Prognostic markers in pheochromocytoma

Annexin II (AII) belongs to a family of glycoproteins that bind negatively charged phospholipids in the presence of calcium. The annexins exert various biological functions. We have previously shown that soluble AII suppresses mitogen-induced lymphoproliferation in vitro. In this study we address the question of whether soluble AII may also affect immunoglobulin secretion. Mononuclear cells from peripheral blood were stimulated with pokeweed mitogen in vitro and immunoglobulin-secreting cells were quantified using an ELISPOT assay. Retroplacental serum and soluble AII significantly inhibited secretion of IgG and IgM when added at concentrations that did not affect lymphoproliferation or cell viability. The inhibitory effect was dose- and time dependent. Significant suppression was observed when soluble AII was added at concentrations of 0.1 and 0.01 microg/ml. The strongest inhibition was observed when soluble AII or retroplacental serum was added initially. The data demonstrate that soluble AII can suppress immunoglobulin secretion in vitro. AII seems to be a potent immunosuppressive substance. The presence of high levels of soluble AII in retroplacental serum may indicate a possible immunomodulatory role in normal pregnancy.     

Membrane-destabilizing properties of C2-ceramide may be responsible for its ability to inhibit platelet aggregation

We have studied the effects of short-chain ceramides on platelet structure and function. N-Acetylsphingosine (C2-ceramide), a cell-permeable short-chain analogue, and N-acetyldihydrosphingosine (C2-dihydroceramide), which lacks the 4-5 double bond, have been investigated. C2-Ceramide (15 microM) inhibited ADP-induced aggregation by 50% at a platelet concentration of 1.25 x 10(8)/mL, while it took twice that concentration to inhibit aggregation by 50% when the platelet concentration was doubled. This indicates that the effect of C2-ceramide on ADP-induced platelet aggregation depends on the ratio of ceramide to total platelet lipid, with a ratio of 0.2 giving significant inhibition. C2-Ceramide at a ceramide: lipid ratio of 0.2 caused platelets to form fenestrations and pseudopodia which were longer and thinner than those caused by agonists such as ADP or thrombin. C2-Dihydroceramide had no effect on ADP-induced aggregation or platelet morphology at any ceramide:lipid ratio. Platelet lysis was induced by C2-ceramide at higher ceramide:lipid ratios (0.5), whereas C2-dihydroceramide did not induce lysis, suggesting that C2-ceramide is able to destabilize membranes. This was tested directly by assessing whether the ceramides induced leakage of 6-carboxyfluorescein from lipid vesicles. C2-Ceramide caused nearly total leakage of dye from the vesicles at a ceramide:lipid ratio of 10. The leakage caused by C2-dihydroceramide at a ceramide:lipid ratio of 10 was equal to that induced by C2-ceramide at a ratio of 0.2 (approximately 3%). The ability of the ceramides to destabilize membranes was also examined by measuring changes in fluorescence anisotropy of the fluorescent dye 1,6-diphenyl-1,3,5-hexatriene (DPH) incorporated into lipid vesicles. C2-Ceramide induced a larger decrease in anisotropy than a detergent (Triton X-100) which is known to lyse membranes. C2-Dihydroceramide did not alter membrane fluidity. The ability of C2-ceramide to cause platelet fenestrations, formation of irregular platelet pseudopodia, platelet lysis, lipid vesicle leakage, and increases in the fluidity of lipid vesicles all suggest that C2-ceramide inhibits platelet aggregation because it destabilizes the platelet membrane. C2-Dihydroceramide did not inhibit platelet aggregation and lacked the nonspecific effects on membranes that C2-ceramide possessed, suggesting that C2-dihydroceramide is not an appropriate control for the nonspecific effects of C2-ceramide.     

Bias and bulimia nervosa: how typical are clinic cases?

