Capacitative Ca2+ entry in enteric glia induced by thapsigargin and extracellular ATP

Mobilization of intracellular Ca2+ stores is coupled to Ca2+ influx across the plasma membrane, a process termed capacitative Ca2+ entry. Capacitative Ca2+ entry was examined in cultured guinea pig enteric glia exposed to 100 microM ATP, an inositol trisphosphate-mediated Ca2+-mobilizing agonist, and to 1 microM thapsigargin, an inhibitor of microsomal Ca2+ ATPase. Both agents caused mobilization of intracellular Ca2+ stores followed by influx of extracellular Ca2+. This capacitative Ca2+ influx was inhibited by Ni2+ (88 +/- 1%) and by La3+ (87 +/- 1%) but was not affected by L- or N-type Ca2+ channel blockers. Pretreatment of glia with 100 nM phorbol 12-myristate 13-acetate for 24 h decreased capacitative Ca2+ entry by 48 +/- 2%. Chelerythrine (0.1-10 microM), a specific antagonist of protein kinase C (PKC), dose dependently inhibited capacitative Ca2+ entry. The nitric oxide synthase inhibitor NG-nitro-L-arginine (1 mM) decreased Ca2+ influx by 42 +/- 1%. Capacitative Ca2+ entry was inhibited to a similar degree by the guanylate cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one). Capacitative Ca2+ entry occurs in enteric glial cells via lanthanum-inhibitable channels through a process regulated by PKC and nitric oxide.

Endothelin-stimulated capacitative calcium entry in enteric glial cells: synergistic effects of protein kinase C activity and nitric oxide

Depletion of intracellular calcium stores by agonist stimulation is coupled to calcium influx across the plasma membrane, a process termed capacitative calcium entry. Capacitative calcium entry was examined in cultured guinea pig enteric glial cells exposed to endothelin 3. Endothelin 3 (10 nM) caused mobilization of intracellular calcium stores followed by influx of extracellular calcium. This capacitative calcium influx was inhibited by Ni2+ (89 +/- 2%) and by La3+ (78 +/- 2%) but was not affected by L-, N-, or P-type calcium channel blockers. Chelerythrine, a specific antagonist of protein kinase C, dose-dependently inhibited capacitative calcium entry. The nitric oxide synthase inhibitor NG-nitro-L-arginine decreased calcium influx in a dose-dependent manner. The combination of chelerythrine and NG-nitro-L-arginine produced synergistic inhibitory effects. Capacitative calcium entry occurs in enteric glial cells via lanthanum-inhibitable channels through a process regulated by protein kinase C and nitric oxide.

Tachykinin neuropeptide-evoked intracellular calcium transients in cultured guinea pig myenteric neurons

Substance P and related tachykinins are present in the mammalian gut and act as neurotransmitters. Microfluorimetric measurement of intracellular calcium ([Ca2+]i) was used to study tachykinin-sensitive myenteric neurons. Substance P (0.001-10 microM) evoked concentration-dependent increases in percentage of neurons responding (6-75%) and delta [Ca2+]i (88 +/- 24 to 212 +/- 16 nM). Neurokinin A (0.001-1 microM) produced similar responses. Removal of extracellular Ca2+ abolished substance P-induced Ca2+ signals, as did the addition of the Ca2+ channel blockers lanthanum chloride (5 mM) and nickel chloride (2.5 mM). Both nifedipine (1-50 microM) and diltiazem (1-50 microM) inhibited substance P-evoked Ca2+ responses in a dose-dependent manner. Substance P and related tachykinins evoke Ca2+ signaling in cultured myenteric neurons by the influx of extracellular Ca2+ through L and N-type plasma membrane Ca2+ channels.

Epidemiological and clinical features of pulmonary blastomycosis

The epidemiological and clinical aspects of Blastomycosis are reviewed. The central United States is the most heavily endemic area in the world, although the extent of the endemic zone has been mapped only by individual case finding, rather than by large skin test surveys (as was done for histoplasmosis). The difficulties in developing a sensitive and specific skin test antigen are reviewed, and the sequence of antigens from Blastomycin to antigen A to the ASWS (alkali and water soluble) antigen to the WI (Wisconsin) antigen are discussed. The absence of good immunological markers of remote subclinical disease means that the size of the iceberg of subclinical cases relative to clinically apparent and diagnosed pulmonary and extrapulmonary cases remains uncertain. Clinical presentations of blastomycosis range from (1) asymptomatic, currently discovered only in outbreak situation, (2) flulike illness of brief duration resembling other upper respiratory infections, (3) illness resembling bacterial pneumonia with acute onset, high fever, lobar infiltrates, and productive cough, (4) subacute or chronic respiratory illness with symptom complex resembling tuberculosis or lung cancer and radiographic presentation of fibronodular infiltrates or mass-like lesions, and (5) fulminant infectious adult respiratory distress syndrome (ARDS) with high fever, diffuse infiltrates, and progressive respiratory failure. Radiographic presentations are highly variable and even more confusing because of lack of standard terminology to describe these abnormalities. Examples of some of the radiographic presentations of blastomycosis are shown. Available information concerning computed tomographic studies is also reviewed. Special mention is made of blastomycosis in AIDS, which is uncommon but tends to be fulminant, systemic, and rapidly progressive. An overview of current diagnostic strategies and treatment options is also presented.

