Immunoelectron microscopic study for polyamines

Nucleosome destabilization by polyamines

The roles and molecular interactions of polyamines (PAs) in the nucleus are not fully understood. Here their effect on nucleosome stability, a key regulatory factor in eukaryotic gene control, is reported, as measured in agarose embedded nuclei of H2B-GFP expressor HeLa cells. Nucleosome stability was assessed by quantitative microscopy [1,2] in situ, in close to native state of chromatin, preserving the nucleosome constrained topology of the genomic DNA. A robust destabilizing effect was observed in the millimolar concentration range in the case of spermine, spermidine as well as putrescine, which was strongly pH and salt concentration-dependent, and remained significant also at neutral pH. The integrity of genomic DNA was not affected by PA treatment, excluding DNA break-elicited topological relaxation as a factor in destabilization. The binding of PAs to DNA was demonstrated by the displacement of ethidium bromide, both from deproteinized nuclear halos and from plasmid DNA. The possibility that DNA methylation patterns may be influenced by PA levels is contemplated in the context of gene expression and DNA methylation correlations identified in the NCI-60 panel-based CellMiner database: methylated loci in subsets of high-ODC1 cell lines and the dependence of PER3 DNA methylation on PA metabolism.

Metabolism and disposition of oseltamivir (OS) in rats, determined by immunohistochemistry with monospecific antibody for OS or its active metabolite oseltamivir carboxylate (OC): A possibility of transporters dividing the drugs' excretion into the bile and kidney

Among any drugs, no comparative pharmacological study on how prodrug and its active metabolite behave in animal bodies is available. Immunohistochemistry (IHCs) using newly prepared two monoclonal antibodies, AOS‐96 and AOC‐160, monospecific for oseltamivir (OS) and its metabolite oseltamivir carboxylate (OC) were developed, simultaneously detecting the uptake or excretion of OS and OC in the intestine, liver, and kidney of rats to which OS was orally administered. In the intestine, IHC for OS revealed OS highly distributed to the absorptive epithelia with heavily stained cytoplasmic small granules (CSGs). IHC for OC showed that OC also distributed highly in the epithelia, but without CSGs, suggesting that OS was partly converted to OC in the cells. In the liver, OS distributed in the hepatocytes and on their bile capillaries, as well as on the lumina from the bile capillaries to the interlobular bile ducts. OC distributed in the whole cell of the hepatocytes, but without CSGs nor on any lumina through the interlobular bile ducts. In the kidney, a few levels of OS distributed in the cytoplasm of almost all the renal tubule cells, but they contained numerous CSGs. In contrast, OC distributed highly in the proximal tubules, but very slightly in the lower renal tubules of the nephrons. Thus, it was concluded that the two drugs behave in completely different ways in rat bodies. This paper also discusses a possibility of the correlation of OS or OC levels in tissue cells with their known transporters.

Expression and distribution patterns of spermine, spermidine, and putrescine in rat hair follicle

No expression and distribution patterns of polyamines (PAs), spermine, spermidine, and their precursor putrescine in mammalian hair follicle are available, although polyamines are known to correlate well with hair growth and epidermal tumor genesis. Immunohistochemistry (IHC) using our original two monoclonal antibodies (mAbs) ASPM-29 specific for spermine or spermidine, and APUT-32 specific for putrescine allowed us to detect immunoreactivity for polyamines in hair follicles from normal adult rats. A wide range of immunoreactivity for the total spermine and spermidine was observed in the compartments of hair follicle: The highest degree of immunoreactivity for polyamines was observed in the matrix, in the Huxley's layer, in the deeper Henle's layer, and in the cuticle of the inner root sheath/the hair cuticle, while moderate immunoreactivity existed in the lower-to-mid cortex and the companion layer, followed by lower immunoreactivity in the outer root sheath, including the bulge region and in the deeper medulla, in which the immunoreactivity was also evident in their nuclei. In addition, somewhat surprisingly, with IHC by APUT-32 mAb, we detected significant levels of putrescine in the compartments, in which the immunostaining pattern was the closely similar to that of the total spermine and spermidine. Thus, among these compartments, the cell types of the matrix, the Huxley's layer, the deeper Henle's layer, and the cuticle of the inner root sheath/the hair cuticle seem to have the biologically higher potential in compartments of anagen hair follicle, maybe suggesting that they are involved more critically in the biological event of hair growth. In addition, we noted sharp differences of immunostaining by IHCs between ASPM-29 mAb and APUT-32 mAb in the epidermis cells and fibroblast. ASPM-29 mAb resulted in strong staining in both the cell types, but APUT-32 mAb showed only very light staining in both types. Consequently, the use of the two IHCs could be extremely useful in further studies on hair cycle and epidermal tumor genesis experimentally or clinically.

