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Biomedical subjects

J Gu

Publications and source records attributed to J Gu.

At least 37 records · Page 2Linked to original sources

A 588-gene microarray analysis of the peripheral blood mononuclear cells of spondyloarthropathy patients.

OBJECTIVES: To identify genes which are more highly expressed in the peripheral blood mononuclear cells (PBMC) of patients with spondyloarthropathy (SpA), rheumatoid arthritis (RA) and psoriatic arthritis (PsA), in comparison to normal subjects. METHODS: A 588-gene microarray was used as a screening tool to select a panel of such genes from PBMC of these subjects and of normal subjects. Results were then validated by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: The following genes were more highly expressed in arthritis patients than in normal subjects: macrophage differentiation marker MNDA (myeloid nuclear differentiation antigen), MRP8 and MRP14 (migratory inhibitory factor-related proteins); signalling molecules JAK3 (janus kinase 3) and MAP kinase p38 (mitogen-activated protein kinase); receptors TNFR2/p75, C-C-chemokine receptor type 1 (CCR1), C-X-C-chemokine receptor type 4 (CXCR4) and integrin beta1; and the cytokines/chemokines interleukin (IL) 1beta and IL-8. Expression of CXCR4 was unexpectedly high among all arthritis subjects. Using RT-PCR, ELISA and immunohistology, expression of stromal cell-derived factor 1 (SDF-1) was demonstrated in arthritis joints. CONCLUSIONS: The CXCR4/SDF-1 is a potential pro-inflammatory axis for RA, PsA and SpA.

Adolescent↗

Over-expression of beta-1,4-galactosyltransferase V increases the growth of astrocytoma cell line.

Our previous study showed that the gene expression of beta-1,4-galactosyltransferase V (beta-1,4-GalT V), preferentially galactosylating GlcNAc1-->6Man of oligosaccharides, increased in the process of astrocytoma progress, with the highest level in grade IV astrocytoma. To investigate the function of this beta-1,4-GalT in cell proliferation, the sense and antisense cDNA of beta-1,4-GalT V was constructed as pcDNA3-HA-GalT V and pcDNA3-anti-GalT V respectively and transfected into SHG cell, a kind of human astrocytoma cell line. The transfection was confirmed with Northern and Western blot assay. It was found that the growth of SHG/HA-GalT V in serum-containing medium was faster than that of mock-transfectant with the vector pcDNA3, whereas the growth of SHG/GalTV-AS was slower than that of mock-transfectant. GalTV-HA/SHG showed a stronger capability for colony formation than that of GalTV-AS/SHG as evaluated by anchorage-independent growth in soft agar assay. This result was consistent with that of the growth curve. By RCA-1 lectin assay, the galactosylation on the surface of GalTV-HA/SHG and SHG/GalTV-AS was stained stronger (P<0.001) and weaker (P<0.05) respectively compared with the mock transfectant. This indicates that beta-1,4-GalT V was involved in the malignant phenotype of astrocytoma cells, possibly causing the high galactosylation on the cell surface.

Astrocytoma↗

Roles of phytanoyl-CoA alpha-hydroxylase in mediating the expression of human coagulation factor VIII.

The coagulation factor VIII (FVIII) is the coagulation factor deficient in the X-chromosome-linked bleeding disorder hemophilia A. Previous transfection studies demonstrated that factor VIII was 10-100-fold less efficiently expressed than the homologous coagulation factor, factor V. To investigate the regulatory mechanisms of FVIII synthesis and secretion, we used the yeast two-hybrid system as an approach to search for proteins that associated with FVIII. The A2 domain (337-740 amino acids) of factor VIII (FVIII-A2) was used as a bait and phytanoyl-CoA alpha-hydroxylase (PAHX) was identified as a binding protein of FVIII-A2. PAHX had potential to interact with the residues 373-508 within the A2 domain, but not with A1 and A3 (the homologous domains of A2). The interaction between the A2 domain and PAHX was independent of the type 2 peroxisomal targeting signal (PTS2) of PAHX. Overexpression of PAHX in FVIII-produced cells decreased the expression of FVIII by about 70%. The elevated expression of von Willebrand factor had no effect on the suppression of FVIII secretion by PAHX. Expression of the green fluorescent PAHX fusion protein in SMMC-7721 cells affected the intracellular trafficking of FVIII-A2. These results suggested that the interaction between PAHX and FVIII-A2 was in part responsible for the low-level expression of factor VIII.

