Role of cytokine in the induction of adhesion molecules on cultured human gingival fibroblasts

This study was undertaken in an effort to understand the role of cytokines on human gingival fibroblasts and T lymphocyte trafficking into inflamed gingival tissue. Using flow cytometry we examined gingival fibroblasts to determine the level of cell surface expression and the percentage of cells positive for intercellular adhesion molecule 1 (ICAM-1), the HLA-DR antigen, lymphocyte function-associated antigen 3 (LFA-3), and the CD44 molecule, which are involved in antigen presentation. The following cytokines were used: interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), IL-6, and IL-8. The levels of ICAM-1 expression were enhanced in a dose- and time-dependent manner by IL-1 beta, TNF-alpha, or IFN-gamma, but not by IL-6 or IL-8. HLA-DR surface expression was induced only by IFN-gamma in a dose- and time-dependent manner, but not by the other cytokines tested. In contrast, the expression of LFA-3 and the CD44 molecule could be detected without the stimulation of any cytokine, but the levels of their expression were not significantly changed by any cytokines. The enhanced ICAM-1 expression by cytokines was reduced in a time-dependent manner following the removal of cytokines from the reaction mixture, while IFN-gamma-induced HLA-DR expression was maintained even 7 days after the removal of IFN-gamma. These data support an interactive role for inflammatory cytokines and the expression of adhesion molecules on gingival fibroblasts in the pathogenesis of gingival inflammation in periodontal disease.

Structure and differential expression of two distinct genes encoding the chloroplast elongation factor Tu in tobacco

We have isolated two nuclear genes, tufA and tufB, encoding chloroplast EF-Tu from a tobacco (Nicotiana sylvestris) genomic library. The tufA gene encodes a polypeptide of 478 amino-acid residues, consisting of a putative transit peptide of 70 residues and a mature EF-TuA of 408 residues. The tufB gene codes for a precursor proteins of 485 residues, containing a transit peptide of 77 residues and a mature EF-TuB of 408 residues. No introns were found in either gene. The sequence similarity within the coding regions of the two genes is 84.3% for nucleotides and 89.7% for amino acids. Multiple 5' ends of transcripts were observed for both tuf genes. Northern analysis revealed that the EF-Tu mRNA accumulated at least 30-fold more in leaf than in root tissue. Ribonuclease protection assays using gene-specific probes showed that the level of tufB mRNA is three-fold higher than that of tufA mRNA in leaves but in roots the tufB mRNA levels is less than half that of tufA mRNA. The relative amount of tufB mRNA is 30-fold higher in leaves than in roots whereas tufA messages are only five-fold higher in leaves. These data suggest that expression of both tuf genes is differentially regulated according to tissue and plastid type.

Assessment of interleukin-6 in the pathogenesis of periodontal disease

This study was performed to investigate the aspects of interleukin-6 (IL-6) production in both the gingival tissue and the peripheral blood of patients with periodontal disease and of periodontally healthy subjects. In addition, IL-6 expression in human gingival tissues was studied by reverse transcription-polymerase chain reaction analysis and by immunoperoxidase staining with anti-IL-6 monoclonal antibody. The levels of IL-6 in the culture supernatants from peripheral blood mononuclear cells (PBMC) stimulated with lipopolysaccharide and in serum were examined by bioassay. We detected IL-6 mRNA expression in all inflamed gingival tissues (17/17) examined and in 2/4 in healthy gingival tissues. IL-6 protein was detected mainly in endothelial cells, fibroblasts, and macrophages but not in the area containing T or B cells in the inflamed gingival tissues, and was not detected at all in healthy gingival tissues. There was no significant difference between the subjects with periodontal disease and those with healthy gingival tissues either in serum IL-6 levels or in the amount of IL-6 produced by PBMC. These results suggest that non-lymphoid cells in inflamed gingival tissue may contribute to the pathogenesis of periodontal disease via IL-6 production, and that the IL-6 produced in gingival tissue may not reflect the IL-6 levels in peripheral blood.

