Vascular smooth muscle cell growth kinetics in vivo in aged rats.

Age is a risk factor in the development of atherosclerosis. In this study we investigated the hypothesis that proliferation of vascular smooth muscle cells (SMCs), an integral part of atherosclerotic plaque formation, changes with age. SMC growth kinetics of old rats (21-24 months) were compared to those of young adult rats (3-4 months). Rat aortas were denuded of their endothelium and the animals were killed after [3H]thymidine and Evans blue injections at 0-28 days after denudation. Incorporation of [3H]thymidine into SMC peaked in the young animals by day 2, whereas the older animals responded to endothelial removal with greater incorporation at day 2 and a more sustained rate of incorporation peaking at day 4. The [3H]thymidine incorporation curves decreased sharply from their peaks at 2 and 4 days, respectively, and paralleled each other after day 7. [3H]Thymidine uptake reflected the subsequent SMC intimal growth as measured morphometrically, with old animals showing greater numbers of intimal SMC than did the younger animals. The difference in response of SMC to injury with age suggests that aging produces a change in the vascular SMC that enhances proliferation. This change in response implies that the more pronounced atherosclerotic plaque growth seen with aging may be a result of an age-related increase in response to injury rather than merely the accumulation of time-related intimal change.     

Potentiation of purified erythropoietin with serum proteins

• 1 Non-neutralizing antiserum, normal rabbit, human and mouse sera potentiate the erythropoietic activity of anaemic human urinary Fraction II + III. This substantiates the concepts introduced by Kuratowska, Lewartowski and Lipinski.
• 2 Orosomucoid (alpha-1 acidic-glycoprotein) similarly potentiates the erythropoietic activity of anaemic human urinary Fraction II + III.
• 3 The erythropoietic activity of Standard B was not enhanced by the addition of serum proteins.
• 4 The erythropoietic activity of human urinary concentrates was enhanced by the addition of normal serum proteins and suggestive enhancement of anaemic human serum and plasma was noted.

     

Inhibition of interleukin 1 beta induced rat and human cartilage degradation in vitro by the metalloproteinase inhibitor U27391.

Interleukin 1 induced proteoglycan loss from cartilage in vitro was prevented by a biochemical inhibitor of metalloproteinase activity. The inhibitor also partially relieved the inhibition of proteoglycan synthesis caused by interleukin 1. The loss of glycosaminoglycan by rat and human femoral head cartilage in response to human recombinant interleukin 1 beta (rhIL-1 beta) was established, and the modulation of this loss by the metalloproteinase inhibitor U27391 was investigated. Rat femoral head cartilage consistently lost glycosaminoglycan in response to rhIL-1 beta whereas only a proportion (30%) of normal human femoral head cartilage did so. Concentrations of 10-100 mumol/l U27391 inhibited the action of rhIL-1 beta on rat femoral head cartilage, reversing both the loss of glycosaminoglycan and the inhibition of glycosaminoglycan synthesis. U27391 also prevented the reduction in glycosaminoglycan content of those human femoral head cartilage explants responsive to rhIL-1 beta. Metalloproteinase inhibition therefore prevents rhIL-1 beta induced glycosaminoglycan loss by rat and human femoral head cartilage, suggesting that inhibitors of such enzymes may prove to be of therapeutic benefit in erosive diseases in humans.     

Immunogenicity of a vaccine preparation representing the variable regions of the HIV type 1 envelope glycoprotein

Variability of the major antigenic sites of the envelope glycoprotein of HIV-1 constitutes a major problem in the formulation of effective vaccines. We have prepared a synthetic peptide vaccine that represents the major hypervariable epitopes (V1 through V5) of the clade B HIV-1 envelope glycoprotein (gp120). We refer to this preparation as variable epitope immunogen or VEI vaccine. This construct takes into consideration the type and frequency of amino acid substitutions found at each epitope during the evolution of the virus in individual patients and in the target population. Immunization of mice, rabbits, and rhesus macaques with the VEI vaccine resulted in the induction of long-lasting, high-titered HIV-1 antibodies, including antibodies that neutralize primary isolates. We also documented lymphocyte proliferative responses to the VEI vaccine, its individual components, analogs, and subtype-specific peptides representing the major hypervariable regions of HIV-1 gp120. Delayed-type hypersensitivity responses to these antigens were also demonstrated in mice. Our results show that this vaccine is highly immunogenic and safe in animals. Our data suggest that this formulation could become an important component of combination vaccine approaches against HIV-1 and other antigenically variable pathogens.     

