A complex four-point method for the evaluation of ohmic and faradaic losses within a redox flow battery single-cell

We propose a complex 4-point method for characterization of flow batteries. The distribution of ohmic and faradaic losses within a single-cell is evaluated from electrochemical impedance spectra and load curves of positive and negative half-cells measured with platinum wire pseudo-reference electrodes positioned in respective electrode compartment. The developed method can be used e.g., for the component screening and in-situ durability studies on single-cell scale. The method was validated on a vanadium redox flow battery single-cell; however, it can be analogically employed for various chemistries of flow battery. •Complex 4-point method for characterization of flow battery single-cell was developed.•Method is based on electrochemical impedance spectra and load curve measurements.•Direct evaluation of ohmic and faradaic losses distribution within battery single-cell by the method.

Cereblon modulator iberdomide induces degradation of the transcription factors Ikaros and Aiolos: immunomodulation in healthy volunteers and relevance to systemic lupus erythematosus

OBJECTIVES

IKZF1 and IKZF3 (encoding transcription factors Ikaros and Aiolos) are susceptibility loci for systemic lupus erythematosus (SLE). The pharmacology of iberdomide (CC-220), a cereblon (CRBN) modulator targeting Ikaros and Aiolos, was studied in SLE patient cells and in a phase 1 healthy volunteer study.

METHODS

CRBN, IKZF1 and IKZF3 gene expression was measured in peripheral blood mononuclear cells (PBMC) from patients with SLE and healthy volunteers. Ikaros and Aiolos protein levels were measured by Western blot and flow cytometry. Anti-dsDNA and anti-phospholipid autoantibodies were measured in SLE PBMC cultures treated for 7 days with iberdomide. Fifty-six healthy volunteers were randomised to a single dose of iberdomide (0.03-6 mg, n=6 across seven cohorts) or placebo (n=2/cohort). CD19+ B cells, CD3+ T cells and intracellular Aiolos were measured by flow cytometry. Interleukin (IL)-2 and IL-1β production was stimulated with anti-CD3 and lipopolysaccharide, respectively, in an ex vivo whole blood assay.

RESULTS

SLE patient PBMCs expressed significantly higher CRBN (1.5-fold), IKZF1 (2.1-fold) and IKZF3 (4.1-fold) mRNA levels compared with healthy volunteers. Iberdomide significantly reduced Ikaros and Aiolos protein levels in B cells, T cells and monocytes. In SLE PBMC cultures, iberdomide inhibited anti-dsDNA and anti-phospholipid autoantibody production (IC50 ≈10 nM). Single doses of iberdomide (0.3-6 mg) in healthy volunteers decreased intracellular Aiolos (minimum mean per cent of baseline: ≈12%-28% (B cells); ≈0%-33% (T cells)), decreased absolute CD19+ B cells, increased IL-2 and decreased IL-1β production ex vivo.

CONCLUSIONS

These findings demonstrate pharmacodynamic activity of iberdomide and support its further clinical development for the treatment of SLE.

TRIAL REGISTRATION NUMBER

NCT01733875; Results.

Aiolos Overexpression in Systemic Lupus Erythematosus B Cell Subtypes and BAFF-Induced Memory B Cell Differentiation Are Reduced by CC-220 Modulation of Cereblon Activity

BAFF is a B cell survival and maturation factor implicated in the pathogenesis of systemic lupus erythematosus (SLE). In this in vitro study, we describe that soluble BAFF in combination with IL-2 and IL-21 is a T cell contact-independent inducer of human B cell proliferation, plasmablast differentiation, and IgG secretion from circulating CD27⁺ memory and memory-like CD27^-IgD^- double-negative (DN) B cells, but not CD27^-IgD⁺ naive B cells. In contrast, soluble CD40L in combination with IL-2 and IL-21 induces these activities in both memory and naive B cells. Blood from healthy donors and SLE patients have similar circulating levels of IL-2, whereas SLE patients exhibit elevated BAFF and DN B cells and reduced IL-21. B cell differentiation transcription factors in memory, DN, and naive B cells in SLE show elevated levels of Aiolos, whereas Ikaros levels are unchanged. Treatment with CC-220, a modulator of the cullin ring ligase 4-cereblon E3 ubiquitin ligase complex, reduces Aiolos and Ikaros protein levels and BAFF- and CD40L-induced proliferation, plasmablast differentiation, and IgG secretion. The observation that the soluble factors BAFF, IL-2, and IL-21 induce memory and DN B cell activation and differentiation has implications for extrafollicular plasmablast development within inflamed tissue. Inhibition of B cell plasmablast differentiation by reduction of Aiolos and Ikaros may have utility in the treatment of SLE, where elevated levels of BAFF and Aiolos may prime CD27⁺ memory and DN memory-like B cells to become Ab-producing plasmablasts in the presence of BAFF and proinflammatory cytokines.