Isolation and characterization of a 53 kDa major cell envelope protein antigen from Treponema denticola ATCC 35405

A major cell envelope protein was purified from the cell envelope fraction of Treponema denticola ATCC 35405 by ion exchange chromatography after extraction with Zwittergent 3-14. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a relative molecular mass of 53 kDa for this protein with a pI of 6.3-6.8. Amino acid analysis revealed that this protein contained high proportions of hydrophobic amino acids (40.4%), and no cysteine could be detected. The N-terminus of the protein was blocked to Edman degradation. Rabbit antiserum raised against the purified 53 kDa protein reacted with the outer envelope of the T. denticola cell surface as confirmed by immunoelectron microscopy. This rabbit antiserum reacted with 4 of the 11 strains of treponemes tested in this study. Sera from 9 to 18 periodontitis patients reacted strongly with this 53 kDa cell envelope protein of T. denticola as determined by immunoblotting analysis.

Conversion of G-protein specificity of insulin-like growth factor II/mannose 6-phosphate receptor by exchanging of a short region with beta-adrenergic receptor

The 14-residue peptide (peptide 14) corresponding to Arg2410-Lys2423 of the insulin-like growth factor II receptor (IGF-IIR) can activate the adenylate cyclase-inhibitor guanine nucleotide-binding protein Gi, and the 15-residue beta III-2 peptide Arg259-Lys273 of the beta 2-adrenergic receptor (beta 2AR) can activate the stimulatory protein Gs. In phospholipid vesicles, IGF-IIR and beta 2AR activate Gi and Gs in response to IGF-II and isoproterenol, respectively. We constructed a chimeric IGF-II receptor (beta III-2/IGF-IIR) by converting its native peptide 14 sequence to the beta III-2 sequence. In cells expressing beta III-2/IGF-IIR, membrane adenylate cyclase activity markedly increased without IGF-II and was further promoted by IGF-II. This was verified by measuring chloramphenicol acetyltransferase (CAT) activity in beta III-2/IGF-IIR cells with cotransfection of a cAMP response element-CAT construct. This study shows not only the conversion of G-protein specificity of a receptor from Gi to Gs but also the simulation of G protein-coupled receptor signals by using a short receptor region and intact cells. These findings indicate that the G protein-activation signals are interchangeable, self-determined structural motifs that function in the setting of either a single-spanning or multiple-spanning receptor.

GTP-binding protein-activator sequences in the insulin receptor

Some functions of the insulin receptor (insR) are assumed to be mediated by pertussis toxin-sensitive Gi/G(o) proteins. Here we have located G-protein-activator domains in the cytoplasmic region of the human insR. We searched the sequence of insR and found three candidate regions at residues 1039-1061, 1147-1168 and 1325-1345, referred to as ISRP1, ISRP2 and ISRP3, respectively. Among them, the Gi/G(o)-activating function was observed only in peptide ISRP3. ISRP1 specifically activated Gs, whereas ISRP2 had no effect on G proteins. ISRP2 and ISRP3 contained five of six autophosphorylated tyrosine residues in insR. After tyrosine phosphorylation, ISRP2 showed specific Gi-activating function, and ISRP3 potentiated its ability and became capable of activating G proteins generally. This is the first study that specifies G-protein-activator domains in insR and describes their modification by autophosphorylation.

P53 tumor-suppressor gene and cyclic adenosine-monophosphate in breast and esophageal cancer are regulated through high-concentration of epidermal growth-factor

To reveal the molecular mechanism of the growth-inhibitory effects of high concentrations of EGF, accumulations of p53 protein and p21ras expression in MX-1 and UM-1 breast cancer and ES-4 esophageal cancer transplanted into nude mice were investigated after local injections of 2 mug of EGF or 2 mug of TGF-beta. The accumulation of p53 protein and expression of p21ras were determined by using the methods of Western immunoblotting and p53 mutant selective quantitative ELISA assay. p53 mutation was investigated by using the PCR analysis and DNA sequencing. Contents of intra-cellular-cAMP of these tumors were also determined by radioimmunoassay. Results showed that the high concentration of EGF induced the accumulations not only of wild type p53 protein, but also of mutant p53 protein in these tumors growth-inhibited by EGF. In ES-4 esophageal cancer, 2 mug of EGF induced the up-regulation of p53 and the down-regulation of p21ras. On the contrary, 2 mug of TGF-beta induced the down-regulation of p53 and the up-regulation of p21ras in UM-1 human breast cancer. The point mutation of p53 gene was found at codon 181 contained C to T transversions (Amino acid switch: Arg --> Cys) in ES-4 esophageal cancer. The accumulations of p53 proteins were also associated with the down regulated intra-cellular-cAMP induced by high concentrations of EGF. These results indicate that p53 gene and ras gene are involved in the signal pathway of EGF and that the p53 gene may have some important role as a negative growth factor by suppressing ras oncogene in the mechanism of tumor growth inhibition through the high concentration of EGF.

