Close association of verotoxin (Shiga-like toxin) production with enterohemolysin production in strains of Escherichia coli

Sixty-four verotoxin-producing (VT+) Escherichia coli strains were analyzed for VT1- and VT2-specific DNA sequences and for production of hemolysin. Strains of human origin were of the following serotypes: O157:H7 or H-, O111:H8 or H-, O26:H11, O114:H4, and rough:H7. Strains of serotypes O157:H7, O113:H21, O116:H21, and rough:H- were from cattle, while those of serotype O139:K12:H1 were from pigs. All 64 isolates carried either VT1 or VT2 or both genes. Sixty of the strains (93.8%) were hemolytic (Hly+). The three O139:K12:H1 strains examined produced alpha-hemolysin, as shown by their reaction with the alpha-hemolysin-specific monoclonal antibody h2A and by DNA hybridization with an alpha-hly gene probe. The remaining 57 Hly+ strains (95%) produced a different type of hemolysin (enterohemolysin), which is genetically and serologically unrelated to alpha-hemolysin. The two types of hemolysin are further distinguished by the appearance of the lysis zone on blood agar and by the time interval for the detection of hemolysis. In contrast to alpha-hemolysin, enterohemolysin can be detected only on blood plates containing washed erythrocytes. The frequent association of enterohemolysin with verotoxin production (89%) makes it useful as an epidemiological marker for rapid and simple detection of potential VT+ E. coli.

Seroconversion to human herpesvirus 6 following liver transplantation is a marker of cytomegalovirus disease

Human herpesvirus 6 (HHV-6) infection is common after transplantation; HHV-6 is known to interact with other viruses and induce immunosuppression. Whether HHV-6 plays a role in the occurrence of cytomegalovirus (CMV) infection after transplantation was investigated. In a cohort of 247 liver transplant recipients, HHV-6 seroconversion was identified as a significant risk factor for development of symptomatic CMV infection (P < .001), including CMV organ involvement (P < .001), even in the presence of the other significant risk factors: D+/R- CMV serologic status (P < .001) or use of OKT3 after transplantation (P = .002). Subgroup analysis indicated that HHV-6 seroconversion was significantly associated with symptomatic CMV infection in the D+/R+ but not in the D+/R- CMV serologic group (P < .001 and P = .11, respectively). These results indicate that HHV-6 seroconversion is a marker for CMV disease after transplantation and suggest that additional studies using more sensitive diagnostic techniques are warranted to determine the relationship between HHV-6 and CMV infection after transplantation.

High plasma levels of nitrogen oxides are associated with severe disease and correlate with rapid parasitological and clinical cure in Plasmodium falciparum malaria

Plasma levels of nitrogen oxide (NO), neopterin and C-reactive protein (CRP) were compared in 3 groups of Gabonese patients with Plasmodium falciparum malaria before and after therapy: adults with uncomplicated malaria, children with uncomplicated malaria, and children with severe malaria. Plasma levels of all 3 molecules were significantly higher in severe malaria than in uncomplicated malaria. High levels of neopterin and CRP during the acute phase of malaria significantly correlated with slow parasitological and clinical cure after therapy. In contrast, high NO plasma levels during the acute phase of malaria predicted accelerated cure. These findings provide further evidence for the protective role of NO in malaria. However, as NO levels were highest in severe disease, overproduction may be harmful for the patients.

Prediction of accelerated cure in Plasmodium falciparum malaria by the elevated capacity of tumor necrosis factor production

Cytokine regulation was compared in three groups of Gabonese patients with Plasmodium falciparum malaria before and after therapy; adults with uncomplicated malaria, children with uncomplicated malaria, and children with severe malaria. Plasma levels of tumor necrosis factor (TNF), interleukin-6 (IL-6), IL-8, TNF receptors (TNF R), and the TNF/TNF R ratios were significantly higher in severe malaria compared with uncomplicated malaria. High plasma levels of all immunoregulatory molecules were associated with slow cure after therapy. In all patients, phytohemagglutinin-induced cytokine production was depressed on admission compared with convalescence. A significant difference was the higher TNF production capacity in patients with severe malaria on day 2 and day 5 compared with that in patients with uncomplicated malaria. In contrast to IL-6 and IL-8, a high TNF production capacity during the acute phase of malaria predicted a rapid clinical and parasitologic cure in the patients. These findings illustrate the dual role of TNF in the protection and pathology of malaria.