Phosphodiesterase 4 in inflammatory diseases: Effects of apremilast in psoriatic blood and in dermal myofibroblasts through the PDE4/CD271 complex

Phosphodiesterases 4 (PDE4) act as proinflammatory enzymes via degradation of cAMP, whereas PDE4 inhibitors play an anti-inflammatory role in vitro and in vivo. In particular, apremilast has been recently approved for the treatment of psoriasis and psoriatic arthritis. However, little is known on the expression pattern of PDE4 in psoriasis. We report that PDE4B and PDE4D mRNA are overexpressed in peripheral blood mononuclear cells (PBMC) from psoriasis, as compared with normal controls, while apremilast reduces PBMC production of a number of pro-inflammatory cytokines and increases the levels of anti-inflammatory mediators. PDE4 expression is up-regulated in psoriatic dermis as compared with normal skin, with particular regard to fibroblasts. This is confirmed in vitro, where both dermal fibroblasts (DF) and, to a greater extent, myofibroblasts (DM) express all PDE4 isoforms at the mRNA and protein level. Because PDE4 interacts with the nerve growth factor (NGF) receptor CD271 in lung fibroblasts, we evaluated the relationship and function of PDE4 and CD271 in normal human skin fibroblasts. All PDE4 isoforms co-immunoprecipitate with CD271 in DM, while apremilast inhibits apoptosis induced by β-amyloid, a CD271 ligand, in DM. Furthermore, apremilast significantly reduces NGF- and transforming growth factor-β1 (TGF-β1)-induced fibroblast migration, and inhibits DF differentiation into DM mediated by NGF or TGF-β1. Finally, in DM, apremilast significantly reduces cAMP degradation induced by treatment with β-amyloid. Taken together, these results indicate that PDE4 play an important role in psoriasis. In addition, the study reveals that the PDE4/CD271 complex could be important in modulating fibroblast functions.

Development of a tonometric sensor for measurement and recording of arterial pressure waveform

There are many techniques and devices for measurement and recording of arterial blood pressure. Some of them allow (enable) additionally to observe the shape of a wave of arterial pressure, which can be regarded as one of the most important diagnostic parameters of human cardiovascular system. This paper presents a novel design and prototype of a new, non-invasive blood waveform measuring device. It expounds theoretical and experimental (including latest preliminary clinical) results obtained during several years of extensive investigations into blood pressure waveform measuring and monitoring problem. According to investigations performed in the laboratory and preliminary clinical evaluation, the sensor has linear steady-state characteristics and satisfactory dynamic properties. It is an efficient and accurate tool for blood pressure waveform monitoring and assessing the cardiovascular condition of the patients. The novelty of this solution is that the device is equipped with a pneumatic pressure sensor based on the pneumatic nozzle flapper amplifier principle with negative feedback. Due to such a technical solution, the device does not require any cuff, which remains an essential component of the majority of contemporary non-invasive blood pressure measurement devices; therefore, it can be used on the artery where the application of a cuff would be impossible (e.g., carotid artery). This advantage makes possible to obtain an accurate shape of blood pressure waveform with high fidelity, comparable to a direct measurement method. Moreover, during the measurement the device converts directly "pressure into pressure." Such a principle of operation makes possible to eliminate additional calibration (at the current stage of research we have eliminated the necessity of calibration in laboratory conditions).

Lenalidomide efficacy in activated B-cell-like subtype diffuse large B-cell lymphoma is dependent upon IRF4 and cereblon expression

Durable responses with lenalidomide monotherapy have been reported in patients with non-Hodgkin lymphoma. In relapsed/refractory diffuse large B-cell lymphoma (DLBCL), higher responses were observed in the activated B-cell-like (ABC) subtype than in the germinal centre B-cell-like subtype. Herein, the molecular mechanisms involved in the differential efficacy of lenalidomide in DLBCL subtypes were investigated. Using DLBCL cell lines, lenalidomide treatment was found to preferentially suppress proliferation of ABC-DLBCL cells in vitro and delay tumour growth in a human tumour xenograft model, with minimal effect on non-ABC-DLBCL cells. This tumouricidal effect was associated with downregulation of interferon regulatory factor 4 (IRF4), a hallmark of ABC-DLBCL cells. IRF4 inhibition by lenalidomide induced downregulation of B-cell receptor (BCR)-dependent NF-κB. Whereas IRF4-specific small, interfering RNA mimicked the effects of lenalidomide reducing NF-κB activation, IRF4 overexpression enhanced NF-κB activation and conferred resistance to lenalidomide. These findings indicate the crucial role of IRF4 inhibition in lenalidomide efficacy in ABC cells. Furthermore, lenalidomide-induced IRF4 downregulation required the expression of cereblon, a molecular target of lenalidomide. Taken together, these findings suggest that lenalidomide has direct antitumour activity against DLBCL cells, preferentially ABC-DLBCL cells, by blocking IRF4 expression and the BCR-NF-κB signalling pathway in a cereblon-dependent manner.

Absorption, metabolism and excretion of [14C]pomalidomide in humans following oral administration

Purpose

To investigate the pharmacokinetics and disposition of [¹⁴C]pomalidomide following a single oral dose to healthy male subjects.

Methods

Eight subjects were administered a single 2 mg oral suspension of [¹⁴C]pomalidomide. Blood (plasma), urine and feces were collected. Mass balance of radioactivity and the pharmacokinetics of radioactivity, pomalidomide and metabolites were determined. Metabolite profiling and characterization was performed. The enzymes involved in pomalidomide metabolism and the potential pharmacological activity of metabolites were evaluated in vitro.