Animals↗

The genetic structure of recombinant inbred mice: high-resolution consensus maps for complex trait analysis.

BACKGROUND: Recombinant inbred (RI) strains of mice are an important resource used to map and analyze complex traits. They have proved particularly effective in multidisciplinary genetic studies. Widespread use of RI strains has been hampered by their modest numbers and by the difficulty of combining results derived from different RI sets. RESULTS: We have increased the density of typed microsatellite markers two- to five-fold in each of several major RI sets that share C57BL/6 as a parental strain (AXB, BXA, BXD, BXH and CXB). A common set of 490 markers was genotyped in just over 100 RI strains. Genotypes of around 1,100 additional microsatellites in one or more RI sets were generated, collected and checked for errors. Consensus RI maps that integrate genotypes of approximately 1,600 microsatellite loci were assembled. The genomes of individual strains typically incorporate 45-55 recombination breakpoints. The collected RI set - termed the BXN set - contains approximately 5,000 breakpoints. The distribution of recombinations approximates a Poisson distribution and distances between breakpoints average about 0.5 centimorgans (cM). Locations of most breakpoints have been defined with a precision of < 2 cM. Genotypes deviate from Hardy-Weinberg equilibrium in only a small number of intervals. CONCLUSIONS: Consensus maps derived from RI strains conform almost exactly to theoretical expectation and are close to the length predicted by the Haldane-Waddington equation (x3.6 for a 2-3 cM interval between markers). Non-syntenic associations between different chromosomes introduce predictable distortions in quantitative trait locus (QTL) datasets that can be partly corrected using two-locus correlation matrices.

Alleles↗

A novel growth suppressor gene on chromosome 17p13.3 with a high frequency of mutation in human hepatocellular carcinoma.

Previous studies have shown that there is a high frequency of loss of heterozygosity (LOH) on chromosome 17p13.3 in hepatocellular carcinoma [HCC (M. Fujimori et al., Cancer Res., 51: 89-93, 1991; H. Nagai et al., Oncogene, 14: 2927-2933, 1997; V. Boige et al., Cancer Res., 57: 1986-1990, 1997; Z. Piao et al., Int. J. Cancer, 75: 29-33, 1998; and B. Charroux et al., J. Cell Biol., 148: 1177-1186, 2000)]. The minimum region of LOH on chromosome 17p13.3 in HCC has been defined within the region between D17S643 and D17S1574. Moreover, D17S926 in the minimum region of LOH has the highest frequency of LOH, and its sequencing analysis has been accomplished. In this region, 6 of 13 novel genes have been characterized (X. Zhao, D. Wan, M. He, Yu. Ye, Yi. He, L. Han, M. Guo, Y. Huang, W. Qin, M-W. Wang, W. Chong, J. Chen, L. Zhang, N. Yang, B. Xu, M. Wu, L. Zuo, and J. Gu. A high frequency LOH region on chromosome 17p13.3 in human HCC with densely clustered genes identified, submitted for publication). Here we describe the cloning and characterization of one of these novel genes, designated HCC suppressor 1 (HCCS1), located at this region. HCCS1 had 18 exons, and its full-length cDNA was 2.0 kb. The protein expression product of HCCS1 was located in mitochondria. HCCS1 had a high frequency of mutations in HCC samples, whereas no alteration has been found in matched noncancerous liver tissues. Immunohistochemistry revealed a significantly higher expression of HCCS1 in the noncancerous liver tissues (33 of 35 samples) than in the HCC samples (2 of 35 samples). Transfection of HCCS1 cDNA into the HCC cell line remarkably reduced the efficiency of its colony formation and inhibited tumor growth in nude mice. Taken together, these findings strongly suggest a potential role of HCCS1 as a HCC putative suppressor gene.

3T3 Cells↗

Sensitization of differentiated PC12 cells to apoptosis by presenilin-2 is mediated by p38.

