Calcaneus and vertebrae bone mineral density values and fracture threshold

The calcaneus bone mineral density values (BMDs) of healthy Japanese women peaked at 20 to 25 years of age with 435 +/- 66 mg/cm2 (mean +/- S.D.), decreased 0.51% on the average every year thereafter until 45 years of age, 1.72% between 45 and 55 years (menopause) and 0.55% thereafter. The vertebrae bone mineral density value peaked at 30 to 35 years of age with 1.06 +/- 0.13 g/cm2 (mean +/- S.D.), decreased 0.67% on the average every year thereafter until 45 years of age, 1.23% between 45 and 55 years (menopause) and 0.70% thereafter. Mean -2.0 S.D. of the peak bone mass was considered appropriate as the fracture threshold for both the calcaneus and vertebra, judging from the BMDs of osteoporosis patients.

Decrease in spermidine content during logarithmic phase of cell growth delays spore formation of Bacillus subtilis

Bacillus subtilis 168M contained a large amount of spermidine during the logarithmic phase of growth, but the amount decreased drastically during the stationary phase. The extracts, prepared from B. subtilis cells harvested in the logarithmic phase, contained activity of arginine decarboxylase (ADC) rather than the activity of ornithine decarboxylase. In the presence of alpha-difluoromethylarginine (DFMA), a specific and irreversible inhibitor of ADC, the amount of spermidine in B. subtilis during the logarithmic phase decreased to about 25% of the control cells. Under these conditions, spore formation of B. subtilis 168M delayed greatly without significant inhibition of cell growth. The decrease in spermidine content in the logarithmic phase rather than in the stationary phase was involved in the delay of sporulation. Electron microscopy of cells at 24 hrs. of culture confirmed the delay of spore formation by the decrease of spermidine content. Furthermore, the delay of sporulation was negated by the addition of spermidine. These data suggest that a large amount of spermidine existing during the logarithmic phase plays an important role in the sporulation of B. subtilis.

Epitope mapping and functional characterization of monoclonal antibodies specific for the alpha subunit of Escherichia coli RNA polymerase

The epitopes have been localized for a set of monoclonal antibodies specific for the alpha subunit of the Escherichia coli RNA polymerase. The antibodies are classified into three groups based on their epitopic assignments. Group 1, mAb 123C2, maps in the N terminus of alpha between amino acids 1 and 23; Group 2 antibodies (mAb 129C4, mAb 124D1 and mAb 121C5) map in the central region between amino acids 190 and 210; Group 3 antibodies (mAb 130B1 and mAb 125C6) map in the C terminus between amino acids 310 and 320. mAb 130C2 is anomalous since it maps to the N terminus between amino acids 1 and 23 as well as to the C terminus between amino acids 320 and 329. The antibodies were used to investigate the role of alpha in transcription activation with cAMP receptor protein-dependent promoters. Three antibodies (130C2, 121C5, and 125C6) inhibited cAMP receptor protein-dependent initiation with lac P+ but not with lac UV5 or gal P+. Inhibition was observed with free RNA polymerase and the closed promoter complex; the preformed open promoter complex was insensitive. Only lac P+ was sensitive to these anti-alpha antibodies supporting the concept that the mode of interaction of RNA polymerase with cAMP receptor protein differs between lac P+ and gal P+.

Polyamine-sensitive magnesium transport in Saccharomyces cerevisiae

In Saccharomyces cerevisiae we found a toxic effect of polyamines, well-known metabolites important for cell proliferation; in magnesium-limited (50 microM Mg2+) synthetic medium, cell growth was severely inhibited by spermine, spermidine and putrescine in descending order. In conjunction with a decrease in the growth rate by the addition of 0.5 mM spermine, the internal Mg2+ content decreased and the spermine content increased. When cell growth ceased, the Mg2+ content had finally decreased to about 40% of the value before the addition of spermine (120-130 nmol/mg dry weight), and the spermine content concomitantly increased 30-fold (from 1 to 30 nmol/mg dry weight); spermine4+ apparently took the internal place of Mg2+ with a probable stoichiometry of 1:2. However, the total amount of Mg2+ retained in the cells remained constant even with the addition of spermine, suggesting that spermine blocks Mg2+ accumulation. In high (2 mM) Mg2+ medium, cell growth was hardly affected by polyamines, and an exchange of spermine and Mg2+ was minimal. Energy-dependent Mg2+ uptake by whole cells was inhibited by spermine, spermidine and putrescine in a similar manner as the growth rates. On the other hand, Mg2+ inhibited spermine uptake. These results suggest that competition takes place between extracellular spermine and Mg2+ for their accumulations. It is thus clear that polyamine-sensitive Mg2+ transport system is indispensable for the physiology of this organism.

