Associations between Borg’s rating of perceived exertion and changes in urinary organic acid metabolites after outdoor weight-bearing hiking

BACKGROUND

Developing methods to monitor exercise load and evaluate body fatigue and muscle injury over time in hiking training remains a key problem to be solved. A widely used psycho-physical tool to assess the subjective perception of effort during exercise is Borg’s rating of perceived exertion (BRPE) scale. Data on the relationships and validity of the BRPE compared to objectively assessed metabolic criteria are still lacking, especially urinary organic acid concentrations.

AIM

To verify whether the BRPE scale could be used in the prescription of outdoor hiking with weight-bearing and reveal the relationship between the BRPE scale and urinary physiological measures.

METHODS

Eighty-nine healthy men (average age: 22 years) were enrolled in a 40 km (6 h) hiking training exercise with a 20 kg load. After training, the BRPE scale (6-20) was completed. All participants were divided into three groups according to the rating of the BRPE scale. Urine samples were collected before and after training. Urinary myoglobin levels were measured immediately using the fluorescent immunoassay method. The remaining urine was subpacked and frozen for the subsequent detection of urinary organic acids using gas chromatography and mass spectrometry.

RESULTS

The contents of organic acids and myoglobin in urine were significantly increased after participants hiked 40 km (6 h) with a 20 kg load. Only orthogonal partial least-squares discrimination analysis performed well in separating the group with a BRPE score of 6-12 from the group with a BRPE score of 13-20. Significant differences in the urine levels of several organic acids were observed between the two groups, and the heatmap also presented different metabolic profiles based on BRPE. According to the standard of a variable importance in the projection > 1, fold change > 1.5 and P < 0.05, 19 different metabolites of urinary organic acids were screened and enriched in pathways mainly including the citrate cycle (tricarboxylic acid cycle) and alanine, aspartate and glucose metabolism.

CONCLUSION

The BRPE scale identified significantly different urinary organic acid profiles between the higher and lower BRPE value groups, and, thus, could be used to monitor body fatigue in individuals participating in long-distance outdoor hiking with weight bearing.

Hsa-miR-10a-5p promotes pancreatic cancer growth by BDNF/SEMA4C pathway

This article aims to explore the expression and mechanism of miR-10a-5p in pancreatic cancer. MiR-10a-5p mimic, MiR-10a-5p inhibitor and negative control were transfected into human pancreatic cancer cell line SW1990. Real-time quantitative PCR technology was used to analyze the expression level of miR-10a-5p in pancreatic cancer tissues and cells. The proliferation, invasion and apoptosis of SW1990 cells in each group were detected by CCK-8 analysis, Transwell analysis, TUNEL method and flow cytometry. Targetscan7.2 was used to predict the target protein of MiR-10a-5p, and the expression of related proteins was detected by Western blot analysis. The results showed that the expression of miR- 10a-5p in cancer tissues of patients with pancreatic cancer was significantly higher than that in adjacent tissues (P <0.05). The expression of miR-10a-5p in cancer cells increased significantly, which could promote the proliferation and invasion of SW1990 cells and inhibit apoptosis (P <0.05). Overexpression of miR-10a-5p can regulate the expression of BDNF and SEMA4C. miR-10a-5p can promote the occurrence and development of pancreatic cancer by regulating the BDNF / SEMA4C pathway, and may become a molecular target for the diagnosis and treatment of pancreatic cancer in the future.

[Healthy China Strategy and schistosomiasis control]

This paper summarizes the changes in the policy associated with schistosmiasis control in the new era, analyzes the background of Health China Strategy and its association with the current schistosomiasis control program in China, describes several schistosomiasis control models and proposes some suggestions responding to the challenges in current schistosomiasis control program of China, so as to provide insights into the development of the effective control strategy for schistosomiasis.

[Expression of iNOS in the testis of Fmr1 knockout mice in different developmental stages]

OBJECTIVE

To analyze the expression of inducible nitric oxide synthase (iNOS) in the testis tissues of Fmr1 (fragile X mental retardation 1) knockout and wild-type male mice in different developmental stages, and provide background information for researches on fragile X syndrome.

