Biomedical subjects

H J Chung

Publications and source records attributed to H J Chung.

At least 55 records · Page 3Linked to original sources

PubMed1999

Nisin A depletes intracellular ATP and acts in bactericidal manner against Mycobacterium smegmatis.

Nisin is a bacteriocin produced by many strains of Lactococcus lactis. This study examined the effect of nisin on Mycobacterium smegmatis, a non-pathogenic species of Mycobacterium. Nisin had a minimum inhibitory concentration of 8.0 micrograms ml-1 and a minimum inhibitory dose of 7.5 micrograms ml-1 against Myco. smegmatis. Treatment with 25.0 micrograms ml-1 nisin caused partial inhibition of Myco smegmatis; the survivors were nisin-sensitive when tested in a separate experiment. Mycobacterium smegmatis cells exposed to 50.0 micrograms ml-1 of nisin, lost their viability. the effect of nisin on the growth of Myco. smegmatis was both time- and concentration-dependent. Nisin (10.0 micrograms ml-1) caused 97.7 +/- 2.0% reduction in internal ATP and leakage of intracellular ATP out of Myco. smegmatis cells after several hours of treatment. These data suggest that nisin inhibits Myco. smegmatis by the same mechanism by which it inhibits other bacteria and warrants further investigation as a possible antitubercular agent.

Adenosine Triphosphate↗

PubMed1999

Arabidopsis alcohol dehydrogenase expression in both shoots and roots is conditioned by root growth environment.

It is widely accepted that the Arabidopsis Adh (alcohol dehydrogenase) gene is constitutively expressed at low levels in the roots of young plants grown on agar media, and that the expression level is greatly induced by anoxic or hypoxic stresses. We questioned whether the agar medium itself created an anaerobic environment for the roots upon their growing into the gel. beta-Glucuronidase (GUS) expression driven by the Adh promoter was examined by growing transgenic Arabidopsis plants in different growing systems. Whereas roots grown on horizontal-positioned plates showed high Adh/GUS expression levels, roots from vertical-positioned plates had no Adh/GUS expression. Additional results indicate that growth on vertical plates closely mimics the Adh/GUS expression observed for soil-grown seedlings, and that growth on horizontal plates results in induction of high Adh/GUS expression that is consistent with hypoxic or anoxic conditions within the agar of the root zone. Adh/GUS expression in the shoot apex is also highly induced by root penetration of the agar medium. This induction of Adh/GUS in shoot apex and roots is due, at least in part, to mechanisms involving Ca2+ signal transduction.

Alcohol Dehydrogenase↗

PubMed1999

Negative regulation of the gene for Fe-containing superoxide dismutase by an Ni-responsive factor in Streptomyces coelicolor.

In Streptomyces coelicolor, transcription of the sodF genes, encoding Fe-containing superoxide dismutases, is negatively regulated by nickel. Gel mobility shift assays with sodF1 promoter fragments and cell extracts from the A3(2) strain indicate the presence of a nickel-responsive DNA-binding protein, most likely a transcriptional repressor. The boundary for the Ni-responsive cis-acting region was identified both in vitro and vivo. Ni does not regulate the level of the putative repressor but only the binding competence of this protein.

Artificial Gene Fusion↗

PubMed1999

The loss of expression of transforming growth factor-beta receptors correlates with the histopathologic tumor grade in bladder transitional cell carcinoma patients.

Transforming growth factor-beta (TGF-beta), a pleiotropic growth factor, is a potent inhibitor of cellular proliferation in cells of epithelial origin. Recently, it has been suggested that a loss of sensitivity to TGF-beta through a loss of expression of TGF-beta receptors T beta R-I and T beta R-II--is associated with tumor initiation and progression. Therefore, to investigate the relationship between TGF-beta receptors expression and carcinogenesis of bladder TCC, this study examined the expression of T beta R-I and T beta R-II in 46 bladder TCC patients using immunohistochemistry. Since histopathological grade is a widely accepted marker of prognosis, the results were compared in relation to the three grades of bladder TCC. The results demonstrated that the loss of TGF-beta receptors expression is associated with increasing histopathological grades of bladder TCC. Specifically, both T beta R-I and T beta R-II were readily detected in all 10 normal bladder mucosa specimens. Likewise, all 6 specimens of grade I TCC samples expressed high levels of both TGF-beta receptors. However, among grade II TCC samples, T beta R-I and T beta R-II were detected in 78% and 89%, respectively: among grade III TCC samples, T beta R-I and T beta R-II were detected in 45% and 41%, respectively. These results suggested that loss of sensitivity to TGF-beta may play a role in the progression of TCC from low to high grade disease.