Results

Mean recovery was 88 %, with 73 and 15 % of the radioactive dose excreted in urine and feces, respectively, indicating good oral absorption. Mean C_max, AUC_0−∞ and t_max values for pomalidomide in plasma were 13 ng/mL, 189 ng*h/mL and 3.0 h. Radioactivity and pomalidomide were rapidly cleared from circulation, with terminal half-lives of 8.9 and 11.2 h. Pomalidomide accounted for 70 % of the circulating radioactivity, and no circulating metabolite was present at >10 % of parent compound. Pomalidomide was extensively metabolized prior to excretion, with excreted metabolites being similar to those observed in circulation. Clearance pathways included cytochrome P450-mediated hydroxylation with subsequent glucuronidation (43 % of the dose), glutarimide ring hydrolysis (25 %) and excretion of unchanged drug (10 %). 5-Hydroxy pomalidomide, the notable oxidative metabolite, was formed primarily via CYP1A2 and CYP3A4. The hydroxy metabolites and hydrolysis products were at least 26-fold less pharmacologically active than pomalidomide in vitro.

Conclusions

Following oral administration, pomalidomide was well absorbed, with parent compound being the predominant circulating component. Pomalidomide was extensively metabolized prior to excretion, and metabolites were eliminated primarily in urine.

Nonlinear behaviour of simple ionic systems in hydrogel in an electric field

The stationary behavior of ionic reaction-transport systems contained in hydrogel located between two reservoirs of electrolytes is investigated. The effects of the applied voltage, the composition of the electrolytes in the reservoirs and the distribution of fixed charge in the hydrogel on the spatial patterns of charge, electric potential, temperature and concentrations of the individual components are studied systematically by mathematical modelling. Such systems, containing only several ions (for example, Cl-, K+, OH- and H+) can function as electrolyte diodes and transistors and can exhibit oscillations and hysteresis. The mathematical description of the studied systems is based on balances of species, enthalpy and charge, on Poisson's equation and on the finite rate description of the water dissociation/recombination reaction, without assuming local electroneutrality. The modeling results are compared with experiments, including the system with hydrogel connecting reservoirs of strong base and acid studied by Noszticzius and co-workers. [L.H. Hegedus, N. Kirschner, M. Wittmann and Z. Noszticzius, J. Phys. Chem. A, 1998, 102, 6491 (ref. 1); L. H. Hegedus, N. Kirschner, M. Wittmann, P. Simon and Z. Noszticzius, Chaos, 1999, 9, 283 (ref. 2).]

Impaired aerobic capacity in hypercholesterolemic mice: partial reversal by exercise training

The present study assessed whether impaired aerobic capacity previously observed in hypercholesterolemic mice is reversible by exercise training. Seventy-two 8-wk-old female C57BL/6J wild-type (+, n = 42) and apolipoprotein E-deficient (-, n = 30) mice were assigned to the following eight interventions: normal chow, sedentary (E+, n = 17; E-, n = 8) or exercised (E+ex, n = 13; E-ex, n = 7) and high-fat chow, sedentary (E+chol, n = 6; E-chol, n = 8) or exercised (E+chol-ex, n = 6; E-chol-ex, n = 7). Mice were trained on a treadmill 2 x 1 h/day, 6 days/wk, for 4 wk. Cholesterol levels correlated inversely with maximum oxygen uptake (r = -0.35; P < 0. 02), which was blunted in all hypercholesterolemic sedentary groups (all P < 0.05). Maximum oxygen uptake improved in all training groups but failed to match E+ex (all P < 0.05). Vascular reactivity and nitric oxide (NO) synthesis correlated with anaerobic threshold (r = 0.36; P < 0.025) and maximal distance run (r = 0.59; P < 0.007). We conclude that genetically induced hypercholesterolemia impairs aerobic capacity. This adverse impact of hypercholesterolemia on aerobic capacity may be related to its impairment of vascular NO synthesis and/or vascular smooth muscle sensitivity to nitrovasodilators. Aerobic capacity is improved to the same degree by exercise training in normal and genetically hypercholesterolemic mice, although there remains a persistent difference between these groups after training.

CCR5- and CXCR4-utilizing strains of human immunodeficiency virus type 1 exhibit differential tropism and pathogenesis in vivo

CCR5-utilizing (R5) and CXCR4-utilizing (X4) strains of human immunodeficiency virus type 1 (HIV-1) have been studied intensively in vitro, but the pathologic correlates of such differential tropism in vivo remain incompletely defined. In this study, X4 and R5 strains of HIV-1 were compared for tropism and pathogenesis in SCID-hu Thy/Liv mice, an in vivo model of human thymopoiesis. The X4 strain NL4-3 replicates quickly and extensively in thymocytes in the cortex and medulla, causing significant depletion. In contrast, the R5 strain Ba-L initially infects stromal cells including macrophages in the thymic medulla, without any obvious pathologic consequence. After a period of 3 to 4 weeks, Ba-L infection slowly spreads through the thymocyte populations, occasionally culminating in thymocyte depletion after week 6 of infection. During the entire time of infection, Ba-L did not mutate into variants capable of utilizing CXCR4. Therefore, X4 strains are highly cytopathic after infection of the human thymus. In contrast, infection with R5 strains of HIV-1 can result in a two-phase process in vivo, involving apparently nonpathogenic replication in medullary stromal cells followed by cytopathic replication in thymocytes.

