase treatment resulted in a 90.6% +/- 4.4% and 53.1% +/- 8.7% inhibition of IAV activation of neutrophils and viral binding, respectively. Resialation with ganglioside GT1b totally restored viral binding, but did not reverse the inhibition of activation. Thus, although HA was shown to mediate binding and neutrophil activation, viral binding per se was insufficient to stimulate the cell. Having demonstrated the functional role of HA, we sought to establish the mechanism of stimulation. HA in three different forms (BHA, HA-rosettes, and HA-liposomes) failed to activate the cell, although H2O2 production evoked by IAV stimulation was reduced in competitive inhibition studies with each preparation. Upon cross-linking with a monoclonal antibody to HA, activation comparable to that of intact virus was observed. The requirement for cross-linking of functional receptors, as opposed to activation through the neutrophil Fc receptor, was confirmed in experiments using staphylococcal A protein. These studies have shown the chemical specificity of IAV binding to the human neutrophil, the character of the receptor(s) stimulated to activate the IAV-evoked response, and the activation requirement for cross-linking those receptors responsible for stimulating functional responses.

Upper respiratory disease in deployed U.S. Navy shipboard personnel

A study was conducted to determine the risk of upper respiratory disease among deployed U.S. Navy shipboard personnel. Between January and June 1989, a Patient Encounter Form was used to collect disease information from 10 U.S. Navy ships. Patients with a diagnosis of upper respiratory infection (URI) on initial sick-call visit were used in this study. Information on time spent in various ports and time at sea for each of the 10 ships was also collected. A classification scheme was developed to permit daily estimates of URI rates and to indicate whether the ship was in port or at sea. Of 967 cases of URI, 64.4% occurred while at sea, with an average daily rate of 0.5/1,000 crew members; 35.4% of the cases occurred while in port, with an average daily rate of 0.4/1,000 crew members. There was an increase in URI rates after 9 days at sea or in port. These data suggest that there are defined periods of increased transmission of upper respiratory infections aboard ships, both at sea and in port.

Regional limb perfusion for antibiotic treatment of experimentally induced septic arthritis

Septic arthritis was induced in one antebrachiocarpal joint of seven horses by the intra-articular injection of 1 mL Staphylococcus aureus suspension containing a mean of 10(5) colony-forming units. Twenty-four hours after inoculation, four horses were treated by regional perfusion with 1 g of gentamicin sulfate, and three horses received 2.2 mg/kg gentamicin sulfate intravenously (IV) every 6 hours. Synovial fluid was collected for culture and cytology at regular intervals, and the synovial membranes were collected for culture and histologic examination at euthanasia 24 hours after the first treatment. Gentamicin concentration in the septic synovial fluid after three successful perfusions was 221.2 +/- 71.4 (SD) micrograms/mL; after gentamicin IV, it was 7.6 +/- 1.6 (SD) micrograms/mL. The mean leukocyte count in the inoculated joints decreased significantly by hour 24 in the successfully perfused joints. Terminal bacterial cultures of synovial fluid and synovial membranes were negative in two horses with successfully perfused joints. S. aureus was isolated from the infected joints in all three horses treated with gentamicin IV.

Regional perfusion of the equine carpus for antibiotic delivery

Regional perfusion of carpal tissues by forced intramedullary administration of fluids was evaluated in 10 horses. Results of subtraction radiography after perfusion with a contrast medium demonstrated that perfusate was delivered to the carpal tissues by the venous system. Perfused India ink was distributed uniformly in the antebrachiocarpal and middle carpal synovial membranes. Histologically, the ink was within the venules of the synovial villi. Immediately after perfusion with gentamicin sulfate (1 g), the gentamicin concentrations in the synovial fluid and synovial membrane of the antebrachiocarpal joint were 349 +/- 240 micrograms/mL and 358 +/- 264 micrograms/g, respectively. When gentamicin concentrations in the synovial fluid of the antebrachiocarpal joint and serum were measured 0, 0.5, 1, 4, 8, 12, and 24 hours after carpal perfusion, the mean peak gentamicin concentration in the synovial fluid was 589 +/- 429 micrograms/mL. At hour 24, the mean gentamicin concentration in the synovial fluid was 4.8 +/- 2.0 micrograms/mL. The resulting peak gentamicin concentration in the serum was 23.7 +/- 14.5 micrograms/mL immediately after the perfusion; it decreased below the desired trough level of 1 micrograms/mL between hours 4 and 8.

