Harry Lander

In Parkinson's disease (PD) dopaminergic neurons in the substantia nigra (SN) become dysfunctional and many ultimately die. We report that the tellurium immunomodulating compound ammonium trichloro(dioxoethylene-O,O'-)tellurate (AS101) protects dopaminergic neurons and improves motor function in animal models of PD. It is effective when administere...

The Ras family is the most widely mutated group of human proto-oncogene. Previously, we found an organic Tellurium compound, AS101, which exhibits immunomodulatory activity and strong anti-tumor effects. Whether these properties can be exploited for cancer therapy was examined using v-Ha-Ras transformed and V-mos transformed fibroblasts cells. In t...

Rap1 and Ral, the small GTPases belonging to the Ras superfamily, have recently attracted much attention; Ral because of Ral-specific guanine nucleotide exchange factors which are regulated by direct binding to Ras and Rap1 because of its proposed role as an antagonist of Ras signaling. We have previously demonstrated that nitric oxide (NO) activat...

Allicin, the main organic allyl sulfur component in garlic, exhibits immune-stimulatory and antitumor properties. Allicin stimulated [(3)H]thymidine incorporation in mouse splenocytes and enhanced cell-mediated cytotoxicity in human peripheral mononuclear cells. Multiple administration (i.p.) of allicin elicited a marked antitumor effect in mice in...

The synthetic immunomodulator AS101[ammonium trichloro(dioxoethylene-o,o')tellurate] was previously found to protect cancer patients from chemotherapy-induced bone marrow toxicity and alopecia. Here we show that AS101 induces hair growth in nude and normal mice. AS101 possesses the dual ability to both induce anagen and retard spontaneous catagen i...

Ferrocene, a stable, synthetic, iron-containing compound induces in vitro and in vivo activation of mouse lymphocytes and macrophages. Ferrocene also has a marked antitumor effect in mice, upon its administration intraperitoneally and in drinking water. Ferrocene's antitumor activity is attributed to its immune-stimulatory property. This conclusion...

Nitric oxide plays crucial roles in human physiology. It is synthesized in most tissues, and is diffusible and can take on several chemical forms, each of which has its own reactive specificity. The major chemical modification produced by these species is nitrosylation of the target, generally a protein iron or thiol. The direct interaction of nitr...

Free radicals derived from nitrogen and oxygen have been found to have a significant role in physiological and pathophysiological processes. Originally, free radicals were believed to be associated exclusively with cellular damage. Free radicals are now widely implicated in cellular signaling, a fact that attacks the classic notion of biological me...

Nitric oxide (NO) and related species serve as cellular messengers in various physiological and pathological processes. The monomeric G protein, Ras, transduces multiple signaling pathways with varying biological responses. We have previously reported that NO triggers Ras activation and recruitment of an effector, phosphatidylinositol 3'-kinase (PI...

Nitric oxide (NO) is a small, labile molecule that plays a key role as an intercellular and intracellular messenger. Interest in the mechanisms by which NO exerts its effects has increased tremendously along with the vast experimental evidence implicating NO in a variety of physiological and pathophysi-ological conditions. Here, we describe a metho...

p21(c-Ha-Ras) (Ras) can be activated by the guanine nucleotide exchange factor mSOS1 or by S-nitrosylation of cysteine 118 via nitric oxide (NO). To determine whether these two Ras-activating mechanisms modulate distinct biological effects, a NO-nonresponsive Ras mutant (Ras(C118S)) was stably expressed in the PC12 cells, a cell line that generates...

Nitric oxide (*NO) is a short-lived free radical with many functions including vasoregulation, synaptic plasticity, and immune modulation and has recently been associated with AIDS pathology. Various pathophysiological conditions, such as viral infection, trigger inducible nitric oxide synthase (iNOS) to synthesize NO in the cell. NO-derived specie...

Nitric oxide (NO) is a naturally occurring free radical with many functions. The oxidized form of NO, the nitrosonium ion, reacts with the thiol group of cysteine residues resulting in their modification to S-nitrosothiols. The human immunodeficiency virus type 1 (HIV-1) protease (HIV-PR) has two cysteine residues that are conserved amongst differe...

Reactive free radical species are known to trigger biochemical events culminating in transcription factor activation and modulation of gene expression. The cytosolic signaling events triggered by free radicals that result in nuclear responses are largely unknown. Here we identify a signaling cascade triggered immediately upon redox activation of Ra...