Dendritic cells that process and present nominal antigens to naive T lymphocytes are derived from CD2+ precursors

Dendritic cells (DC) are potent APC that, in mature form, can be distinguished from other mononuclear cells on the basis of their distinct morphology, absence of lineage markers, and dense expression of MHC and costimulatory molecules. While comparing different DC preparation methods, we observed that DC derived from cultured PBMC that had been depleted of CD2+ cells before culture were functionally distinct from DC derived from PBMC that had not been depleted of CD2+ cells. Thus, both types of DC stimulated allogeneic T cells to proliferate in the MLR, but only DC derived from CD2+ precursors could sensitize naive T cells to soluble Ags such as keyhole limpet hemocyanin and HIV gp160 glycoprotein. Subsequent studies confirmed the existence of CD2+ and CD2- DC precursor populations among HLA-DRbright, lineage-negative PBMC. Immediately after their isolation, these populations were morphologically similar to one another by light and electron microscopy, and neither had substantial Ag-presenting activity. After culture for 24 to 48 h with supernatant from PHA-activated PBMC, both populations developed dendrites, formed clusters with T cells, and stimulated allogeneic T cell responses in the MLR as well as autologous T cell responses to tetanus toxoid, a recall Ag. However, CD2+ DC precursors alone gave rise to APC that presented soluble Ags to naive CD4+ T cells, a property that could be inhibited by Abs to CD4, CD11a, and CD28 on T cells or CD86 on DC. The expression of CD54 and CD86 on CD2+ DC precursors was increased markedly after their culture and differentiation, while the expression of these molecules on CD2- DC precursors was not remarkably changed. These findings reveal the existence of two functionally distinct populations of DC, each derived from a phenotypically distinct precursor present in monocyte-depleted peripheral blood.

Dendritic cells that process and present nominal antigens to naive T lymphocytes are derived from CD2+ precursors

Dendritic cells (DC) are potent APC that, in mature form, can be distinguished from other mononuclear cells on the basis of their distinct morphology, absence of lineage markers, and dense expression of MHC and costimulatory molecules. While comparing different DC preparation methods, we observed that DC derived from cultured PBMC that had been depleted of CD2+ cells before culture were functionally distinct from DC derived from PBMC that had not been depleted of CD2+ cells. Thus, both types of DC stimulated allogeneic T cells to proliferate in the MLR, but only DC derived from CD2+ precursors could sensitize naive T cells to soluble Ags such as keyhole limpet hemocyanin and HIV gp160 glycoprotein. Subsequent studies confirmed the existence of CD2+ and CD2- DC precursor populations among HLA-DRbright, lineage-negative PBMC. Immediately after their isolation, these populations were morphologically similar to one another by light and electron microscopy, and neither had substantial Ag-presenting activity. After culture for 24 to 48 h with supernatant from PHA-activated PBMC, both populations developed dendrites, formed clusters with T cells, and stimulated allogeneic T cell responses in the MLR as well as autologous T cell responses to tetanus toxoid, a recall Ag. However, CD2+ DC precursors alone gave rise to APC that presented soluble Ags to naive CD4+ T cells, a property that could be inhibited by Abs to CD4, CD11a, and CD28 on T cells or CD86 on DC. The expression of CD54 and CD86 on CD2+ DC precursors was increased markedly after their culture and differentiation, while the expression of these molecules on CD2- DC precursors was not remarkably changed. These findings reveal the existence of two functionally distinct populations of DC, each derived from a phenotypically distinct precursor present in monocyte-depleted peripheral blood.

Association of CD4+ T cell-dependent, interferon-gamma-mediated necrosis of the small intestine with genetic susceptibility of mice to peroral infection with Toxoplasma gondii

Since there is a remarkable difference in susceptibility to peroral infection with Toxoplasma gondii among inbred strains of mice, we performed studies to examine the mechanism(s) of this difference in susceptibility. After peroral infection with the ME49 strain of T. gondii, C57BL/6 (B6) mice all died whereas BALB/c mice all survived. At day 7 of infection (when B6 mice began dying), massive necrosis of the villi and mucosal cells in the ilea were observed in B6 but not in BALB/c mice. To analyze the role of T cells in resistance against death and development of necrosis in the ilea after infection, studies were performed using athymic nude and euthymic control B6 and BALB/c mice. Athymic B6 mice all died after infection, but surprisingly, they survived significantly longer than control B6 mice, indicating that T cells predispose to early death in these mice. Necrosis in the ilea was observed in control B6 but not in athymic B6 mice; however, significantly less numbers of tachyzoites were observed in the ilea of the former than the latter mice. These results indicate that necrosis in the ilea of the B6 mice was not due to destruction of tissue by tachyzoites but was mediated by T cells. This deleterious effect of T cells appears to contribute to early death in these mice. In contrast, T cells conferred resistance against death in BALB/c mice but did not cause necrosis in their ilea. To analyze the T cell subset(s) that induces necrosis of the ilea in B6 mice, we examined histological changes of the small intestines after infection of mutant mice deficient in different T cell subsets (with the same H-2b haplotype as B6 mice). Mice deficient in alpha/beta or CD4+ T cells did not develop necrosis in the ilea, whereas wild-type control mice and mice deficient in gamma/delta or CD8+ T cells did, suggesting that the cells that induce necrosis in the ilea after infection are CD4+ alpha/beta T cells. Since interferon (IFN)-gamma has been shown to be critical for survival of BALB/c mice after infection with T. gondii, we examined the role of this cytokine in resistance/susceptibility of infected B6 mice. Treatment of B6 mice with anti-IFN-gamma monoclonal antibody shortly before they developed illness prolonged time to death and prevented necrosis in the ilea in these mice. These results indicate that IFN-gamma mediates necrosis in the ilea of B6 mice after infection. This CD4+ T cell-dependent, IFN-gamma-mediated necrosis of the small intestines appears to be a mechanism that underlies the genetic susceptibility of B6 mice to peroral infection with T. gondii, whereas the same cytokine plays a critical role in the resistance of genetically resistant BALB/c mice.