METHODS

This study included 4, 6, 8 and 10 weeks old Fmr1 knockout and wild-type male mice, 6 in each age group. We identified the genotype of the mice by PCR, and detected and compared the expression of iNOS in the testis tissues of the Fmr1 knockout and wild-type mice by immunohistochemistry.

RESULTS

The iNOS expression was weakly positive in the Leydig cells of the 4-week-old mice, moderately positive in the 6-week-old ones, and strongly positive in 8- and 10-week-old ones, significantly weaker in the Fmr1 knockout than in the wild-type ones.

CONCLUSION

The expression of iNOS significantly decreases in the testis of Fmr1 knockout mice, suggesting that iNOS may be involved in the pathogenesis of fragile X syndrome.

Injection of frozen-thawed porcine first polar bodies into enucleated oocytes results in fertilization and embryonic development

The objective was to determine whether enucleated oocytes injected with frozen porcine first polar bodies (pPB1s) could be fertilized and developed into viable embryos in vitro. Metaphase II (MII) oocytes with pPB1s were frozen (vitrified) and stored for 2 mo. The pPB1s were isolated from thawed MII oocytes and injected into enucleated recipient oocytes by micromanipulation. All recipients injected with thawed pPB1s were fertilized by intracytoplasmic sperm injection (ICSI), and the resulting recombinant zygotes were incubated to assess their developmental competence in vitro. Furthermore, double-antibody immunohistochemistry was used to verify that the nucleus of the pPB1 participated in fertilization and supported embryonic development. Porcine embryos (2- to 8-cell stage) were obtained from the recombinants. The average in vitro cleavage rate of 2-, 4-, and 8-cell stage recombinant embryos was 25.3, 17.7, and 9.3% (P < 0.05), respectively. Chromosomes in the labeled pPB1 participated in the formation of the two blastomere nuclei of 2-cell stage embryos derived from recombinant oocytes. In conclusion, nuclear materials of frozen-thawed pPB1 supported oocyte fertilization and subsequent embryonic development, thereby providing a new way to use frozen PB1s for preservation and reproduction of mammals.

Use of genotypic selection to detect P53 codon 273 CGT>CTT transversion: application to an occupationally exposed population

CGT>CTT transversion in codon 273 of the P53 tumor-suppressor gene is one of the major mutations detected in human tumors. Within an epidemiological framework, we investigated the use of a genotypic selection method to measure this point mutation. The allele-specific polymerase chain reaction (AS-PCR) that was developed was able to detect 10 mutant copies of the gene among a total of 5 x 10(5) wild-type copies. We used this assay to detect CGT>CTT transversions in buccal cell DNA of production workers (n=76) from a viscose factory exposed to carbon disulfide (amongst other pollutants) and in the DNA of non-exposed office workers (n=67). The mutation appeared more frequently in the exposed than in the non-exposed worker who were smokers. The results of the study indicate that occupational exposure results in a significant increase in P53 CGT>CTT transversions and more especially identified occupational exposure in combination with smoking as a significant risk factor for the mutation. We conclude that AS-PCR of the P53 273rd codon transversions is a suitable technique for studying the effects of occupational exposure.

Prostanoids mediate the protective effect of trefoil factor 3 in oxidant-induced intestinal epithelial cell injury: role of cyclooxygenase-2

Trefoil factors are small peptides found in several mammalian tissues including gut, respiratory tract and brain. Their physiological function is not well understood. Among them, trefoil factor 3 (intestinal trefoil factor) is known to be cytoprotective in the gut. However, the molecular mechanism and secondary mediators of trefoil factor 3 action are not known. In the present study, we examined whether the cyclooxygenase pathway is involved in trefoil factor 3 action. We showed that trefoil factor 3 significantly induces the production of prostaglandin E(2) and prostaglandin I(2) in IEC-18 cells (an intestinal epithelial cell line) in a dose dependent manner. Western blot and immunohistochemistry revealed that trefoil factor 3 (2.5 microM) up-regulates the expression of cyclooxygenase-2 but not cyclooxygenase-1 in IEC-18 cells. Treating cells with trefoil factor 3 (10 microM) significantly attenuated reactive oxygen species-induced IEC-18 cell injury. This effect is blocked by NS-398 (10 microM), a selective cyclooxygenase-2 inhibitor. Moreover, we demonstrated that exogenously administered carbacyclin (1 microM, a stable analogue of prostaglandin I(2)) and/or prostaglandin E(2) (1 microM) caused a significant reduction of reactive oxygen species-induced cell injury, mimicking the effect of trefoil factor 3. In summary, our results indicate that trefoil factor 3 activates cyclooxygenase-2 in intestinal epithelium to produce prostaglandin I(2) and prostaglandin E(2), which function as survival factors and mediate the cytoprotective action of trefoil factor 3 against oxidant injury.