Immunocytochemistry for Drugs Containing an Aliphatic Primary Amino Group in the Molecule, Anticancer Antibiotic Daunomycin as a Model

An immunocytochemistry (ICC) for the anticancer antibiotic daunomycin (DM) was developed using a combination of anti-DM serum produced against N-(gamma-male-imidobutyryloxy)succinimide (GMBS)-conjugated DM, and DM-uptake human melanoma BD cells. The antiserum was demonstrated to be specific for DM and the structurally related analogs adriamicin and epirubicin by an ICC model system of the enzyme immunoassay (EIA) using glutaraldehyde (GA)-conjugated DM as a solid phase antigen. No cross-reaction occurred with any of the other antibiotics tested such as bleomycin, pepleomycin, and mitomycin C. Successful DM ICC required a series of processes prior to the immunocytochemical reaction: the cells were first fixed with GA, then reduced with NaBH4, treated with hydrochloric acid, and finally digested with protease. The cell specimens were then subjected to immunoreaction with anti-DM serum followed by peroxidase-labeled goat anti-rabbit IgG/Fab', and in both immune reagents the detergent Triton X-100 was contained as well. The present ICC covering all these processes successfully stained for DM in the nucleus and in the perinuclear Golgi region of the cytoplasm of the BD cells, consistent with the results obtained by the DM autofluorescence method. This ICC was found to be three times as sensitive as the cytofluorometric method and applicable to the paraffin sections of the liver of rats 24 hr after an IV injection of DM. The principle used in the present study for developing DM ICC might be applied to other drugs containing the primary amino group(s) in the molecule. Thus, these ICCs for drugs are direct, precise and easy new methods that should have potential for pharmacology and toxicology studies of drugs, revealing the localization of a drug in cells and tissues.

Intracellular Localization of Ornithine Decarboxylase and Its Regulatory Protein, Antizyme-1

The enzyme ornithine decarboxylase (ODC) and its regulatory protein antizyme-1 (AZ1) are key regulators in the homeostasis of polyamines. To gain more insight into the exact intracellular distribution of ODC and AZ1, we performed immunocytochemical and Green Fluorescent Protein-fluorocytochemical studies in cultured human cervix carcinoma and human prostatic carcinoma (PC-346C) cells. ODC localization patterns varied from predominantly cytoplasmic to both cytoplasmic and nuclear staining, whereas AZ1 was mostly found in the nucleus. In cells that were synchronized in the mitotic phase, localization of both ODC and AZ1 changed from perinuclear at the beginning of mitosis into nucleoplasmic at close proximity to the chromosomes during meta-, ana- and telophase. Upon completion of mitosis, localization of ODC and AZ1 was reverted back to the cytoplasm, i.e., predominantly perinuclear immediately after cytokinesis. When PC-346C cells were treated with polyamines to induce AZ1-regulated ODC degradation, ODC was predominantly found in the nucleus and colocalized with immunoreactive AZ1. A comparable accumulation of ODC and AZ1 in the nucleus was found in PC-346C cells treated with the polyamine analog SL-11093. The present study suggests that AZ1 is involved in nucleocyto-plasmic shuttling of ODC, which may be a prerequisite for ODC regulation and/or function.

Endogenous polyamine function--the RNA perspective

Recent progress with techniques for monitoring RNA structure in cells such as ‘DMS-Seq’ and ‘Structure-Seq’ suggests that a new era of RNA structure-function exploration is on the horizon. This will also include systematic investigation of the factors required for the structural integrity of RNA. In this context, much evidence accumulated over 50 years suggests that polyamines play important roles as modulators of RNA structure. Here, we summarize and discuss recent literature relating to the roles of these small endogenous molecules in RNA function. We have included studies directed at understanding the binding interactions of polyamines with polynucleotides, tRNA, rRNA, mRNA and ribozymes using chemical, biochemical and spectroscopic tools. In brief, polyamines bind RNA in a sequence-selective fashion and induce changes in RNA structure in context-dependent manners. In some cases the functional consequences of these interactions have been observed in cells. Most notably, polyamine-mediated effects on RNA are frequently distinct from those of divalent cations (i.e. Mg²⁺) confirming their roles as independent molecular entities which help drive RNA-mediated processes.