Modulation of apoptosis in human myeloid leukemic cells by GM-CSF

Apoptosis (programmed cell death) regulates cell population size. To determine the mechanisms whereby hematopoietic growth factors (HGFs) modulate apoptosis in human myeloid leukemic cells, we evaluated the roles of protein and mRNA synthesis for altering apoptosis in growth factor-stimulated vs. quiescent leukemic TF1 cells. Lysates of cells from the granulocyte-macrophage colony-stimulating factor (GM-CSF)-dependent myeloid leukemic cell line TF1 were separated into high molecular weight (HMW) pellets of intact DNA and supernatants of fragmented low MW (LMW) DNA, and the DNA purified from these fractions was quantified. In the absence of both GM-CSF and fetal bovine serum (FBS), 70% of the DNA was fragmented after 3 days in culture, with a characteristic apoptotic ladder-like pattern on agarose gel electrophoresis, whereas this proportion had initially been < 5%. In contrast, less than 5% of the DNA was fragmented in cells incubated with GM-CSF plus FBS or GM-CSF alone. Delayed addition of GM-CSF, but not FBS, permitted partial rescue of the cells, inhibiting increasing rates of accumulation of fragmented DNA. When the macro-molecular synthesis inhibitor cycloheximide (CHX) or actinomycin D (Act D) was present for 26 hours in the absence of GM-CSF and FBS, apoptosis was inhibited. In contrast, in the presence of GM-CSF or FBS, apoptosis was enhanced upon addition of CHX or Act D. The latter effect persisted even with the late addition of CHX. These findings indicate that disparate mechanisms of enhancing or inhibiting apoptosis exist in myeloid leukemic cells related to environmental conditions, including HGF-regulated cellular synthesis of distinct proteins and mRNA.

Coronary bypass grafting with biological grafts in a canine model

BACKGROUND

Poor patency rates have limited the success of biological vascular grafts in the coronary artery position. Recently, two bovine internal mammary arterial grafts have been developed for possible use as coronary artery bypass graft (CABG) conduits: (1) Denaflex grafts (Baxter Health-care Co, 3-mm ID) treated with polyepoxy compounds and with heparin ionically bound to the luminal surface and (2) Bioflow grafts (Bio-Vascular, Inc, 3-mm ID) treated with dialdehyde starch.

METHODS AND RESULTS

Thirty dogs underwent CABG with either a Denaflex (n = 20) or Bioflow (n = 10) graft to the left circumflex coronary artery (LCx). The left main coronary artery (n = 12) or proximal LCx (n = 18) was then ligated. Six-month patency (Kaplan-Meier) for Denaflex grafts was 44 +/- 13% (+/- SEM), compared with 12 +/- 11% for Bioflow grafts, but this difference did not reach statistical significance (P = .56). Among grafts open at 14 days, however, there were no occlusions among six Denaflex grafts versus five occlusions among seven Bioflow grafts. At 6 months, all six surviving Denaflex grafts appeared normal, while the only remaining patent Bioflow graft was angiographically dilated and had diffuse luminal irregularities. At 1 year, three Denaflex grafts angiographically had no dilation, stenosis, or luminal irregularities. Macroscopically, all explanted long-term (6 to 12 months) Denaflex grafts had a smooth, clean luminal surface, whereas the only patent Bioflow graft had multifocal thrombi. Microscopically, all Denaflex grafts had minimal degenerative changes, but the Bioflow graft had transmural linear cracks and medial deterioration.

CONCLUSIONS

These data suggest that long-term (> 6-month) patency is possible with small-caliber, low-flow biological grafts in the canine coronary position, although both types of grafts are prone to early occlusion. If these early failures are excluded, the Denaflex graft appears to be associated with better long-term patency and an absence of degenerative changes.

Dietary arginine prevents atherogenesis in the coronary artery of the hypercholesterolemic rabbit

OBJECTIVES

This study was designed to test the hypothesis that long-term oral supplementation of dietary L-arginine (to provide a sustained elevation of nitric oxide activity) would inhibit atherogenesis in hypercholesterolemic rabbits, as assessed by histomorphometric measurements.

BACKGROUND

Endothelium-derived nitric oxide inhibits a number of processes that are critical in atherogenesis. Hypercholesterolemia reduces endothelial nitric oxide activity, and we postulate that this may promote atherogenesis. This reduction in nitric oxide activity can be reversed acutely by intravenous infusion of L-arginine, the precursor of nitric oxide. We show that dietary supplementation of L-arginine abrogates the development of coronary atheroma in hypercholesterolemic rabbits.