Adult↗

PubMed1998

Isolation and characterization of the Drosophila melanogaster cDNA encoding the sepiapterin reductase.

We have isolated and characterized the cDNA encoding Drosophila melanogaster sepiapterin reductase (SR). The amino acid sequence deduced from the cDNA sequence was 29% identical to those of mammalian SRs. The active site residues proposed from the three-dimensional structure of mouse SR are well conserved in Drosophila SR. The protein-coding region of the cDNA was expressed in Escherichia coli as a histidine fusion protein, and the resulting recombinant protein proved to have SR activity. The SR activity of the recombinant protein was inhibited by two indoleamines, N-acetyl serotonin and melatonin. Southern analysis suggests that the Drosophila SR gene is encoded by a single copy gene. RNA blot analysis revealed that the gene expresses 1.5 kb mRNA in both adult heads and bodies.

Alcohol Oxidoreductases↗

PubMed1998

Transcriptional and post-transcriptional regulation by nickel of sodN gene encoding nickel-containing superoxide dismutase from Streptomyces coelicolor Müller.

A novel type of superoxide dismutase containing nickel as a cofactor (NiSOD) has been discovered in several Streptomyces spp. The gene for NiSOD (sodN) was cloned from S. coelicolor Müller using degenerate oligonucleotide probes designed from the N-terminal peptide sequence of the purified enzyme. It encodes a polypeptide of 131 amino acids (14703 Da), without any apparent sequence similarity to other known proteins. The N-terminus of the purified NiSOD was located 14 amino acids downstream from the initiation codon of the deduced open reading frame (ORF), indicating the involvement of protein processing. The molecular mass of the processed polypeptide was predicted to be 13201 Da, in close agreement with that of the purified NiSOD (13.4 kDa). The transcription start site of the sodN gene was determined by S1 mapping and primer extension analysis. Ni2+ regulates the synthesis of NiSOD polypeptide. S1 mapping of both 5' and 3' ends of sodN mRNA revealed that Ni2+ increased the level of monocistronic sodN mRNA by more than ninefold without changing its half-life, thus demonstrating that Ni2+ regulates transcription. Both precursor and processed NiSOD polypeptides with little SOD activity were produced from the cloned sodN gene in S. lividans in the absence of sufficient Ni2+; however, on addition of Ni2+, active NiSOD consisting of only processed polypeptide was formed. Expression of the full-length sodN gene in E. coli produced NiSOD polypeptide without any SOD activity even in the presence of Ni2+. However, deletion of nucleotides encoding the N-terminal 14 amino acids from the sodN gene allowed the production of active NiSOD in E. coli, indicating that N-terminal processing is required to produce active NiSOD. These results reveal the unique role of nickel as a multifaceted regulator in S. coelicolor controlling sodN transcription and protein processing, as well as acting as a catalytic cofactor.

Amino Acid Sequence↗

PubMed1998

Dihydrokainate-sensitive neuronal glutamate transport is required for protection of rat cortical neurons in culture against synaptically released glutamate.