Immunocytochemistry for vancomycin using a monoclonal antibody that reveals accumulation of the drug in rat kidney and liver

We prepared monoclonal antibodies against N-(γ-maleimidobutyryloxy)succinimide-conjugated vancomycin (VM). The monoclonal antibody was specific for conjugated or free VM. The monoclonal antibody enabled us to develop an immunocytochemical method for detecting the uptake of VM in the rat kidney and liver. Three hours after a single intravenous (i.v.) injection of VM at the therapeutic dose, the immunocytochemistry revealed that VM accumulated in large amounts in both the S1 and S2 segments and in much smaller amounts in the S3 segment of the proximal tubules as well as in the distal tubules and collecting ducts. The drug was detected in the cytoplasm, cytoplasmic irregular granules, nuclei, and microvilli of the proximal tubule cells. The distal tubules and collecting ducts contained scattered swollen cells in which both the nuclei and cytoplasm were heavily immunostained. Twenty-four hours after injection, most of the swollen cells returned back to normal size and had somewhat decreased immunostaining. Also, significant amounts of VM remained accumulated for as long as 8 days postadministration. In the liver, similar drug accumulation was observed in the Kupffer cells and the endothelial cells of the hepatic sinusoids but not in the hepatocytes, suggesting that vancomycin cannot be eliminated via the liver. Immunoelectron microscopic studies demonstrated that in the collecting ducts, uptake of VM occurred exclusively in the lysosomes and cytoplasm of the principal cells and scarcely in the intercalated cells. Furthermore, double fluorescence staining using rats simultaneously administered with VM and gentamicin strongly suggests that both drugs colocalized in lysosomes in the proximal tubule cells of kidneys.

Polyamines are implicated in the emergence of the embryo from obligate diapause

Embryonic diapause is a poorly understood phenomenon of reversible arrest of embryo development prior to implantation. In many carnivores, such as the mink (Neovison vison), obligate diapause characterizes each gestation. Embryo reactivation is controlled by the uterus by mechanisms that remain elusive. Because polyamines are essential regulators of cell proliferation and growth, it was hypothesized that they trigger embryo reactivation. To test this, mated mink females were treated with α-difluoromethylornithine, an inhibitor of ornithine decarboxylase 1, the rate-limiting enzyme in polyamine biosynthesis, or saline as a control during the first 5 d of reactivation. This treatment induced polyamine deprivation with the consequence of rearrest in embryo cell proliferation. A mink trophoblast cell line in vitro subjected to α-difluoromethylornithine treatment likewise displayed an arrest in cell proliferation, morphological changes, and intracellular translocation of ornithine decarboxylase 1 protein. The arrest in embryo development deferred implantation for a period consistent with the length of treatment. Successful implantation and parturition ensued. We conclude that polyamine deprivation brought about a reversible rearrest of embryo development, which returned the mink embryo to diapause and induced a second delay in embryo implantation. The results are the first demonstration of a factor essential to reactivation of embryos in obligate diapause.

Ornithine decarboxylase antizyme inhibitor 2 regulates intracellular vesicle trafficking

Antizyme inhibitor 1 (AZIN1) and 2 (AZIN2) are proteins that activate ornithine decarboxylase (ODC), the key enzyme of polyamine biosynthesis. Both AZINs release ODC from its inactive complex with antizyme (AZ), leading to formation of the catalytically active ODC. The ubiquitously expressed AZIN1 is involved in cell proliferation and transformation whereas the role of the recently found AZIN2 in cellular functions is unknown. Here we report the intracellular localization of AZIN2 and present novel evidence indicating that it acts as a regulator of vesicle trafficking. We used immunostaining to demonstrate that both endogenous and FLAG-tagged AZIN2 localize to post-Golgi vesicles of the secretory pathway. Immuno-electron microscopy revealed that the vesicles associate mainly with the trans-Golgi network (TGN). RNAi-mediated knockdown of AZIN2 or depletion of cellular polyamines caused selective fragmentation of the TGN and retarded the exocytotic release of vesicular stomatitis virus glycoprotein. Exogenous addition of polyamines normalized the morphological changes and reversed the inhibition of protein secretion. Our findings demonstrate that AZIN2 regulates the transport of secretory vesicles by locally activating ODC and polyamine biosynthesis.

