Effect of clofibrate on arginine-stimulated glucagon and insulin secretion in man

Insulin and glucagon have been reported to have opposing effects upon the mechanisms regulating serum triglyceride concentration. Glucagon in excess of insulin will lower serum lipids in man. In the present studies, we have examined the possibility that a change in glucagon and insulin regulation might contribute to the hypolipemic action of the drug clofibrate. Control insulin and glucagon secretion were evaluated in 24 normal subjects by intravenous arginine infusion, which resulted in a prompt rise in both serum immunoreactive insulin and glucagon concentration. During the maximum rise in concentration of these hormones, plasma triglyceride concentration was acutely reduced from basal levels of $\text{104 ± 6}\text{mg}\text{100}\text{ml}$ to $\text{75 ± 5}\text{mg}\text{100}\text{ml}$ (p ≤ 0.001). Following 7 days of clofibrate therapy, basal plasma triglyceride concentration attained a new mean level of $\text{78 ± 5}\text{mg}\text{100}\text{ml}$, while basal insulin and glucagon concentrations remained unchanged. However, arginine infusion now resulted in a reduction of the insulin secretory response to 56% of the preclofibrate studies with an associated normal glucagon secretory response. Serum triglyceride concentration was further reduced during arginine infusion to $\text{46 ± 3}\text{mg}\text{100}\text{ml}$, demonstrating this minimum level as maximum plasma glucagon levels were attained, representing an excess of this hormone relative to the reduced insulin concentration. These observations are consistent with an effect of clofibrate on the hormonal regulation of triglyceride physiology in man. Glucose tolerance was unimpaired by clofibrate therapy in these normal subjects, in spite of an apparent reduction in glucose-stimulated insulin secretion.     

von Willebrand disease R1374C: Type 2A or 2M? A challenge to the revised classification. High frequency in the northwest of Spain (Galicia)

Patients initially diagnosed with type 1 von Willebrand disease (VWD) have been reclassified as type 2 after a more exhaustive analysis in several studies. Our study's objectives were (1) to reanalyze patients that were previously diagnosed as type 1 to achieve a more accurate diagnosis and (2) to compare the von Willebrand factor (VWF) ristocetin cofactor assay (VWF:RCo) and the VWF collagen binding assay (VWF:CB) in order to evaluate the possibility of replacing the former assay with the latter in the diagnosis of VWD. Twenty-one patients from two large unrelated families and 104 normal controls were studied. VWF:Ag, VWF:RCo, FVIII coagulant activity (FVIII:C), bleeding time (BT), PFA(100), and multimeric analysis of VWF were tested. Genetic analysis by sequencing exon 28 on the VWF gene was also carried out. Patients presented lower levels of VWF:Ag and VWF:RCo, a dissociation between VWF:RCo/VWF:Ag, and the presence of all sizes of multimers in plasma VWF. The results for VWF:CB varied depending on the type of collagen used. The genetic analysis showed that the mutation R1374C is responsible for type 2M VWD. A high frequency of the R1374C mutation is observed in northwestern Spain (Galicia). Some types of 2M VWD are misdiagnosed as type 1 VWD. The VWF:CB (with type I collagen) assay was unable to discriminate defective platelet binding of the R1374C VWF. This confirms that VWF:CB cannot substitute for VWF:RCo, and both should be tested when diagnosing VWD.     

Anti-HPA-1a-mediated platelet phagocytosis by monocytes in vitro and its inhibition by Fc gamma receptor (FcgammaR) reactive reagents

The study was undertaken to delineate mechanisms of platelet destruction by phagocytosis during fetal/neonatal alloimmune thrombocytopenia (FAIT/NAIT) because of maternal antibodies against human platelet antigen 1a (HPA-1a). By employing a platelet phagocytosis assay based on the ORPEGEN flow cytometric bacterial phagocytosis test, we measured monocyte ingestion of platelets mediated by anti-HPA-1a antibodies. Moreover, we tested, as potential therapeutic agents, FcgammaR reactive reagents, for their inhibition of this process. Four of six anti-HPA-1a sera tested mediated phagocytosis of HPA-1a-positive platelets in a concentration-dependent manner. Monocyte ingestion of platelets was almost completely inhibited by cytochalasin D. No anti-HPA-1a-mediated phagocytosis was observed with anti-HPA-1a-negative platelets. The humanised anti-FcgammaRI monoclonal antibody H22 at concentrations 1-100 microg/ml, completely inhibited anti-HPA-1a-mediated phagocytosis as did similar concentrations of ivIg. By contrast, a mouse monoclonal anti-FcgammaRII (IV.3, Fab) at 10 microg/ml caused little or no suppression of platelet phagocytosis mediated by two anti-HPA-1 sera. Furthermore, the addition of anti-FcgammaRII (10 microg/ml) to sub-optimal concentrations of H22 did not significantly increase the inhibitory effect of the latter compound. Monomeric IgG (0.1-10 microg/ml) failed to suppress anti-HPA-1 mediated platelet ingestion by the phagocytes, as did anti-FcgammaRIII. To our knowledge this is a rare example of an assay that measures platelet phagocytosis in vitro. The results suggest that FcgammaRI plays a major role in anti-HPA-1a-mediated platelet phagocytosis by monocytes while FcgammaRIIa, is of little or minor importance only. Moreover, the findings indicate the use of H22 as an alternative to interavenous Ig (ivIg) in the management of FAIT/NAIT.     