Transcription factor NF-kappaB signals antianoikic function of trefoil factor 3 on intestinal epithelial cells

Transcription factor NF-kappaB has both pro-apoptotic and anti-apoptotic properties depending on the cell type. Its role in the intestinal epithelial cell has not been well elucidated. Trefoil factor 3 (TFF3) is an anti-apoptotic peptide secreted by intestinal goblet cells. Here we show that TFF3 activated NF-kappaB p50/p65 heterodimer within 1 h in IEC-18 cells (a nontransformed rat intestinal epithelial cell line). Moreover, we found that TFF3-treated IEC-18 cells are resistant to anoikis, an anchorage-related apoptosis in epithelium. In addition, the stable expression of a mutant form of the endogenous NF-kappaB inhibitor (IkappaBalpha(mut)) in IEC-18 cells results in a significant attenuation of anti-anoikic effect of TFF3. Taken together, these data indicate that (1) TFF3 is an endogenous gastrointestinal peptide with anti-anoikic property; (2) TFF3 activates NF-kappaB in enterocytes; and (3) TFF3-induced resistance to anoikis in intestinal epithelial cells is mediated by a distinct signaling cascade linked to NF-kappaB. Furthermore, our study implicates NF-kappaB as an important regulator in survival pathway of intestinal epithelial cells.

Prostanoids mediate the protective effect of trefoil factor 3 in oxidant-induced intestinal epithelial cell injury: role of cyclooxygenase-2

Trefoil factors are small peptides found in several mammalian tissues including gut, respiratory tract and brain. Their physiological function is not well understood. Among them, trefoil factor 3 (intestinal trefoil factor) is known to be cytoprotective in the gut. However, the molecular mechanism and secondary mediators of trefoil factor 3 action are not known. In the present study, we examined whether the cyclooxygenase pathway is involved in trefoil factor 3 action. We showed that trefoil factor 3 significantly induces the production of prostaglandin E(2) and prostaglandin I(2) in IEC-18 cells (an intestinal epithelial cell line) in a dose dependent manner. Western blot and immunohistochemistry revealed that trefoil factor 3 (2.5 microM) up-regulates the expression of cyclooxygenase-2 but not cyclooxygenase-1 in IEC-18 cells. Treating cells with trefoil factor 3 (10 microM) significantly attenuated reactive oxygen species-induced IEC-18 cell injury. This effect is blocked by NS-398 (10 microM), a selective cyclooxygenase-2 inhibitor. Moreover, we demonstrated that exogenously administered carbacyclin (1 microM, a stable analogue of prostaglandin I(2)) and/or prostaglandin E(2) (1 microM) caused a significant reduction of reactive oxygen species-induced cell injury, mimicking the effect of trefoil factor 3. In summary, our results indicate that trefoil factor 3 activates cyclooxygenase-2 in intestinal epithelium to produce prostaglandin I(2) and prostaglandin E(2), which function as survival factors and mediate the cytoprotective action of trefoil factor 3 against oxidant injury.

Intestinal trefoil factor binds to intestinal epithelial cells and induces nitric oxide production: priming and enhancing effects of mucin