Reactive free radicals are known to trigger biochemical events culminating in transcription factor activation and modulation of gene expression. We have identified Ras as an initial signaling target of reactive free radicals and cellular redox stress. Here, we identify the signaling cascade triggered immediately distal to Ras activation. We examine...

We determined whether local bradykinin production modulates cardiac adrenergic activity. Depolarization of guinea pig heart sympathetic nerve endings (synaptosomes) with 1 to 100 mmol/L K+ caused the release of endogenous norepinephrine (10% to 50% above basal level). This release was exocytotic, because it depended on extracellular Ca2+, was inhib...

Mechanisms contributing to altered heterotrimeric G-protein expression and subsequent signaling events during cholesterol accretion have been unexplored. The influence of cholesterol enrichment on G-protein expression was examined in cultured smooth muscle cells that resemble human atherosclerotic cells by exposure to cationized LDL (cLDL). cLDL, w...

PGI2 generation by the vessel wall is an agonist for cyclic-AMP-dependent cholesteryl ester hydrolysis. The process of enhanced PGI2 synthesis is stimulated, in part, by G-protein-coupled receptor ligands. Cellular cholesterol enrichment has been hypothesized to alter G-protein-mediated PGI2 synthesis. In the studies reported herein, cells generate...

Advanced glycation end products (AGEs) exert their cellular effects on cells by interacting with specific cellular receptors, the best characterized of which is the receptor for AGE (RAGE). The transductional processes by which RAGE ligation transmits signals to the nuclei of cells is unknown and was investigated. AGE-albumin, a prototypic ligand,...

It is well accepted that extracellular ligands trigger nuclear signals through a cascade of protein-protein interactions. Many of these pathways have been carefully defined and provide an important framework by which we can understand and intervene in the processes they initiate. Recent data in the literature indicate that many extracellular ligand...

We have identified the site of molecular interaction between nitric oxide (NO) and p21ras responsible for initiation of signal transduction. We found that p21ras was singly S-nitrosylated and localized this modification to a fragment of p21ras containing Cys118. A mutant form of p21ras, in which Cys118 was changed to a serine residue and termed p21...

We have identified the site of molecular interaction between nitric oxide (NO) and p21ras responsible for initiation of signal transduction. We found that p21ras was singly S-nitrosylated and localized this modification to a fragment of p21ras containing Cys118. A mutant form of p21ras, in which Cys118 was changed to a serine residue and termed p21...

Triggering of lymphocytes by mitogens leads to a complex biochemical cascade culminating in cellular activation. Data are accumulating that suggest that reactive free radicals participate in signal transduction. We have examined the effects of nitric oxide (NO) on some parameters of lymphocyte activation and have also performed mechanistic studies....

Many studies have identified nitric oxide (NO) and related chemical species (NOx) as having critical roles in neurotransmission, vasoregulation, and cellular signaling. Previous work in this laboratory has focused on elucidating the mechanism of NOx signaling in cells. We have demonstrated that NOx-induced activation of the guanine nucleotide-bindi...

We previously showed that prejunctional histamine H3-receptors downregulate norepinephrine exocytosis, which is markedly enhanced in early myocardial ischemia. In the present study, we investigated whether H3-receptors modulate nonexocytotic norepinephrine release during protracted myocardial ischemia. In this setting, decreased pH(i) in sympatheti...

Alterations in G-protein-mediated production of secondary messengers have been documented in atherosclerosis. However, the influence of cholesterol (CH) accumulation on G-protein-mediated signalling events leading to PGI2 synthesis are unknown. We tested the hypothesis that CHenrichment alters Ga expression and PGI2 synthesis. CH-enrichment reduced...

Reactive free radicals have been implicated in mediating signal transduction by a variety of stimuli. We have investigated the role of p21ras in mediating free radical signaling. Our studies revealed that signaling by oxidative agents which modulate cellular redox status, such as H2O2, hemin, Hg2+, and nitric oxide was prevented in cells in which p...

Nerve growth factor (NGF) and epidermal growth factor (EGF) elicit contrasting actions on PC12 pheochromocytoma cells; NGF causes neuronal differentiation, and EGF induces proliferation. However, ectopic expression of the Src homology 2 (SH2) and SH3-containing oncogenic adaptor protein v-Crk in PC12 cells results in EGF-inducible neuronal differen...

Norepinephrine release contributes to ischemic cardiac dysfunction and arrhythmias. Because activation of histamine H3-receptors inhibits norepinephrine release, we searched for the presence of H3-receptors directly in sympathetic nerve endings (cardiac synaptosomes) isolated from surgical specimens of human atria. Norepinephrine was released by de...