Quinine plus clindamycin improves chemotherapy of severe malaria in children

In a randomized trial, a 4-day quinine-clindamycin regimen was compared with the standard 7-day quinine regimen for 100 Gabonese children (50 children in each group) with severe Plasmodium falciparum malaria. In each group, only one patient died. Parasite clearance and fever clearance times were significantly shorter in the quinine-clindamycin group (P = 0.03 and P = 0.01, respectively) than in the quinine group, and significantly more recurring fever episodes occurred in the quinine group than in the quinine-clindamycin group shortly after initial fever clearance and parasite clearance (P < 0.001).

Fibrin deposits and organ failure in newborn foals with severe septicemia

BACKGROUND

Septicemia in human neonates frequently is complicated by activation of the coagulation system, disseminated intravascular coagulation (DIC) and multiple organ failure syndrome, which may contribute to high mortality. In adult horses with DIC, the lung has been the organ most frequently affected by fibrin deposits. In addition, in vivo studies suggest that hemostatic mechanisms may be immature in foals < 1-day old.

HYPOTHESIS

Newborn foals with severe septicemia have fibrin deposits in their tissues independently of their age, and these fibrin deposits are associated with organ failure.

ANIMALS

Thirty-two septic and 4 nonseptic newborn foals euthanized for poor prognosis.

METHODS

Tissue samples (kidney, lung, and liver) collected on postmortem examination were stained with phosphotungstic acid hematoxylin (PTAH) and immunohistochemistry (IHC) for blind histologic examination. A fibrin score (grades 0-4) was established for each tissue sample and for each foal. Medical records were reviewed for assessing clinical evidence of organ failure during hospitalization.

RESULTS

Fibrin deposits were found in most septic foals (28/32 when using IHC and 21/32 when using PTAH), independently of the age of the foal. The lung was the most affected tissue (97% of the septic foals). Additionally, organ failure was diagnosed in 18/32 septic foals (8 with respiratory failure, 14 with renal failure), although a statistical association with severe fibrin deposition was not identified.

CONCLUSIONS AND CLINICAL IMPORTANCE

Nonsurviving septic foals have fibrin deposits in their tissues, a finding consistent with capillary microthrombosis and DIC.

Prognostic value of tumour-associated macrophages in canine mammary tumours

Tumour-associated macrophages (TAMs) have already been associated in human breast cancer to a poor prognosis. As a part of a tumoural microenvironment, TAMs have an important contribution influencing neoplastic progression. Hitherto, in canine mammary tumours (CMT) the prognostic value of TAMs has not been reported. In this study, MAC387 immunohistochemical expression was evaluated in 59 CMTs (20 benign and 39 malignant). The TAM value was significantly higher in malignant than benign CMT (P = 0.011). In malignant CMT, TAMs were associated with skin ulceration (P = 0.022), histological type (P = 0.044), nuclear grade (P = 0.031) and tubular differentiation (P = 0.042). The survival analysis revealed a significant association between tumours with higher levels of TAMs and the decrease in overall survival (P = 0.030). TAMs have proven to have a prognostic value. These findings suggest the future possibility of using TAMs as a novel therapeutic target in CMT.

Effects of Plasmodium vinckei hemozoin on the production of oxygen radicals and nitrogen oxides in murine macrophages

When murine peritoneal macrophages were loaded in vitro with Plasmodium vinckei hemozoin and stimulated with opsonized zymosan for 90 min or with lipopolysaccharide and/or murine interferon-gamma for 24 hr, significant decreases in the production of oxygen radicals and nitrogen oxides, respectively, could be detected by comparison with macrophages without hemozoin. Moreover, nonradioactive in situ hybridization and immunohistologic analysis in liver sections of P. vinckei-infected mice with more than 60% parasitemia showed that liver cells were still expressing considerable levels of inducible nitric oxide synthase in the late phase of murine malaria, but most of the liver macrophages presenting accumulation of malaria pigment were negative in this analysis. These results further indicate that malaria pigment accumulation may be responsible for toxicity and impairment of macrophage functions during murine malaria.

Giant aneurysm arising from a single arteriovenous fistula in a child. Case report

A case is presented of a child with an arteriovenous fistula and a giant aneurysm located beside the brain stem under the right temporal lobe. It was successfully treated by clipping its feeding artery, a branch of the right posterior cerebral artery. The similarities to, and the differences from, aneurysms of the vein of Galen are discussed.