Intestinal trefoil factor (ITF or TFF3), NO and epithelium-associated mucin have important roles in sustaining mucosal integrity in the gastrointestinal tract. In the present study we examined ITF-binding molecules on IEC-18 cells (an intestinal epithelial cell line) with the use of flow cytometry and localized these molecules on the cell surface by confocal microscopy. Furthermore, we studied the interaction of mucin and ITF and their co-operative effect on NO production by the epithelium. Stimulation of cells with mucin (5 mg/ml) for 90 min resulted in a 5-fold increase in ITF binding. Treatment of IEC-18 cells with actinomycin D or cycloheximide attenuated mucin-enhanced ITF binding. Ligand blot analysis confirmed the induction of ITF-binding protein in IEC-18 cells by mucin. These results indicate that transcriptional and translational mechanisms are involved in the effect of mucin. Treatment with ITF overnight resulted in a low level of nitrite production by the cells, a 5-fold increase over control, in a concentration-dependent manner. ITF-induced NO production was attenuated by 1400W, a selective type II nitric oxide synthase (NOS2) inhibitor. By immunoblotting we found that NOS2 was up-regulated by ITF treatment. Priming IEC-18 cells with mucin for 90 min enhanced the effect of ITF on NO production, suggesting that the up-regulation of ITF-binding molecules by mucin might be physiologically relevant. Taken together, these observations indicate (1) that ITF-binding molecules that are up-regulated by mucin exist on the intestinal epithelial surface, and (2) that ITF modulates epithelial NO production via the NOS2 pathway, which is enhanced by mucin.

Roles of nitric oxide synthases in platelet-activating factor-induced intestinal necrosis in rats

OBJECTIVE

To examine the role of constitutive and inducible nitric oxide synthases (cNOS and iNOS) in platelet-activating factor (PAF)-induced shock and intestinal injury.

DESIGN

Prospective, randomized, controlled experimental study.

SETTING

Hospital research laboratory.

SUBJECTS

Young adult male Sprague-Dawley rats were anesthetized and studied.

INTERVENTIONS

Rats were injected with PAF, either alone or after the following pretreatments: a) selective iNOS inhibitors aminoguanidine or S-methylisothiourea; b) 3-morpholinosydnonimine, a NO donor; c) S-methylisothiourea + 3-morpholinosydnonimine; and d) antineutrophil antibody (to deplete neutrophils).

MEASUREMENTS AND MAIN RESULTS

Blood pressure, hematocrit, white blood cell counts, intestinal injury, and intestinal cNOS and iNOS activities were assessed. We found that: a) cNOS is the predominant NOS in the intestine and its activity is inversely correlated to the level of tissue injury; b) there is a time-dependent increase in cNOS activity in sham-operated animals, which was abolished by PAF; c) Western blotting and immunohistochemistry showed iNOS present in the normal intestine, localizing mainly in crypt cells; d) iNOS inhibitors attenuated PAF-induced injury in animals with high cNOS activity, but had no protective effect in animals with low cNOS activity; e) 3-morpholinosydnonimine, alone or together with S-methylisothiourea, alleviated PAF-induced injury; and f) neutrophil depletion blocked the suppressive effect of PAF on cNOS and prevented injury.

CONCLUSIONS

We conclude that cNOS and iNOS play different roles in PAF-induced intestinal injury. Caution should be exerted concerning potential therapeutic uses of iNOS inhibitors.

Rapid growth of cutaneous metastases after surgical resection of thrombospondin-secreting small blue round cell tumor of childhood

In animal models, the importance of tumor-derived antiangiogenic factors in controlling metastases has been demonstrated by the growth acceleration of distant metastases after surgical excision of a primary tumor mass. We report the case of an infant who developed rapidly growing cutaneous metastases after surgical resection of a neoplasm of an upper extremity. The tumor was undifferentiated, with some morphological features of primitive neuroectodermal tumor. To test the possibility that the primary tumor was secreting an angiogenic inhibitor, cells from the primary tumor were grown in culture, and the culture medium was tested with an in vitro endothelial cell migration assay and Western blot. The cultured cells secreted sufficiently high levels of an angiogenic inhibitor to overcome the inducing ability of vascular endothelial growth factor and basic fibroblast growth factor. One of the secreted proteins was thrombospondin-1, a potent antiangiogenic glycoprotein. The rapid dissemination of distant metastases after resection of the primary tumor in this case suggests that tumor-derived angiogenic inhibitors are important in maintaining the local net balance of angiogenic mediators controlling the growth of micrometastasis.

