Carbohydrate-mediated recognition of a circulating placental alkaline phosphatase-immunoglobulin M complex

We detected an abnormal alkaline phosphatase (AP) electrophoretically in the serum of a patient with rheumatoid arthritis, who had a macromolecular AP linked with immunoglobulin M (IgM) bearing a kappa light chain. The IgM isolated from the AP-IgM complex in the patient's serum reacted apparently with all of the AP isozymes tested, i.e. those originating in the liver, bone, intestine and placenta, but the alpha-mannosidase-treated IgM from the patient's serum bound to placental AP (PAP) alone. This suggests that untreated IgM recognizes multivalent epitopes of the AP and that the complex of AP with alpha-mannosidase-treated IgM is a specific antibody-antigen complex. In order to investigate further the multivalent binding capacity for the PAP-untreated IgM complex, we prepared a monoclonal antibody (MoAb) against PAP and identified it as an IgM with a kappa light chain. The binding affinities and their circulating half-lives of the synthetic complexes of PAP and respective MoAbs were examined with and without treatment with several glycosidases. The untreated MoAb bearing IgM had binding affinity for all of the AP isozymes tested, while alpha-mannosidase-treated IgM attached only to PAP, the same as the IgM isolated from the PAP-IgM complex in the patient's serum. The circulating clearance of the PAP-IgM complex in rabbits was faster than either component alone. In addition, the PAP-IgM complex treated with alpha-mannosidase was found to have the shortest half-life of all the complexes of PAP and Igs treated with the several glycosidases tested. These results suggest that the formation of the PAP-IgM complex as an enzyme-linked antibody and the clearance of the complex in vivo are dependent on the sugar moieties of the Igs.

Enzyme-linked immunosorbent assay for human pulmonary surfactant protein D

We developed a simple and sensitive enzyme-linked immunosorbent assay (ELISA) for human pulmonary surfactant protein D (SP-D). Human SP-D was purified from bronchoalveolar lavage fluids of patients with pulmonary alveolar proteinosis. Nine monoclonal antibodies (MAbs) were established from BALB/c mice immunized with the purified human SP-D. All MAbs were directed to either 43 kDa SP-D contained in lung lavage fluids of patients with pulmonary alveolar proteinosis or in amniotic fluids from healthy normal pregnancies. The ELISA is based on a sandwich method using two MAbs, 6B2 and 7C6. Cross-reactivity to human SP-A or rat SP-D was evaluated as below 0.6%. The recovery of different concentrations of SP-D ranged from 94.4% to 111.2%, and serial dilutions of amniotic fluids showed good linearity. SP-D concentrations in 21 amniotic fluids from normal pregnancies were measured by the ELISA. The mean concentration in amniotic fluids from pregnancies in the third trimester was significantly higher than that from earlier stages of gestation (p < 0.001), indicating that this ELISA may be applicable for prediction of fetal lung maturity.

Cdc25A is a novel phosphatase functioning early in the cell cycle

The cdc25+ tyrosine phosphatase is a key mitotic inducer of the fission yeast Schizosaccharomyces pombe, controlling the timing of the initiation of mitosis. Mammals contain at least three cdc25+ homologues called cdc25A, cdc25B and cdc25C. In this study we investigate the biological function of cdc25A. Although very potent in rescuing the S.pombe cdc25 mutant, cdc25A is less structurally related to the S.pombe enzyme. Northern and Western blotting detection reveals that unlike cdc25B, cdc25C and cdc2, cdc25A is predominantly expressed in late G1. Moreover, immunodepletion of cdc25A in rat cells by microinjection of a specific antibody effectively blocks their cell cycle progression from G1 into the S phase, as determined by laser scanning single cell cytometry. These results indicate that cdc25A is not a mitotic regulator but a novel phosphatase that plays a crucial role in the start of the cell cycle. In view of its strong ability to activate cdc2 kinase and its specific expression in late G1, cdc2-related kinases functioning early in the cell cycle may be targets for this phosphatase.