Association of Actinobacillus actinomycetemcomitans leukotoxin with nucleic acids on the bacterial cell surface

Actinobacillus actinomycetemcomitans, a periodontopathic gram-negative bacterium, produces a leukotoxin that is a member of the RTX cytotoxin family. Although genes may function in toxin secretion, the leukotoxin is not secreted extracellularly but remains associated with the bacterial cell surface. We report here that this toxin-cell surface association is mediated by nucleic acids and directly demonstrate that the extracellular secretion of toxin occurs in growing cultures with increased ionic strength of medium. All examinations were performed with freshly harvested A. actinomycetemcomitans 301-b from anaerobic fructose-limited chemostat cultures. The occurrence of cell surface-localized DNA was shown by directly digesting whole cells with the restriction endonuclease EcoRI or HindIII, which yielded many DNA fragments. The cell surface DNA constituted about 20% of the total cellular DNA. The leukotoxin was released from the whole cells by digestion with DNase I as well as restriction endonucleases. Because the leukotoxin binds ionically to DNA, it is dependent on the ionic strength of buffers or media. Accordingly, the toxin was released from cells suspended in saline at pH 7.5 in the presence of increasing amounts of MgCl2 (0 to 10 mM) or NaCl (0 to 50 mM). Moreover, a considerable quantity of leukotoxin was detected in the culture supernatant of fructose-limited chemostat cultures when sodium succinate solution was pumped into the steady state as an additional salt (30 and then 50 mM). This toxin-DNA association was also found in well-characterized strains including not only the leukotoxin-producing ATCC 29522 but also the toxin production-variable ATCC 29523 and the non-leukotoxin-producing ATCC 33384 when these strains were grown in the chemostat culture.

Abnormal proportion of gamma delta T cells in peripheral blood is frequently detected in patients with periodontal disease

The proportions of gamma delta T cells in the peripheral blood of 8 early-onset periodontitis (EOP) patients, 8 later-onset periodontitis (LOP) patients, and of 17 healthy subjects (HS) were assessed by immunofluorescence assay using an anti-pan gamma delta T cell monoclonal antibody (TCR-delta 1) to study the population attributes of peripheral blood gamma delta T cells in patients with periodontal disease. The distribution of the proportions of gamma delta T cells in both EOP and LOP patients was found to be one and one half times broader than that in the HS; however, there was no significant difference in the proportion of gamma delta T cells between each group. An abnormally high proportion of peripheral blood gamma delta T cells in pan T cells (> 9.90%) was observed in 37.5% of both the EOP patients and the LOP patients. An abnormally low proportion (< 5.57%) was observed in 50% of the EOP patients and in 25% of the LOP patients. The higher occurrences of the high or low gamma delta T cell proportions were significant between EOP and HS, and between EOP+LOP and HS. There was no correlation between the proportion of gamma delta T cells and age or the clinical parameters of periodontal status. It was concluded that an abnormal proportion of gamma delta T cells is frequently detected in patients with periodontal disease. These findings are consistent with the proposed role of the gamma delta T cells for playing a unique role as a first line defense against infections at body surfaces.

[A case of papillary fibroelastoma of the heart found 13 years after open mitral commissurotomy]

A patient, 68-year-old female, underwent open mitral commissurotomy (OMC) for rheumatic mitral stenosis in April, 1979. In July of 1992, during the postoperative follow-up echocardiogram showed 8 x 7 mm mitral subvalvular tumor mass and mitral restenosis. Then, mitral valve replacement was performed using prosthetic valve (Carbomedics #25 mm). The tumor was located on the top of postero-medial papillary muscle and its chordae, and histologically was diagnosed as benign papillary fibroelastoma. Based on the findings of periodic echocardiogram, the tumor doubling time was estimated to be 283 days. The postoperative course was uncomplicated and she was discharged on the 34th post operative day. Papillary fibroelastoma is a rare benign cardiac tumor. Pathological origin of this tumor is still unknown. However, Lambl's excrescence, long-term inflammatory stimulation and/or thrombi are supposed to be etiologic factors. This tumor is generally found incidentally at the time of autopsy or operation because the patients are often asymptomatic. However, because the tumor causes embolism at times, periodic examination by echocardiogram after operation preserving valves is recommended, and surgical resection is required when the diagnosis is established.