Intestinal NF-kappaB is activated, mainly as p50 homodimers, by platelet-activating factor

NF-kappaB, a transcription factor, upregulates gene transcription of many inflammatory mediators. Here, we examined the activity of NF-kappaB in the rat small intestine, and how it may be affected by platelet-activating factor (PAF), an important mediator for intestinal injury and inflammation. Ileal nuclear extracts from sham-operated and PAF (1.5 microg/kg)-injected rats were prepared for the assessment of NF-kappaB DNA-binding activity, and the identification of NF-kappaB subunits. The experiment was also performed on neutrophil-depleted rats to examine whether the PAF effect is neutrophil-dependent. Cellular NF-kappaB was localized by immunohistochemistry. We found that: (a) NF-kappaB is constitutively active in rat small intestine; (b) PAF at a dose below that causing shock and bowel necrosis enhances DNA-binding activity of NF-kappaB within 30 min after injection; activated NF-kappaB contains predominantly p50 subunits; (c) immunohistochemistry showed that PAF induced translocation of p50 into the nucleus of cells of the lamina propria, as well as of the epithelium; and (d) the effect of PAF is abrogated by neutrophil depletion, suggesting a role of neutrophils in NF-kappaB activation. Our study suggests that NF-kappaB is weakly active constitutively in the intestine, and inflammatory stimuli such as PAF activate NF-kappaB and enhance its DNA-binding activity in the intestine, which contains predominantly p50 subunits.

Platelet-activating factor (PAF) up-regulates plasma and tissue PAF-acetylhydrolase activity in the rat: effect of cycloheximide

Platelet-activating factor (PAF) is a proinflammatory phospholipid mediator implicated in necrotizing enterocolitis. Regulation of PAF-acetylhydrolase (AH), the enzyme degrading PAF, is poorly understood. In this study we found that administration of a dose of PAF (1.5 microg/kg, i.v.), which does not cause gross intestinal injury, increased plasma and intestinal PAF-AH in the rat. Cycloheximide (CHX, 5 mg/kg, i.v.) reduced the activity of plasma (but not intestinal tissue) AH in control, as well as in PAF-injected rats, and aggravated systemic inflammation and tissue injury in the latter. The intestinal necrosis induced by PAF and CHX was ameliorated by posttreatment with WEB2170 (a PAF antagonist), indicating a role of endogenous PAF in mediating injury. Both WEB2170 and anti-TNF antibody reduced PAF-induced AH activity in intestinal tissue, but not in the plasma. Allopurinol largely prevented the injury induced by PAF and CHX, but had no effect on the up-regulation of AH. We conclude: 1) de novo protein synthesis is required to maintain physiologic AH level in the plasma; 2) PAF up-regulates plasma and intestinal AH activity; 3) CHX enhances the injurious effect of PAF; 4) endogenous PAF and TNF also play a role in the up-regulation of intestinal AH; the former probably mediating the intestinal injury by PAF; and 5) reactive oxygen species may mediate the injurious effect of PAF plus CHX, but do not contribute to the regulation of AH by PAF.

Characterization of a putative receptor for intestinal trefoil factor in rat small intestine: identification by in situ binding and ligand blotting

Intestinal trefoil factor (ITF), a small peptide secreted by intestinal goblet cells, maintains mucosal integrity and promotes epithelial wound healing. Although ITF has been cloned, the detailed mechanism by which ITF interacts with intestinal epithelium remains elusive. In the present study, we expressed mature rat ITF (rITF) with pXa (a prokaryotic expression vector) in Escherichia coli to generate a biotinylated rITF fusion protein (bTag-ITF). By using bTag-ITF probe, we identified ITF binding cells in the crypts of the small intestine and mucous cells of the region of gastric glands. Using a ligand blotting technique, we further characterized a 50 kDa glycosylated protein from the membrane fraction of the small intestine, which bound to bTag-ITF. Our data suggest that this 50 kDa membrane glycoprotein is a putative receptor for ITF in the gastrointestinal tract.