Antizyme protects against abnormal accumulation and toxicity of polyamines in ornithine decarboxylase-overproducing cells

Exposure of ornithine decarboxylase (ODC; L-ornithine carboxy-lyase, EC 4.1.1.17)-overproducing mouse FM3A cells to micromolar levels of spermine or spermidine caused abnormal accumulation and toxicity of polyamines. This was apparently due to the inefficiency of negative feedback control of polyamine transport by polyamines in ODC-overproducing cells. Since antizyme is the only protein thus far recognized that can interact with ODC, depletion of free antizyme was regarded as the reason for the abnormal accumulation of polyamines. Accordingly, ODC-overproducing cells were transfected with pMAMneoZ1 possessing rat antizyme cDNA under the control of a glucocorticoid-inducible promoter. In the transfected cells, the addition of dexamethasone caused an increase in the amount of antizyme with an apparent molecular mass of 27 kDa, a decrease in the amount of ODC, a decrease in the polyamine transport activity, and the recovery of growth inhibition or cell death. The results indicate that antizyme can regulate not only the amount of ODC but also the activity of polyamine transport.

Properties and structure of spermidine acetyltransferase in Escherichia coli

Spermidine acetyltransferase (SAT) from Escherichia coli was purified about 40,000-fold. The molecular mass of native SAT was 95 kDa, and it consisted of four identical subunits. The products formed from the reaction of acetyl-CoA with spermidine by SAT were N1- and N8-acetylspermidine. The Km values for acetyl-CoA, spermidine, and spermine were 2 microM, 1.29 mM, and 220 microM, respectively. The enzymatic activity increased by 2.5-3.5-fold under the condition of poor nutrition but not in response to cold shock or high pH. By using synthetic oliogonucleotides deduced from amino acid sequences of the peptides in SAT, a polymerase chain reaction product with a length of 250 nucleotides was obtained. Using this polymerase chain reaction product, the gene encoding SAT (speG) was cloned and mapped at 35.6 min in the E. coli chromosome. E. coli cells transformed with the cloned speG gene increased SAT activity by 8-40-fold. The gene encoded a 186-amino acid protein, but SAT consisted of 185 amino acids because the initiator methionine was liberated from the protein. Thus, the predicted molecular mass was 21,756 Da. Significant similarity to aminoglycoside acetyltransferase and peptide N-acetyltransferase was observed in the amino acid sequence 87-141, and some similarity with spermidine-preferential binding protein (potD protein) in the spermidine-preferential uptake system was observed in the amino acid sequence 122-141. The results suggest that the active center of SAT may be located in the COOH-terminal portion.

Anchorage and retentive effects of a bisphosphonate (AHBuBP) on tooth movements in rats

The purpose of this study was to examine the effect of 4-amino-1-hydroxybutylidene-1,1-bisphosphonate (AHBuBP), a potent blocker of bone resorption, on orthodontic tooth movements in rats. In the first experiment, the right and left upper first molars were moved buccally for 3 weeks with a uniform standardized expansion spring under systemic administration of AHBuBP every other day. The total tooth movement during the 3-week experimental period was 40% of that in the control at a dose of 0.5 mg P/kg. In the second experiment, the right and left upper first molars were first moved buccally for 3 weeks without AHBuBP. The spring was then removed and administration of AHBuBP was initiated. The total relapse movement during the 3-week experimental period was 50% of that in the control at a dose of 0.5 mg P/kg. Results of the first and second experiments were both dose dependent. Histologic examination showed that in the experimental animals fewer osteoclasts appeared on the alveolar bone surface, and both bone resorption and root resorption were inhibited. Inhibition of tooth movement was also observed when AHBuBP was applied topically. These results suggest that AHBuBP could be useful in enhancing anchorage or retaining teeth in orthodontic treatment.

