Pseudomonas moraviensis subsp. stanleyae, a bacterial endophyte of hyperaccumulator Stanleya pinnata, is capable of efficient selenite reduction to elemental selenium under aerobic conditions.

AIMS: To identify bacteria with high selenium tolerance and reduction capacity for bioremediation of wastewater and nanoselenium particle production. METHODS AND RESULTS: A bacterial endophyte was isolated from the selenium hyperaccumulator Stanleya pinnata (Brassicaceae) growing on seleniferous soils in Colorado, USA. Based on fatty acid methyl ester analysis and multi-locus sequence analysis (MLSA) using 16S rRNA, gyrB, rpoB and rpoD genes, the isolate was identified as a subspecies of Pseudomonas moraviensis (97.3% nucleotide identity) and named P. moraviensis stanleyae. The isolate exhibited extreme tolerance to SeO3(2-) (up to 120 mmol l(-1)) and SeO4(2-) (>150 mmol l(-1)). Selenium oxyanion removal from growth medium was measured by microchip capillary electrophoresis (detection limit 95 nmol l(-1) for SeO3(2-) and 13 nmol l(-1) for SeO4(2-)). Within 48 h, P. moraviensis stanleyae aerobically reduced SeO3(2-) to red Se(0) from 10 mmol l(-1) to below the detection limit (removal rate 0.27 mmol h(-1) at 30 °C); anaerobic SeO3(2-) removal was slower. No SeO4(2-) removal was observed. Pseudomonas moraviensis stanleyae stimulated the growth of crop species Brassica juncea by 70% with no significant effect on Se accumulation. CONCLUSIONS: Pseudomonas moraviensis stanleyae can tolerate extreme levels of selenate and selenite and can deplete high levels of selenite under aerobic and anaerobic conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: Pseudomonas moraviensis subsp. stanleyae may be useful for stimulating plant growth and for the treatment of Se-laden wastewater.

Potentiation by carbon tetrachloride of the immunosuppressive effects of fibrosarcoma and toxic material produced by fibrosarcoma cells.

SaD2-AG fibrosarcomas growing in DBA/2 mice caused nonspecific immunodepression. Injection of soluble material produced by cultured SaD2-AG cells into normal DBA/2 recipients caused nonspecific immunodepression and signs of systemic toxicity. These in vivo effects were enhanced by prior treatment of the recipients with carbon tetrachloride (CCl4). In contrast, material released by syngeneic fibroblasts was neither immunosuppressive nor toxic to normal mice or mice previously treated with CCl4. A soluble toxic material released by the fibrosarcoma cells may be responsible for at least some of the systemic effects of localized SaD2-AG tumors growing at a site not involving vital structures, and a protective host mechanism whose maximum capacity can be decreased by the administration of CCl4 may minimize the toxic effects of the cancer-derived material.

Expression of grass carp growth hormone by baculovirus in silkworm larvae.

A total of five recombinant Bombyx mori nuclear polyhedrosis viruses (BMNPV) carrying the grass carp (Ctenopharyngodon idellus) growth hormone (GH) cDNA were constructed in this study. Two of them were able to express the hormone up to a level of 12 microgram/ml medium when cultured B. mori cells were infected for 4 days. Inoculation of the viruses into silkworm (B. mori) host significantly increased the level of GH achievable. The amount of hormone produced per larva was estimated to be around 1 mg. The recombinant grass carp GH had immunological and biological activities similar to the native hormone. The N-terminal sequence of the recombinant hormone was the same as the native one, indicating that the fish signal peptide was correctly processed by the insect cells. Silkworm powder prepared from larvae infected with the recombinant virus was used as food supplement for fish. Compared with the control, this dietary supplement was effective in increasing the growth rate of juvenile carp.

Comparison of oral capecitabine versus intravenous fluorouracil plus leucovorin as first-line treatment in 605 patients with metastatic colorectal cancer: results of a randomized phase III study.