Platelet activating factor and endotoxin increase the enzyme activity and gene expression of type II phospholipase A2 in the rat intestine. Role of polymorphonuclear leukocytes

Type II phospholipase A2 (PLA2-II) may regulate eicosanoid synthesis; is involved in various inflammatory processes, septic shock, and inflammatory bowel disease; and is up-regulated by LPS and inflammatory cytokines in vitro. We have previously shown that the platelet-activating factor (PAF)-induced intestinal injury is attenuated by peptido-leukotriene antagonists, suggesting a role of PLA2. The purpose of this study is to examine the regulation of intestinal PLA2-II by PAF and LPS. Using synthesized competitor RNA as competitor, we quantified PLA2-II transcripts by competitive reverse transcription-PCR. We found that PLA2-II gene is constitutively expressed in the rat ileum. PAF at a dose (1.5 micrograms/kg) below that causing intestinal injury rapidly up-regulated intestinal PLA2-II at both transcriptional and post-transcriptional levels, almost tripling its transcripts and significantly increasing enzyme activity in 30 min. LPS (5 mg/kg) also up-regulated PLA2-II. This effect could not be blocked by PAF antagonist. Depletion of circulating polymorphonuclear leukocytes (PMNs) abolished the effect of PAF on PLA2-II gene expression and enzyme activation. In contrast, PMN depletion prevented LPS-induced PLA2-II enzyme activity but enhanced the gene expression. We conclude that: 1) both PAF and LPS induce gene transcription and enzyme activation of PLA2-II in the small intestine; 2) PAF up-regulates PLA2-II via PMN activation; 3) LPS effect is independent of endogenous PAF formation; and 4) different pathways exist for PAF and LPS in the regulation of intestinal PLA2-II gene expression in vivo.

Platelet activating factor and endotoxin increase the enzyme activity and gene expression of type II phospholipase A2 in the rat intestine. Role of polymorphonuclear leukocytes

Type II phospholipase A2 (PLA2-II) may regulate eicosanoid synthesis; is involved in various inflammatory processes, septic shock, and inflammatory bowel disease; and is up-regulated by LPS and inflammatory cytokines in vitro. We have previously shown that the platelet-activating factor (PAF)-induced intestinal injury is attenuated by peptido-leukotriene antagonists, suggesting a role of PLA2. The purpose of this study is to examine the regulation of intestinal PLA2-II by PAF and LPS. Using synthesized competitor RNA as competitor, we quantified PLA2-II transcripts by competitive reverse transcription-PCR. We found that PLA2-II gene is constitutively expressed in the rat ileum. PAF at a dose (1.5 micrograms/kg) below that causing intestinal injury rapidly up-regulated intestinal PLA2-II at both transcriptional and post-transcriptional levels, almost tripling its transcripts and significantly increasing enzyme activity in 30 min. LPS (5 mg/kg) also up-regulated PLA2-II. This effect could not be blocked by PAF antagonist. Depletion of circulating polymorphonuclear leukocytes (PMNs) abolished the effect of PAF on PLA2-II gene expression and enzyme activation. In contrast, PMN depletion prevented LPS-induced PLA2-II enzyme activity but enhanced the gene expression. We conclude that: 1) both PAF and LPS induce gene transcription and enzyme activation of PLA2-II in the small intestine; 2) PAF up-regulates PLA2-II via PMN activation; 3) LPS effect is independent of endogenous PAF formation; and 4) different pathways exist for PAF and LPS in the regulation of intestinal PLA2-II gene expression in vivo.

Primary hepatic neuroendocrine carcinoma in a child. Morphologic, immunocytochemical, and molecular biologic studies

BACKGROUND

Primary neuroendocrine tumor of the liver is uncommon, and virtually all reported patients with the tumor have been adults. Most of the tumors were carcinoids. The authors report an 8-year-old girl with primary hepatic neuroendocrine carcinoma.

METHODS

Histologic, ultrastructural, and immunocytochemical studies and Southern blot analysis of tumor N-myc DNA were performed in the patient.

RESULTS

Histologically, the tumor revealed a characteristic organoid pattern with a spectrum of differentiation varying from well-differentiated carcinoid-like areas to poorly differentiated pleomorphic areas. Ultrastructural features included neurosecretory granules and interdigitating cytoplasmic extensions. The tumor cells showed immunoreactivity to neuron-specific enolase (NSE), S-100 protein, chromogranin, and synaptophysin. No evidence of amplification of tumor N-myc DNA was present. However, the molecular weight of the tumor N-myc DNA (1.8 kb) was significantly lower than the normal control (from normal liver tissue) (2.0 kb).