METHODS

Male New Zealand White rabbits were fed normal rabbit chow, 1% cholesterol chow or 1% cholesterol chow with dietary arginine or methionine supplementation to increase their intake of these amino acids sixfold. After 1 or 10 weeks of dietary intervention, the left main and left anterior descending coronary arteries were harvested for histologic study. Plasma cholesterol measurements were elevated to the same degree in all groups of rabbits receiving the 1% cholesterol diet, whereas plasma arginine levels were doubled in the arginine-treated group. High density lipoprotein (HDL) cholesterol values were not affected by arginine treatment.

RESULTS

In rabbits receiving the 1% cholesterol diet, with or without methionine supplementation, light and electron microscopy revealed a marked increase from 1 to 10 weeks in the intimal accumulation of macrophages, associated with an increase in the intimal area of the left main coronary artery. By contrast, in arginine-treated hypercholesterolemic rabbits, there was a near absence of adherent monocytes and tissue macrophages and no progression of intimal thickness from 1 to 10 weeks.

CONCLUSIONS

Dietary supplements of L-arginine prevent intimal thickening in the coronary arteries of hypercholesterolemic rabbits. This antiatherogenic effect is not due to an alteration in plasma total cholesterol, HDL cholesterol or caloric or nitrogen balance. The data are consistent with the hypothesis that nitric oxide has antiatherogenic properties.

Experimental hepatic tumor necrosis. Comparison of spin-echo and pulsed magnetization transfer contrast magnetic resonance imaging

RATIONALE AND OBJECTIVES

We compared the effectiveness of pulsed magnetization transfer contrast (MTC) magnetic resonance imaging (MRI) and spin-echo MRI in detecting tumor necrosis.

METHODS

Adenocarcinoma cells were transplanted in the livers of 12 syngenic BDIX rats. To induce various degrees of tumor necrosis, the rats were randomly assigned to the following groups: 1) control; 2) localized hyperthermia; 3) intralesional cisplatin; and 4) hyperthermia plus intralesional cisplatin. At day 7 after treatment, the rats were imaged using a 1.5-T imager with 1) multiplanar gradient-recalled echo sequence (MPGR) 500/8/20 degrees with and without magnetization transfer contrast (MTC); 2) spin-echo 2500/20,80, and 3) spin-echo 300/20 pulse sequences. The rats were then sacrificed and pathologic specimens were prepared using MR images as guidance. T2 and ratios of signal intensity after saturation to signal intensity before saturation (Ms/Mo ratios) of the necrotic and granulation tissues and viable tumors were determined in 10 rats.

RESULTS

Compared with standard MPGR images, MPGR images with MTC provided better contrast between the pathologic tissues and normal liver. However, T2 values were more useful than Ms/Mo ratios in distinguishing necrotic areas from viable tumor. The T2 values of coagulative necrosis and granulation tissue were significantly different from that of viable tumor. No significant difference between the Ms/Mo ratios of the different pathologic tissues and normal liver was found.

CONCLUSION

Pulsed magnetization transfer contrast MRI was inferior to spin-echo MRI in distinguishing necrotic from viable tumors in rat livers using the pulse sequences described, and none of the sequences studied was thought to be reliable enough for this purpose.

HIV induces thymus depletion in vivo

Human immunodeficiency virus (HIV) disease is typified by declining CD4+ T lymphocyte counts in the peripheral circulation, a loss which may be secondary to accelerated destruction, to suppressed differentiation, and/or to sequestration of circulating cells into tissue spaces. As it is hard to distinguish between these possibilities in human subjects, the pathogenic mechanisms associated with HIV infection are unclear. In particular, little is known about the events that occur within infected lymphoid organs in which most CD4 T lymphocytes mature and function. To obtain a better description of HIV pathogenesis in vivo, we have implanted human haematolymphoid organs into the immunodeficient SCID mouse to create the SCID-hu mouse. We have previously shown that these organ systems promote long-term multilineage human haematopoiesis and are permissive for infection with HIV. Here we report that human thymopoiesis is suppressed by HIV infection, thereby precluding regeneration of the peripheral T-cell compartment.

Human immunodeficiency virus-infected monocyte-derived macrophages express surface gp120 and fuse with CD4 lymphoid cells in vitro: a possible mechanism of T lymphocyte depletion in vivo

Monocyte-derived macrophages (MDM) infected in vitro with a macrophage-tropic strain of human immunodeficiency virus (HIV) fused with uninfected, CD4-expressing T lymphoblastoid cells, but not with a subclone of these cells lacking surface CD4. Infected MDM also fused with uninfected autologous and heterologous MDM. Recombinant soluble CD4 protein (rsCD4) (10 micrograms/ml) and full-length recombinant glycosylated gp120 (20 micrograms/ml) each inhibited fusion by 94-99%; the inhibition was dose-dependent. The N-terminal portion of gp120 did not inhibit syncytium formation. Fusion was also inhibited by a monoclonal antibody to an epitope which binds gp120 (S3.5), but not by antibody to an epitope not involved in gp120 binding (OKT4). HIV-infected MDM specifically bound fluorescein-conjugated rsCD4, and virus could be visualized budding from the surface of these cells. HIV-infected MDM express viral gp120 on their surface and fuse with CD4-bearing cells in a fashion similar to lymphoid cells. Macrophages may contribute to CD4 lymphocyte depletion in vivo by this fusion mechanism.

Pachymeningitis associated with a pulmonary nodule

The authors report a case of hypertrophic pachymeningitis, a rare cause of spinal cord compression. In this patient, dural inflammation was associated with a histologically identical pulmonary lesion. Such an association has not been described previously and supports the hypothesis that this disease is related to other connective tissue disorders.