PURPOSE: To compare the response rate, efficacy parameters, and toxicity profile of oral capecitabine with bolus intravenous (IV) fluorouracil plus leucovorin (5-FU/LV) as first-line treatment in patients with metastatic colorectal cancer. PATIENTS AND METHODS: We prospectively randomized 605 patients to treatment with oral capecitabine for 14 days every 3 weeks or 5-FU/LV by rapid IV injection daily for 5 days in 4-week cycles. RESULTS: The overall objective tumor response rate among all randomized patients was significantly higher in the capecitabine group (24.8%) than in the 5-FU/LV group (15.5%; P =.005). In the capecitabine and 5-FU/LV groups, median times to disease progression were 4.3 and 4.7 months (log-rank P =.72), median times to treatment failure were 4.1 and 3.1 months (P =.19), and median overall survival times were 12.5 and 13.3 months (P =.974), respectively. Capecitabine, compared with bolus 5-FU/LV treatment, produced a significantly lower incidence (P <.0002) of diarrhea, stomatitis, nausea, and alopecia. Patients treated with capecitabine also displayed lower incidences of grade 3/4 stomatitis and grade 3/4 neutropenia (P <.0001) leading to significantly less neutropenic fever/sepsis. Grade 3 hand-foot syndrome (P <.00001) and grade 3/4 hyperbilirubinemia were the only toxicities more frequently associated with capecitabine than with 5-FU/LV treatment. CONCLUSION: Oral capecitabine was more active than 5-FU/LV in the induction of objective tumor responses. Time to disease progression and survival were at least equivalent for capecitabine compared with the 5-FU/LV arm. Capecitabine also demonstrated clinically meaningful benefits over bolus 5-FU/LV in terms of tolerability.

Steroidogenic factor 1 and estradiol receptor act in synergism to regulate the expression of the salmon gonadotropin II beta subunit gene.

The orphan nuclear receptor steroidogenic factor-1 (SF-1) regulates the expression of several genes involved in the reproductive function and development of the adrenal, the gonads, and the pituitary gonadotropes. It also confers the gonadotrope-specific expression of the glycoprotein hormone a subunit gene by the binding to a gonadotrope-specific element (GSE). In this study, we have shown that SF-1 transactivates the salmon gonadotropin II beta subunit (sGTHII beta) gene expression. SF-1 alone offered a slight but significant enhancement on sGTHII beta promoter activity (7.2 +/- 0.6 fold). However, it stimulated sGTHII beta gene expression dramatically (127 +/- 37 fold) when combined with the estrogen receptor (ER). This synergistic interaction was specific for sGTHII beta promoter as well as for both SF-1 and ER and was estradiol-dose dependent. 5'-Deletion studies of the sGTHII beta promoter identified two putative SF-1 binding sites (GSE) and one previously identified proximal estrogen-responsive element (pERE) at -274 bp involved in this activation. The two GSE sequences located at -354 bp (sGSE(3) and -162 bp (sGSE(2) upstream of the transcription site, although imperfect as compared with the consensus GSE, bound specifically to the in vitro-translated mouse SF-1 protein. 5'-Deletion studies, competition experiments, and site-directed mutagenesis showed that binding to pERE and GSE(2) were necessary for the SF-1/ER synergistic effect. These studies suggest that the synergistic interaction of SF-1 and ER, possibly through cooperative binding or protein-protein interaction, is essential in conferring a cell type-specific expression of the GTHII beta subunit gene.

Dopamine stimulates growth hormone release from the pituitary of goldfish, Carassius auratus, through the dopamine D1 receptors.

Previously, we have demonstrated that ip injection of apomorphine, a nonselective dopamine (DA) agonist, increases serum GH levels in the goldfish, suggesting a possible role of DA in GH regulation. In the present study, the effects of DA on GH release in the goldfish were further characterized using an in vitro perifusion system for pituitary fragments. DA increased GH release in a dose-dependent manner with an ED50 of 0.26 +/- 0.06 microM. SKF38393, a DA D1 agonist, mimicked the GH-releasing effect of DA with an ED50 of 0.41 +/- 0.12 microM. Stereoselectivity consistent with mammalian DA D1 systems was demonstrated for the GH response to SKF38393; only the (+)- but not (-)-enantiomer of SKF38393 induced a dose-dependent GH release. Two other D1 agonists, SKF77434 and SKF82958, were also found to have GH-releasing activity. In contrast, high doses (up to 1 microM) of the DA D2 agonists, bromocriptine and LY171555, did not affect basal GH levels. The receptor specificity for DA-stimulated GH release was further investigated by using D1 and D2 antagonists; the D1 antagonists SCH23390 and SKF83566 completely abolished the GH response to DA or the D1 agonist SKF38393, whereas the D2-specific antagonists domperidone and (-)-sulpiride were not effective in this respect. Taken together, the present study demonstrates that DA is stimulatory to GH release from the pituitary of goldfish, and its action is mediated through receptors resembling the mammalian DA D1 receptors. The apparent similarities of the DA D1 receptor pharmacology between the goldfish and the mammals also indicate that D1 receptor is highly conserved during vertebrate evolution.