High COX-2 expression is associated with increased angiogenesis, proliferation and tumoural inflammatory infiltrate in canine malignant mammary tumours: a multivariate survival study

COX-2 expression affects mammary tumourigenesis by promoting angiogenesis and cell proliferation, encouraging metastatic spread and tumour-associated inflammation. Samples of canine mammary tumours (n = 109) were submitted to immunohistochemistry to detect COX-2, CD31, VEGF, Ki-67, CD3 and MAC387 expression. Concurrent high expression of COX-2/CD31, COX-2/VEGF, COX-2/Ki-67, COX-2/CD3 and COX-2/MAC was associated with elevated grade of malignancy, presence of intravascular emboli and presence of lymph node metastasis. Tumours with high COX-2 (P < 0.001) and tumours with concurrent expression of high COX-2 and high CD31 (P = 0.008); high VEGF (P < 0.001); high Ki-67 (P < 0.001); high CD3+ T-lymphocytes (P = 0.002) and elevated MAC387 macrophages (P = 0.024) were associated with shorter overall survival (OS) time. Interestingly the groups with high COX-2/CD31 and high COX-2/VEGF retained their significance after multivariate analysis arising as independent predictors of OS. Present data highlight the importance of COX-2 in canine mammary tumourigenesis.

Brain and ocular metastases from a transmissible venereal tumour in a dog

A five-year-old crossbred dog was referred with rapidly growing masses over its penis and right popliteal lymph node. The dog had severe blepharospasm, congestion of episcleral vessels and rubeosis iridis of the left eye. A presumptive diagnosis of transmissible venereal tumour (TVT) and iridocyclitis was made based on the results of fine needle aspiration. Chemotherapy with vincristine and prednisolone was initiated and after four months the dog made a complete recovery. However, the dog subsequently relapsed, showing miosis, blepharospasm and a well defined mass within the anterior chamber of the left eye. In addition, the dog exhibited generalised 'grand mal' type seizures. Computed tomographic (CT) examination of the brain revealed two distinct masses in the left frontal lobe. Because of the poor prognosis, the owners elected to have the dog euthanased. On histopathology, metastases of TVT in the left eye and left cerebral hemisphere were found, showing no specific staining for CD3, immunoglobulin (Ig) G, IgM and lambda light chains. It was therefore concluded that the tumour growth was progressive, and that there was an absence of local humoral immune response against TVT in this case.

Tumour necrosis factor alpha and interleukin 6 gene expression in keratocytes from patients with rheumatoid corneal ulcerations

BACKGROUND/AIMS

Ultrastructural alterations in the stroma adjacent to corneal perforations have previously been reported in patients with longstanding rheumatoid arthritis. Since patients with rheumatoid arthritis often present upregulation of proinflammatory cytokines in serum and in synovial fluid, it was of interest to analyse the gene expression of these cytokines-for example, tumour necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6), in corneal samples from patients with corneal ulcerations and/or perforations associated with rheumatoid arthritis.

METHODS

Corneal samples from seven patients with corneal ulcerations and/or perforations associated with rheumatoid arthritis were collected in 4% paraformaldehyde in "RNAse-free" conditions. Paraffin sections were fixed on silan coated slides and further analysed by systematic non-radioactive in situ hybridisation, using specific gene probes for TNF-alpha and IL-6 labelled with digoxigenin (DIG). Detection of hybrids was carried out by using a commercially available DIG detection system.

RESULTS

Whereas an extended TNF-alpha gene expression could be clearly observed in the keratocytes surrounding the corneal ulcerations and/or perforations from five of the seven analysed patients, all seven patients presented clearly positive results for an extended IL-6 gene expression in the analysed tissue samples.

CONCLUSIONS

Alterations in corneal cells surrounding ulcerations and/or perforations in patients with rheumatoid arthritis may occur with implication for inflammatory processes. Upregulation of the proinflammatory cytokines TNF-alpha and IL-6 may modify the production of metalloproteinases in the corresponding cells resulting in collagenolytic corneal damage.

Clonal diversity and virulence factors in strains of Escherichia coli of the classic enteropathogenic serogroup O114

Eighty-eight Escherichia coli strains of the enteropathogenic (EPEC) group O114 that were isolated from humans and animals in geographically different places and over more than 30 years were examined for virulence markers, O:H serotypes, and for electrophoretic types by multilocus enzyme electrophoresis. Four major genetically tightly related clusters of strains showed close correlation between electrophoretic types and other phenotypic characters. Cluster I contained 35 EPEC class II strains of serotypes O114:H9 and O114:H- and 5 enterotoxigenic E. coli belonging to O114:H21 and O114:H49. Clusters II and III comprised 36 O114:H4, O114:H32, and O114:H- strains; most were of doubtful pathogenicity except one Verotoxin-positive O114:H4 strain isolated from a human with diarrhea. Cluster IV contained 9 classic EPEC strains of serogroup O114:H2 that were characterized by localized adherence to HEp-2 cells and by the EPEC adherence factor.