Glutamate transport in nearly pure rat cortical neurons in culture (less than 0.2% astrocytes) is potently inhibited by dihydrokainate, l-serine-O-sulphate, but not by l-alpha-amino-adipate. This system allows for a test of the hypothesis that glutamate transport is important for protecting neurons against the toxicity of endogenous synaptically released glutamate. In support of this hypothesis, a 20-24 h exposure to 1 mm dihydrokainate reduced cell survival to only 14.8 +/- 9.8% in neuronal cultures (P < 0.001; n = 3), although it had no effect on neuronal survival in astrocyte-rich cultures (P > 0.05; n = 3). Dihydrokainate also significantly caused accumulation of glutamate in the extracellular medium of cortical neuronal cultures (6.6 +/- 4.9 micrometer, compared to 1.2 +/- 0.3 micrometer in control, n = 14, P < 0.01). The neurotoxicity of dihydrokainate was blocked by 10 micrometer MK-801, 10 micrometer tetrodotoxin, and an enzyme system that degrades extracellular glutamate. The latter two also abolished the accumulation of glutamate in the extracellular medium. Dihydrokainate (1 mm) inhibited the 45calcium uptake stimulated by 30 micrometer N-methyl-d-aspartate (NMDA), but not by higher concentrations consistent with a weak antagonist action of dihydrokainate at the NMDA receptor. Whole cell recordings showed that 1 mm dihydrokainate produced approximately 25% inhibition of 30 micrometer NMDA-induced current in cortical neurons. Dihydrokainate (1 mm) alone generated a small current (17% of the current produced by 30 micrometer NMDA) that was blocked by 30 micrometer 5,7-dichlorokynurenate and only weakly by 10 micrometer cyano-7-nitroquinoxaline-2,3-dione (CNQX). These results suggest that the toxicity of dihydrokainate in neuronal cultures is due to its ability to block glutamate transport in these cultures, and that dihydrokainate-sensitive neuronal glutamate transport may be important in protecting neurons against the toxicity of synaptically released glutamate.

Animals↗

PubMed1998

High affinity glutamate transport in rat cortical neurons in culture.

We assayed glutamate transport activity in cultures of rat cortical neurons containing < 0.2% astrocytes. Using [3H]L-glutamate as the tracer, sodium-dependent high affinity glutamate transport was demonstrated [K(m) = 17.2 +/- 2.4 microM; Vmax = 3.3 +/- 0.32 nmol/mg of protein/min (n = 5)]. Dihydrokainate (1 mM) inhibited uptake of radioactivity by 88 +/- 3% and had a Ki value of 65 +/- 7 microM. L-alpha-Aminoadipate (1 mM) inhibited uptake by only 25 +/- 4%. L-trans-2,4-Pyrrolidine dicarboxylate, L-serine-O-sulfate, and kainate potently inhibited transport activity with Ki values of 5.1 +/- 0.3, 56 +/- 6, and 103 +/- 9 microM, respectively (n = 3). Voltage-clamp studies of GLT1-expressing oocytes showed that, as in cortical neurons, glutamate transport was not inhibited by L-alpha-aminoadipate. Dihydrokainate was a potent inhibitor (Ki = 8 +/- 1 microM), and L-serine-O-sulfate produced a GLT1-mediated current with a K(m) value of 312 +/- 33 microM. Immunoblot analysis showed that neuronal cultures express excitatory amino acid carrier 1 (EAAC1), shown previously to be relatively insensitive to dihydrokainate, plus a trace amount of GLT1, but no GLAST. These studies establish that a major component of the glutamate transport activity of cortical neurons is dihydrokainate sensitive and distinct from the previously recognized neuronal transporter excitatory amino acid carrier 1.

2-Aminoadipic Acid↗

PubMed1998

Expression and regulation of the sodF gene encoding iron- and zinc-containing superoxide dismutase in Streptomyces coelicolor Müller.

Streptomyces coelicolor Müller contains two superoxide dismutases (SODs), nickel-containing (NiSOD) and iron- and zinc-containing SOD (FeZnSOD). The sodF gene encoding FeZnSOD was isolated by using PCR primers corresponding to the N-terminal peptide sequence of the purified FeZnSOD and a C-terminal region conserved among known FeSODs and MnSODs. The deduced amino acid sequence exhibited highest similarity to Mn- and FeSODs from Propionibacterium shermanii and Mycobacterium spp. The transcription start site of the sodF gene was determined by primer extension. When the sodF gene was cloned in pIJ702 and introduced into Streptomyces lividans TK24, it produced at least 30 times more FeZnSOD than the control cells. We disrupted the sodF gene in S. lividans TK24 and found that the disruptant did not produce any FeZnSOD enzyme activity but produced more NiSOD. The expression of the cloned sodF gene in TK24 cells was repressed significantly by Ni, consistent with the regulation pattern in nonoverproducing cells. This finding suggests that the cloned sodF gene contains the cis-acting elements necessary for Ni regulation. When the sodF mRNA in S. coelicolor Muller cells was analyzed by S1 mapping of both 5' and 3' ends, we found that Ni caused a reduction in the level of monocistronic sodF transcripts. Ni did not affect the stability of sodF mRNA, indicating that it regulates transcription. S. lividans TK24 cells overproducing FeZnSOD became more resistant to oxidants such as menadione and lawsone than the control cells, suggesting the protective role of FeZnSOD. However, the sodF disruptant survived as well as the wild-type strain in the presence of these oxidants, suggesting the complementing role of NiSOD increased in the disruptant.