Recent studies have demonstrated the biological importance of the interaction of nitric oxide (NO) with proteins. Protein-associated targets of NO include heme, Cys, and Tyr. Electrospray ionization-mass spectrometry was used to monitor the results of exposure of model peptides and an enzyme to NO under different conditions and thus addressed aspec...

The protooncogene p21ras, a monomeric G protein family member, plays a critical role in converting extracellular signals into intracellular biochemical events. Here, we report that nitric oxide (NO) activates p21ras in human T cells as evidenced by an increase in GTP-bound p21ras. In vitro studies using pure recombinant p21ras demonstrate that the...

A mechanism by which nitric oxide (NO) enhances prostaglandin-H synthase-1 (PCHS-1) activity is described. Under aerobic conditions, NO stimulates the conversion of arachidonic acid to prostaglandin E(2) (PGE(2)) and PGD(2) in a dose- (5-100 mu M) and time- (over 5 min) dependent manner. PGHS-1 possesses several potential targets for NO interaction...

Researches indicate that in resistance vessels nitric oxide (NO) attenuates adrenergic responses by a postjunctional action, but not by decreasing norepinephrine (NE) release. In the heart NO does not modulate the chronotropic response to adrenergic nerve stimulation, but does enhance NE overflow in association with coronary vasodilation and ischem...

The effects of bacterial lipopolysaccharide (LPS) on macrophage gene expression are mediated in part by its ability to induce activation of transcription factor NF-kappa B. We compared the ability of LPS-treated macrophages from Lpsn (LPS-responsive) C3H/HeN and Lpsd (LPS-hyporesponsive) C3H/HeJ mice to mobilize NF-kappa B by electrophoretic mobili...

Oxygen free radical generation has been implicated in mediating signal transmission initiated by a variety of stimuli (1–4). For example, Novogrodsky et al. (2) discovered that hydroxy radical scavengers blocked phorbol ester-induced mitogenesis in lymphocytes. Also, Schreck et al. (1) found that treating T lymphocytes with the free radical scaveng...

We have previously reported various inductive effects of nitric oxide on human PBMC. We describe a novel and potentially important mechanism of nitric oxide signaling-through direct activation of guanine nucleotide-binding proteins (G proteins). We have found that nitric oxide treatment of membranes isolated from fresh human PBMC enhances the abili...

Following our previous observation that haemin is mitogenic for human lymphocytes, we investigated the ability of haemin to enhance glucose uptake in these cells. We found that preincubation of human peripheral-blood mononuclear cells (PBMC) with haemin for 60 min increased up to 5-fold the rate of 2-deoxy-D-[1-3H]glucose uptake by the cells. Actin...

Hemin, an oxidant which is mitogenic for lymphocytes, was found to induce cap formation for Con A sites in murine and human lymphocytes and for IgG and Thy 1.2 sites in murine lymphocytes. Doses of hemin which induced capping also induced a redistribution of actin to a detergent-insoluble form. Similar to hemin, we found that heat shock also induce...

Recent work in this laboratory has identified immune-stimulatory properties of the oxidant hemin. In this study, we examined whether the nitrogen-based oxidant nitric oxide (NO) had inductive effects on human lymphocytes. We found that the NO-generating compounds sodium nitroprusside and S-nitroso-N-acetylpenicillamine rapidly enhanced the rate of...

Oxidants, heavy metals, and heat shock, collectively known as stress stimuli, induce the synthesis of a variety of proteins, termed stress proteins, and enhance glucose uptake. In this study, we have demonstrated that stress stimuli enhance protein tyrosine phosphorylation (PTyr-P), modulate protein tyrosine phosphatase (PTPase) activity, activate...

Experiments were performed using an established human glioblastoma cell line to determine the effect of lipoproteins on regulating their growth. It was found that synthetic and natural human high density lipoproteins (HDL) were effective in inhibiting tumor cell growth in a nontoxic, dose-dependent manner, and that the LD50 was 10-fold lower than t...

Tyrosine kinases of the src family, p56lck and p59fyn, were implicated in the transduction of signals via the T-cell receptor complex. These kinases are negatively regulated by phosphorylation of a carboxyl-terminal tyrosine residue. Tyrphostins are synthetic low molecular weight compounds that selectively inhibit different protein tyrosine kinases...

Hemin stimulates cAMP production in human peripheral blood mononuclear cells (PBMC). The kinetics are similar to that of hormone-induced cAMP generation, namely a rapid effect followed by a desensitization phase. Several experimental findings suggest that prostaglandins do not mediate this effect. First, macrophage depleted T and B cells purified b...