Characterization of D1 receptors mediating dopamine-stimulated growth hormone release from pituitary cells of the goldfish, Carassius auratus.

Previously, we demonstrated that dopamine (DA) stimulates GH release from the pituitary of goldfish, and this action is mediated by D1-like receptors. In the current study, we have provided evidence for the presence of D1-specific binding sites in the pituitary cells of goldfish. These D1-binding sites were found to be saturable, stereospecific, and selective for D1 ligands. The rank order of binding affinity of these D1-binding sites is (+)SCH23390 > SKF83566 >> (-)SCH23390 > domperidone > LY171555 >> serotonin. The association of these D1-binding sites with [3H]SCH23390, a D1-specific radioligand, was rapid, reversible, and exhibited a high binding affinity in the nanomolar range. The Kd values were estimated to be 33.7 +/- 8.5 nM for mixed populations of pituitary cells and 10.9 +/- 2.5 nM for pituitary cell preparations enriched with somatotrophs. Autoradiographic studies revealed that specific binding of [3H]SCH23390 was predominantly localized in the pars distalis, not in the neurointermediate lobe of the goldfish pituitary. Furthermore, these D1-binding sites in the goldfish pituitary cells could be functionally correlated with the GH-releasing actions of DA. Since these D1-binding sites exhibited the expected pharmacological properties of mammalian D1 receptors, we conclude that DA D1 receptors are present in the goldfish pituitary and are responsible for the mediation of DA D1-stimulated GH release. The apparent similarities of the D1 receptor pharmacology between goldfish and mammals also suggests that DA D1 receptors are highly conserved during vertebrate evolution.

Characterization of purinergic receptors and receptor-channels expressed in anterior pituitary cells.

Purinergic G protein-coupled receptors (P2YR) and ion-conducting receptor-channels (P2XR) are present in the pituitary. However, their identification, expression within pituitary cell subpopulations, and the ability to elevate intracellular Ca2+ concentration ([Ca2+]i) in response to ATP stimulation were incompletely characterized. Here we show that mixed populations of rat anterior pituitary cells express messenger RNA transcripts for P2Y2R, P2X2aR, P2X2bR, P2X3R, P2X4R, and P2X7R. The transcripts and functional P2Y2R were identified in lactotrophs and GH3 cells, but not in somatotrophs and gonadotrophs, and their activation by ATP led to an extracellular Ca2+-independent rise in [Ca2+]i in about 40% of cells tested. Lactotrophs and GH3 cells, but not somatotrophs, also express transcripts for P2X7R, P2X3R, and P2X4R. Functional P2X7R were identified in 74% of lactotrophs, whereas 50% of these cells expressed P2X3R and 33% expressed P2X4R. Coexpression of these receptor subtypes in single lactotrophs was frequently observed. Purified somatotrophs expressed transcripts for P2X2aR and P2X2bR, and functional receptors were identified in somatotrophs and gonadotrophs, but not in lactotrophs. Consistent with the cell-specific expression of transcripts for P2X2R and P2X3R, the expression of their functional heteromers was not evident in pituitary cells. Receptors differed in their capacities to elevate and sustain Ca2+ influx-dependent rise in [Ca2+]i during the prolonged ATP stimulation. These results indicate that the purinergic system of anterior pituitary is extremely complex and provides an effective mechanism for generating a cell- and receptor-specific Ca2+ signaling pattern in response to a common agonist.

Interactions of cyclic adenosine 3',5'-monophosphate, protein kinase-C, and calcium in dopamine- and gonadotropin-releasing hormone-stimulated growth hormone release in the goldfish.