Immunocytochemical demonstration of polyamines in nucleoli and nuclei

Although biochemical studies have shown that polyamines (PAs) occur in the nucleus, only few studies have examined the intranuclear distribution of these organic cations. By immunocytochemistry, we have previously demonstrated that PAs are located in ribosomes. We now show that PAs also are present in both nucleoli and nuclei of a variety of cell types. Detection of nucleolar and nuclear PAs required novel pretreatment procedures involving protease and/or DNase digestion of specimens prior to immunoreaction. Double fluorescence staining confirmed the localizations. This suggests that PAs may be important to the formation of ribosomes in nucleoli, as well as adds support to biochemical studies suggesting that PAs are involved in many biological events in the nucleus. Further biochemical studies will be needed to substantiate this hypothesis.

Subcellular distribution of spermidine/spermine N1-acetyltransferase

The subcellular distribution of the polyamine catabolic enzyme spermidine/spermine N(1)-acetyltransferase (SSAT) was studied in L56Br-C1 cells treated with 10 microM N(1),N(11)-diethylnorspermine (DENSPM) for 24 h. Cells were fractioned into three subcellular fractions. A particulate fraction containing the mitochondria was denoted as the mitochondrial fraction. After DENSPM treatment, an increase in SSAT activity was mainly found in the mitochondrial fraction. Western blot analysis showed an increased level of the SSAT protein in the mitochondrial fraction compared to the cytosolic fraction. Immunofluorescence microscopy and immunogold labeling transmission electron microscopy also showed a mitochondrial association of SSAT. Transmission electron microscopy revealed that the endoplasmic reticulum was devoid of ribosomes in DENSPM-treated cells, in contrast to control cells that contained ample ribosomes. An increased SSAT activity in connection with the mitochondria may be part of the mechanism of DENSPM-induced apoptosis.

Polyamines in spermatocytes and residual bodies of rat testis

Immunocytochemistry for polyamines in the rat testis revealed intense staining of small bodies close to the lumen of seminiferous tubules of spermatogenic stage VII and VIII as well as of spermatocytes. Methyl green-pyronin and propidium iodide staining combined with DNase or RNase predigestion showed that the small bodies contained RNA, but not DNA and double fluorescence staining showed that polyamines (PAs) colocalized with RNA in the bodies. Electron microscopy confirmed the absence of nuclei in the bodies and revealed that PA immunoreactivity was associated with ribosomes. These results strongly suggest that the small bodies correspond to the residual bodies, and agree with previous results showing localization of PAs to ribosomes in neurons and gastrointestinal epithelial cells. The accumulation of PAs in residual bodies may reflect a termination of their role in spermiogenesis with respect to protein synthesis.

Improved immunocytochemical detection of daunomycin

Improved immunocytochemical (ICC) detection of the anthracycline anticancer antibiotic daunomycin (DM) has been achieved by use of hydrogen peroxide oxidation prior to ICC staining for DM. The new method greatly enhanced the localization of DM accumulation in cardiac, smooth and skeletal muscle of rats after a single i.v. dose of the drug. DM accumulated in the nuclei as well as in the sarcoplasm, where it occurred in the form of small granules, which were particularly evident in cardiac muscle cells. The distribution of the granules coincided with that of mitochondria. Uptake of DM in nuclei and mitochondria of heart muscle cells may help to improve our understanding of the cardiac toxicity of DM and related anthracycline antibiotics. A number of ELISA tests were carried out in order to elucidate the mechanisms of H2O2-assisted antigen retrieval. A possible mechanism is that DM is reduced and converted to its semiquinone and/or hydroquinone derivative in vivo. Oxidation by hydrogen peroxide acts to convert these derivatives back to the native antigen. The improved ICC methodology using oxidation to recreate native antigens from reduced metabolites may be helpful also with respect to the localization of other drugs.