Cloning and characterization of the mouse neu promoter

We have isolated a genomic clone containing the mouse neu gene. The 5' end of the mouse neu gene was localized by Southern analysis, subcloned and characterized. DNA sequence analysis revealed that the promoter region is 67% G+C-rich and lacks a TATA box, although a CAAT box is present. By sequence comparison, we identified several consensus recognition sequences for general transcription factors such as Sp1, E4TF1, AP2, OTF-1 and GCF, as well as recognition sequences for RVF, E1A and GTG, which have recently been identified in the rat neu promoter. Functional promoter activity was demonstrated by the ability of the promoter to drive transcription of the bacterial chloramphenicol acetyltransferase gene. Using a series of 5'-end deletion mutants, we have identified multiple positive and negative cis-acting elements that regulate mouse neu gene transcription.

Anomalous features of human neutrophil activation by influenza A virus are shared by related viruses and sialic acid-binding lectins

Influenza A virus (IAV) causes both activation and deactivation of the human neutrophil, which may, respectively, contribute to host defense against the virus and enhanced susceptibility to bacterial superinfection. We have shown that certain features of neutrophil activation by IAV are distinctive compared with activation by chemoattractants in terms of both the stoichiometry of the respiratory burst response and the signal transduction events that precede it. We here demonstrate that related myxoviruses as well as sialic acid-binding lectins elicit a respiratory burst response similar to that induced by IAV, in which hydrogen peroxide is formed with minimal accompanying superoxide generation. Brief preincubation of neutrophils with these agents fully inhibits subsequent activation by IAV, implying that they are binding to the same surface membrane components as IAV. Preincubation with Limax flavus agglutinin (LFA) does, in fact, substantially reduce binding of radiolabeled IAV to the neutrophil. This lectin, like IAV, both activates and deactivates the neutrophil. As in the case of IAV, LFA-induced activation (1) is mediated via stimulation of phospholipase C, (2) is pertussis toxin insensitive, and (3) entails a lesser contribution of calcium influx than is the case for chemoattractants.

Comparison of influenza A virus and formyl-methionyl-leucyl-phenylalanine activation of the human neutrophil

Influenza A virus (IAV) activates the human neutrophil, but induces a dysfunctional state as well. Cell activation may contribute to the containment of the virus and/or cause local tissue damage. Certain features of the neutrophil activation response elicited by IAV are distinctive when compared with that triggered by formyl-methyl-leucyl-phenylalanine (FMLP). An atypical respiratory burst response occurs in which hydrogen peroxide, but no superoxide, is formed. This unusual respiratory burst stoichiometry persists despite marked priming of the IAV-induced response. A comprehensive examination of the activation cascade initiated by these stimuli failed to show an explanation for these differences. Both IAV and FMLP comparably stimulate inositol trisphosphate and phosphatidic acid production. The subsequent increase in intracellular calcium (Ca2+i) upon FMLP stimulation was more dependent on extracellular Ca2+ than with IAV activation, but both stimuli induced Ca2+ influx. FMLP and IAV exhibited equal susceptibility to inhibition by protein kinase inhibitors in eliciting the respiratory burst, and actin polymerization occurred in response to each agonist. A possible explanation for the anomalous respiratory burst induced by IAV is that O2- is generated at an intracellular site inaccessible to assay, and/or virus binding to sialic acid constituents of the plasma membrane alters the O2- generating capacity of the respiratory burst oxidase; evidence for each mechanism is offered.

Analyses of exobiological and potential resource materials in the Martian soil

Potential Martian soil components relevant to exobiology include water, organic matter, evaporites, clays, and oxides. These materials are also resources for human expeditions to Mars. When found in particular combinations, some of these materials constitute diagnostic paleobiomarker suites, allowing insight to be gained into the probability of life originating on Mars. Critically important to exobiology is the method of data analysis and data interpretation. To that end we are investigating methods of analysis of potential biomarker and paleobiomarker compounds and resource materials in soils and rocks pertinent to Martian geology. Differential thermal analysis coupled with gas chromatography is shown to be a highly useful analytical technique for detecting this wide and complex variety of materials.

Membrane-permeable luciferin esters for assay of firefly luciferase in live intact cells

Five esters of luciferin were synthesized and compared with native luciferin as substrates for firefly luciferase expressed in live intact mammalian cells. The esters themselves were not substrates for purified luciferase, but four were substrates for a purified esterase and all appeared to be hydrolysed to luciferin within mammalian cells. At a substrate concentration of 0.01 mM, the peak luminescence from the cos cells expressing luciferase was up to 6-fold greater with the esters than with unmodified luciferin. At 0.1 mM, the difference between luciferin and the esters was decreased. The kinetics of the luminescent signal with the different luciferin esters varied significantly, indicating possible differences in the rates of uptake, breakdown and enzyme inhibition. The esters did not support luminescence from Escherichia coli cells expressing firefly luciferase, suggesting a lack of appropriate esterase activity in this particular strain. The esters could be useful for the assay of luciferase expression in intact mammalian cells when luciferin levels are limiting, for example in tissues, and in plants. Alternative luciferin derivatives may allow further improvements in sensitivity.