PACAP-38 causes phospholipase C-dependent calcium signaling in rat acinar cell line

BACKGROUND

Pituitary adenylate cyclase activating peptide (PACAP-38), a neuropeptide of the vasoactive intestinal peptide/secretin family, localizes to intrapancreatic neurons and stimulates exocrine secretion from the pancreas. PACAP-38 stimulates calcium signaling in the rat pancreatic cell line AR42J. The purpose of this study was to elucidate the mechanisms of PACAP-evoked calcium signaling in these cells.

METHODS

Continuous measurements of intracellular calcium were taken by fluorescent digital microscopy with the dye fura-2. Mechanisms of PACAP-38-evoked calcium signals were determined by a panel of inhibitors. Inositol phosphates production in response to PACAP-38 was measured. The ability of PACAP-38 to stimulate amylase release was used to determine a relevant dose range for these studies.

RESULTS

We have shown that (1) AR42J cells respond to PACAP-38 with biphasic increases in [Ca2+]i in a dose-dependent fashion; (2) PACAP-38 acts through phospholipase C to release inositol triphosphate (IP3)-sensitive Ca2+ stores with (3) a subsequent influx of extracellular Ca2+.

CONCLUSIONS

PACAP-38 activates calcium signaling through phospholipase C at concentrations that stimulate amylase release in AR42J cells.

Fungal pulmonary complications

With AIDS has come a new level of T-cell immunosuppression, beyond that previously seen. The impact of the HIV pandemic on the field of fungal infections includes a major increase in the number of serious fungal infections, an increase in the severity of those infections, and even some entirely new manifestations of fungal illness. In this article fungal pulmonary complications of AIDS are discussed. T-cell opportunists including Cryptococcus neoformans and the endemic mycoses are the most important pathogens. Phagocyte opportunists, including Aspergillus species and agents of mucormycosis, are less important.

Coccidioidomycosis in patients infected with human immunodeficiency virus: review of 91 cases at a single institution

We retrospectively evaluated the clinical manifestations, diagnosis, treatment, and outcome of coccidioidomycosis in 91 patients infected with human immunodeficiency virus (HIV) at a single institution. Coccidioidomycosis was the AIDS-defining illness in 37 patients. Fever and chills, weight loss, and night sweats were the most frequent symptoms. The lung was the most frequently involved organ (80%), followed by the meninges (15%). A diffuse reticulonodular infiltrate was seen in 59 patients (65%), and 13 (14%) had focal pulmonary disease; for 15 patients (16%), the chest radiograph was normal. Coccidioidal serologies were positive for 60 patients (68%), while for 23% with proven coccidioidomycosis such tests were negative Most patients were treated with systemic amphotericin B and then an oral azole. The mortality for the whole group was 60%. Patients with diffuse pulmonary disease had the highest mortality (68%), with a median duration of survival of 54 days (P < .05; 95% confidence interval, 147-175 days). The presence of diffuse pulmonary disease and a CD4 lymphocyte count of < 50/microL were independent predictors of death. In our experience, coccidioidomycosis is an important opportunistic infection that causes substantial morbidity and mortality among HIV-infected patients living in an area of endemicity.

Endemic mycosis complicating human immunodeficiency virus infection

Persons infected with the human immunodeficiency virus are prone to the development of many fungal diseases. Normal hosts with intact immunity usually recover from infection by these less-invasive fungi. In persons with compromised T-cell-mediated immunity, however, widespread dissemination from a pulmonary focus occurs. In this review, we discuss the epidemiology, clinical manifestations, diagnosis, and treatment of the three major North American mycoses, histoplasmosis, blastomycosis, and coccidioidomycosis. In most cases, amphotericin B is the initial drug of choice, followed by one of the azoles for lifelong maintenance therapy.