Distribution of anticancer antibiotic daunomycin in the rat heart and kidney revealed by immunocytochemistry using monoclonal antibodies

Two monoclonal antibodies (ADM-1-11 and 79-31 mAbs) were raised against daunomycin (DM) conjugated to bovine serum albumin via the cross-linker N-(gamma-maleimidobutyryloxy)succinimide. The monoclonal antibodies (mAbs) specifically detected DM as well as its analogs doxorubicin and epirubicin, but did not react with other anticancer antibiotics, including pepleomycin, mitomycin C, and actinomycin D. The mAbs reacted strongly with glutaraldehyde-conjugated DM in an enzyme linked immunosorbent assay (ELISA) used as a model system for immunocytochemistry as well as in appropriately pretreated sections of tissues from animals injected with DM. No staining occurred in tissues from uninjected animals. In order to perform DM ICC a number of tissue treatment conditions critical to the detection of low molecular weight substances were employed. Uptake of DM was studied in rats after a single i.v. or i.p. administration of the drug. In the heart, accumulation of DM occurred in nuclei and in the cytoplasm. In the kidney, DM immunoreactivity accumulated in all segments of the nephron except for the proximal tubules. Since the proximal tubules are known to be where a variety of transport systems including P-glycoprotein (Pgp) and organic anion-transporting polypeptides (OATPs) in drug interactions occur, the absence of DM accumulation in these segments may reflect a transport phenomenon depending upon such transporters. The availability of methods to study sites of accumulation of DM offers possibilities for understanding toxic side effects of this drug on the heart and kidney. Moreover, the immunocytochemical methodology developed may prove useful for the localization of other low molecular weight drugs that can be fixed in situ by glutaraldehyde.

A Novel Protein Kinase CK2 Substrate Indicates CK2 Is Not Directly Stimulated by Polyamines in Vivo

The activity of the protein kinase (CK2) is enhanced in vitro by the binding of polyamines to the CK2beta regulatory subunit. The overexpression of ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis, also elevates CK2 kinase activity in primary keratinocytes and tissues of K6/ODC transgenic mice. In an effort to better characterize the mechanisms by which polyamines may affect CK2 in vivo, we constructed a transfectable CK2 substrate cDNA consisting of the enhanced green fluorescence protein appended with a canonical CK2 phosphorylation sequence (EGFP-S). In contrast to unmodified EGFP, the EGFP-S protein was extensively phosphorylated by CK2, and this phosphorylation was stimulated by the polyamine spermine in a dose-dependent manner. The in vivo phosphorylation of EGFP-S was examined in cell lines which inducibly express either wild-type CK2 holoenzyme or a CK2 holoenzyme which contains activating mutations in the polyamine-binding region of its CK2beta regulatory subunit. Neither the overexpression of ODC in either cell line nor the mutation of the CK2beta subunit conferred an increase in CK2 kinase activity as measured by the in vivo phosphorylation of EGFP-S. Rather, our data indicate that polyamines increase total CK2 kinase activity through increases in steady-state levels of both CK2alpha and CK2beta subunits. The overexpression of ODC resulted in a 3-fold increase in steady-state levels of both exogenous and endogenous CK2 transcripts but did not increase the half-life of wild-type or mutated CK2 protein. These data suggest that the regulation of intracellular CK2 by the polyamines may occur through mechanisms distinct from the direct stimulation of CK2 by polyamines in vitro as previously described.

Immunoelectron microscopic study of polyamines in the gastrointestinal tract of rat

Polyamines (PAs) are ubiquitous polycationic metabolites in the eukaryotic and prokaryotic cells and are believed to be intimately involved in the regulation of DNA, RNA, and protein biosynthesis. However, the subcellular localization of PAs has not yet been fully elucidated in a variety of cell types. In the present study, a pre-embedding indirect immunoperoxidase approach was used to define the fine structural localization of PAs in the gastrointestinal tract of rat, which was fixed with glutaraldehyde and the monoclonal antibody ASPM-29 specific for spermine (Spm) and spermidine (Spd). Examination by a transmission electron microscopy showed that the peroxidase end products were commonly and predominantly localized in the free and attached ribosomes of the rough endoplasmic reticulum (rER) in the active protein- or peptide-secreting cells, and in rapidly proliferating cells including the gastric chief cells, mucous neck cells, and intestinal crypt cells. The nuclei, mitochondria, and secretory vesicles were devoid of PAs. Of note is the new finding that PAs are also located even on the small number of ribosomes in the cytoplasm of the parietal cells and of the villus-tip cells, because these were the cell types that were found to be almost PA-negative at the light microscopic level. These results seem to be completely consistent with those recently obtained for rat neurons. Thus, the present study generalized the subcellular localization of PAs on the ribosomes, and demonstrated that PAs are one of the components of biologically active ribosomes, possibly in any type of cell, that are closely involved in the translation processes of protein biosynthesis.