The association of fixed and dynamic left ventricular outflow obstruction.

Twelve patients were investigated echocardiographically and angiographically and were shown to have severe fixed obstruction to the left ventricular outflow tract. Eight had valvular stenosis, and four had discrete subvalvular membranes. Two of the patients had additional dynamic obstruction of the left ventricular outflow tract. This was recognized preoperatively by echocardiography because of abnormal systolic motion of the mitral leaflet. At the time of definitive surgery for relief of the fixed obstruction, the additional dynamic obstruction was identified and treated, since persistent residual obstruction may lead to death in the immediate postoperative period or to long-term symptoms. The dynamic left ventricular outflow obstruction is probably a result of the hypertrophy produced by the fixed obstruction.     

Echocardiographic diastolic ventricular abnormality in hypertensive heart disease: Atrial emptying index

To analyze changes in left ventricular diastolic properties in hypertensive heart disease, the atrial emptying index was used to assess the rapid phase of diastolic filling of the left ventricle. Ten normal subjects (Group 1), 11 hypertensive patients without evidence of cardiac involvement (Group 2) and 10 hypertensive patients with echocardiographic evidence of left ventricular hypertrophy (Group 3) were compared using M mode echocardiography and systemic hemodynamic data. Where as cardiac index (dye-dilution method) and rate of circumferential fiber shortening (echocardiogram) were normal in all three groups, there was a progressive increase in left atrial index (p <0.001, Group 1 versus Group 2 and versus Group 3) and a progressive decrease in the atrial emptying index (p <0.001, Group 1 versus Group 2 and versus Group 3). No correlation existed between the atrial emptying index and the left atrial index, mean arterial pressure or total peripheral resistance in any of the three groups. These data suggest that rapid filling of the left ventricle is reduced early in hypertension, even before electrocardiographic or systolic echocardiographic abnormalities are detectable. The atrial emptying index therefore appears to be an early indicator of abnormalities of left ventricular diastolic compliance in uncomplicated hypertension.     

Successful treatment of drug-resistant atrial tachycardia and intractable congestive heart failure with permanent coupled atrial pacing

Temporary coupled atrial stimulation slowed the ventricular rate by nearly 50% in an adolescent patient with intractable congestive heart failure and focal repetitive atrial tachycardia that was resistant to drug treatment. Because of the success with the temporary pacemaker, a specially designed permanent pacemaker was implanted to provide coupled atrial stimulation. The necessary electrophysiologic conditions for ventricular slowing by coupled atrial pacing are: (1) an atrial effective refractory period shorter than that of the atrioventricular junction, and (2) depolarization of the ectopic atrial pacemaker by the responses to coupled atrial stimulation. During a 4 year follow-up period the treatment resulted in elimination of the tachycardia, followed by return of the heart size to normal and complete clinical recovery. Coupled atrial stimulation can provide effective treatment in selected patients with disabling drug-resistant atrial tachycardia in whom this mode of therapy is shown to be effective by careful electrophysiologic studies.     

Individual patient risk stratification of high‐risk neuroblastomas using a two‐gene score suited for clinical use

Several gene expression‐based prognostic signatures have been described in neuroblastoma, but none have successfully been applied in the clinic. Here we have developed a clinically applicable prognostic gene signature, both with regards to number of genes and analysis platform. Importantly, it does not require comparison between patients and is applicable amongst high‐risk patients. The signature is based on a two‐gene score (R‐score) with prognostic power in high‐stage tumours (stage 4 and/or MYCN‐amplified diagnosed after 18 months of age). QPCR‐based and array‐based analyses of matched cDNAs confirmed cross platform (array‐qPCR) transferability. We also defined a fixed cut‐off value identifying prognostically differing subsets of high‐risk patients on an individual patient basis. This gene expression signature independently contributes to the current neuroblastoma classification system, and if prospectively validated could provide further stratification of high‐risk patients, and potential upfront identification of a group of patients that are in need of new/additional treatment regimens.     

Soluble IL6R represents a miR-34a target: potential implications for the recently identified IL-6R/STAT3/miR-34a feed-back loop

We previously reported that IL-6R, STAT3 and miR-34a form a positive feedback-loop, which promotes epithelial to mesenchymal transition (EMT), invasion, and metastasis of colorectal cancer (CRC) [1]. In that study only the membrane-bound form of the IL-6R was shown to be repressed by miR-34a. Here, we show that also the mRNA encoding the soluble IL6R (s-IL-6R) is directly targeted and repressed by miR-34a. Accordingly, the concentration of s-IL6R protein was decreased in conditioned media of CRC cell lines ectopically expressing miR-34a. The s-IL-6R mediates IL-6 trans-signaling, which also affects cells that do not express the IL-6R. Since IL-6 trans-signaling is involved in numerous inflammatory disease states these findings may be relevant for future therapeutic approaches.