The endemic mycoses: surgical considerations

Surgical consultation is regularly requested for diagnosis and treatment of pulmonary complications of the endemic mycosis, Histoplasma capsulatum, Blastomyces dermatitidis and Coccidioidomycosis immitis, and the yeast Cryptococcus neoformans. All resemble pulmonary malignancies. Histoplasmosis causes pericarditis, mediastinal fibrosis and mediastinal granuloma, which can cause entrapment of vascular structures, the esophagus, and the trachea. Coccidioidomycosis can cause spontaneous pneumothorax and thin wall cavities that can be superinfected with tuberculosis and Aspergillosis. The pathogenesis, diagnosis, and treatment of these organisms are discussed with emphasis on the new oral therapies and complications encountered in persons with human immunodeficiency virus (HIV) infection.

Therapy for fungal infections

In the past, few pharmacologic agents were available for management of fungal disease. After the early introduction of amphotericin B and miconazole, the more recent advent of several new antifungal agents, including ketoconazole, fluconazole, and itraconazole has expanded the options for treatment of fungal infections. The dramatic increase in number of immunocompromised patients--both those with acquired immunodeficiency syndrome (AIDS) and those with immunosuppression for other reasons, such as organ transplantation--emphasizes the importance of therapeutic strategies for combating systemic mycoses. In this article, we review our personal recommendations for treating histoplasmosis, blastomycosis, coccidioidomycosis, and cryptococcosis, along with other less common fungal infections, and discuss the efficacy and toxic effects of the various antifungal drugs.

Diabetic ketoacidosis associated with pulmonary coccidioidomycosis

We describe three patients who developed diabetic ketoacidosis in association with pulmonary coccidioidomycosis and review the literature concerning the influence of diabetes on coccidioidomycosis. Our cases demonstrate that coccidioidomycosis is an infection that can be associated with diabetic ketoacidosis and that should be considered in the differential diagnosis of pneumonia in patients who live in a region in which Coccidioides immitis is endemic.

Diabetic ketoacidosis associated with pulmonary coccidioidomycosis

We describe three patients who developed diabetic ketoacidosis in association with pulmonary coccidioidomycosis and review the literature concerning the influence of diabetes on coccidioidomycosis. Our cases demonstrate that coccidioidomycosis is an infection that can be associated with diabetic ketoacidosis and that should be considered in the differential diagnosis of pneumonia in patients who live in a region in which Coccidioides immitis is endemic.

Characterization of the T cell antigen receptor--p60fyn protein tyrosine kinase association by chemical cross-linking

Engagement of the TCR by specific antigen results in activation of a tyrosine kinase pathway. A candidate for the kinase responsible for the rapid tyrosine phosphorylation detected with T cell activation is p60fyn, a member of the src kinase family. In an earlier study [Samelson et al. (1990) Proc. Natl Acad. Sci. USA 87:4358] this enzyme was co-immunoprecipitated with the TCR from T cells solubilized in digitonin. In that study a sensitive in vitro kinase assay was used to detect the associated p60fyn. It was subsequently found that the reproducibility of the interaction depended on lot-to-lot variations in digitonin. To eliminate the possibility that the association of antigen receptor and kinase is an artifact of solubilization with ill-defined digitonin preparations, a cross-linking protocol was developed to stabilize the interaction between the TCR and p60fyn. T cells were permeabilized with tetanolysin and proteins were cross-linked with the water soluble chemical cross-linker, 3,3' dithiobis(sulfosuccinimidylpropionate). These experiments allowed the confirmation of the interaction between the TCR, p60fyn, and several additional proteins. The cross-linking studies also enabled the mapping of the interaction of p60fyn and associated proteins to the TCR zeta-chain. This technique should have a general use in stabilizing interactions between other receptors and molecules required for intracellular signaling.

Pyomyositis in North America: case reports and review

We report two cases and review the characteristics of pyomyositis. The courses of patients who presented with pyomyositis at the Maricopa Medical Center (Phoenix) are detailed. Ninety-eight reported cases over the last 20 years in North America, found through a MEDLINE search, are summarized. Infection with the human immunodeficiency virus (HIV) may predispose the patient to pyomyositis. The onset is usually insidious with progression to large purulent collections and significant morbidity. The diagnosis is frequently suggested by findings of imaging studies. Staphylococcus aureus is responsible for most cases in tropical areas but is less frequently associated with cases in North America. Since infection with HIV predisposes patients to bacterial infections, pyomyositis will occur more frequently in this patient population. Increased awareness of the disease will improve management. Following aspiration or surgical drainage, therapy with broad-spectrum empirical antibiotics may be considered initially in the treatment of pyomyositis.