Antizyme delays the restoration by spermine of growth of polyamine-deficient cells through its negative regulation of polyamine transport

Effects of antizyme on polyamine transport and spermine restoration of the growth of polyamine-deficient cells were examined by using mouse FM3A cells transfected with pMAMneoZ1 possessing rat antizyme cDNA under the control of glucocorticoid-inducible promoter. Treatments of the transfected cells with alpha-difluoromethylornithine (DFMO), an inhibitor of ornithine decarboxylase (ODC), and dexamethasone, an inducer of antizyme, both caused a decrease in ODC activity and polyamine contents and inhibition of cell growth. However, spermine uptake of the transfected cells was repressed by dexamethasone but stimulated by DFMO. The decrease in the rate of spermine uptake in dexamethasone-treated cells was attributed to an increase in Km value and a slight decrease in Vmax value. Accordingly, restoration of cell growth by spermine was less effective in dexamethasone-treated cells than DFMO-treated cells. These results clearly indicate that antizyme has dual functions: one for ODC degradation and the other for negative regulation of polyamine transport.

Angiogenic activity of the recombinant hst-1 protein

The hst-1 transforming gene encodes a protein which belongs to the FGF family of growth factors. We showed previously that a human hst-1 protein produced in silkworm cells has in vitro mitogenic activity to vascular endothelial cells. Here we report effective synthesis of an unfused human hst-1 protein in E. coli and a potent in vivo angiogenic activity of this hst-1 protein by two in vivo assays for angiogenesis, chick chorioallantoic membrane assay and rat cornea assay. The NIH3T3 transformant transfected with the hst-1 gene appeared to develop a highly-vascularized tumor on nude mice. These data showed that the hst-1 protein has an angiogenic activity in vivo as well as in vitro.

Effects of topical administration of a bisphosphonate (risedronate) on orthodontic tooth movements in rats

In orthodontics, undesirable movement of anchor teeth during tooth movement and relapse of moved teeth after treatment are the main causes of unsuccessful results. If these tooth movements could be prevented with pharmacological agents, a less complex orthodontic force system and less extensive retention would be required. The purpose of this study was to examine the effect of topical administration of a bisphosphonate (risedronate), a potent blocker of bone resorption, on orthodontic tooth movements in rats. In the first experiment, both the right and left upper first molars were moved buccally with a standardized expansion spring under administration of risedronate. Risedronate solution was injected into the subperiosteum area adjacent to the left upper first molar. The right first molar served as a control with an injection of 0.9% NaCl solution. The topical administration of risedronate caused a significant and dose-dependent reduction of tooth movement after the orthodontic force was applied. In the second experiment, the right and left upper molars were first moved buccally for three weeks. The spring was then removed, and administration of risedronate was begun. The topical administration of risedronate inhibited relapse of the tooth in a dose-dependent manner. The administration of risedronate did not affect either overall growth of the animals or longitudinal growth of tibiae. These results suggest that topical application of risedronate may be helpful in anchoring and retaining teeth under orthodontic treatment.

Prolactin activates the interferon-regulated p91 transcription factor and the Jak2 kinase by tyrosine phosphorylation

The prolactin (PRL) receptor is a member of the family of cytokine receptors that lack intrinsic tyrosine kinase activity but contain two conserved cysteines in their N-terminal regions and a WSXWS motif adjacent to their transmembrane domains. In a manner similar to the interferons (IFNs), exposure of cells to PRL results in tyrosine phosphorylation of several cellular proteins and the rapid transcriptional induction of the IFN regulatory factor 1 gene. In this communication, we demonstrate that treatment of rat Nb2 lymphoma cells with PRL activates a latent protein factor so that it binds to an enhancer in the IFN regulatory factor 1 gene. This enhancer has been shown to be required for IFN-gamma-activated expression of this gene. PRL-induced assembly of the DNA binding complex, PRL-stimulated factor, required tyrosine phosphorylation. PRL-stimulated factor contained at least one protein that was antigenically similar to the p91 transcription factor, a component of several transcription complexes required for cytokine-activated gene expression. PRL not only induced the tyrosine phosphorylation of p91 but also induced tyrosine phosphorylation of Jak2, a tyrosine kinase required for IFN-gamma-activated gene expression. These results provide evidence for a signaling mechanism, some of whose components are shared by both PRL and IFN-gamma receptors, that results in the expression of early response genes.