Molecular cloning of a novel Ca(2+)-binding protein (calmegin) specifically expressed during male meiotic germ cell development

During mammalian spermatogenesis, many specific molecules are expressed. We have recently identified a 93-kDa male meiotic germ cell-specific antigen (Meg 1) exclusively expressed in germ cells from the pachytene spermatocyte to the spermatid stage using the monoclonal antibody TRA 369 (Watanabe, D., Sawada, K., Koshimizu, U., Kagawa, T., and Nishimune, Y. (1992) Mol. Reprod. Dev. 33, 307-312). In this study, we cloned a cDNA representing this antigen from a mouse testis cDNA expression library, using the monoclonal antibody TRA 369. Northern blotting showed that this transcript was 2.3 kilobases in length and was expressed only in the testis and not in other somatic tissues or in the ovary. The expression of the mRNA was first detected at the pachytene spermatocyte stage of male germ cell development, and this expression was correlated with the expression of the protein. Sequence analysis of the cDNA revealed that the predicted protein consists of 611 amino acids, including a hydrophobic NH2 terminus characteristic of a signal peptide, two sets of internal repetitive sequences (four repeats of IPDPSAVKPEDWDD and GEWXPPMIPNPXYQ), and a hydrophilic COOH terminus. The deduced amino acid sequence has 58% homology with dog calnexin (the ER membrane phosphoprotein of pancreatic cells) and significant partial homology with calreticulin (high affinity Ca(2+)-binding protein of the ER membrane) at the repetitive sequence. Furthermore, we demonstrated the 45Ca2+ binding ability of this antigen by a 45Ca2+ overlay assay, and the name calmegin is proposed for this antigen. Calmegin is a novel Ca(2+)-binding protein that is specifically expressed in spermatogenesis. The highly regulated, specific, and abundant expression of calmegin suggests that it has important roles in spermatogenesis.

Participation of an arginyl residue of insulin chain B in the inhibition of hemagglutination by Porphyromonas gingivalis

Insulin chain B, containing each one arginyl and lysyl residue in its peptide chain, inhibited hemagglutination by Porphyromonas gingivalis. To determine the further inhibitory profile, chain B was digested into 4 fragments by protease, which was contained in the preparation of hemagglutinin from P. gingivalis. Identification of each fragment by the amino acid analysis revealed that the chain was cleaved at the carboxyl site of arginyl and/or lysyl residues, but one fragment contained citrulline instead of arginine at its carboxyl terminal. This citrulline might have originated from arginine by an arginine deiminase-like enzyme of P. gingivalis. Only one fragment that contained the arginyl residue exhibited inhibitory activity on hemagglutination, but it was considerably weakened compared with that of the intact chain B. The difference in the inhibitory activity seemed to depend on the position of an arginyl residue in the peptide; this was also confirmed using several derivatives of bradykinin. The present result suggests that the internal arginyl residue in a peptide chain may be critical for the inhibition of the hemagglutination by P. gingivalis.

Modification of 1 alpha,25-dihydroxyvitamin D3 metabolism by introduction of 26,26,26,27,27,27-hexafluoro atoms in human promyelocytic leukaemia (HL-60) cells: isolation and identification of a novel bioactive metabolite, 26,26,26,27,27,27-hexafluoro-1 alpha,23(S),25-trihydroxyvitamin D3

To study whether the introduction of fluoro atoms into C-26 and C-27 positions on the 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3] molecule could affect metabolism in human promyelocytic leukaemia (HL-60) cells, we compared the metabolism of 26,26,26,27,27,27-hexafluoro-1 alpha,25-dihydroxyvitamin D3 [26,27-F6-1 alpha,25(OH)2D3] and 1 alpha,25(OH)2D3 in HL-60 cells. 26,27-F6-1 alpha,25(OH)2D3 was mainly converted into a new bioactive metabolite, 26,26,26,27,27,27-hexafluoro-1 alpha,23(S),25- trihydroxyvitamin D3 [26,27-F6-1 alpha,23(S),25(OH)3D3], but not into 26,26,26,27,27,27-hexafluoro-1 alpha,24(R),25-trihydroxyvitamin D3 [26,27-F6-1 alpha,24(R),25(OH)3D3] in HL-60 cells. 26,27-F6-1 alpha,23(S),25(OH)3D3 was identified by combinations of h.p.l.c., u.v. spectroscopy and g.c.-mass spectrometry. Evidence is presented that 26,27-F6-1 alpha,25(OH)2D2 was metabolized to 26,27-F6-1 alpha,23(S),25(OH)3D3 by C-23 hydroxylation as a first step of the metabolism, and the 23-hydroxylated bioactive metabolite was accumulated in the cells, whereas 1 alpha,25(OH)2D3 was initially deactivated and metabolized to 1 alpha,24(R),25(OH)3D3 by C-24 hydroxylation through a side-chain oxidation pathway resulting in C23-C24 cleavage, yielding 24,25,26,27-tetranor-1 alpha,23(OH)2D3 in HL-60 cells. These results show that 26,27-F6-1 alpha,25(OH)2D3 and 1 alpha,25(OH)2D3 are metabolized by different metabolic pathways in HL-60 cells.