Tumour-associated macrophages are associated with vascular endothelial growth factor expression in canine mammary tumours

Tumour-associated macrophages (TAMs) have been implicated in carcinogenesis including an important role in angiogenesis. In this study, we describe the relationship between TAMs and angiogenesis in canine mammary tumours (CMT). Formalin-fixed paraffin-embedded CMT samples [(n = 128: malignant (n = 97) and benign (n = 31)] were submitted to immunohistochemical staining to detect MAC387, vascular endothelial growth factor VEGF and CD31 expression. A statistical analysis was carried out to assess possible associations with clinicopathological variables and biological markers of tumour angiogenesis. TAMs, detected by MAC387 expression, were significantly associated with malignant CMT (P < 0.001) and VEGF positive tumours (P = 0.002) and also associated with VEGF expression within malignant CMT (P = 0.043). Associations with clinicopathological variables were found between TAMs and the presence of infiltrative growth (P = 0.031), low tubule formation (P = 0.040) and lymph node metastasis (P = 0.016). The results support the hypothesis that TAMs influence angiogenesis in CMT suggesting TAMs may represent a therapeutic target in this disease.

Ki-67 and PCNA Expression in Canine Mammary Tumors and Adjacent Nonneoplastic Mammary Glands: Prognostic Impact by a Multivariate Survival Analysis

The assessment of tumor proliferation has been considered a determining prognostic factor in canine mammary tumors (CMTs). However, no studies have assessed the prognostic importance of proliferation in adjacent nonneoplastic mammary glands. We included 64 CMTs (21 benign and 43 malignant) and studied the proliferation index (PI) of Ki-67 and proliferating cell nuclear antigen (PCNA) together with several clinicopathological characteristics. A positive and statistically significant correlation between the PI of Ki-67 and PCNA in tumors and adjacent nonneoplastic mammary glands was observed in benign and malignant tumors. Tumor size, skin ulceration, histological type, mitotic index, nuclear grade, differentiation grade, histological grade of malignancy, lymph node metastasis, Ki-67, and PCNA expression in tumors and adjacent nonneoplastic mammary glands were statistically associated with overall survival by univariate analysis in malignant cases (n = 43). Histological grade of malignancy and high intratumoral PCNA retained their significance by multivariate analysis arising as independent predictors of overall survival. Interestingly, the PI of Ki-67 and PCNA of adjacent nontumoral mammary glands were associated with clinicopathological features of tumor aggressiveness and shorter overall survival, demonstrating the need to better explore this adjacent non-neoplastic tissue.

The effects of sertraline on nicotine self-administration and food-maintained responding in squirrel monkeys

Recent reports suggested the involvement of serotonergic mechanisms in nicotine self-administration. The present study assessed the effects of sertraline, a selective serotonergic uptake inhibitor, on the reinforcing effects of i.v. nicotine (30 microgram/kg per injection) in squirrel monkeys responding under a fixed-ratio schedule. Nicotine (10-100 micrograms/kg per injection) produced a significant inverted U-shaped distribution on FR rate. Vehicle or sertraline (3, 6, 12, 24 mg/kg, p.o.) produced no changes in the response rates maintained by 30 micrograms/kg per injection i.v. nicotine, but sertraline produced non-significant increases response rates maintained by 10 micrograms/kg per injection nicotine and vehicle. In a separate group of monkeys, sertraline given in combination with i.m. doses of nicotine produced a significant dose-dependent decrease in responding maintained by food-pellet delivery. Thus, sertraline produced differential effects on response rates that may be related to (1) route of nicotine administration and (2) whether the behavior was maintained by nicotine or food. In addition, the results of the self-administration study suggest that sertraline would not disrupt well-maintained responding for nicotine.