Presenilin 2 (PS2), the chromosome 1 familial Alzheimer's disease gene, has been shown to sensitize differentiated PC12 (dPC12) cells to apoptosis. In this investigation we show that activation of the p38 mitogen activated protein kinase pathway occurs downstream of PS2 and is required for sensitizing the cells to apoptosis. Overexpression of PS2 led to a dramatic increase in p38 activity, which is correlated with an increased susceptibility of dPC12 cells to apoptosis. Inhibition of p38 by the specific inhibitor SB203580 or interfering with the p38 pathway by overexpression of dominant negative MKK6 effectively blocked PS2 sensitized apoptosis. Expression of ALG-3, a truncated PS2 which acts as a dominant negative PS2, significantly suppressed p38 activation induced by trophic factor withdrawal. These data suggest that PS2 is a signaling molecule upstream of the p38 MAPK pathway in apoptotic dPC12 cells.

Animals↗

Subcellular distribution of p53 and p73 are differentially regulated by MDM2.

The binding of MDM2 targets p53, but not p73, for degradation, whereas it suppresses the transactivation function of both proteins. MDM2 also mediates p53 nuclear export, but its role in the regulation of p73 distribution is unknown at the present time. We show here that, in sharp contrast to p53, MDM2 induces p73 to form nuclear aggregates that colocalize with MDM2 but are distinct from the promyelocytic leukemia dots. The MDM2 ring-domain that is necessary for mediating p53 nuclear export is not required for the induction of the p73 nuclear aggregates. Using a domain-swapping approach, we demonstrate that the inability of p73 to nuclear-export is attributable to its nonfunctional nuclear-export sequence.

Cell Nucleus↗

[Analysis of inflammation related gene expression spectrum in ankylosing spondylitis patients using cDNA microarray].

OBJECTIVE: To test the difference of gene expression patterns in peripheral blood mononuclear cells (PBMCs) among patients with ankylosing spondylitis (AS) or rheumatoid arthritis (RA) and healthy volunteers and to find potential discriminating genes. METHODS: The PBMC gene expression spectra of 7 patients with active AS, 6 patients with active RA, and 7 healthy volunteers were tested by microarray assay with 588 target gene filters. Semi-quantitative RT-PCR was performed to test the expression rates of thirteen inflammation related genes which had been with high expression rates in at least 4 arthritis patients by microarray assay, among 22 AS patients, 8 RA patients, and 7 healthy volunteers. RESULTS: The expression rates of inflammation related genes by cDNA microarray assay in healthy volunteer group, AS group, and RA group were 8.4%, 32.5% and 44.8% respectively (P < 0.001). The positive rate in RA patients was much higher than that in AS patients (P < 0.012). A significant increase of positive rate of these genes was also noticed in 2 active pulmonary tuberculosis patients. The expression rates of the 13 genes which were positive in at least 4 arthritis patients tested by semiquantitative RT-PCR in 22 AS patients, 8 RA patients and 7 healthy volunteers were very similar to those expression rates tested by cDNA microarray. CONCLUSION: The gene expression profiles of PBMC among AS patients are significantly abnormal and are significantly different from those among RA patients. The high expression of the 13 cytokines is not specific to AS.

Adolescent↗

Tumor formation and inactivation of RIZ1, an Rb-binding member of a nuclear protein-methyltransferase superfamily.

The retinoblastoma protein-interacting zinc finger gene RIZ (PRDM2) is a member, by sequence homology, of a nuclear protein-methyltransferase (MTase) superfamily involved in chromatin-mediated gene expression. The gene produces two protein products, RIZ1 that contains a conserved MTase domain and RIZ2 that lacks the domain. RIZ1 gene expression is frequently silenced in human cancers, and the gene is also a common target of frameshift mutation in microsatellite-unstable cancers. We now report studies of mice with a targeted mutation in the RIZ1 locus. The mutation inactivates RIZ1 but not RIZ2. These RIZ1 mutant mice were viable and fertile but showed a high incidence of diffuse large B-cell lymphomas (DLBL) and a broad spectrum of unusual tumors. RIZ1 deficiency also accelerated tumorigenesis in p53 heterozygous mutant mice. Finally, several missense mutations of RIZ1 were found in human tumor tissues and cell lines; one of these was particularly common in human DLBL tumors. These missense mutations, as well as the previously described frameshift mutation, all mapped to the MTase functional domains. All abolished the capacity of RIZ1 to enhance estrogen receptor activation of transcription. These data suggest a direct link between tumor formation and the MTase domain of RIZ1 and describe for the first time a tumor susceptibility gene among methyltransferases.