Amino Acid Sequence↗

PubMed1998

Lower-extremity saphenous vein transposition arteriovenous fistula: an alternative for hemodialysis access in AIDS patients.

Arteriovenous access for long-term hemodialysis in patients with the acquired immunodeficiency syndrome (AIDS) represents a special challenge. Many of these patients are chronic intravenous drug abusers and do not have patent superficial upper-extremity veins available for conventional arteriovenous fistulas. This group of patients is also particularly prone to infections, which contraindicates the use of prosthetic grafts. Over a period of 13 months, five lower-extremity saphenous vein transposition arteriovenous fistulas (SVTAFs) were performed. Four patients had a diagnosis of AIDS at the time of operation; all of these were intravenous drug abusers. Three patients were male, two were female, and their age ranged from 34 to 66 years (mean, 48). Three patients had a SVTAF as their first hemodialysis access, and in two it was performed after multiple failed upper-extremity accesses. Four fistulas remain patent to date, after a mean follow-up of 11 months (range, 4 weeks to 16 months). One fistula thrombosed 4 weeks postoperatively, due to a hematoma that occurred after premature venipuncture for dialysis. There were no other major complications. We conclude that SVTAF is a suitable alternative to the limited hemodialysis venous access sites, especially in the AIDS population.

AIDS-Associated Nephropathy↗

PubMed1997

Isolation of a novel class of bZIP transcription factors that interact with ABA-responsive and embryo-specification elements in the Dc3 promoter using a modified yeast one-hybrid system.

Dc3 is a carrot lea class gene that is abundantly expressed during somatic and zygotic embryogenesis. Its expression is normally embryo-specific and also can be induced by abscisic acid. The regulatory elements mediating the embryo-specific expression of Dc3 reside within the proximal promoter region (-117 to +26), which is also essential for ABA-induced expression. In this study, an optimized version of the yeast one-hybrid system has been used to clone factors that bind to the promoter region of the Dc3 gene. Twenty-five million yeast transformants were screened in a single experiment, and nine independent cDNA clones were isolated from a sunflower library that encode proteins that specifically bind to functional cis-regulatory elements in the Dc3 promoter. Analysis of these clones showed that they are derived from three different mRNA species that encode two basic leucine zipper proteins. The basic regions of these proteins, named DPBF-1 and 2 (Dc3 Promoter-Binding Factor-1 and 2), respectively, are nearly identical to each other and are similar to the plant G-box binding factor GBF-4. Outside the basic region, however, DPBF-1 and 2 diverge significantly from each other and from other known factors. Both factors have transcriptional activity in yeast, and bind to DNA as dimers. Unlike other plant bZIP factors, DPBF-1 and 2 recognize sequences containing the ACACNNG core. Cloning of these factors demonstrates the power of the one-hybrid approach when optimally applied.

Abscisic Acid↗

PubMed1997

Embryonic abnormality caused by male pheromonal effect in pregnancy block in mice.

BALB/cA females mated with BALB/cA males and exposed to DDK males showed 100% pregnancy block when exposure started at Days 0-3 of pregnancy. When the exposure to DDK males started at Days 4, 5, 6, and 7, the pregnancy rate was 33.3%, 50%, 90%, and 100%, respectively. (Hereafter, the BALB/cA females exposed to DDK males are referred to as the experimental females, and those exposed to other BALB/cA males as the control females.) Cell number of embryos at Day 3 of pregnancy from the experimental and control females after exposure starting from Day 0 was, respectively, 27.0 +/- 1.2 (mean +/- SEM) vs. 48.6 +/- 1.0 (p < 0.05) for the morulae and 34.8 +/- 1.3 vs. 64.1 +/- 2.0 (p < 0.05) for the blastocysts. Embryos from the experimental and control females after exposure starting from Day 3 or Day 4 were histologically examined after 24-h exposure. Poor development of trophoblast and inner cell mass was observed at Day 4 as general defects of the experimental embryos. In addition, about one third of the embryos were unexpectedly at the more advanced stages than the controls (abnormal overdevelopment). At Day 5, disintegration of the trophoblast layer and primitive endoderm was observed as common abnormalities of experimental embryos, but overdevelopment was not observed at this stage. Disturbance in trophoblast differentiation or failure of its maintenance may be the primary developmental defect displayed by embryos developing in a deteriorated uterine environment under the influence of the odor of alien males.