Cytotoxicity of Porphyromonas gingivalis toward cultured human gingival fibroblasts

Direct cytotoxicity of black-pigmented anaerobic rods was studied on the confluent monolayer of human gingival fibroblasts in vitro. Only strains of Porphyromonas gingivalis caused morphological alteration (cell-rounding) and notable depression of viability of fibroblasts. To determine the location of the cytotoxicity, bacterial surface components, i.e., outer membrane, lipopolysaccharide, fimbriae and outer membrane vesicles were prepared from P. gingivalis and their cytotoxicity was assessed. Among these preparations, only outer membrane vesicles are supposed to have high affinity to human gingival fibroblasts, and the cytotoxicity of outer membrane vesicles was found to be much stronger than that of the other constituents. This cytotoxic factor seemed to consist largely of protein and to be associated with the enzyme activity of outer membrane vesicles. The effects of some protease inhibitors and L-cysteine on the cytotoxicity of outer membrane vesicles suggest that the mechanism of cell-rounding is different from that of cell death.

Cyclin G: a new mammalian cyclin with homology to fission yeast Cig1

A new gene encoding a cyclin-like protein has been isolated from a rat fibroblast cDNA library by cross-hybridization with a mixture of c-src family proto-oncogene kinase domains as a probe. This putative cyclin, called cyclin G, contains a typical cyclin box at the N-terminus but no apparent 'destruction box' or 'PEST' sequence. Interestingly, in its C-terminus region, it has a sequence homologous with a tyrosine phosphorylation site of the epidermal growth factor receptor. Although this cyclin is phylogenetically related to HCS26 of Saccharomyces cerevisiae, it most resembles Cig1, a B-type cyclin, of Schizosaccharomyces pombe, which has been suggested to act at the G1/S phase of the cell cycle. Cyclin G mRNA is induced within 3 h after growth stimulation and remains elevated with no apparent cell cycle dependency, indicating its close association with growth stimuli but not with the cell cycle.

Dephosphorylation of human p34cdc2 kinase on both Thr-14 and Tyr-15 by human cdc25B phosphatase

In mammalian cells, p34cdc2 kinase undergoes phosphorylation at threonine-14, tyrosine-15 and threonine-161 in the S and G2 phases of the cell cycle. At the onset of mitosis, the kinase becomes dephosphorylated at threonine-14 and tyrosine-15, resulting in activation. Cdc25 phosphatase has been shown to dephosphorylate tyrosine-15 in vitro, but whether it also does at threonine-14 remains unclear. In this study, we have found that human cdc25B phosphatase dephosphorylates both threonine-14 and tyrosine-15 but not threonine-161.

[Fluorescein fundus angiography of optic nerve head in primary open angle glaucoma and low tension glaucoma]

Fluorescein fundus angiography was performed at angle of 20 degrees in the 58 low tension glaucoma (LTG) eyes (30 cases) and 77 primary open angle glaucoma (POAG) eyes (41 cases) and the relation of the optic nerve head fluorescein changes to visual field disturbances (stage classification of Kosaki) was compared between POAG and LTG groups. The filling defect of fluorescein in the deep area and the decrease in number of superficial capillaries were observed in the optic nerve head. The filling defect area of fluorescein in the optic nerve head corresponding to Bjerrum scotoma was recognized even in the mild visual field disturbance cases of both LTG and POAG. The following findings were noted in both LTG and POAG cases; expansion of the filling defect area and the decrease in number of superficial capillaries in the same area with progression of visual field disturbances. Filling defect area of fluorescein of the optic nerve head accorded with visual field disturbance area in 19 LTG eyes (32.8%) and 61 POAG eyes (79.2%). On the contrary, the filling defect area of the optic nerve head was wider than the visual disturbance area in 37 LTG eyes (63.8%) and 16 POAG eyes (20.8%). These findings suggest that blood circulatory disorders of the optic nerve head occurred earlier in LTG than in POAG and that the development of LTG might be closely associated with the blood circulatory disorders.