T lymphocyte-synovial fibroblast interactions induced by mycobacterial proteins in rheumatoid arthritis

An in vitro system was established in which single-cell suspensions of lymphocytes and synovial cells from the joints of patients with rheumatoid arthritis were cultured and produced an outgrowth of an organized inflammatory tissue with an extracellular matrix and capsule. The tissue outgrowth, which had histologic features of pannus, required the addition of mycobacterial antigen and interleukin-2 to the tissue culture medium and was dependent upon the presence of T lymphocytes and their interaction with synovial fibroblasts.

Polypoid Menetrier's disease associated with acromegaly

There are two forms of Menetrier's disease. The common form involves thickened gastric rugae, while the rare form involves discrete gastric polyps. The clinical literature suggests an association between Menetrier's disease and acromegaly, as well as other neuroendocrine neoplasms; the radiological literature has not addressed the issue. We describe a patient with acromegaly who developed the rare polypoidal form of Menetrier's disease.

Evidence that cytotoxic lymphocytes alter and traverse allogeneic endothelial cell monolayers

In an attempt to study the effects of allogeneic lymphocytes on endothelial cells (EC) and analyze the mechanism whereby such lymphocytes traverse an EC barrier, we have established human microvascular EC monolayers, in vitro, and analyzed the effects of lymphocyte subpopulations on such monolayers. Previous studies have shown that CD16+ (natural killer) and CD8+ (cytotoxic) lymphocytes but not CD4+ (helper) cells bind and induce the appearance of class II major histocompatibility complex antigens on allogeneic EC. The current findings indicate that these same lymphocyte subsets induce marked swirling and elongation of allogeneic EC, and traverse intact EC monolayers. In contrast, none of the functional consequences of the initial lymphocyte-EC adhesion were observed using autologous combinations, despite the presence of significant intercellular binding. Scanning and electron micrographs demonstrate extensive areas of lymphocyte-EC surface contact and EC-coated pit formation, whereas a panel of recombinant cytokines known to alter the surface phenotype of EC fail to induce the same morphologic changes whether used singly or in combination. We postulate that the cellular interactions observed here, in vitro, may represent the initial steps in the rejection of vascularized allografts in vivo.

Leiomyoma of the testis: sonographic and pathologic findings

This is the first report of an intratesticular leiomyoma. On ultrasonography the lesion was hypoechoic, indistinguishable from a malignant testicular neoplasm, but similar in appearance to other leiomyomas occurring elsewhere in the body.

Gastrointestinal manifestations of essential mixed cryoglobulinemia

A patient with essential mixed cryoglobulinemia (EMC) presented initially with gastric ulcers and, six months later, with a lesion of the ileum, mild stricture of the transverse colon, and stricture of the sigmoid colon with deep ulceration. The initial diagnosis was Crohn's disease, but pathologic examination of the resected sigmoid lesion showed vasculitis secondary to EMC. Patients with EMC can present with gastrointestinal manifestations mimicking Crohn's disease. A review and classification of the gastrointestinal manifestations of EMC are presented.

The interaction between excimer laser energy and vascular tissue

The effects of XeF1 excimer laser on isolated normal and atherosclerotic aorta were studied. Experiments were performed in flowing water at constant temperature, flow rate, water depth, pulse width (10 nsec), wavelength (351 nm), beam size (1 mm2) and focal length (50 cm). The number of pulses, the pulse energy, and the pulse frequency were varied, and the vascular tissue was studied histologically. The following observations were made: tissue ablation required a minimum threshold pulse energy and was nonlinearly proportional to the number of pulses and the pulse energy delivered; precise tissue ablation occurred at low pulse frequencies, but changes resembling a thermal process were seen as pulse frequency increased; calcified plaque was more photoresistant than atheroma or normal vessel; excimer laser energy was markedly attenuated by blood; and the time interval between pulses and high peak power are related to the precision of ablation by pulsed excimer laser. It is concluded that excimer laser can rapidly and precisely ablate vascular tissue by a photothermal process.

Cystic dysplasia of the testis: sonographic and pathologic findings

Sonographic and laboratory findings are presented for a case of left-scrotum testicular cysts in a 30-year-old man. Previously reported cases of this rare congenital malformation have occurred in infants and young boys. The patient showed previous evidence of the cyst at age 13. Sonographic images correlated well with previously published gross and microscopic descriptions.

Dual-energy projection radiography in the evaluation of femoral neck strength, density, and mineralization

Two different dual-energy projection radiography techniques were utilized in an attempt to predict femoral neck strength, bone density, and bone mineral content in 19 pairs of cadaver specimens. Positive simple linear correlation was observed between dual-energy scanned projection measurements and dry density, ash fraction, cross-sectional cortical bone area and, to a lesser degree, force required for fracture, but not trabecular bone volume, failure time, or Singh trabecular grade. Dual-energy film radiography was found to be a less reliable indicator of femoral neck strength, density, and mineral content. Dual-energy scanned projection results related linearly to mineral-equivalent solution (K2HPO4) concentration, and demonstrated long-term reproducibility in repeated specimen studies. Correction factors derived to account for differences in femoral size and rotation were shown to be reliable over a moderate range of neck projections. Although bone mineral measurement at other sites may provide comparable or greater information concerning hip fracture risk, dual-energy scanned projection radiography appears to be a useful technique for assessment of bone density, mineral content, and strength in the femoral neck.