In the goldfish, GH release is under the stimulatory control of multiple neuroendocrine factors, including dopamine (DA) and GnRH. We have previously shown that DA-stimulated GH release in the goldfish is mediated via D1 receptors and is dependent on cAMP, whereas the GH response to GnRH involves protein kinase-C (PKC) and extracellular Ca2+ entry through voltage-sensitive Ca2+ channels (VSCC). In this study, the interactions of PKC, cAMP, and Ca2+ in the regulation of GH release responses to DA and GnRH were examined using dispersed goldfish pituitary cells. The GnRH-induced GH secretion was unaffected by a protein kinase-A (PKA) inhibitor, but was additive to the GH responses to 8-bromo-cAMP (8-Br-cAMP), the phosphodiesterase inhibitor isobutylmethylxanthine, or the D1 agonist SKF38393. Similarly, the GH responses to PKC activators were additive to those to 8-Br-cAMP, forskolin, SKF38393, or the general DA agonist apomorphine. In contrast, depletion of cellular PKC content inhibited the GH responses to GnRH and PKC activators, but not those to DA, SKF38393, 8-Br-cAMP, or forskolin. Furthermore, the GH response to 8-Br-cAMP or SKF38393 was unaffected by the selective PKC inhibitor H7. Taken together, these results suggest that GnRH and DA D1 mechanisms stimulate GH release in the goldfish independently via PKC- and cAMP-dependent intracellular signaling pathways, respectively. However, both the cAMP (D1) and PKC (GnRH) mechanisms also interacted with VSCC. The VSCC agonist Bay K8644 potentiated, whereas the VSCC blocker verapamil reduced, the GH responses to GnRH, PKC activators, SKF38393, and activators of the cAMP pathway. A hypothesis is proposed based on these findings. GnRH and DA initiate GH release independently by activation of PKC- and cAMP-dependent mechanisms. The secondary activation of VSCC by either PKC or cAMP/PKA further enhances the GH response.

Hypophysiotropic action of pituitary adenylate cyclase-activating polypeptide (PACAP) in the goldfish: immunohistochemical demonstration of PACAP in the pituitary, PACAP stimulation of growth hormone release from pituitary cells, and molecular cloning of pituitary type I PACAP receptor.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a member of the glucagon/secretin peptide family, and its molecular structure is highly conserved in vertebrates. In this study, the functional role of PACAP in regulating GH release in the goldfish was investigated. Using immunohistochemical staining, nerve fibers with PACAP immunoreactivity were identified in the vicinity of goldfish somatotrophs, suggesting that this neuropeptide may influence GH release in the goldfish. The direct regulatory action of PACAP on GH secretion was demonstrated in vitro in perifused goldfish pituitary cells. PACAPs (0.01 nM to 1 microM) from different species, including ovine PACAP27, ovine PACAP38, frog PACAP38, zebra fish PACAP27, and zebra fish PACAP38, were all effective in stimulating GH release with ED50 values of 8.9 +/- 3.5, 3.3 +/- 1.6, 14.4 +/- 3.5, 15.4 +/- 4.1, and 1.4 +/- 0.2 nM, respectively. Similar concentrations of vasoactive intestinal polypeptide (VIP), a peptide related to PACAP, was not effective in this respect. In addition, the GH-releasing action of ovine PACAP38 (10 nM) was inhibited by the PACAP antagonist PACAP(6-38) (10 microM), but not by the VIP antagonist [4-Cl-D-Phe6,Leu17]VIP (10 microM). The pharmacology of these GH responses is consistent with the mammalian type I PACAP receptors, suggesting that a similar receptor subtype is present in the goldfish pituitary and mediates the GH-releasing action of PACAP. To establish the structural identity of this goldfish PACAP receptor, a complementary DNA (cDNA) clone sharing a high degree of sequence homology with mammalian type I PACAP receptors was isolated from a goldfish pituitary cDNA library. This cDNA was 5.2 kb in size with a 1.4-kb open reading frame and encoded a 465-amino acid protein with the typical structure of a 7-transmembrane domain-containing, G protein-coupled receptor. Functional expression of this cDNA in COS-7 cells revealed that this fish type I PACAP receptor could be activated by ovine PACAP27 and PACAP38 to increase cAMP synthesis with ED50 values of 2.4 +/- 0.8 and 4.2 +/- 1.2 nM, respectively. Other structurally related peptides, including VIP (100 nM), GH-releasing hormone (100 nM), glucagon (100 nM), secretin (100 nM), gastric inhibitory polypeptide (100 nM), and PTH (100 nM), were not effective in altering cAMP production. Using Northern blot and RT-PCR, messenger RNA transcripts of this PACAP receptor were identified in the brain, heart, and pituitary of the goldfish. These results, taken together, support the hypothesis that PACAP functions as a novel GH-releasing factor in the goldfish through activation of type I PACAP receptors.

Induction of chinook salmon growth hormone promoter activity by the adenosine 3',5'-monophosphate (cAMP)-dependent pathway involves two cAMP-response elements with the CGTCA motif and the pituitary-specific transcription factor Pit-1.