Generation of plasma kinin by three types of protease isolated from Porphyromonas gingivalis 381

Three types of protease (A, B and C) isolated from the culture supernatant of Porphyromonas gingivalis 381 had peculiar activities on kinin generation from high molecular-weight kininogen in vitro. Protease C released bradykinin from the kininogen in a reaction mixture containing 2 mM dithiothreitol, but A and B did not. However, the activity of degrading bradykinin was much stronger in protease A and B than in C. These findings suggest that only protease C shows plasma kallikrein activity.

Elongation factor-1 alpha gene determines susceptibility to transformation

Elongation factor-1 alpha (EF-1 alpha), an essential component of the eukaryotic translational apparatus, is a GTP-binding protein that catalyses the binding of aminoacyl-transfer RNAs to the ribosome. Expression of the EF-1 alpha gene decreases towards the end of the lifespans of mouse and human fibroblasts, but forced expression of EF-1 alpha prolongs the lifespan of Drosophila melanogaster. Eukaryotic initiation factor-4E, another component of the translational machinery, is mitogenic or oncogenic when constitutively expressed in some mammalian cells. Thus, components of the protein synthesis apparatus seem to be involved in the control of cell proliferation. Using expression cloning, we have isolated a complementary DNA clone from a BALB/c 3T3 mouse fibroblast variant, A31-I-13 (ref. 10), which specifies a factor determining the susceptibility of BALB/c3T3 to chemically and physically induced transformation. Here we report that the factor is EF-1 alpha and that its constitutive expression causes BALB/c 3T3 A31-I-1 (ref. 10), C3H10T1/2 (ref. 11) and Syrian hamster SHOK fibroblasts to become highly susceptible to transformation induced by 3-methylcholanthrene and ultraviolet light. EF-1 alpha messenger RNA is also constitutively expressed in a quiescent culture of the highly susceptible variant A31-I-13. We conclude that the removal of regulation of the expression of these components of the translational machinery may predispose cells to become more susceptible to malignant transformation.

Survey of a receptor protein in human erythrocytes for hemagglutinin of Porphyromonas gingivalis

The purpose of this study is to survey a receptor protein in human erythrocyte membrane for the hemagglutinin (HA) of Porphyromonas gingivalis. Human erythrocytes were modified by either chymotrypsin or P. gingivalis HA along with the disappearance of their hemagglutinating ability and the removal of the band 3 protein. By preparative electrophoresis, this protein was isolated and purified from human erythrocytes. The purified protein showed strong inhibitory activity for hemagglutination and the binding to P. gingivalis cells, whose binding sites were calculated to be approximately 9000, suggesting its binding to the active site of HA. Hemagglutinin purified from P. gingivalis by affinity absorption to sheep erythrocyte ghosts possessed strong trypsin-like activity, and both the HA and the enzyme activities were inhibited by arginine. Specific modification of arginyl residues in human erythrocytes by phenylglyoxal diminished the hemagglutinating ability. From the similarity of the inhibition profile and possible active sites between HA and the trypsin-like protease, it is suggested that hemagglutination may occur as a result of the primary reaction of the enzyme (protease) and the substrate. These results suggest that band 3 may be a key protein in human erythrocyte membrane for HA from P. gingivalis and its binding sites may be arginyl residues of the protein.