Localization of spermine binding sites in 23S rRNA by photoaffinity labeling: parsing the spermine contribution to ribosomal 50S subunit functions

Polyamine binding to 23S rRNA was investigated, using a photoaffinity labeling approach. This was based on the covalent binding of a photoreactive analog of spermine, N¹-azidobenzamidino (ABA)-spermine, to Escherichia coli ribosomes or naked 23S rRNA under mild irradiation conditions. The cross-linking sites of ABA-spermine in 23S rRNA were determined by RNase H digestion and primer-extension analysis. Domains I, II, IV and V in naked 23S rRNA were identified as discrete regions of preferred cross-linking. When 50S ribosomal subunits were targeted, the interaction of the photoprobe with the above 23S rRNA domains was elevated, except for helix H38 in domain II whose susceptibility to cross-linking was greatly reduced. In addition, cross-linking sites were identified in domains III and VI. Association of 30S with 50S subunits, poly(U), tRNA^Phe and AcPhe-tRNA to form a post-translocation complex further altered the cross-linking, in particular to helices H11–H13, H21, H63, H80, H84, H90 and H97. Poly(U)-programmed 70S ribosomes, reconstituted from photolabeled 50S subunits and untreated 30S subunits, bound AcPhe-tRNA in a similar fashion to native ribosomes. However, they exhibited higher reactivity toward puromycin and enhanced tRNA-translocation efficiency. These results suggest an essential role for polyamines in the structural and functional integrity of the large ribosomal subunit.

Immunohistochemical analysis of tumor polyamines discriminates high-risk patients undergoing nephrectomy for renal cell carcinoma

Renal cell carcinoma (RCC) is known to display a wide variation in biological behavior and clinical outcome. Although usual bioclinical prognostic parameters (eg, nuclear grade, tumor stage) are to a certain extent useful in predicting the outcome of RCC after radical nephrectomy, they now appear to be insufficient. The polyamines (spermidine, spermine, and putrescine) are ubiquitous polycations that are essential for cell proliferation. To support their excessive proliferation, cancer cells have high rates of polyamine metabolism. Indeed, malignant cells typically have higher polyamine levels than their normal counterparts. Before this report, antipolyamine antibodies that are potentially valuable tools for the in situ observation of polyamines had not been exploited in clinical conditions. In the present study, tumor tissues obtained from radical nephrectomy performed for RCC (n = 73) were immunostained with the anti-spermine monoclonal antibody Spm8-2, and the immunoreactivity was evaluated as a prognostic tool. RCC cells displayed various reactivity to the antibody Spm8-2 that translated into a heterogeneous cytoplasmic staining. The prognostic value of the labeling index (LI) on clinical outcome was correlated with the usual clinicopathologic parameters, and the cell proliferation rate was evaluated using Ki-67 labeling. Multiple correspondence analysis and ascending hierarchical classification were performed to determine significant prognostic factors. Univariate statistical survival analysis demonstrated that tumor size (P < .001), nuclear grade (P < .01), necrosis (P < .007), tumor stage (P < .004), metastasis (P < .001), Ki-67 LI (P < .0003), and Spm8-2 immunoreactivity (P < .0001) were predictors of tumor-related death. A positive correlation was found between Ki-67 LI and Spm8-2 immunoreactivity (r' = .53). Multivariate analysis revealed that only Ki-67 LI and Spm8-2 immunoreactivity were significant independent factors in patients with metastases (P < .04 and <.001, respectively) and in patients without metastases (P < .006 and <.001, respectively). Moreover, 100% of the patients with Spm8-2 immunoreactivity <10% were alive at the end of the follow-up. In terms of predictive values, Spm8-2 immunoreactivity had the highest predictive values (sensitivity, 89; specificity, 75; risk ratio, 11) of all clinicopathologic parameters. This study demonstrates that the anti-spermine monoclonal antibody Spm8-2 may be used at the time of radical nephrectomy as a reliable prognostic marker for defining RCC patients at high risk for progression.