In this study, the functional role of two cAMP-response elements (CRE) in the promoter of the chinook salmon GH gene and their interactions with the transcription factor Pit-1 in regulating GH gene expression were examined. A chimeric construct of the chloramphenicol acetyltransferase (CAT) reporter gene with the CRE-containing GH promoter (pGH.CAT) was transiently transfected into primary cultures of rainbow trout pituitary cells. The expression of CAT activity was stimulated by an adenylate cyclase activator forskolin as well as a membrane-permeant cAMP analog 8-bromo-cAMP. Furthermore, these stimulatory responses were inhibited by a protein kinase A inhibitor H89, suggesting that these CREs are functionally coupled to the adenylate cyclase-cAMP-protein kinase A cascade. This hypothesis is supported by parallel studies using GH4ZR7 cells, a rat pituitary cell line stably transfected with dopamine D2 receptors. In this cell line, D2 receptor activation is known to inhibit adenylate cyclase activity and cAMP synthesis. Stimulation with a nonselective dopamine agonist, apomorphine, or a D2-specific agonist, Ly171555, suppressed the expression of pGH.CAT in GH4ZR7 cells, and this inhibition was blocked by simultaneous treatment with forskolin. These results indicate that inhibition of the cAMP-dependent pathway reduces the basal promoter activity of the CRE-containing pGH.CAT. The functionality of these CREs was further confirmed by deletion analysis and site-specific mutagenesis. In trout pituitary cells, the cAMP inducibility of pGH.CAT was inhibited after deleting the CRE-containing sequence from the GH promoter. When the CRE-containing sequence was cloned into a CAT construct with a viral thymidine kinase promoter, a significant elevation of cAMP inducibility was observed. This stimulatory response, however, was abolished by mutating the core sequence, CGTCA, in these CREs, suggesting that these cis-acting elements confer cAMP inducibility to the salmon GH gene. The interactions between CREs and the transcription factor Pit-1 in mediating GH gene expression were also examined. In HeLa cells, a human cervical cancer cell line deficient in Pit-1, both basal and cAMP-induced expression of pGH.CAT were apparent only with the cotransfection of a Pit-1 expression vector. These results taken together indicate that the two CREs in the chinook salmon GH gene are functionally associated with the cAMP-dependent pathway and that their promoter activity is dependent on the presence of Pit-1

Neuropeptide-Y stimulates growth hormone and gonadotropin-II secretion in the goldfish pituitary: involvement of both presynaptic and pituitary cell actions.

We have previously reported that neuropeptide-Y (NPY) stimulates GH and gonadotropin-II (GtH-II) release from perifused pituitary fragments in the goldfish. Since the teleost pituitary is directly innervated by neurosecretory terminals from the brain, we further investigated the possible sites of action of NPY. Both synthetic human NPY and NPY-(18-36), an agonist selective for the NPY Y2-receptor, stimulated GH and GtH-II release from the pituitary fragments; the magnitude of the response to NPY (18-36) was smaller than that to the whole molecule of NPY. NPY also stimulated the release of GH and GtH-II from perifused dispersed pituitary cells. In contrast, NPY-(18-36) had no effect on either GH or GtH-II release from dispersed pituitary cells. These data suggest that Y2 action is not direct at the level of pituitary cells, but may be indirect through actions on nerve terminals in the pituitary. The hypothesis that the action of NPY on GH and GtH-II release is mediated in part by GnRH was then tested. Both NPY and NPY-(18-36) stimulated the GnRH release from preoptic-anterior hypothalamic slices and pituitary fragments with similar potency. Furthermore, a GnRH antagonist significantly reduced the effects of NPY on both GH and GtH-II release in perifused pituitary fragments. Similar to previous findings, NPY, when given at 55-min intervals, desensitized the hormone responses in pituitary fragments. Similarly, the same treatment with NPY in perifused dispersed pituitary cells induced desensitization of GH and GtH-II responses. Together, these results suggest that 1) more than one type of NPY receptors are present in the goldfish pituitary; and 2) NPY has at least two sites of action in the pituitary. One site of action is the pituitary cells, where NPY directly stimulates GH and GtH-II secretion; the second is the nerve terminals, where NPY presynaptically stimulates GnRH release via Y2-like receptors, and GnRH, in turn, stimulates GH and GtH-II release.

Preoperative chemotherapy and pelvic radiation for tethered or fixed rectal cancer: a phase II dose escalation study.