Alleles↗

Molecular evidence for the independent origin of extra-ovarian papillary serous tumors of low malignant potential.

BACKGROUND: Molecular data suggest that peritoneal tumors in women with advanced-stage ovarian papillary serous adenocarcinoma are monoclonal in origin. Whether the same is true for ovarian tumors of low malignant potential is not known. We compared peritoneal and ovarian tumors from women with advanced-stage ovarian papillary serous tumors of low malignant potential to determine whether the peritoneal tumors arose from the same clone as the ovarian tumors. METHODS: We studied the clonality of 73 peritoneal and ovarian tumors from 18 women with advanced-stage ovarian papillary serous tumors of low malignant potential. Formalin-fixed, paraffin-embedded tumors and representative normal tissues were sectioned and stained with hematoxylin-eosin, representative sections from separate tumors were manually microdissected, genomic DNA was extracted from the microdissected tumors, and the polymerase chain reaction was used to amplify a CAG polymorphic site in the human androgen receptor locus on the X chromosome to determine the inactivation pattern of the X chromosome and the clonality of the tumors. RESULTS: The pattern of X-chromosome inactivation could be determined from the tumors of 13 of 18 patients. Of the 13 patients, seven (54%) had nonrandom inactivation of the X chromosome, and six of the seven had different inactivation patterns in the peritoneal and ovarian tumors. Three of these patients also had different patterns of nonrandom X-chromosome inactivation in tumors from each ovary. The remaining six patients had random patterns of X-chromosome inactivation in the peritoneal and ovarian tumors. CONCLUSIONS: Our data suggest that peritoneal and ovarian tumors of low malignant potential arise independently.

Adenocarcinoma, Papillary↗

Apoptosis induction in cancer cells by a novel analogue of 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalenecarboxylic acid lacking retinoid receptor transcriptional activation activity.

The retinoid 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalenecarboxylic acid (AHPN) is reported to have anticancer activity in vivo. Induction of cell cycle arrest and apoptosis in cancer cell lines refractory to standard retinoids suggests a retinoid-independent mechanism of action for AHPN. Conformational studies suggested that binding of AHPN does not induce an unusual conformation in retinoic acid receptor (RAR) gamma. The 3-chloro AHPN analogue MM11453 inhibited the growth of both retinoid-resistant (HL-60R leukemia, MDA-MB-231 breast, and H292 lung) and retinoid-sensitive (MCF-7 breast, LNCaP prostate, and H460 lung) cancer cell lines by inducing apoptosis at similar concentrations. Before apoptosis, MM11453 induced transcription factor TR3 expression and loss of mitochondrial membrane potential characteristic of apoptosis. MM11453 lacked the ability to significantly activate RARs and retinoid X receptor alpha to initiate (TREpal)(2)-tk-CAT reporter transcription. These results, differential proteolysis-sensitivity assays, and glutathione S-transferase-pulldown experiments demonstrate that, unlike AHPN or the natural or standard synthetic retinoids, MM11453 does not behave as a RAR or retinoid X receptor alpha transcriptional agonist. These studies strongly suggest that AHPN exerts its cell cycle arrest and apoptotic activity by a signaling pathway independent of retinoid receptor activation.

Antineoplastic Agents↗

A sequence element of p53 that determines its susceptibility to viral oncoprotein-targeted degradation.

The molecular basis that the viral oncoproteins, including HPV16 E6 and E1B55k/E4 34k complex, differentially target p53 but not its homolog p73 for degradation remains elusive. Using a series of p53/p73 chimeras, we demonstrated that despite binding to the different regions of p53, both HPV16 E6 and E1B55k/E4 34k required a very same p53 sequence, amino acid residues 92 to 112 [p53(aa.92-112)], previously identified as a necessity for Mdm2-mediated degradation, to target p53 for degradation. Removal of the p53(aa.92-112) by either substitution or deletion resulted in a p53 protein that was no longer degradable by the viral proteins. More significantly, swapping the oncoprotein-binding motif and the p53(aa.92-112) rendered p73 susceptible to oncoprotein-mediated degradation. Collectively, our data supports a model in which the p53(aa.92-112) functions as a determinant for p53 stability while the binding of the oncoproteins directs p53 into the specific pathway for proteolysis.