Characteristics of alpha-hemolytic strains of Escherichia coli isolated from dogs with gastroenteritis

Twenty-four hemolysin producing (Hly+) strains of Escherichia coli isolated from dogs with gastroenteritis were investigated for their virulence markers and their phenotypic properties. The strains were distributed over eleven known E. coli O-serogroups and most of them were heterogeneous for their phenotypes. All strains were found to produce alpha-hemolysin which was detected by Southern hybridization and colony immunoblotting using a specific gene probe and a monoclonal antibody. Eight strains were carrying plasmids encoding alpha-hemolysin sequences (hly-plasmids) and 16 strains carried chromosomal hly-determinants. Twelve of the strains showed enterotoxic activities which were tested for in different assays. Among these, three O42:H37 and two O70:H-strains carrying hly-plasmids were found to harbour other plasmids encoding the heat-stable enterotoxin STA1. The other seven strains showing enterotoxicity in the ileal loop or the suckling mouse assay were negative for STA1, STA2, or LT. None of the 24 strains were positive for invasiveness or for production of Vero (Shiga-like) toxins. The production of alpha-hemolysin was closely associated with the production of cytotoxic necrotizing factor (CNF), which was detected in 17 of 24 strains. Of these, 16 elaborated CNF1 and one strain produced an unknown CNF type. Surprisingly, all strains carrying ST-plasmids and six of eight strains carrying hly-plasmids were negative for CNF. Thus, in canine E. coli strains CNF production seems to be closely associated with production of chromosomally encoded alpha-hemolysin whereas hly-plasmids are more often associated with ST-producing, CNF negative isolates.

Enterohemolysin, a new type of hemolysin produced by some strains of enteropathogenic E. coli (EPEC)

42 Escherichia coli O26 strains which had been isolated at geographically different places and over a long time period were examined for hemolysin synthesis. 17 of these were found to be hemolysin-negative, nine strains were found to produce plasmid encoded alpha-hemolysin and 16 strains were shown to produce a phenotypically different hemolysin. This new type of hemolysin was called enterohemolysin and found to be genetically and immunologically non-related with the already described E. coli alpha-hemolysin. Enterohemolytic E. coli were not found in feces of 200 healthy infants under the age of two years. However, four E. coli O111 strains, one O121:H- and one O25:K5:H- strain, all from infants with diarrhoea were also enterohemolysin producers.

Effect of glandular kallikrein on renin release in isolated rat glomeruli

Numerous studies have suggested that a functional relationship may exist between the kallikrein-kinin and the renin-angiotensin systems within the kidney. We investigated the effects of glandular kallikrein on renin release by using an in vitro preparation of isolated rat glomeruli with their attendant arterioles. The effect of kallikrein was studied in the presence or absence of 0.1% bovine serum albumin (BSA) in Krebs superfusion fluid. We also studied the effect of inactivating kallikrein by treatment with phenylmethylsulfonyl fluoride or by inhibiting it with aprotinin. In the absence of BSA, kallikrein caused a 12-fold increase in renin release, from 5.1 +/- 1.2 ng angiotensin I (ANG I)/min to 66.0 +/- 2.27 ng ANG I/min (p less than 0.025). In the presence of BSA, renin release increased twofold, from 13.0 +/- 1.8 ng ANG I/min to 24.3 +/- 4.8 ng ANG I/min (p less than 0.025). The basal level of renin measured when the glomeruli were superfused with BSA-Krebs was two to three times greater than when they were superfused with Krebs alone (p less than 0.001). This finding suggests that media protein inhibited renin loss during either the superfusion or storage of renin samples. Neither phenylmethylsulfonyl fluoride-inactivated nor aprotinin-inhibited kallikrein stimulated renin release. We propose that kallikrein can stimulate renin release in isolated glomeruli.(ABSTRACT TRUNCATED AT 250 WORDS)

Systemic and uterine vascular response to serotonin in third trimester pregnant ewes

Released from aggregating platelets, serotonin (5HT) among other vasoactive components is considered to play an important role in preeclampsia, one of the most common medical complications of pregnancy. This study was designed to evaluate the simultaneous uterine and systemic vascular effects of systemically administered serotonin in pregnant sheep and compare them to the well known effects of angiotensin II and norepinephrine. Nine instrumented pregnant ewes received intravenous (inferior vena cava) infusions of increasing doses of serotonin, norepinephrine and angiotensin II in random order. Cardiac output, arterial blood pressure, heart rate, and uterine blood flow were recorded. Systemic administration of serotonin at doses of 2, 4, and 8 micrograms/kg body weight/min caused a slight increase in mean arterial blood pressure (1, 4 and 11%), a large decrease in uterine blood flow (10, 37, and 71%) but did not change cardiac output. Serotonin led to an increase in uterine vascular resistance with only small changes in systemic vascular resistance (UVR 17, 107, and 363% vs. SVR 3, 10 and 11%). In contrast, angiotensin II increased both systemic and uterine vascular resistance (SVR 16, 37, 56, and 95% and UVR 5, 16, 28 and 99%). Norepinephrine also raised both systemic and uterine vascular resistance, though to a different extent (SVR 5, 17, 37, and 118% vs. UVR 5, 46, 84 and 304%). Systemic infusions of serotonin in third trimester pregnant ewes resulted in uterine vasoconstriction. In contrast to the marked effect on the uterine vasculature, the systemic cardiovascular responses were small, thus demonstrating a nearly selective effect of serotonin on the uterine vasculature at the doses administered.(ABSTRACT TRUNCATED AT 250 WORDS)