Animals↗

PubMed1997

Is renal function at the tumor side a prognostic factor in ureteral transitional cell carcinoma?

OBJECTIVES: To evaluate whether the ipsilateral renal function on the tumor side is a prognostic factor in transitional cell carcinoma (TCC) of the ureter. PATIENTS AND METHODS: We retrospectively reviewed 129 consecutive patients with ureteral TCC between September 1973 and July 1993 at our hospital. There were 98 males and 31 females aged from 31 to 84 years (mean 64.9). Of them, 126 patients who received intravenous pyelography (IVP) were divided into 3 groups according to their radiological findings (group 1: nonvisualization of kidney at tumor side; group 2: hydronephrosis or hydroureter; group 3: no obstruction). Eighty patients receiving radionuclide (131I-hippuran) renal function test (RRFT) with available effective renal plasma flow (ERPF) were divided into 2 groups using ipsilateral ERPF 50 ml/min as a cutoff value (group 1: < 50 ml/min; group 2: > or = 50 ml/min). The mean survival of each group was estimated by the Kaplan-Meier method. RESULTS: For patients receiving IVP, the mean survivals were 61.7, 99.7 and 83.8 months for groups 1, 2, and 3, respectively, and the differences between each 2 of the 3 groups were statistically significant (p < 0.05). For patients having RRFT, the mean survivals were 65.8 months for group 1 and 89.2 months for group 2 patients, and the difference between them was statistically significant (p < 0.05). When renal function, tumor number, grade, stage and type of treatment were analyzed using a multivariate method, only tumor stage was statistically significant as a prognostic factor. CONCLUSION: Ipsilateral renal function at the tumor side is not a good prognostic factor for patients with ureteral TCC. However, when the stage of tumor is not available, renal function at the tumor side may provide an implication of the patient's prognosis.

Adult↗

PubMed1996

Molecular characterization of the lysosomal acid phosphatase from Drosophila melanogaster.

In Drosophila, unlike humans, the lysosomal acid phosphatase (Acph-1) is a non-essential enzyme. It is also one of the most rapidly evolving gene-enzyme systems in the genus. In order to determine which parts of the enzyme are conserved and which parts are apparently under little functional constraint, we cloned the gene from Drosophila melanogaster via a chromosomal walk. Fragments from the gene were used to recover an apparently full-length cDNA. The cDNA was sub-cloned into a Drosophila transformation vector where it was under the control of the 5' promoter sequence of the hsp-70 gene. Three independent transformants were obtained; in each, Acph-1 expression from the cDNA was constitutive and not dependent on heat shock, as determined by densitometric analyses of the allozymic forms of the enzyme. The pattern of expression indicates the hsp-70 and endogenous Acph-1 promoters act together in some, but not all, tissues. The sequence of the cDNA was determined using deletions made with exonuclease III, and primers deduced from the cDNA sequence were used to sequence the genomic clone. Five introns were found, and putative 5' upstream regulatory sequences were identified. Amino acid sequence comparisons have revealed several highly conserved motifs between Drosophila Acph-1 and vertebrate lysosomal and prostatic acid phosphatases.

Acid Phosphatase↗

PubMed1996

Stress analysis of a cantilevered fixed partial denture with normal and reduced bone support.

A two-dimensional finite element model was constructed to analyze the simulated mechanical behavior of a cantilevered fixed partial denture. The variations of the models were made by altering the degree of bone support, the number of splinted abutments, and the length of the pontics. High stress concentrations were observed around the connectors of the fixed prosthesis and the tooth closest to the cantilever. Reduced bone support increased the deflection and stress concentrations. There was reduction in displacement and stress concentration when the teeth were splinted together. To improve the prognosis of the fixed partial denture cantilever, the number of abutments should be increased and the number of pontics decreased.

Alveolar Bone Loss↗

PubMed1996

Alterations in pulmonary function after retroperitoneoscopic surgery.