PURPOSE: To study the impact of preoperative radiation dose escalation and postoperative adjuvant chemotherapy on the outcome of tethered and fixed rectal carcinoma. METHODS AND MATERIALS: We have treated 156 patients with 3 consecutive preoperative chemoradiation protocols with escalating treatment intensity. Schedule 1 consisted of 40 Gy radiation with concurrent 5-fluorouracil (5-FU) infusion and mitomycin C. Schedule 2 used a sandwich design with preoperative (40 Gy) and postoperative (18 Gy) radiation with concomitant 5-FU infusion, leucovorin, and mitomycin C. In schedule 3, the preoperative radiation dose was increased to 50 Gy and adjuvant 5-FU/leucovorin chemotherapy was added following surgery. There were 54, 27, and 75 patients treated in schedules 1, 2, and 3, respectively. RESULTS: The resectability was 91% for schedule 1 and 100% for both schedules 2 and 3. A dose-response relationship was observed between the radiation dose and the tumor downstaging and local control. The pathological complete response (T0N0M0) rates for schedules 1, 2, and 3 were 4%, 15%, and 25%, respectively. The respective rates of tumor downstaging were 41%, 33%, and 68%, respectively. The 5-year local relapse-free rates were 67% for schedule 1 (40 Gy), 96% for schedule 2 (58 Gy), and 92% for schedule 3 (50 Gy) (p = 0.0011). The addition of postoperative chemotherapy appeared to improve both the survival and the relapse-free survival. The 5-year survival was increased from 52% to 84% (p = 0.0004) and the 5-year progression-free survival was improved from 48% to 74% (p = 0.0008). CONCLUSION: Preoperative 5-FU infusion, leucovorin, mitomycin C, and 50-Gy pelvic radiation, followed by postoperative bolus 5-FU/leucovorin chemotherapy, appeared to be an effective treatment for tethered/fixed rectal cancers. However, its therapeutic efficacy could only be validated in randomized studies.

"Sandwich" preoperative and postoperative combined chemotherapy and radiation in tethered and fixed rectal cancer: impact of treatment intensity on local control and survival.

PURPOSE: The present "sandwich" preoperative and postoperative chemotherapy and radiation study was undertaken to evaluate the impact of treatment intensity on the local control and survival in tethered or fixed rectal adenocarcinoma (T3, 4 NX M0). METHODS AND MATERIALS: Between 1990 and 1992, 27 patients were treated with this sandwich protocol. Preoperative therapy consisted of 4 weeks of concurrent radiation (40 Gy) and chemotherapy (mitomycin C on day 1, 5-fluorouracil infusion and leucovorin on days 1-4 and days 15-18, respectively), and one cycle of bolus 5-fluorouracil and leucovorin chemotherapy. After surgery, they received 2 additional weeks of radiation (18 Gy) and 4 days of similar chemotherapy. The outcome was compared to another 54 patients who were treated with our previous preoperative chemoradiation protocol (mitomycin C, 5-fluorouracil infusion and 40 Gy of pelvic RT). RESULTS: The complete resectability rate was improved from 91% in the preoperative protocol to 100% in the sandwich protocol, and the pathologic complete response rate (T0 N0 M0) was increased from 4 to 15%. There was no local recurrence in the sandwich protocol. The 4-year local failure rate was 23 vs. 0% (p = 0.005). The 4-year distant failure rate was 47 vs. 28% (p = 0.079). The 2-year and 4-year survival were 63 and 41% for the preoperative protocol, vs. 92 and 72% for the sandwich protocol, respectively (p = 0.014). There were more treatment-related Grade 2 diarrhea, but not Grade 3/4 diarrhea in the sandwich protocol. Two patients (7%) in the sandwich protocol developed late gastrointestinal complications. CONCLUSIONS: More intensive radiation and chemotherapy appeared to improve the resectability, local control, and survival in tethered and fixed rectal cancers. There was a moderate but acceptable increase in the bowel morbidity.

Norepinephrine regulation of growth hormone release from goldfish pituitary cells. I. Involvement of alpha2 adrenoreceptor and interactions with dopamine and salmon gonadotropin-releasing hormone.