OBJECTIVE: Since patients being treated for bulimia nervosa constitute only a minority of persons with the disorder, the cases seen in clinics may be subject to sampling bias. The aim of this study was to investigate sampling bias as it affects secondary referrals for bulimia nervosa. METHOD: The personal and family characteristics of a consecutive series of 60 women with secondary referrals for bulimia nervosa (clinic subjects) were compare with those of 83 subjects with bulimia who were recruited directly from the community. Most of the data were collected by interview. RESULTS: The demographic characteristics of the two groups were similar. The clinic subjects had a more severe eating disorder and much greater impairment of social functioning. There was no difference between the groups in duration of the eating disorder or level of general psychiatric disturbance. The community subjects were heavier and had stronger family histories of obesity. CONCLUSIONS: There is sampling bias among secondary referrals for bulimia nervosa. The relative absence of persons prone to obesity among secondary subjects is important, since there is evidence that vulnerability to obesity is a poor prognostic feature as well as being a risk factor for the development of bulimia nervosa. The greater social impairment among the clinic subjects is suggestive of greater personality disturbance in this group. Caution is warranted when generalizing from clinic cases to the disorder as a whole.     

Central venous pressure and cardiac function during spaceflight

Early in spaceflight, an apparently paradoxical condition occurs in which, despite an externally visible headward fluid shift, measured central venous pressure is lower but stroke volume and cardiac output are higher, and heart rate is unchanged from reference measurements made before flight. This paper presents a set of studies in which a simple three-compartment, steady-state model of cardiovascular function is used, providing insight into the contributions made by the major mechanisms that could be responsible for these events. On the basis of these studies, we conclude that, during weightless spaceflight, the chest relaxes with a concomitant shape change that increases the volume of the closed chest cavity. This leads to a decrease in intrapleural pressure, ultimately causing a shift of blood into the vessels of the chest, increasing the transmural filling pressure of the heart, and decreasing the central venous pressure. The increase in the transmural filling pressure of the heart is responsible, through a Starling-type mechanism, for the observed increases in heart size, left ventricular end-diastolic volume, stroke volume, and cardiac output.     

Purification and characterization of chlorite dismutase: a novel oxygen-generating enzyme

A novel enzyme that catalyzes the disproportionation of chlorite into chloride and oxygen was purified from a gram-negative bacterium, strain GR-1 to homogeneity. A four-step purification procedure comprising Q-Sepharose, hydroxyapatite, and phenyl-Superose chromatography and ultrafiltration resulted in a 13.7-fold purified enzyme with a final specific activity of 2.0 mmol min-1 (mg protein)-1. The dismutase obeyed Michaelis-Menten kinetics. The Vmax and Km calculated for chlorite were 2,200 U (mg protein)-1 and 170 microM, respectively. Dismutase activity was inhibited by hydroxylamine, cyanide, and azide, but not by 3-amino-1,2,4-triazole. Chlorite dismutase had a molecular mass of 140 kDa and consisted of four 32-kDa subunits. The enzyme was red-colored and had a Soret peak at 392 nm. Per subunit, it contained 0.9 molecule of protoheme IX and 0.7 molecule of iron. Chlorite dismutase displayed maxima for activity at pH 6.0 and 30 degrees C.     

Prostate carcinoma: transrectal US after cryosurgical ablation

The effects of denervation of central noradrenergic system on the interpartner relationships of adult cats were examined in a predatory test in the competitive situation for paired animals. Direct administration of the noradrenaline neurotoxin, N-2-chloroethyl-N-ethyl-2-bromobenzylamine (DSP-4 12 microg) into the medial forebrain bundle (MFB) of submissive cats changed previously established dominant-submissive relationship. Biochemical analysis demonstrated a significant reduction of noradrenaline (NA) concentration in the hypothalamus (AH), amygdala (AM), hippocampus (HC), and frontal cortex (CTX), and elevation of NA content in the midbrain central gray matter (CG) in MFB-lesioned cats. Simultaneously, DSP-4-induced lesions exerted significant decrease of 3-methoxy-4-hydroxyphenylethylene glycol (MHPG) content in AH, CG, HC and CTX, and increased GABA level in AH, CG, AM, and HC. These results suggest that a coincident decrease of NA metabolism and increase of GABA metabolism led to fear drive reduction.     