[A morphological study of the lesioned carotid artery--comparison with WHHL rabbit and Japanese white rabbit]

It is necessary for a neurosurgeon to know the course of repair of vascular injury caused by the procedure of an operation. And further more, it is very important to understand how existence of hypercholesteremia would affect it. Injuries of operations were caused to carotid arteries of Watanabe heritable hyperlipidemic (WHHL) rabbit and a morphological study of the course of repair was made. Japanese white rabbit (JWR) were treated exactly same as WHHL, and their course of repair was compared and examined as control. One week after operation, both WHHL rabbit and JWR showed edematous thickening of a intima, increase in grade of thickening which was continued until two of three months after operation was observed, however gradually decrease thereafter. In case of WHHL rabbit, thickened intima at suture portion was formed by smooth muscle cells migrated from media. Foamy cells were not observed here. The grade of thickening of WHHL rabbits was lower than that of JWR, and that WHHL rabbits tended to show slower change of elastofibrosis in thickened intima rather than JWR. It was considered that the smooth muscle cells of WHHL rabbit has a poor activity naturally.

Molecular cloning and characterization of mouse TIE and TEK receptor tyrosine kinase genes and their expression in hematopoietic stem cells

To identify receptor tyrosine kinases (RTKs) critical to early hematopoiesis, we performed polymerase chain reaction-based cloning from yolk sac and highly enriched bone marrow hematopoietic stem cells (HSCs). Characterization of two novel genes of their full-length cDNA sequences revealed that they were mouse homologues of the endothelial cell RTK genes, TIE and TEK. They shared a unique structural property of coexistent immunoglobulin-like domain, epidermal growth factor-like repeats, and fibronectin type III repeats in their extracellular domains. Both genes were expressed in a similar fashion in adult tissues and primitive hematopoietic cells, predominantly in the bone marrow HSCs.

[Intraperitoneal administration of cis-diamminedichloroplatinum (II) for peritoneal carcinomatosis caused by gastric cancers]

The effectiveness of the intraperitoneal administration of cis-diamminedichloroplatinum (II) for peritoneal carcinomatosis by gastric cancers was evaluated through experimental and clinical studies. In experimental studies, the effect of sodium thiosulfate (STS) on cytotoxic activity of DDP was evaluated by MTT assay using human gastric cancer cell lines. The cytotoxic activity of DDP was reduced by 50% with 100-fold STS in the area under the curve (AUC), whereas 10-fold STS in AUC did not reduce the cytotoxicity of DDP. In clinical studies, patients were treated with one of three protocols: Group A was treated by the intraperitoneal injection (ip) of DDP at a dose of 70 mg/m2, and group B or C was treated by ip DDP at a dose of 110 mg/m2 with or without STS rescue. The pharmacodynamics and the adverse effects of treatments were evaluated between these three protocols. In group C, the means of AUC of STS were 2.43-, 10.8- and 86.8-fold those of total platinum in the peritoneal cavity, plasma, and urine, respectively. There were 1/5, 1/2 and 2/2 partial responses in peritoneal carcinomatosis patients treated with A, B and C. Renal toxicity was not observed in the patients treated with DDP and STS rescue. STS does not seem to reduce the antitumor activity of DDP in peritoneal cavity and plasma, while the renal cytotoxicity was reduced by STS rescue. The result led us to conclude that intraperitoneal DDP treatment combined with STS rescue would be useful chemotherapy against peritoneal carcinomatosis by gastric cancer.