Morbidity and mortality in U.S. Navy personnel from exposures to hazardous materials, 1974-85

A total of 1,371 hospitalizations and 136 deaths occurred in U.S. Navy enlisted personnel from 1974 to 1985 as a result of exposures to hazardous materials. Exposures to various gas fumes and vapors accounted for the largest percentage of all hospitalizations (38%), and the second largest percentage of deaths (20.6%). The most frequent cause of death was from carbon monoxide poisoning; nearly 74% of all reported deaths were attributed to this gas. Hospitalization rates were highest among the 17- to 19-year-olds across all race categories. This may be attributed either to their lack of experience and knowledge concerning the safe handling of these materials, or perhaps a disproportionate number of 17- to 19-year-olds are given tasks which put them at higher risk. The Navy occupations showing the highest risk for various exposures to hazardous materials were Utilitiesman, Hull Maintenance Technician, and Boatswain's Mate. It is the inhalation of these compounds which poses the greatest health risk to personnel both onshore and aboard ships.

Occupational sunlight exposure and melanoma in the U.S. Navy

Melanoma is the second most common cancer, after testicular cancer, in males in the U.S. Navy. A wide range of occupations with varying exposures to sunlight and other possible etiologic agents are present in the Navy. Person-years at risk and cases of malignant melanoma were ascertained using computerized service history and inpatient hospitalization files maintained at the Naval Health Research Center. A total of 176 confirmed cases of melanoma were identified in active-duty white male enlisted Navy personnel during 1974-1984. Risk of melanoma was determined for individual occupations and for occupations grouped by review of job descriptions into three categories of sunlight exposure: (1) indoor, (2) outdoor, or (3) indoor and outdoor. Compared with the U.S. civilian population, personnel in indoor occupations had a higher age-adjusted incidence rate of melanoma, i.e., 10.6 per 100,000 (p = .06). Persons who worked in occupations that required spending time both indoors and outdoors had the lowest rate, i.e., 7.0 per 100,000 (p = .06). Incidence rates of melanoma were higher on the trunk than on the more commonly sunlight-exposed head and arms. Two single occupations were found to have elevated rates of melanoma: (1) aircrew survival equipmentman, SIR = 6.8 (p less than .05); and (2) engineman, SIR = 2.8 (p less than .05). However, there were no cases of melanoma or no excess risk in occupations with similar job descriptions. Findings on the anatomical site of melanoma from this study suggest a protective role for brief, regular exposure to sunlight and fit with recent laboratory studies that have shown vitamin D to suppress growth of malignant melanoma cells in tissue culture. A mechanism is proposed in which vitamin D inhibits previously initiated melanomas from becoming clinically apparent.

Incidence of leukemia in occupations with potential electromagnetic field exposure in United States Navy personnel

Leukemia is the fourth most commonly occurring cancer in the United States population between the ages of 17 and 34 years, an age group heavily represented in the US Navy. Historical computerized military career records maintained at the Naval Health Research Center, San Diego, California, were used to determine person-years at risk (total, 4,072,502 person-years) by demographic characteristics and occupation for active-duty naval personnel during 1974-1984. Computerized inpatient medical records were searched for first hospitalizations for leukemia. Cases of leukemia (n = 102) were verified by using pathology reports or Navy Medical Board or Physical Evaluation Board findings. For comparisons, age-adjusted incidence rates and standardized incidence ratios were calculated by using rates for the US population provided by the Surveillance, Epidemiology, and End Results program of the National Cancer Institute. The overall age-adjusted incidence rate of leukemia in active-duty naval personnel was found to be very close to that of the Surveillance, Epidemiology, and End Results program population (6.0 vs. 6.5 per 100,000 person-years). Only one occupation, electrician's mate, emerged with a borderline statistically significant excess risk of leukemia (standardized incidence ratio compared with the Surveillance, Epidemiology, and End Results program population = 2.4, 95% confidence interval 1.0-5.0). This finding is intriguing in the light of several studies showing an excess risk of leukemia associated with exposure to electromagnetic fields.