Animals↗

3D-QSAR model of flavonoids binding at benzodiazepine site in GABAA receptors.

With flavone as a structural template, three-dimensional quantitative structure-activity relationship (3D-QSAR) studies and ab initio calculations were performed on a series of flavonoids. A reasonable pharmacophore model was built through CoMFA, CoMSIA, and HQSAR analyses and electrostatic potential calculations. A plausible binding mode for flavonoids with GABA(A) receptors was rationalized. On the basis of the commonly recognized binding site, the specific S1 and S2 subsites relating to substituent positions were proposed. The different binding affinities could be explained according to the frontier orbitals and electrostatic potential (ESP) maps. The ESP could be used as a novel starting point for designing more selective BZ-binding-site ligands.

Benzodiazepines↗

Evidence for a distinct inhibitory factor in the regulation of p53 functional activity.

Under normal conditions, tumor suppressor protein p53 exists in the cell in its latent form and is unable to function as a transcription factor. The allosteric model of p53 regulation postulates that the extreme portion of p53 carboxyl terminus (aa 364-393) binds to the core domain of the protein, thereby abrogating specific DNA binding in that region. In this study we propose an alternative mechanism of p53 functional regulation, which involves a separate molecule acting in trans to inhibit p53 transcriptional activity. Through the use of chimeric proteins of p53, p63gamma and p73beta, we show that the extreme COOH-terminal domain of p53 exerts a powerful and specific inhibitory effect on the p73- and p63-driven expression of a reporter gene. Moreover, fusion of p53 extreme COOH terminus to a completely unrelated transcriptional activator Gal4-VP16 also results in significant inhibition of transactivation activity. Since p73, p63, or Gal4-VP16 cannot associate with any part of the p53 molecule, we conclude that p53(aa 364-393) represses transcriptional activity of chimeric proteins and p53 itself through the binding of external negative modulator(s) in that region and not by the allosteric mechanism of regulation. In accordance with the "distinct inhibitor" hypothesis, the activity of wild type p53 is substantially increased by overexpression of chimeric proteins bearing p53(aa 364-393), which might be due to the competitive removal of transcriptional inhibitor(s). Our findings provide the basis for the identification of such negative modulators of p53 transcriptional activity.

Allosteric Site↗

Laminin-10/11 and fibronectin differentially regulate integrin-dependent Rho and Rac activation via p130(Cas)-CrkII-DOCK180 pathway.

The alpha(5) chain-containing laminin isoforms, laminins-10 and -11 (laminin-10/11), are the major components of the basement membrane, having potent cell-adhesive activity. We examined the cell-adhesive and integrin-mediated signaling activities of laminin-10/11 in comparison to fibronectin, the best characterized extracellular adhesive ligand. We found that laminin-10/11 are more active than fibronectin in promoting cell migration and preferentially activate Rac, not Rho, via the p130(Cas)-CrkII-DOCK180 pathway. Cells adhering to fibronectin develop stress fibers and focal contacts, whereas cells adhering to laminin-10/11 do not, consistent with the high cell migration-promoting activity of laminin-10/11. Pull-down assays of GTP-loaded Rac and Rho demonstrated the preferential activation of Rac on laminin-10/11, in contrast to the activation of Rho on fibronectin. Activation of Rac by laminin-10/11 was associated with the phosphorylation of p130(Cas) and an increased formation of a p130(Cas)-CrkII-DOCK180 complex. Cell migration on laminin-10/11 was suppressed by the expression of either a dominant-negative Rac or CrkII mutants defective in p130(Cas) or DOCK180 binding. This is the first report demonstrating a distinct activation of Rho family GTPases resulting from adhesion to different extracellular ligands.

Cell Movement↗

The interaction of the calcium- and integrin-binding protein (CIBP) with the coagulation factor VIII.