[Possible mechanisms of inositol phosphate-diacylglycerol signalling pathway in the regulation of intraocular pressure]

To clarify the role of the inositol phosphate diacylglycerol (IP/DAG) signalling pathway in the regulation of intraocular pressure (IOP), the effect of tumor promoter phorbol ester (PMA) and Ca ionophore (A23187) on IOP responses was examined in albino rabbits. PMA stimulates protein kinase C (PKC) directly and A23187 elevates intracellular Ca2+ concentration. In this study, the topical application of 10 microM PMA or 15 microM A23187 slightly reduced IOP. However topical application of both 10 microM PMA and 15 microM A23187 significantly reduced IOP. The maximum IOP decrease was 5.0 mmHg. This decrease was inhibited by pretreatment with 0.5 microM staurosporin, a PKC inhibitor. Quantitative changes of inositol 1,4,5-trisphosphate (IP3) and PKC activity in cultured ciliary epithelia (CE), stimulated with several ocular hypotensive agents were also studied. When cultured CE was stimulated with 50 microM carbachol, the PKC activity and IP3 content rapidly increased. When CE was stimulated with 50 microM epinephrine, isoproterenol or timolol, PKC activity did not show any change and IP3 level declined. These studies suggest that the IP/DAG signalling pathway somehow mediates aqueous dynamic changes in ciliary epithelia.

Structural organization of the gene for prostaglandin D synthase in the rat brain

A 3-kilobase-pair gene for rat brain prostaglandin D synthase [(5Z,13E)-(15S)-9 alpha,11 alpha-epidoxy-15-hydroxyprosta-5,13- dienoate D-isomerase, EC 5.3.99.2], which belongs to the lipocalin family, was isolated from a rat genomic DNA library by plaque hybridization with the cDNA for the enzyme. The gene contains seven exons, and all the splice donor and acceptor sites conform to the GT/AG rule. Transcription initiates at a guanine residue 39 base pairs upstream of the translation initiation codon, as determined by primer-extension analysis of rat brain mRNA. The 5'-flanking region of the gene lacks typical transcriptional regulatory sequences, such as TATA and CAAT boxes, but contains several sets of inverted repeats, direct repeats, and sequences resembling the transcriptional factor Sp1-binding site. The gene structure of prostaglandin D synthase is remarkably analogous to those of other lipocalins, such as beta-lactoglobulin, alpha 2-urinary globulin, placental protein 14, and alpha 1-microglobulin, in terms of number and sizes of exons and phase of splicing of introns. Furthermore, in a multiple alignment of the deduced amino acid sequences, positions of exon/intron junction of the prostaglandin D synthase gene are highly conserved and located around the positions of those of the genes for other lipocalins despite a weak homology.

A marked molecular heterogeneity of growth hormone (GH) detected in the plasma but not pituitary of a patient with acromegaly: comparison with other acromegalics and an implication for discrepant plasma levels of GH and insulin-like growth factor

We experienced a 41-year-old acromegalic male (Case 1) in whom the basal plasma GH was extremely high (320-450 ng/mL) but plasma IGF-I was only slightly elevated (2.0-2.8 U/mL). His nutritional condition and associated diabetes mellitus did not appear to be responsible for the relatively low IGF-I level, and a GH-autoantibody in the plasma was absent. We thus performed gel filtration analyses of his plasma and somatotroph adenoma to determine elution patterns of immunoreactive (IR) and receptor active (RA) GH. For comparison, the same studies were carried out on plasmas and somatotroph adenomas obtained from three other acromegalics (Cases 2-4) whose basal plasma GH and IGF-I levels were 22-45 ng/mL and 3.5-6.0 U/mL, respectively. IR GH in Case 1's plasma distributed over an extremely wide range keeping similar titers rather than showing three discernible components (big-big, big, and little GH) as did plasmas and adenomas from Cases 2-4. And, most of the IR GH in Case 1's plasma was eluted in such fractions that contained low levels of RA GH, indicating a minor proportion of biologically active GH. However, interestingly, the chromatographic profile and total GH content of Case 1's adenoma were similar to those of Cases 2-4's adenomas. These results may, at least in part, explain the discrepancy between the plasma GH and IGF-I levels of Case 1. The unexpectedly different GH elution patterns between the plasma and adenoma from this patient, may suggest a contribution of certain plasma factor(s) to the unusual chromatographic profile of plasma GH.