Exploring new biomarkers in the tumour microenvironment of canine inflammatory mammary tumours

Human inflammatory breast cancer (IBC) and canine inflammatory mammary cancer (CIMC) are the most aggressive forms of mammary cancer. Current research aims to identify new therapeutic targets. Here, we investigated gene expression levels of biomarkers associated with the inflammatory microenvironment. A total of 32 formalin-fixed paraffin-embedded samples of canine mammary carcinoma (CIMC = 26; non-CIMC = 6) were used and their cDNA subjected to quantitative polymerase chain reaction (qPCR) to establish gene expression levels for mediators commonly implicated in linking carcinogenesis with inflammation. Gene expression differences between CIMC and non-CIMC types were obtained for cyclooxygenase 2 (COX-2) (P = 0.004), synuclein gamma (SNCG) (P = 0.006), tribbles 1 (P = 0.025), vascular endothelial growth factor (VEGF) (P = 0.017) and CSF1R (P = 0.045). Among these biomarkers correlations were found, particularly between SNCG and tribbles 1 (r = 0.512, P = 0.001). The efficient metastasis of CIMC is intimately linked to components in the tumour microenvironment. This study suggests that upregulation and correlation of SNCG and tribbles 1 deserves to be further explored.

R-Type Ca 2+ -channel Activity Is Associated with Chromogranin A Secretion in Human Neuroendocrine Tumor BON Cells

This electrophysiological study was undertaken to investigate the role of voltage-operated Ca(2+) channels (VOCCs) in cultivated human neuroendocrine tumor (NET) cells. Patch-clamp techniques, measurements of intracellular Ca(2+) ([Ca(2+)](i)), and secretion analysis were performed using cultured human NET BON cells. Ba(2+) inward currents through R-type channels (Ca(V)2.3) were measured and identified by SNX-482 (10 n M), a novel voltage-sensitive R-type Ca(2+) channel antagonist. In the presence of nifedipine (5 micro M), omega-Conotoxin GVIA (100 n M) and omega-Agatoxin IVA (20 n M), R-type channel currents were also detectable. Release of Ca(2+) from intracellular Ca(2+) stores by intracellular application of inositol-1,4,5-trisphosphate (InsP(3); 10 micro M) via the patch pipette during whole-cell configuration as well as induction of capacitative Ca(2+) entry (CCE), a passive maneuver to release Ca(2+) from intracellular Ca(2+) stores, led to an increase in [Ca(2+)](i). This effect could be reduced by SNX-482 (20 n M). In addition, SNX-482 (25 n M) also decreased chromogranin A (CgA) secretion, whereas omega-Conotoxin GVIA (500 n M) and nifedipine (5 micro M) failed to reduce CgA secretion. We conclude that these data reveal neuronal R-type channel activity (Ca(V)2.3), for the first time associated with CgA secretion in BON cells. Influx of Ca(2+) by activation of R-type channels may lead to an increase of intracellular Ca(2+), which stimulates CgA secretion. Thus, R-type channels could play an important role in certain clinical characteristics of NETs, such as the hypersecretion syndrome.

Production of interleukin-6 by human and murine mononuclear leukocytes stimulated with Plasmodium antigens is enhanced by pentoxifylline, and tumor necrosis factor secretion is reduced

When pentoxifylline was present during stimulation of human mononuclear leukocytes with Plasmodium falciparum exogenous antigens, an increase in interleukin-6 production was observed simultaneously with a reduction of tumor necrosis factor secretion. Similar results were obtained in murine macrophages stimulated with P. vinckei antigens. This indicates the independence of interleukin-6 and tumor necrosis factor secretion in response to malaria antigens.