Who Benefits From a Defibrillator—Balancing the Risk of Sudden Versus Non-sudden Death

Purpose of Review

Treatment with a defibrillator can reduce the risk of sudden death by terminating ventricular arrhythmias. The identification of patient groups in whom this function reduces overall mortality is challenging. In this review, we summarise the evidence for who benefits from a defibrillator.

Recent Findings

Recent evidence suggests that contemporary pharmacologic and non-defibrillator device therapies are altering the potential risks and benefits of a defibrillator.

Summary

Who benefits from a defibrillator is determined by both the risk of sudden death and the competing risk of other, non-sudden causes of death. The balance of these risks is changing, which calls into question whether historic evidence for the use of defibrillators remains robust in the modern era.

     

Interaction of physalaemin, substance P, and eledoisin with specific membrane receptors on pancreatic acinar cells.

We have prepared 125I-labeled physalaemin and have examined the kinetics, stoichiometry, and chemical specificity with which the labeled peptide binds to dispersed acini from guinea pig pancreas. Binding of 125I-labeled physalaemin was saturable, temperature-dependent, and reversible and reflected interaction of the labeled peptide with a single class of binding sites on the plasma membrane of pancreatic acinar cells. Each acinar cell possessed approximately 500 binding sites, and binding of the tracer to these sites could be inhibited by physalaemin [concentration for half-maximal effect (Kd), 2 nM], substance P (Kd, 5 nM), or eledoisin (Kd, 300 nM) but not by cholecystokinin, caerulein, bombesin, litorin, gastrin, secretin, vasoactive intestinal peptide, glucagon, somatostatin, neurotensin, bovine pancreatic polypeptide, leucine-enkephalin, methionine-enkephalin, atropine, or carbamylcholine. With physalaemin, substance P, and eledoisin, there was a close correlation between the relative potency for inhibition of binding of labeled physalaemin and that for stimulation of amylase secretion. For a given peptide, however, a 3-fold higher concentration was required for half-maximal inhibition of binding than for half-maximal stimulation of amylase secretion, calcium outflux, or cyclic GMP accumulation. These results indicate that dispersed acini from guinea pig pancreas possess a single class of receptors that interact with physalaemin, substance P, and eledoisin and that occupation of 45% of these receptors will cause a maximal biological response.     

The U3 portion of feline leukemia virus DNA identifies horizontally acquired proviruses in leukemic cats.

The presence and location of DNA sequences related to the U3 and U5 portions of the infectious exogenous feline leukemia virus (FeLV) long terminal repeat (LTR) in various cat DNAs have been determined by hybridization experiments. In uninfected cat DNAs, the U5 LTR segment from the Gardner-Arnstein strain B virus is present at approximately 150 copies per cell. This level is approximately 10-fold greater than that of endogenous internal FeLV sequences. The U5 sequences differ in copy number and, to some extent, in location from one animal to another. For any one animal, the sequence organization of the U5 segments is the same among different tissues, showing that the pattern is inherited through the germ line. Most importantly, the viral U3 LTR probe hybridizes only very weakly with uninfected cat DNAs. Both the U3 and the U5 regions of the LTR from the Gardner-Arnstein strain of virus cross-hybridize with DNA derived from four other infectious FeLVs representing A, B, and C subtypes. Thus, the C3 region may be used as a probe for studying the number and location of exogenously acquired FeLV proviruses in infected cat tissues. In some cases exogenously acquired proviruses are present in unique sites in the genome of virus-positive cat lymphosarcomas, indicating a monoclonal origin for the tumor. In other tumors, the proviral sequences are randomly distributed over many sites. Lymphosarcomas of virus-negative cats have no exogenous U3 sequences despite epidemiological evidence of an association of virus-negative leukemia with exposure to FeLV.