CONCLUSIONS

This report documents the occurrence of primary hepatic neuroendocrine carcinoma in a child. Thorough studies and complete clinical evaluation are essential to the establishment of diagnosis. The result of N-myc DNA analysis probably is attributable to deletion of part of the tumor N-myc gene. The clinical implication of this finding is unknown, and additional investigation is warranted.

Pancreatic hepatocytes. An in vivo model for cell lineage in pancreas of adult rat

Multiple foci of hepatocytes differentiate in the pancreas of adult rats subjected to a copper depletion-repletion regimen. Copper deficiency for seven to nine weeks causes an irreversible depletion of over 80% of the acinar cells in the pancreas. When transferred to a normal diet, these rats exhibit only a minimal and spotty acinar cell recovery. This disruption of tissue organization appears to trigger a profound change in cellular commitment, which leads to hepatocyte differentiation in the "oval cells" in the periductal interstitium and the epithelial cells lining the small pancreatic ductules. Pancreatic hepatocytes express several liver-specific genes including albumin, a2u-globulin, carbamoylphosphate synthetase-I, and urate oxidase. Both carbamoylphosphate synthetase-I and glutamine synthetase, the ammonia-metabolizing enzymes, are expressed by all pancreatic hepatocytes; in liver, these are expressed by different populations of hepatocytes. The magnitude of hepatocyte differentiation in this model should facilitate studies on the molecular events regulating changes in cell lineage or differentiation commitment within the pancreas.

Coexpression of glutamine synthetase and carbamoylphosphate synthase I genes in pancreatic hepatocytes of rat

In the mammalian liver the distribution of ammonia-detoxifying enzymes, glutamine synthetase (GS) and carbamoylphosphate synthase I (ammonia) (CPS-I), is mutually exclusive in that these enzymes are expressed in two distinct populations of hepatocytes that are zonally demarcated in the liver acinus. In the present study we examined the distribution of GS and CPS-I in pancreatic hepatocytes to ascertain if the expression of these two genes in these hepatocytes is also mutually exclusive. Multiple foci of hepatocytes showing no clear acinar organization develop in the adult rat pancreas as a result of a change in the differentiation commitment after dietary copper deficiency. Unlike liver, GS and CPS-I are detected by immunofluorescence in all pancreatic hepatocytes. In situ hybridization revealed that all pancreatic hepatocytes contain GS and CPS-I mRNAs. The sizes of these two mRNAs in pancreas with hepatocytes are similar to those of the liver. The concomitant expression of GS and CPS-I genes in pancreatic hepatocytes may be attributed, in part, to the absence of portal blood supply to the pancreas vis-à-vis the lack of hormonal/metabolic gradients as well as to possible matrix homogeneity in the pancreas.

Role of periductal and ductular epithelial cells of the adult rat pancreas in pancreatic hepatocyte lineage. A change in the differentiation commitment

Development of pancreatic hepatocytes in adult rats maintained on copper deficient diet containing 0.6% trien (CuDT) has been reported recently. To elucidate the histogenesis of hepatocytes a sequential study was undertaken using morphologic, histochemical, immunochemical, in situ hybridization, and Northern blot analysis. Male F-344 rats weighing 80 to 90 g were fed CuDT for 8 weeks and returned to normal rat chow. Beginning from 4 weeks of copper depletion, there was a progressive loss of acinar cells and by 8 weeks more than 90% of the acinar tissue was lost. During this period, there was an increase in the number of adipocytes in the interstitium, and in the number of interstitial and ductular cells. Morphologic observations were confirmed by immunoblot and Northern blot analysis, in which the amount of pancreatic proteins and their mRNAs decreased between 5 and 8 weeks. During this period, a progressive increase in the level of albumin mRNA was observed. In situ hybridization, performed at 7 weeks of copper deficiency, showed localization of albumin mRNA over interstitial and ductular cells. Pancreatic hepatocytes were identified immediately after the rats were returned to a normal diet and gradually increased in number. The hepatocytes occupied almost 60% of the pancreatic volume by 8 weeks. During the early recovery phase, hepatocytes were identified in ductules as well as in the interstitium. Based on these studies, it is concluded that both the ductular cells and interstitial cells, which resemble oval cells of liver, are capable of transforming into pancreatic hepatocytes and these cells may be considered stem-cell equivalent.