Distribution patterns of ornithine decarboxylase in cells and tissues: facts, problems, and postulates

Ornithine decarboxylase (ODC) is a key enzyme in polyamine biosynthesis. Increased polyamine levels are required for growth, differentiation, and transformation of cells. In situ detection of ODC in cells and tissues has been performed with biochemical, enzyme cytochemical, immunocytochemical, and in situ hybridization techniques. Different localization patterns at the cellular level have been described, depending on the type of cells or tissues studied. These patterns varied from exclusively cytoplasmic to both cytoplasmic and nuclear. These discrepancies can be partially explained by the (lack of) sensitivity and/or specificity of the methods used, but it is more likely that (sub)cellular localization of ODC is cell type-specific and/or depends on the physiological status (growth, differentiation, malignant transformation, apoptosis) of cells. Intracellular translocation of ODC may be a prerequisite for its regulation and function.

Differential distribution of spermidine/spermine-like immunoreactivity in neurons of the adult rat brain

The polyamines spermidine and spermine are small, widely distributed polycations. In the brain, they confer rectification properties upon inwardly rectifying potassium channels and Ca(2+)-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA)/kainate receptors and also modify functional properties of N-methyl-D-aspartate receptors. Therefore, functional roles of spermidine/spermine in the adult brain will depend on the colocalization of the spermidine/spermine-sensitive receptors/channels and the polyamines either in the same or in closely associated cell types. We previously immunocytochemically demonstrated a prominent localization of spermidine/spermine in glial cells, especially astrocytes (Laube and Veh [ 1997] Glia 19:171-179). In contrast to the commonly accepted assumption of a ubiquitous distribution of polyamines in various cell types, in neurons of the rat brain, we detected a highly diverse spermidine/spermine-like immunoreactivity. The immunoreactivity in neurons and neuropil throughout the rat brain is listed according to intensity in arbitrary groups. The strongest neuronal staining was observed in the hypothalamic paraventricular, supraoptic, and accessory neurosecretory nuclei. Strong cytoplasmic staining was also evident in some motor and somatosensory areas such as the Me5 nucleus of the mesencephalic trigeminal tract, the nucleus ruber, and the large motor neurons of the spinal cord ventral horn. In contrast, in most cortical and hippocampal regions spermidine/spermine-like immunoreactivity in neurons was relatively weak, whereas in these areas, the labeling pattern was dominated by a diffuse neuropil labeling. In addition to spermidine/spermine immunocytochemistry, ornithine decarboxylase labeling was performed and the resulting labeling patterns were compared. The prominent localization of spermidine/spermine in neurosecretory neurons might point to a functional role different from channel/receptor modification. In these neurons, polyamines might be involved in secretory processes.

Regulation of macrophage activation and inflammation by spermine: a new chapter in an old story

Spermine, a naturally occurring polyamine, is a ubiquitous structural component of all eukaryotic cells. Regenerating tissues produce higher levels of spermine, and injured or dying cells release spermine into the extracellular milieu, so that tissue levels increase significantly at inflammatory sites of infection or injury. Recent research has focused on delineating the significance of spermine accumulation in the inflammatory process. The discovery that spermine is a negative regulator of macrophage activation provided a mechanism by which spermine influences the biology of inflammation. Mechanistic studies indicate that spermine is incorporated into macrophages and restrains the innate immune response. This anti-inflammatory process is facilitated by the negative acute-phase protein, fetuin.

Immunocytochemical localization of histamine in enterochromaffin-like (ECL) cells in rat oxyntic mucosa: a transmission electron microscopy study using monoclonal antibodies and conventional glutaraldehyde-based fixation

Histamine (HA), contained in the enterochromaffin-like (ECL) cells of the gastric mucosa in animals, plays an important role in gastric acid secretion, although methods for its exact morphological localization are still lacking. We used a pre-embedding indirect immunoperoxidase approach to define the fine structural localization of HA in rat oxyntic mucosa that was fixed with a glutaraldehyde-based fixative and HA monoclonal antibodies (MAbs AHA-1 and 2). Transmission electron microscopy showed that the peroxidase endproduct not only was concentrated in the cores of cytoplasmic granules but also was distributed to a high degree in the cytoplasm peripheral to the granules of the ECL cells. These results suggest that in ECL cells HA is enzymatically synthesized in the cytoplasm, then is transported and stored in the cores of the granules before its release from the basal lamina. The present HA immunoelectron microscopic method with MAbs would be applicable more generally to the ultrastructural identification of HA-containing cells.