Adrenergic regulation of growth hormone (GH) release in the goldfish was examined in vitro using dispersed goldfish pituitary cells under column perifusion. Norepinephrine and epinephrine suppressed basal GH release from goldfish pituitary cells in a reversible and dose-dependent manner. At high doses, a transient rebound of GH release was observed after termination of norepinephrine and epinephrine treatment. In this study, the dose-dependence of adrenergic inhibition on basal GH release was mimicked by the alpha2 agonists clonidine and UK14304. Basal GH secretion, however, was not affected by the beta agonist isoproterenol and alpha1 agonist methoxamine. In addition, the inhibitory actions of norepinephrine and clonidine on basal GH release were blocked by the alpha2 antagonists yohimbine and RX821002. The beta antagonist propranolol and alpha1 antagonists prasozin and benoxathian were not effective in this respect. Salmon gonadotropin-releasing hormone (sGnRH) and dopamine, two known GH-releasing factors in fish, stimulated GH release from goldfish pituitary cells and their GH-releasing actions were inhibited by simultaneous treatment with norepinephrine. Furthermore, the GH rebound after norepinephrine treatment was significantly enhanced by prior exposure to sGnRH and this effect was not observed with dopamine treatment. These results, taken together, suggest that in the goldfish adrenergic input at the pituitary level inhibit basal GH release through activation of alpha2 adrenoreceptors. This alpha2 inhibitory influence may interact with dopaminergic and GnRH input to regulate GH secretion from goldfish pituitary cells. The 'post-inhibition' GH rebound after NE treatment and its sensitivity to sGnRH potentiation may also represent a novel mechanism for GH regulation in fish.

Norepinephrine regulation of growth hormone release from goldfish pituitary cells. II. Intracellular sites of action.

Previous results suggest that norepinephrine decreases growth hormone (GH) release in goldfish by means of alpha-2 adrenoceptor activation. The intracellular mechanisms by which norepinephrine inhibits GH release were examined in the present study using dispersed goldfish pituitary cells. In 2-h static incubation experiments, norepinephrine and the alpha-2 agonist clonidine decreased basal GH release and the GH responses to stimulation by the dopamine D1 agonist SKF38393 and two native gonadotropin-releasing hormones (GnRH). Norepinephrine also reduced GH responses to the adenylate cyclase activator forskolin, two protein kinase C (PKC) activators (phorbol ester and synthetic diacylglycerol), and two Ca2+ ionophores (ionomycin and A23187). Similarly, norepinephrine applied as a 1-h pulse in cell column perifusion experiments reduced basal GH release and abolished the GH response to a 5-min pulse of arachidonic acid. In goldfish, D1-stimulated GH release is mediated by AC-, arachidonic acid-and Ca2+-dependent pathways, whereas GnRH action is coupled to PKC-and Ca2+-dependent mechanisms. These results suggest that norepinephrine activation of alpha-2 receptors inhibits ligand-induced GH secretion by actions subsequent to activation of these second messenger cascades. To further characterize norepinephrine mechanisms of action on unstimulated hormone release, the ability of norepinephrine and an alpha-2 agonist to affect activation of two second messenger cascades under basal conditions was also investigated. Static incubation with clonidine reduced cAMP production in a time-and dose-dependent manner, suggesting that norepinephrine inhibitory action can also be expressed at the level of cAMP production. Resting intracellular free calcium levels in single, identified goldfish somatotropes was unaffected by norepinephrine. However, the inhibitory effects of norepinephrine on basal GH secretion was not observed in the presence of a voltage-sensitive Ca2+ channel agonist. Whether these channels are targets for norepinephrine action on unstimulated GH release requires further investigation.

Signal transduction pathways in GnRH- and dopamine D1-stimulated growth hormone secretion in the goldfish.

In goldfish, growth hormone (GH) secretion is regulated by multiple neuroendocrine factors. Among these regulators, gonadotropin-releasing hormone (GnRH) and dopamine (DA) are effective stimulators of GH release. The stimulatory actions of GnRH and DA are mediated by GnRH and DA D1 receptors on somatotropes, respectively. In this article, results from recent in vitro pharmacological and electrophysiological studies examining the possible involvement of extracellular Ca2+, protein kinase C, voltage-sensitive Ca2+ channels (VSCC) and phospholipase A2 in mediating GnRH-induced GH release are presented. Results from experiments investigating the possible interactions of cyclic adenosine 3',5'-monophosphate (cAMP), and extracellular Ca2+ entry through VSCC in mediating the DA D1-elicited GH response are also reported. These data were discussed in conjunction with other information available in the literature on the signal transduction mechanisms mediating GH secretion in goldfish. Based on these findings, a model for the transduction pathways integrating the initiation and maintenance of the distinct GnRH-induced and DA D1-elicited GH responses was proposed. GnRH and DA stimulate GH release via separate PKC- and cAMP-dependent mechanisms, respectively. These signalling mechanisms appear to act on distinct GH pools. PKC and cAMP subsequently activate VSCC. Ca2+ entry through VSCC plays a role in the sustained GH release response by enhancing the PKC- and cAMP-induced GH release.