Eosinophilia associated with chronic pancreatitis: an analysis of 122 patients with definite chronic pancreatitis

Among 122 patients with chronic pancreatitis, marked eosinophilia (greater than 500 eosinophils/mm3 in the peripheral blood) was observed in 21 cases (17.2%). All of the affected patients were males, and there was no significant difference in the incidence of eosinophilia between patients with alcoholic and nonalcoholic pancreatitis. In the patients with eosinophilia, endocrine pancreatic function was maintained comparatively well, despite marked exocrine pancreatic dysfunction. The eosinophilia of chronic pancreatitis frequently developed in association with severe damage to neighboring organs (pleural effusion, pericarditis, and ascites), as well as in association with pancreatic pseudocyst. Our findings suggest that there is a close correlation between marked eosinophilia and severe tissue injury during acute exacerbations of chronic pancreatitis.

Biological potency of a fluorinated vitamin D analogue in hypoparathyroidism

Several in vivo experiments have revealed that a synthesized fluorinated analogue of vitamin D, 26,26,26,27,27,27-hexafluoro-1,25-dihydroxyvitamin D3 (26,27-F6-1,25(OH)2D3) has a higher and longer-lasting biological activity than 1,25(OH)2D3 in calcium regulating actions. We evaluated the biological potency and the availability for clinical use of this compound in hypocalcemia associated with hypoparathyroidism. In an experimental setting, daily administration of 650 pmol/kg of 26,27-F6-1,25(OH)2D3 showed an equivalent effect to that of 3250 pmol/kg of 1,25(OH)2D3 in elevating whole blood ionized calcium levels in parathyroidectomized rats. Furthermore, an additional clinical study demonstrated that 0.5-1.5 micrograms/day of 26,27-F6-1,25(OH)2D3 were considered adequate maintenance doses in various types of hypoparathyroidism and that changes of medication to the same doses of 1,25(OH)2D3 resulted in prompt decline of urinary calcium excretion and of whole blood ionized calcium levels, and in recurrence of symptoms related to hypocalcemia. Although the mechanism responsible for the high potency of this analogue remains unclear, our experience confirms that 26,27-F6-1,25(OH)2D3 has higher biological activities in bone calcium mobilization and is more potent than 1,25(OH)2D3 in correcting hypocalcemia of hypoparathyroidism in a hospital setting.

Surface electromyogram spectral characterization and motor unit activity during voluntary ramp contraction in men

The relationships were investigated between the surface electromyographic (SEMG) power spectrum analysed by the 20 order autoregressive model (AR spectrum) and underlying motor unit (MU) activity during isometric contractions increasing linearly from 0% to 80% maximal voluntary contraction. Intramuscular spikes and SEMG signals were recorded simultaneously from biceps brachii muscle; the former were analysed by a computer-aided intramuscular MU spike amplitude-frequency (ISAF) histogram and the latter subjected to AR spectral analysis. Results indicated that there was a positive correlation between the force output and the mean amplitude of the ISAF histogram but not with the mean frequency. These changes were accompanied by changes in relative power of the high frequency (100-200 Hz) peak (HL) in the AR spectrum. It was also found that there was a positive correlation between the mean amplitude of the ISAF histogram and the HL value. These data suggested that the power of the high frequency peak in the AR spectrum of the SEMG signal preferentially reflected the progressive recruitment of underlying MU according to their size. Differences between the AR spectrum and the spectrum estimated by fast Fourier transform algorithm have also been discussed.

An additional homolog of the fission yeast cdc25+ gene occurs in humans and is highly expressed in some cancer cells

The gene cdc25+ is a mitotic inducer controlling transition from the G2 to the M phase of the cell cycle in the fission yeast, Schizosaccharomyces pombe. Using phenotypic complementation of a mutant of S. pombe, we have cloned a human homolog (CDC25Hu2) of the cdc25+ gene that differs markedly in structure from CDC25 (referred to here as CDC25Hu1), the first such homolog to be isolated. The carboxyl-terminal region of p63CDC25Hu2 shares significant sequence similarity with cdc25 protein homologs from other eukaryotes and possesses full complementation activity. CDC25Hu2 is expressed in human cell lines 10 to 100 times more than CDC25Hu1, and its expression is particularly high in some cancers, including SV40-transformed fibroblasts. Whereas CDC25Hu1 is predominantly expressed in G2, CDC25Hu2 is expressed throughout the cell cycle with a moderate increase in G2. Thus, at least two homologs of the cdc25 gene exist and are both expressed in human cells. The implications of CDC25Hu2 overexpression in some cancer cells are discussed.