Modulation of Whole-Cell Currents in Plasmodium Falciparum-Infected Human Red Blood Cells by Holding Potential and Serum

Recent electrophysiological studies have identified novel ion channel activity in the host plasma membrane of Plasmodium falciparum -infected human red blood cells (RBCs). However, conflicting data have been published with regard to the characteristics of induced channel activity measured in the whole-cell configuration of the patch-clamp technique. In an effort to establish the reasons for these discrepancies, we demonstrate here two factors that have been found to modulate whole-cell recordings in malaria-infected RBCs. Firstly, negative holding potentials reduced inward currents (i.e. at negative potentials), although this result was highly complex. Secondly, the addition of human serum increased outward currents (i.e. at positive potentials) by approximately 4-fold and inward currents by approximately 2-fold. These two effects may help to resolve the conflicting data in the literature, although further investigation is required to understand the underlying mechanisms and their physiological relevance in detail.     

Amplified region of chromosome band 11q13 in breast and squamous cell carcinomas encompasses three CpG islands telomeric of FGF3, including the expressed gene EMS1

DNA markers that map within the karyotypically defined band q13 on human chromosome 11 are amplified in a subset of mammary and squamous cell carcinomas. It is assumed that the amplified DNA includes a critical gene (or genes) whose overexpression provides a selective force in the development of the tumor. To help identify such genes, we have begun to construct a physical map of CpG islands in the region, making use of a squamous cell carcinoma cell line (UMSCC2) in which the 11q13 region is amplified 11-fold. We previously described the proximal end of this amplicon and the order of markers extending ～800 kb centromeric of the FGF3 locus (formerly INT2). We now report the use of chromosome jumping techniques to define additional CpG islands that lie distal to FGF3. These map within the amplified region in UMSCC2 cells and the most telomeric corresponds to the EMS1 gene. The data imply that the amplified DNA in UMSCC2 cells extends for over 1,500 kb and includes at least 7 potential genes. EMS1 and CCND1 (formerly PRAD1), the best candidates for the key gene on the 11q13 amplicon, are ≥800 kb apart. © 1993 Wiley-Liss, Inc.     

Low-Dose ATG/GCSF in Established Type 1 Diabetes: A Five-Year Follow-up Report

Previously, we demonstrated low-dose antithymocyte globulin (ATG) and granulocyte colony-stimulating factor (GCSF) immunotherapy preserved C-peptide for 2 years in a pilot study of patients with established type 1 diabetes (n = 25). Here, we evaluated the long-term outcomes of ATG/GCSF in study participants with 5 years of available follow-up data (n = 15). The primary end point was area under the curve (AUC) C-peptide during a 2-h mixed-meal tolerance test. After 5 years, there were no statistically significant differences in AUC C-peptide when comparing those who received ATG/GCSF versus placebo (P = 0.41). A modeling framework based on mean trajectories in C-peptide AUC over 5 years, accounting for differing trends between groups, was applied to recategorize responders (n = 9) and nonresponders (n = 7). ATG/GCSF reponders demonstrated nearly unchanged HbA_1c over 5 years (mean [95% CI] adjusted change 0.29% [–0.69%, 1.27%]), but the study was not powered for comparisons against nonresponders 1.75% (–0.57%, 4.06%) or placebo recipients 1.44% (0.21%, 2.66%). These data underscore the importance of long-term follow-up in previous and ongoing phase 2 trials of low-dose ATG in recent-onset type 1 diabetes.     

The effect of an inhibitor of adenylate cyclase on the development of pyrogen,prostaglandin and cyclic AMP fevers in the rabbit

Summary An exotoxin of Bacillus thuringiensis known to inhibit adenylate cyclase in vitro has been used to investigate the role of cyclic AMP in the pathogenesis of fever in the rabbit. Intra-hypothalamic microinjections of the exotoxin are non-pyrogenic and significantly attenuate the hyperthermia caused by intrahypothalamic microinjections of both bacterial pyrogen (endotoxin) and prostaglandin E₁. The hyperthermia produced by dibutyryl cyclic AMP is not affected by the exotoxin. These results support the idea that adenylate cyclase is activated during the development of fever in the rabbit.     

Direct cardiac and vascular actions of adrenomedullin in conscious sheep

1. Adrenomedullin (ADM) is a recently characterized circulating hormone which affects haemodynamic, renal and pituitary function in mammals. We have shown previously that in sheep, ADM produces vasodilatation together with increases in cardiac output and contractility. However, whether these effects are direct or mediated by autonomic reflexes is unclear. The present study examined the cardiovascular actions of an intravenous infusion of ADM in conscious, chronically instrumented sheep with either sympathetic, parasympathetic or autonomic ganglion blockade, to determine the role of the autonomic nervous system in mediating these cardiovascular changes.
2. Human ADM (1–52) was infused for 60 min at 2 μg kg⁻¹ h⁻¹ following: (1) saline control, (2) combined α/β-adrenoceptor (sympathetic) blockade (proporanolol 0.4 mg kg⁻¹ h⁻¹+phentolamine 0.15 mg kg⁻¹ h⁻¹ for 20 h), (3) muscarinic (parasympathetic) blockade (methscopolamine 0.05 mg kg⁻¹ h⁻¹ for 20 h) or (4) ganglion blockade (hexamethonium 3 mg kg⁻¹ h⁻¹ for 4 h). Measurements were made of mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), stroke volume (SV), total peripheral conductance (TPC), maximal aortic flow (Fmax) and maximal rate of change of aortic flow (dF/dt).
3. ADM reduced MAP by 3±1 mmHg, and increased CO (1.2±0.2 l min⁻¹), HR (14±2 beats min⁻¹), TPC (21±3 ml min⁻¹ mmHg⁻¹), Fmax (2.3±0.8 l min⁻¹) and dF/dt (86±21 l min⁻¹ s⁻¹) in normal sheep. In animals with α/β blockade, similar changes were observed with ADM. However, during muscarinic blockade, the increases in HR (32±4 beats min⁻¹), CO (2.1±0.4 l min⁻¹), TPC (31±4 ml min⁻¹ mmHg⁻¹), Fmax (4.0±0.6 l min⁻¹), and dF/dt (150±12 l min⁻¹ s⁻¹) produced by ADM were enhanced. During ganglion blockade, ADM produced a greater reduction in MAP (−10±2 mmHg) compared to controls (−3±1 mmHg). However, there was no increase in HR. The changes in CO, TPC and contractility were similar to those observed in control animals.
4. These results suggest that the vasodilator effects of ADM on the periphery and its ability to increase CO and cardiac contractility are not mediated by the autonomic nervous system, but are probably the result of direct actions of ADM on the heart and vasculature.