OBJECTIVE: To evaluate and compare changes in pulmonary function after retroperitoneoscopic and open surgery. PATIENTS AND METHODS: From June 1994 to October 1995. 11 patients (five men and six women, mean age 44.7 years, range 29-69) underwent retroperitoneoscopic procedures (Group 1) and 11 patients (eight men and three women, mean age 57.5 years, range 22-73) underwent flank-incision procedures (Group 2). The surgery comprised eight adrenalectomies and one each of nephroureterectomy, nephrectomy and pyelolithotomy in Group 1, and five adrenalectomies, four nephroureterectomies, one ureterolithotomy and one excision of a retroperitoneal tumour in Group 2. Pulmonary function tests (PFTs) were performed before and 3 days after surgery; the forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), forced expiratory volume at 25% (FEV25%), FEV1/FVC, vital capacity (VC), total lung capacity (TLC), residual lung volume (RV) and functional residual capacity (FRC) were compared between the groups. The post-operative changes in the PFTs were assessed using a paired t-test and the degree of change in both groups compared using the Mann-Whitney U-test. Other factors possibly influencing PFT were analysed using multiple regression. RESULTS: Pulmonary function was impaired in both groups on the third day after surgery. In Group 2, the FVC, FEV1, FEV25%, VC and TLC had declined significantly (all P < 0.05) from the pre-operative value. In Group 1, only the FVC and VC decreased significantly (P < 0.05). Post-operative pulmonary complications occurred in two patients in Group 2 but in none of those in Group 1, showing that pulmonary function was generally less affected in Group 1 than in Group 2. CONCLUSION: Although pulmonary function was impaired 3 days after surgery in both groups, retroperitoneoscopic surgery, by eliminating a large flank incision, caused less post-operative pulmonary dysfunction than open surgery.

Adult↗

PubMed1995

Serum prolactin in neonates with seizures.

We studied serum prolactin (PRL) in 28 newborn infants with acute encephalopathy. Six patients had electrographically confirmed seizures. Twenty-two patients comprised the nonictal group. In the seizure group, PRL was determined at the first onset of the seizure (baseline) and at 15 and 30 min postictal. In the nonseizure group, PRL was determined at the end of the EEG and 15 min later. EEGs were visually analyzed for the presence of seizures and background abnormality (normal or mildly, moderately, or markedly abnormal). Etiologic diagnoses included congenital heart disease (12), hypoxic-ischemic encephalopathy (4), sepsis (4), respiratory distress syndrome (5) meconium aspiration (1), and metabolic disease (2). Serum PRL was significantly higher (p < 0.05) at baseline and 15 min postictally in the patients with seizures than in the nonictal group. However, PRL levels 15 and 30 min postictally were not statistically different from baseline values. Baseline PRL correlated significantly (p < 0.001) with EEG background abnormality in both groups; therefore, patients with the most abnormal EEG backgrounds had higher levels of PRL than those with a relatively normal EEG background. We conclude that newborns with EEG-confirmed seizures, particularly if seizures are not associated with clinical signs, have high baseline serum PRL levels that do not increase significantly in the immediate postictal period. Serum PRL levels correlate with the severity of the brain insult as evaluated by EEG background. Further studies are needed to enhance our understanding of the dynamics of PRL secretion in newborns with seizures and acute encephalopathy.

Acute Disease↗

PubMed1995

Imaging of the choledochal cyst.

Choledochal cysts are rare and usually manifest in infancy and childhood. They are considered congenital because they occur in fetuses and neonates. Their origin may be related to an abnormal connection between the pancreatic duct and common bile duct and chronic reflux of pancreatic juice into the bile duct, resulting in irritation of the duct and subsequent dilatation. Choledochal cysts appear as cystic or fusiform dilatation of the common bile duct at radiography. Ultrasonography is the best initial method of evaluating dilatation of the intra- and extrahepatic bile ducts. Computed tomography is considered to be more accurate in delineating the intrahepatic biliary tree. Hepatobiliary scintigraphy with technetium-99m disofenin provides physiologic information on hepatic uptake and accumulation of radionuclide in the dilated biliary tree. Endoscopic retrograde cholangiopancreatography, percutaneous transhepatic cholangiography, and intraoperative cholangiography are definitive studies that demonstrate anatomic details of the biliary tree and the pancreaticobiliary ductal junction.

Adolescent↗