The secretogranin II-derived peptide secretoneurin stimulates luteinizing hormone secretion from gonadotrophs.

Secretoneurin (SN) is a 33- to 34-amino acid neuropeptide derived from secretogranin-II, a member of the chromogranin family. We previously synthesized a putative goldfish (gf) SN and demonstrated its ability to stimulate LH release in vivo. However, it was not known whether goldfish actually produced the free SN peptide or whether SN directly stimulates LH release from isolated pituitary cells. Using a combination of reverse-phase HPLC and mass spectrometry analysis, we isolated for the first time a 34-amino acid free gfSN peptide from the whole brain. Moreover, Western blot analysis indicated the existence of this peptide in goldfish pituitary. Immunocytochemical localization studies revealed the presence of SN immunoreactivity in prolactin cells of rostral pars distalis of the anterior pituitary. Additionally, we found that magnocellular cells of the goldfish preoptic region are highly immunoreactive for SN. These neurons send heavily labeled projections that pass through the pituitary stalk and innervate the neurointermediate and anterior lobes. In static 12-h incubation of dispersed pituitary cells, application of SN antiserum reduced LH levels, whereas 1 and 10 nM gfSN, respectively, induced 2.5-fold (P < 0.001) and 1.9-fold (P < 0.01) increments of LH release into the medium, increases similar to those elicited by 100 nM concentrations of GnRH. Like GnRH, gfSN elevated intracellular Ca(2+) in identified gonadotrophs. Whereas we do not yet know the relative contribution of neural SN or pituitary SN to LH release, we propose that SN could act as a neuroendocrine and/or paracrine factor to regulate LH release from the anterior pituitary.

Entry of extracellular calcium mediates dopamine D1-stimulated growth hormone release from goldfish pituitary cells.

Unlike mammals, the goldfish is unique in having dopamine (DA) D1 receptors in the anterior pituitary. In this species, DA stimulates growth hormone (GH) release via D1 receptors coupled to the cAMP-dependent pathway. To further examine the postreceptor mechanisms of this novel pituitary DA D1 system, the role of extracellular Ca2+ ([Ca2+]e] in mediating DA D1-stimulated GH release was studied using dispersed goldfish pituitary cells. The GH responses to DA (1 nM-10 microM), the D1 agonist SKF38393 (1 microM), and the Ca2+ ionophore A23187 (10 microM) were abolished by incubation with Ca(2+)-deficient medium. Incubation with depolarizing doses of KCl (10-25 mM), which activate voltage-sensitive Ca2+ channels (VSCC), induced GH release in a dose-dependent manner. In contrast, the VSCC blockers nifedipine (10 microM), nicardipine (10 microM), and verapamil (10 microM) and the inorganic competitor of Ca2+ entry CoCl2 (5 mM) blocked the GH responses to DA (1 microM) as well as SKF38393 (1 microM). These results strongly indicate that the entry of [Ca2+]e via VSCC is an essential part of the signal transduction mechanisms mediating DA D1-stimulated GH release in the goldfish. In this study, the possible interactions between the Ca(2+)- and cAMP-dependent pathways in DA-induced GH secretion were also investigated. The membrane-permeant cAMP analogue 8Br.cAMP (1 mM) and the adenylate cyclase activator forskolin (10 microM) stimulated GH release from goldfish pituitary cells. These GH responses were suppressed by incubation with Ca(2+)-deficient medium or with the VSCC blocker nifedipine (10 microM). Furthermore, the GH responses to forskolin (10 microM) and the nonselective DA agonist apomorphine (1 microM) were not additive to that of the Ca2+ ionophore A23187 (10 microM). These results suggest that [Ca2+]e entry induced by DA D1 stimulation occur at steps after activation of the cAMP-dependent pathway.

Intracellular mechanisms mediating gonadotropin and growth hormone release in the goldfish, Carassius auratus.

Evidence for the involvement of Ca(2+), protein kinase C, cAMP, and arachidonic acid metabolism in mediating gonadotropin (GTH) and growth hormone (GH) release in the goldfish is reviewed. Models for the signal transduction pathways mediating GTH-releasing hormone (GnRH) and dopamine actions on GTH and GH secretion are postulated. A novel hypothesis that two GnRHs which bind to the same receptor type activate different transduction cascade in two different cell types (GTH vs. GH) as well as within the same cell type (GTH) is presented.