Physiological role of the chaA gene in sodium and calcium circulations at a high pH in Escherichia coli

Ohyama et al. previously isolated Escherichia coli mutant RS1, which had a negligible activity for sodium ion extrusion at alkaline pH (T. Ohyama, R. Imaizumi, K. Igarashi, and H. Kobayashi, J. Bacteriol. 174:7743-7749, 1992). Our present study showed that the mutation of RS1 was compensated for by a cloned chaA gene. It has been proposed that sodium ion extrusion by ChaA is prevented under physiological conditions (D. M. Ivey, A. A. Guffanti, J. Zemsky, E. Pinner, R. Karpel, E. Padan, S. Schuldiner, and T. A. Krulwich, J. Biol. Chem. 268:11296-11303, 1993). In order to clarify the physiological role of chaA in sodium ion circulation at alkaline pH, we constructed a delta chaA mutant. The resultant mutant, TO112, deficient in both nhaA and chaA, was unable to grow at pH 8.5 in medium containing 0.1 M sodium chloride and had negligible sodium ion extrusion activity. However, TO112 grew at pH 7.0 in medium containing 0.4 M sodium chloride. Sodium ions were extruded from TO112 cells at neutral pH. The extrusion activity at pH 7.5 was greatly reduced by the deletion of nhaB. These data demonstrate that the activity of nhaB is low at high pH and that ChaA extrudes sodium ions at alkaline pH. The uptake of calcium ions by everted membrane vesicles prepared from the delta chaA mutant TO110 was 60% of the activity observed in the vesicles of the wild-type strain at pH 8.5, but the activity at neutral pH was not reduced by the deletion of chaA. Therefore, it was also suggested that ChaA plays a role in calcium ion circulation at alkaline pH.

Electron microscopic studies on experimental poisoning in mice induced by cylindrospermopsin isolated from blue-green alga Umezakia natans

The effects of cylindrospermopsin isolated from a blue-green alga Umezakia natans on mice were examined morphologically and biochemically. The main target of the phycotoxin was the liver. The thymus, kidneys and heart were also affected. There were four consecutive phases of the pathological changes in the liver. The initial phase was that of inhibition of the protein synthesis, the second phase of membrane proliferation followed, and then the third phase of fat droplet accumulation and finally the phase of cell death. Using globin synthesis in the rabbit reticulocytes system, it was clearly demonstrated that cylindrospermopsin is a potent inhibitor of the protein synthesis. Protein in microsomes from the mouse livers treated by cylindrospermopsin decreased in amount more significantly than that of phospholipid in microsomes. Furthermore, the amount of total P450 was extensively diminished in the toxin treated with hepatic microsomes.

The analysis of cocaine and its metabolites by liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (LC/APCI-MS)

The method for simultaneous determination of cocaine and its four metabolites (benzoylecgonine, ecgonine methyl ester, ecgonine and norcocaine) in urine by liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (LC/APCI-MS) was studied. The mass spectra showed the quasi-molecular ions, [M+H]+ as the base peak. LC/APCI-MS analysis was performed by focusing the characteristic ions at m/ = 186, 290, 200, 304 and 290 for ecgonine, benzoylecgonine, ecgonine methyl ester, cocaine and norcocaine, respectively. Cocaine and its four metabolites were well separated by high performance liquid chromatography (HPLC). The recoveries of cocaine and its metabolites from the spiked urine were 40.3-94.7% by solid-phase extraction with two type cartridges (Bond Elut Certify and Bond Elut SCX).

Neurotrophin-3 (NT-3) levels in the developing rat nervous system and in human samples

We developed an enzyme immunoassay (EIA) system for neurotrophin-3 (NT-3), based on a biotin-streptavidin detection system capable of measuring concentrations as low as 0.5 pg/ml with high reproducibility. We measured NT-3 levels in the developing rat nervous system as well as in normal subjects and patients with Alzheimer's disease (AD). The developmental change of NT-3 level in rat brain and peripheral tissues coincided with the change in NT-3 mRNA level reported before. We could not find any differences in NT-3 level in serum, cerebrospinal fluid, or brain (hippocampus and parietal cortex) obtained from controls and patients with AD.