Histoplasmosis in hairy cell leukemia: case report and review of the literature

Progressive disseminated histoplasmosis (PDH) has been described in only six patients with hairy cell leukemia (HCL). Herein we describe an additional patient with HCL and disseminated histoplasmosis. Additionally, we note that three of seven cases of disseminated histoplasmosis and HCL have occurred in East Texas. PDH is to be suspected in febrile HCL patients in an endemic area who fail to respond to antibacterial therapy. We emphasize that serologic studies are useful in the diagnosis of PDH in HCL patients, and these patients respond well to therapy.

Disseminated histoplasmosis in patients infected with human immunodeficiency virus

Progressive disseminated histoplasmosis (PDH) is a common opportunistic infection complicating the course of infection with human immunodeficiency virus (HIV). PDH has been noted in areas nonendemic for histoplasmosis and occurs more frequently in areas heavily endemic for the fungus. PDH is frequently the AIDS-defining illness and presents as a febrile and wasting disease. The respiratory component may be overshadowed by the severity of the systemic illness. Chest roentgenograms show diffuse reticulonodular infiltrates. Frequently, the initial chest roentgenogram may show no abnormalities. Timely diagnosis requires a high index of diagnostic suspicion. Blood cultures, with use of the lysis-centrifugation system, are highly useful, as is the examination of the bone marrow, the peripheral blood smear, and the respiratory secretions. An experimental serological test that detects histoplasma polysaccharide antigen appears to be the simplest diagnostic test. Amphotericin B is the drug of choice for initial therapy, followed by further administration of amphotericin B for suppression. Early results with itraconazole are encouraging for long-term suppression.

Community-acquired fungal diseases

The endemic mycoses--histoplasmosis, blastomycosis, and coccidioidomycosis-pose a common problem in the differential diagnosis of the atypical pneumonia syndrome. Careful exposure-and-travel history frequently serves as a strong clue to aid diagnosis. Careful interpretation of serologic data may be useful but seldom timely. In critically ill patients, invasive diagnostic tests are frequently needed.

Amphotericin B. Still the 'gold standard' for antifungal therapy

Amphotericin B (Fungizone) remains the cornerstone of antifungal therapy because of its broad-spectrum fungicidal activity and rapid onset of action. Ketoconazole (Nizoral) and the new triazoles are welcome additions to the therapeutic armamentarium but do not replace amphotericin B. Adverse side effects of amphotericin B treatment are usually manageable and often preventable. Careful attention to detail reduces immediate toxicity and allows completion of the desired therapeutic course without an undue risk of permanent nephrotoxicity.

Progressive disseminated histoplasmosis in the acquired immunodeficiency syndrome: a model for disseminated disease

Progressive disseminated histoplasmosis (PDH) is a relatively common infectious illness in human immunodeficiency virus (HIV)-infected patients. In Houston, Texas, (which is moderately endemic for histoplasmosis) the frequency of PDH is 5% among patients with acquired immunodeficiency syndrome (AIDS), almost as high as that of those with cryptoccal disease. In highly endemic areas, the frequency of PDH in AIDS is even greater, up to 75% in some areas. It is likely that as the HIV epidemic continues to penetrate to more remote, highly endemic areas, more and more cases of PDH will occur. It is also clear that PDH may develop in HIV-infected patients who presently live in nonendemic areas, but who previously resided in endemic areas. It is important that all physicians who care for HIV-infected patients become thoroughly familiar with the clinical manifestation of this illness. Timely diagnosis depends on a high degree of diagnostic suspicion since the illness seldom presents with primary respiratory symptoms. It is prudent to consider PDH in the differential diagnosis of any systemic, wasting, febrile illness in HIV-infected individuals, especially if currently or in the past they have resided in areas endemic for the fungus. Similarly, whenever PDH is diagnosed in any patient who is in a high-risk group for HIV infection, prompt testing for HIV should be performed.

Nocardia asteroides pericarditis: report of a case and review of the literature

In this report, we describe a patient who had purulent Nocardia asteroides pericarditis. In addition, we identified 13 previously suspected and reported cases of Nocardia pericarditis, but only 5 of these studies reported isolation of Nocardia from cultures of pericardial fluid or pericardium. Analysis of the clinical course of these five patients and our patient revealed the importance of long-term sulfonamide antibiotic therapy in combination with surgical pericardial drainage procedures. In our review, only patients who received antibiotics and underwent pericardiectomy survived. Our case substantiates the excellent penetration of sulfisoxazole into the pericardial fluid, even with oral administration of the drug, and provides evidence in support of aggressive management of Nocardia pericarditis.