The gene encoding the C-terminal part of A1-domain of human blood coagulation factor VIII (FVIII), a 110-amino acid fragment from Ala(227) to Arg(336), namely A1(Delta1-226), was cloned and used as a 'bait' to screen a protein, which might interact with this region by using the yeast two-hybrid system. A gene coding for a related protein of FVIII named calcium- and integrin-binding protein (CIBP) was isolated from the normal human liver cDNA library. The results were confirmed by using the mammalian two-hybrid system and coimmunoprecipitation. The gene coding for CIBP was constructed by polymerase chain reaction (PCR) and then cotransfected with the B-domain-deleted FVIII gene into mammalian cell lines using the expression vector of FVIII for transient or stable expression. The culture supernatant was collected and analyzed both by enzyme-linked immunosorbent assay (ELISA) for FVIII antigen level and by one-stage method for procoagulant activity. Coexpressed with CIBP, the antigen level of FVIII in the mammalian cell line baby hamster kidney (BHK) cells increased up to about 170% and its bioactivity rose accordingly.

Animals↗

Antitumor activity and bystander effects of the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) gene.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been reported to specifically kill malignant cells but to be relatively nontoxic to normal cells. To evaluate the antitumor activity and therapeutic value of the TRAIL gene, we constructed adenoviral vectors expressing the human TRAIL gene and transferred them into malignant cells in vitro and tumors in vivo. The in vitro transfer elicited apoptosis, as demonstrated by the quantification of viable or apoptotic cells and by the analysis of activation of pro-caspase-8 and cleavage of poly(ADP-ribose) polymerase. The intratumoral delivery elicited tumor cell apoptosis and suppressed tumor growth. In comparison with Bax gene treatment, which is toxic to normal cells, TRAIL gene treatment caused no detectable toxicity in cultured normal fibroblasts nor in mouse hepatocytes after systemic gene delivery. Furthermore, coculture of cancer cells expressing TRAIL with those expressing green fluorescent protein (GFP) resulted in apoptosis of both cells, whereas coculture of Bax-expressing cells with GFP-expressing cells resulted in the cell death of the Bax-expressing cells only, which suggested that the transfer of the TRAIL gene resulted in bystander effects. Moreover, culture of cells with medium from TRAIL-expressing cells showed the proapoptotic activity and bystander effect of the TRAIL gene to be not transferable with medium. To further demonstrate the bystander effect of the TRAIL gene, we constructed plasmid vectors encoding GFP-TRAIL or GFP-Bik chimeric proteins. Transfection of the GFP-TRAIL gene into cancer cells resulted in the death of GFP-positive cells and their neighbors, whereas transfection of the GFP-Bik gene killed GFP-positive cells only. Finally, GFP-TRAIL genes, transfected into normal human fibroblasts or bronchial epithelial cells, did not kill such cells, whereas transfected GFP-Bik genes did. Thus, the direct transfer of the TRAIL gene led to selective killing of malignant cells with bystander effect, which suggests that the TRAIL gene could be valuable for treatment for cancers. Together, these results suggest that delivering the TRAIL gene to cancerous cells may be an alternative approach to cancer treatment.

Adenoviridae↗

[Significance of expression and secretion of interleukin-8 in ependymal tumor].

OBJECTIVE: To detect the expression and secretion of IL-8 in the ependymal tumor tissue and in primarily cultured cells, and to explore the relationship between IL-8 and ependymal tumor. METHODS: Expression of IL-8 in 50 ependymal tumor specimens was examined by immunohistochemistry. The ependymal tumor tissue obtained during operation was primarily cultured and IL-8 secreted by cultured cells were examined by clouble antibody 5 and which ELISA. The relations of expression of IL-8 to ependymal tumors of different histological degree, and invasiveness was analyzed statistically. RESULTS: All the ependymal tumor tissue expressed IL-8, but the number of IL-8 positive cells in the anaplastic and malignant ependymoma was evidently larger than that in ependymoma (P < 0.01). All the cells cultured from the ependymal tumor secreted IL-8, but the liquid supernatant of anaplastic and malignant ependymoma cells contained more IL-8 than that of ependymoma cells (P < 0.01). The expression and secretion of IL-8 had no close relation to age and sex of patient. CONCLUSION: The expression and secretion of IL-8 may be involved in the progression of ependymal tumor, so IL-8 can be used as an indicator to detect the malignant degree of ependymal tumor.

Adolescent↗