Construction of mutant genes for a non-toxic verotoxin 2 variant (VT2vp1) of Escherichia coli and characterization of purified mutant toxins

The gene encoding a Verotoxin 2 variant, VTvp1, was mutated by oligonucleotide-directed site-specific mutagenesis. Among 6 mutant toxins encoded by the mutated genes, E167Q-R170L (glutamic acid at position 167 and arginine at position 170 from N-terminus of the A subunit were replaced by glutamine and leucine, respectively) was found to have markedly decreased activities; inhibition of protein synthesis, Vero cell cytotoxicity and mouse lethality of the purified E167Q-R170L were 1/1,900, 1/125,000 and 1/2,000, respectively, of those of the purified wild-type VT2vp1. Since the antigenic property of the E167Q-R170L was demonstrated to be similar to that of the wild-type VT2vp1 by Ouchterlony double gel diffusion test and by neutralization test of Vero cell cytotoxicity of the VT2vp1, a possibility to use the mutant VT2vp1, E167Q-R170L, as a toxoid is discussed.

Interferon-gamma induces tyrosine phosphorylation of interferon-gamma receptor and regulated association of protein tyrosine kinases, Jak1 and Jak2, with its receptor

Interferon-gamma (IFN-gamma) induces the expression of a set of early response genes by tyrosine phosphorylation of latent transcription factors such as p91. Although the tyrosine kinases, Jak1 and Jak2, have recently been shown to be critical for signal transduction by IFN-gamma, evidence is lacking for both tyrosine phosphorylation of the IFN-gamma receptor (IFN-gamma R) and the interaction between Jak1, Jak2, and the IFN-gamma R. In this report, we show that binding of IFN-gamma to HeLa cells initiated a series of events that resulted in the extremely rapid (15 s) tyrosine phosphorylation of not only Jak1, Jak2, and p91 but also the IFN-gamma R. Coimmunoprecipitation experiments revealed that Jak1 was associated with the IFN-gamma R prior to ligand binding, whereas Jak2 became part of the IFN-gamma R-Jak1 complex immediately after ligand binding. H2O2/vanadate treatment of cells for 15 min resulted in only the tyrosine phosphorylation of Jak1 and IFN-gamma R. Only after 60 min of this treatment did we observe tyrosine phosphorylation of Jak2 and p91 and assembly of the transcription factor complex FcRF gamma that binds to the promoter of the fcgr1 gene. These data suggest that JAK1 associates with the IFN-gamma R prior to ligand binding. IFN-gamma treatment of cells results in recruitment of JAK2 into the IFN-gamma R-Jak1 complex followed by assembly of the transcription factor FcRF gamma complex.

Sequencing and characterization of the ntp gene cluster for vacuolar-type Na(+)-translocating ATPase of Enterococcus hirae

We have previously reported the DNA and amino acid sequences for the three genes (ntpA, ntpB, and ntpK) encoding the A, B, and K (proteolipid) subunits, respectively, of Na(+)-translocating ATPase of a eubacterium Enterococcus hirae (Kakinuma, Y., Kakinuma, S., Takase, K., Konishi, K., Igarashi, K., and Yamato, I. (1993) Biochem. Biophys. Res. Commun. 195, 1063-1069). In this paper we report the entire nucleotide sequence of the ntp gene cluster coding for this multisubunit enzyme. The cluster contained eight other genes; the order of these 11 genes was ntpF, -I, -K, -E, -C, -G, -A, -B, -D, -H, and -J, encoding proteins with predicted molecular weights of 14,255, 75,619, 16,036, 22,699, 38,162, 11,409, 65,766, 51,139, 27,093, 7,164, and 48,869, respectively. The deduced amino acid sequences of these products suggested that NtpI and NtpJ are hydrophobic proteins and others are hydrophilic. The ntpI gene product, which possesses six membrane-spanning segments in its carboxyl-terminal half, resembled the 116-kDa subunit of vacuolar (V)-ATPase in clathrin-coated vesicles. In addition, the NtpE, NtpC, NtpG, and NtpD proteins resembled bovine kidney ATPase E subunit, Saccharomyces cerevisiae Vma6p, Manduca sexta V-ATPase 14-kDa subunit, and Sulfolobus acidocaldarius gamma subunit, respectively, although the similarities between their amino acid sequences were moderate. Other gene products (NtpF and NtpH) did not show significant sequence similarity to other V-ATPase subunits. Since NtpA, NtpB, and NtpK are homologous counterparts of V-ATPase, these findings suggest that the molecular architecture of E. hirae Na(+)-ATPase complex corresponds to the V-type H(+)-ATPase complex distributed in various eukaryotic endomembrane systems. The sequence of the NtpJ product was similar to those of K+ transport systems of S. cerevisiae (Trk1 and Trk2); its meaning will be discussed. This is the first demonstration of a eukaryotic V-ATPase-like Na+ pump in bacteria.