Calcium-dependent protein kinase C activity of neutrophils in localized juvenile periodontitis

Protein kinase C is a key molecule in neutrophil signal transduction after receptor stimulation by soluble bioactive molecules. It has been reported that neutrophils from most patients with localized juvenile periodontitis (LJP) do not have a normal response after stimulation with a chemotactic ligand such as N-formylmethionylleucylphenylalanine (FMLP). To further clarify the mechanism of this altered response and to confirm and expand earlier observations, the calcium-dependent protein kinase C activity of neutrophils from patients with LJP was evaluated. Peripheral blood neutrophils from 12 patients and 12 healthy subjects, age, sex, and race matched, were sonicated and subsequently subfractionated by ultracentrifugation into a soluble fraction (cytosol rich) and a particulate fraction (membrane rich). The calcium-dependent protein kinase C activity was evaluated in each fraction by phosphorylation of histone with radiolabeled ATP in the presence or in the absence of phorbol 12-myristate 13-acetate stimulation. Results revealed that the total calcium-dependent protein kinase C activity of neutrophils from patients with LJP and depressed chemotactic migration to FMLP (201.0 +/- 63.6 pmol/min/10(7) cells) was lower than that of neutrophils from healthy subjects (287.6 +/- 55.7 pmol/min/10(7) cells) (P < 0.01). The calcium-dependent protein kinase C activity in neutrophils from patients with LJP exhibited a positive correlation with chemotactic migration to FMLP (P < 0.05). The low activity of calcium-dependent protein kinase C in neutrophils from the patients reflected the low activity in the soluble fraction from the neutrophils. After stimulation with phorbol 12-myristate 13-acetate, the calcium-dependent protein kinase C activity was found to be lower from patients with LJP than from healthy subjects. These results suggest that lower calcium-dependent protein kinase C in neutrophils is a predisposing factor for LJP.

Purification of chloroplast elongation factor Tu and cDNA analysis in tobacco: the existence of two chloroplast elongation factor Tu species

We have purified a chloroplast elongation factor Tu (EF-Tu) from tobacco (Nicotiana tabacum) and determined its N-terminal amino acid sequence. Two distinct cDNAs encoding EF-Tu were isolated from a leaf cDNA library of N. sylvestris (the female progenitor of N. tabacum) using an oligonucleotide probe based on the EF-Tu protein sequence. The cDNA sequence and genomic Southern analyses revealed that tobacco chloroplast EF-Tu is encoded by two distinct genes in the nuclear genome of N. sylvestris. We designated the corresponding gene products EF-Tu A and B. The mature polypeptides of EF-Tu A and B are 408 amino acids long and share 95.3% amino acid identity. They show 75-78% amino acid identity with cyanobacterial and chloroplast-encoded EF-Tu species.

Marked increase in fundic mucosal histidine decarboxylase activity in a patient with H+,K(+)-ATPase antibody-positive autoimmune gastritis

A 63-year-old woman was diagnosed as autoimmune gastritis by the presence of serum antibody against alpha-subunit of gastric H+,K(+)-ATPase. The patient did not have pernicious anemia, but showed achlorhydria, marked hypergastrinemia, enterochromaffin-like cell hyperplasia and an extremely high histidine decarboxylase activity in the gastric fundic mucosa. Intragastric acidification by infusion of hydrochloric acid via a nasogastric tube induced a transient reduction of serum gastrin level and fundic mucosal histidine decarboxylase activity. A marked increase in fundic mucosal histidine decarboxylase activity as well as hypergastrinemia appears to be the pathophysiologic response to achlorhydria caused by autoimmunity against gastric H+,K(+)-ATPase.

Antigenic properties of Campylobacter rectus (Wolinella recta) major S-layer proteins

The antigenic properties of the surface layer (S-layer) proteins of various Campylobacter rectus strains including 24 clinical isolates and the type strain ATCC 33238 were examined. S-layer proteins were extracted from whole cells by acid treatment according to the method of McCoy et al. (Infect. Immun. 11, 517-525, 1975). The acid extracts from 23 of the isolates and ATCC 33238 contained two major proteins with molecular masses of 130 kDa and 150 kDa, both of which were identified as subunits of the S-layer after comparison with the protein profiles of acid-treated (S-layer-deficient) cells. An S-layer protein from one isolate (CI-808) demonstrated a different molecular mass (160 kDa). Both the 150-kDa proteins of ATCC 33238 and isolate CI-306 and the 160-kDa protein of CI-808 were purified by ion-exchange chromatography in the presence of urea. In Ouchterlony immunodiffusion experiments with these purified proteins and rabbit antiserum raised to each purified protein, both common and strain-specific antigenic determinants were identified in the C. rectus S-layer proteins.