Selective absorption of ultraviolet laser energy by human atherosclerotic plaque treated with tetracycline

Tetracycline is an antibiotic that absorbs ultraviolet light at 355 nm and preferentially binds to atherosclerotic plaque both in vitro and in vivo. Tetracycline-treated human cadaveric aorta was compared with untreated aorta using several techniques: absorptive spectrophotometry, which demonstrated a distinct absorptive peak at 355 nm in tetracycline-treated plaque that was absent in treated normal vessel; ultraviolet microscopy, which showed that treated atheroma acquired the characteristic fluorescence of tetracycline under ultraviolet light; and tissue uptake of radiolabeled tetracycline, which showed 4-fold greater uptake by atheroma than by normal vessel. In addition, intravenous tetracycline administered to patients undergoing vascular surgery demonstrated characteristic fluorescence in surgically excised diseased arteries. Because of tetracycline's unique properties, we exposed tetracycline-treated and untreated aorta to ultraviolet laser radiation at a wavelength of 355 nm. We found enhanced ablation of tetracycline-treated atheroma compared with untreated atheroma. The plaque ablation caused by ultraviolet laser radiation was twice as extensive in tetracycline-treated vs nontreated plaque (2.2 +/- 0.25 mm vs 1.3 +/- 0.55 mm, p less than 0.017). This study demonstrates the potential of tetracycline plaque enhancement for the selective destruction of atheroma by ultraviolet laser radiation.

Enrichment of murine and human Langerhans cells with solid phase immunoabsorption using pan-leukocyte monoclonal antibodies

Using a solid phase immunoabsorption (panning) technique, we have employed pan-leukocyte monoclonal antibodies to enrich and deplete murine and human Langerhans cells from cell suspensions of normal skin. Langerhans cell-enriched fractions contained 80-99% mononuclear cells, almost all of which had the ultrastructural features of Langerhans cells. These results are comparable to those achieved by panning for human Langerhans cells with anti-Leu-6(T6) antibody. Similarly, less than 1% of these cells were detectable in Langerhans cell-depleted fractions and such fractions were incapable of stimulating allogeneic lymphocytes in the skin cell-lymphocyte reaction. We conclude that panning with pan-leukocyte antibodies is an effective means of enriching or depleting Langerhans cells from heterogeneous skin cell suspensions and can yield results similar to those achieved with more Langerhans cell-specific reagents such as anti-Leu-6(T6). These findings are of particular significance to the enrichment and depletion of murine Langerhans cells since they express no known correlate of the human Leu-6(T6) antigen.

Conjugated estrogens in the treatment of postmenopausal women with hyperparathyroidism

Fourteen postmenopausal women with mild hyperparathyroidism were given conjugated estrogens. Serum calcium levels became normal and urinary calcium excretion was reduced for up to 2 years in ten patients taking an average dose of 1.25 mg of estrogen daily. Hypercalcemia returned quickly when therapy was interrupted. Estrogen did not systematically alter serum immunoreactive parathyroid hormone or calcitriol levels or urinary excretion of cyclic adenosine monophosphate. Significant reductions in urinary hydroxyproline and serum alkaline phosphatase activity during estrogen therapy indicate that the major effect of therapy was to decrease bone turnover. Iliac crest biopsy specimens taken before estrogen therapy showed normal trabecular bone volume and excessive osteoid seams. Follow-up biopsy specimens were taken from six patients after 1 year on therapy. Bone volume remained stable, but hyperosteoidosis had improved in only one patient. Without understanding the long-term impact of untreated mild hyperparathyroidism on bone, the benefits of estrogen therapy on bone remain uncertain. However, therapy with conjugated estrogens provides sustained control of serum and urine calcium in most women with hyperparathyroidism and is a reasonable alternative in patients who are not surgical candidates.

Langerhans cells react with pan-leukocyte monoclonal antibody: ultrastructural documentation using a live cell suspension immunoperoxidase technique

Langerhans cells are generally regarded as members of an Ia+ dendritic cell system capable of potent accessory cell function in immune responses. While it has been shown that murine Langerhans cells are bone marrow-derived, the ontogenic relationships among human Langerhans cells, other dendritic cells, macrophages, and leukocytes in general have yet to be fully clarified. Recently, several pan-leukocyte monoclonal antibodies have been produced which react with the human leukocyte common antigen. This antigen resembles the murine T200 antigen and is expressed by all leukocyte subtypes but not by nonhematopoietic cells. Using an immunoperoxidase technique for staining suspensions of live skin cells, we have documented Langerhans cell reactivity with pan-leukocyte monoclonal antibody L3B12 at the ultrastructural level. Reactivity with this highly sensitive and specific pan-leukocyte marker supports the concept of the human Langerhans cell as a specialized form of bone marrow-derived mononuclear leukocyte and defines an immunologic feature common to dendritic cells, macrophages, and leukocytes that is not shared by other cell types. This finding is discussed in the context of other recent data concerning the immunologic phenotype of Langerhans cells. Since the immunoultrastructural method employed does not require cell fixation of any kind prior to immunologic staining, it should prove particularly useful for studying cell surface antigens that are adversely affected by fixation.