Persistent erythema and edema of the face associated with rosacea and lymph vessel dysplasia

A 24-year-old woman with lymph vessel dysplasia had experienced a progressive edema of her legs since her second year of life and progressive facial edema for the past year. She also had telangiectasias and papules on the background of a diffuse erythema as well as marked seborrhea on her face. Histopathological examination of a representative facial lesion revealed a granulomatous dermatitis with periadnexal distribution mainly consisting of lymphocytes and histiocytes. In addition, there was a moderate fibrosis of the dermis with numerous mast cells. By duplex ultrasound, a diagnosis of a massive edema of the legs without evidence for chronic venous insufficiency was made. The clinical and histopathological findings were consistent with solid persistent erythema and edema of the face associated with rosacea and lymph vessel dysplasia. The chronic course, absence of serological abnormalities and nonspecific histopathological features as well as resistance to therapy are the most important diagnostic criteria of this disease also known as Morbihan's disease.     

Congenital erythrocytosis with elevated erythropoietin level: an incorrectly set "erythrostat"?

It is well documented that IL-6 plays a critical role in B cell terminal differentiation, and in mucosal sites it stimulates proliferation and large-scale secretion of immunoglobulin by B cells, especially those committed to IgA production. The close juxtaposition of IL-6 mRNA+ cells to plasma cells in the intestinal lamina propria supports the proposition that IL-6 production in situ is an important factor determining the outcome of antibody responses at that site. However, it has not been established previously whether exogenous IL-6 could boost antibody responses in the intestine if administered with a challenge antigen. Using a resected gut loop (Thiry-Vella loop) model, we have been able to demonstrate that in mice with double loops, antibody containing cell responses to lumenal administration of ovalbumin were 50% greater in loops given intralumenal recombinant IL-6 with the challenge antigen, than in loops challenged with antigen alone. This demonstrates the efficacy of IL-6 in promoting accumulation of antibody secreting cells in the gut, and suggests a potential therapeutic role for IL-6 to enhance responses to mucosal vaccines.     

Synthesis, and in vitro and in vivo muscarinic pharmacological properties of a series of 1,6-dihydro-5-(4H)-pyrimidinone oximes

A series of 1,6-dihydro-5-(4H)-pyrimidinone oxime derivatives I was synthesized (Scheme 1, Tables 1 and 2) and tested for muscarinic activity (Table 3) in receptor binding assays using [3H]-oxotremorine-M (Oxo-M) and [3H]-pirenzepine (Pz) as ligands. Potential muscarinic agonistic or antagonistic properties of the compounds were determined using binding studies that measured their potencies to inhibit the binding of Oxo-M and Pz. Preferential inhibition of Oxo-M binding was used as an indicator for potential muscarinic agonistic properties; this potential was confirmed in functional studies on isolated organs. The series produced a wide range of active compounds with differing degrees of selectivity in M1, M2, and M3 functional models. Several compounds that have mixed agonist/antagonist profiles were able to reduce cholinergic-related cognitive impairments in models of mnemonic function. Substitutions (I, e.g. R2 or R3 = Me) at the 1,6-dihydro-5-(4H)pyrimidine ring disrupted binding and efficacy, whereas systematic variation of the oximes substituent R1 resulted in various degrees of potency and selectivity dependent on the nature of the substitution.     

The phosphorylation of eukaryotic initiation factor eIF4E in response to phorbol esters, cell stresses, and cytokines is mediated by distinct MAP kinase pathways

Initiation factor eIF4E binds to the 5'-cap of eukaryotic mRNAs and plays a key role in the mechanism and regulation of translation. It may be regulated through its own phosphorylation and through inhibitory binding proteins (4E-BPs), which modulate its availability for initiation complex assembly. eIF4E phosphorylation is enhanced by phorbol esters. We show, using specific inhibitors, that this involves both the p38 mitogen-activated protein (MAP) kinase and Erk signaling pathways. Cell stresses such as arsenite and anisomycin and the cytokines tumor necrosis factor-alpha and interleukin-1beta also cause increased phosphorylation of eIF4E, which is abolished by the specific p38 MAP kinase inhibitor, SB203580. These changes in eIF4E phosphorylation parallel the activity of the eIF4E kinase, Mnk1. However other stresses such as heat shock, sorbitol, and H2O2, which also stimulate p38 MAP kinase and increase Mnk1 activity, do not increase phosphorylation of eIF4E. The latter stresses increase the binding of eIF4E to 4E-BP1, and we show that this blocks the phosphorylation of eIF4E by Mnk1 in vitro, which may explain the absence of an increase in eIF4E phosphorylation under these conditions.