Effect of Ca2+ on the binding of Actinobacillus actinomycetemcomitans leukotoxin and the cytotoxicity to promyelocytic leukemia HL-60 cells

The effects of Ca2+ on the binding of Actinobacillus actinomycetemcomitans leukotoxin (LT) to LT-susceptible promyelocytic leukemia HL-60 cells and the consequent cytotoxicity were investigated in comparison with those on LT-resistant erythroleukemia K-562 cells. The total amount of LT bound to the HL-60 and K-562 cells, as determined by ELISA using anti-LT rabbit serum, was essentially the same for both cells. The percentage of bound LT decreased in the presence of phosphatidylcholine (PC) was also almost equal for both cells. In contrast, EGTA added in the presence of PC enhanced the decrease of bound LT significantly from HL-60, but not from K-562. By monitoring the fluorescence of Fura-2 and of fluorescein as a measure for the change in intracellular calcium ions ([Ca2+]i) and cytotoxic activity, respectively, we showed that the exposure of HL-60 to LT induced the [Ca2+]i increase followed by the cell death, whereas this was distinctly not the case for K-562. These results indicate that a Ca(2+)-dependent LT-binding mechanism is possibly the step characteristic to LT-susceptible HL-60 cells.

Alzheimer amyloid protein precursor complexes with brain GTP-binding protein G(o)

The most characteristic change in progressive dementia of Alzheimer's type is a tissue deposit of amyloid beta/A4 protein, which is derived from its precursor protein APP (ref.2). Structural alterations of APP are implicated in the pathogenesis of Alzheimer's disease, but it is not known how they cause the disease. Although APP has a receptor-like architecture, is located on the neuronal surface, and has a conserved cytoplasmic domain, no receptor function has been demonstrated for APP. Here we report that APP forms a complex with G(o), a major GTP-binding protein in brain. The cytoplasmic APP sequence His 657-Lys 676 shows a specific G(o)-activating function and is necessary for complex formation. G(o) protein treated with GTP-gamma S lost the ability to associate with APP. This suggests that APP is a receptor coupled to G(o) and that abnormal APP-G(o) signalling is involved in the Alzheimer's disease process.

Interleukin-8 is a major neutrophil chemotactic factor derived from cultured human gingival fibroblasts stimulated with interleukin-1 beta or tumor necrosis factor alpha

Inflammatory mediators produced by cells in the gingiva have been implicated in the initiation and progression of periodontal disease, a common infectious disease. In this study, we examined the biological activity of neutrophil chemotactic factors and the kinetics of expression of interleukin-8 (IL-8) mRNA derived from normal gingival fibroblasts in response to inflammatory mediators in an in vitro model. Gingival fibroblasts stimulated by either recombinant human interleukin-1 beta or recombinant human tumor necrosis factor alpha produced neutrophil chemotactic factors after 4 h, whereas expression of cell-derived IL-8 mRNA was detected within 1 h after stimulation. Furthermore, in a neutralization assay, rabbit anti-recombinant human IL-8 antiserum inhibited neutrophil chemotactic activity to basal levels. These results provide evidence that gingival fibroblasts synthesize potent chemotactic factors such as IL-8 in the presence of the inflammatory mediators interleukin-1 beta and tumor necrosis factor alpha. The activity of these factors may contribute to neutrophil-mediated processes in the pathogenesis of periodontal disease.

[Targeting cancer chemotherapy using temperature-sensitive liposomes containing adriamycin conjugated with monoclonal antibodies]

Liposomes have a specific liquid-crystalline phase transition temperature (Tc), at which they release an entrapped drug. Temperature-sensitive liposomes containing adriamycin (TS-Lip-ADM) were made of dipalmitoylphosphatidylcholine (DPPC, Tc: 41 degrees C), distearoylphosphatidylcholine (DSPC, Tc: 54 degrees C), cholesterol and adriamycin. Monoclonal antibodies against human alpha-fetoprotein (AFP) were conjugated to TS-Lip-ADM. When liposomal suspension was immersed in a bath, the release rate of ADM from TS-Lip-ADM = Ab increased, as the temperature increased from 34 degrees C to 42 degrees C. ADM release was dependent on the temperature.