Human neutrophil stimulation by influenza virus: relationship of cytoplasmic pH changes to cell activation

We have previously demonstrated that influenza A virus (IAV) stimulates the human neutrophil through phospholipase C activation. With the use of the fluorescent indicator 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF), cytoplasmic acidification and subsequent alkalinization are shown to accompany this activation. These responses are not inhibited by pertussis toxin (PT). The alkalinization is mediated largely *but not entirely) by the Na(+)-H+ antiporter and is not initiated, or modulated, by the IAV-induced cytosolic Ca2+ (Cai2+) rise. Rather, protein kinase C (PKC) is likely the mediator of cell alkalinization, based on studies using the PKC inhibitor 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7). The acidification can be dissociated from the alkalinization response, which is also independent of Cai2+ fluxes and of PKC. Both pHi responses can be dissociated from the respiratory burst. Cytosolic alkalinization and acidification seem to reflect two independently mediated responses of the activated neutrophil, the former resulting ultimately from phospholipase activation and the latter from other activities that are not yet fully characterized.

Characterization of influenza A virus activation of the human neutrophil

Neutrophil dysfunction consequent to influenza A virus infection has been described in vivo and in vitro and may contribute to the serious bacterial sequelae which occur in influenza-infected hosts. On the premise that such dysfunction may represent a form of "deactivation," we sought to characterize neutrophil activation by the virus in comparison with other agonists. The virus induces a respiratory burst in which H2O2 (but not O2-) are formed. Preceding the respiratory burst, a rise in intracellular calcium (Ca2+i) is noted, but both responses are nearly independent of extracellular Ca2+, unlike those elicited by the other well-characterized Ca2+-dependent agonists, formyl-methyl-leucyl-phenylalanine (FMLP), or Concanavalin-A (Con-A). The Ca2+ increase is paralleled by IP3 generation, implying that it is the result of phospholipase C (PLC) activation. The virus also elicits neutrophil membrane depolarization, which is independently mediated from the Ca2+ increase and respiratory burst and may reflect protein kinase C (PK-C) activation. Virus-induced responses are insensitive to pertussis toxin (PT); cholera toxin does inhibit these responses but in a nonspecific manner. Thus, although influenza virus activates PLC in neutrophils, it does so in a PT-insensitive manner and does not elicit or require a discernible Ca2+ influx to generate a respiratory burst response. In aggregate, the data indicate that influenza A virus activates neutrophils in a manner distinct from that of other well-described neutrophil agonists. These results illustrate the diversity of neutrophil activation mechanisms and support the notion that further characterization of this pathway may facilitate understanding of neutrophil dysfunction induced by the virus.

Orbital neoplasia with enophthalmos in a cat

A 9-year-old cat was evaluated for left-sided enophthalmos and protrusion of the third eyelid. A primary orbital fibrosarcoma was diagnosed. During the orbital exploration, normal periorbital fascia could not be identified in the lateral and ventral region, thus accounting for the enophthalmos.

Experimental visceral leishmaniasis in the opossum

Adult wild-trapped opossums were infected with Leishmania donovani (Khartoum strain, WR 378) and evaluated as an animal model of visceral leishmaniasis. All infected opossums died within 32 days. Loss of body fat, hepatomegaly, and petechiae of skin and abdominal musculature were seen at necropsy. Microscopically, numerous amastigote-laden macrophages were seen in histologic sections of liver, spleen, and lymph nodes; fewer parasite-laden macrophages were in the bronchial-associated lymphoid tissues and renal glomeruli. Hematological findings included thrombocytopenia (terminal), neutropenia, and lymphopenia. Blood lymphocyte blastogenesis in response to concanavalin A and phytohemagglutinin was decreased markedly at day 24 post-infection (PI). Serum antibodies (1:40 dilution) to promastigotes of L. donovani were detected in five of eight infected opossums tested on days 10 and 24 PI. Total bilirubin concentrations and alanine aminotransferase and aspartate aminotransferase activities were increased after day 25 PI. Activated partial thromboplastin times and one-stage prothrombin times were prolonged before death. Concurrently, factors V, VIII, and XII activities were decreased.

Chemotherapy of experimental visceral leishmaniasis in the opossum

Visceral leishmaniasis is a severe chronic disease of people and animals. The disease is caused by several subspecies of a protozoal organism, Leishmania donovani. If not treated, visceral leishmaniasis is often fatal. The most commonly used chemotherapeutic agents to treat the disease are pentavalent antimonials, which can be toxic, must be administered by parenteral routes, and are sometimes ineffective. In this study, meglumine antimoniate, a pentavalent antimony, was compared with WR 6026, an 8-aminoquinoline derivative, as to antileishmanial efficacy. The results indicate that either of these 2 drugs are effective in the suppression of amastigotes in the liver and spleen of the opossum. Despite the marked parasite suppression in the liver and spleen of the infected opossums, the experimental disease was fatal in all of the infected opossums, regardless of the therapy.