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PubMed1995

Prevention of autoimmune diabetes in nonobese diabetic female mice by treatment with recombinant glutamic acid decarboxylase (GAD 65).

The nonobese diabetic (NOD) mouse spontaneously develops insulin-dependent diabetes (IDDM or type I diabetes), resulting from T-lymphocyte-mediated destruction of pancreatic beta cells. This autoimmune phenomenon includes mononuclear cell infiltration of the islets of Langerhans (insulitis) and the presence of circulating autoantibodies. The specificity of the autoantibodies and of the autoreactive T cells was investigated and several autoantigens were proposed, in particular glutamic acid decarboxylase (GAD). This enzyme exists in two forms (GAD 65 and GAD 67) encoded by two independent genes. To explain the role of GAD in type I diabetes, we prepared recombinant rat GAD 65 as fusion protein, produced in an Escherichia coli expression system, and we treated NOD female mice from 4 to 7 weeks of age by repeated intraperitoneal injections of 5 micrograms fusion protein (3 injections per week); control groups received the fusion partner, maltose binding protein (MBP) or dissolving agent (NaCl 0.9%). We investigated two parameters, the degree of insulitis 5 weeks after the last injection and the overall incidence of the disease. Histological examination of the pancreata from GAD-treated mice revealed a significant reduction in the severity of insulitis compared with the two control groups. Furthermore, we observed that the time of onset and the frequency of diabetes in NOD females injected with GAD fusion protein differed significantly from the control groups receiving MBP or NaCl (P < 0.0001). These results show that a 3-week treatment of NOD female mice starting at 4 weeks of age protects them from diabetes, again emphasizing the crucial role of GAD as autoantigen in type I diabetes.

ATP-Binding Cassette Transporters↗
PubMed2001

Micronuclei and other nuclear lesions as genotoxicity indicators in rainbow trout Oncorhynchus mykiss.

The induction of micronuclei and other nuclear abnormalities in renal erythrocytes of rainbow trout Oncorhynchus mykiss by six genotoxic compounds is evaluated. Colchicine, mitomycin, cyclophosphamide, acrylamide, methyl-methanesulfonate, and N-ethyl-N-nitrosourea were intraperitoneally injected in trout. Our results show that cyclophosphamide induces the formation of micronuclei and also the other nuclear abnormalities; N-ethyl-N-nitrosourea, acrylamide, and colchicine induce only micronuclei; mitomycin-C induces only other nuclear abnormalities but not micronuclei. Methyl-methanesulfonate does not induce nuclear abnormalities in rainbow trout at the dose assayed in this work. The possible genotoxic origin for the different nuclear abnormalities is discussed.

Acrylamide↗
PubMed1998

Uptake of inorganic mercury in the olfactory bulbs via olfactory pathways in rats.

Uptake and transport in the olfactory neurons may be an important means by which some heavy metals gain access to the brain. In the present study we explored whether inorganic mercury (203Hg2+) may be taken up in the CNS via the olfactory pathway. Autoradiography and gamma spectrometry showed that intranasal instillation of 203Hg2+ in the right nostrils of rats resulted in much higher levels of the metal in the right olfactory bulbs than in the left ones. At the side of the application of the 203Hg2+ there was also a labeling of the olfactory nerve bundles projecting to the olfactory bulbs as well as in the olfactory nerve-fibres constituting the olfactory nerve layer of the bulbs, which was not seen on the opposite side. The results also showed that the 203Hg2+ accumulated in the glomerular layer of the bulbs. These data indicate that our results can be ascribed to a movement of the mercury along the olfactory axons to their terminal parts in the glomeruli and not to circulatory uptake from the mucosal vasculature. At late survival intervals a low labeling was also discernable in the external plexiform layer, indicating that a low level of 203Hg2+ leaves the terminal arborizations of the axons in the glomeruli. An uptake of 203Hg2+ in the glomerular layer of the olfactory bulbs was also seen in rats given the metal intraperitoneally. This uptake was similar in the right and left bulbs and always much lower than in the right bulbs of the rats given 203Hg2+ in the right nostrils. The intraperitoneal injections in addition resulted in an uptake of the 203Hg2+ in the olfactory epithelium. We propose that in these rats the mercury is taken up from the blood into the olfactory neurons and then moves along the axons to their terminations in the olfactory bulbs. In humans a continuous exposure of the nasal cavity to mercury vapor (Hg0), released from amalgam fillings and oxidized to Hg2+ in the olfactory mucosa, as well as a potential uptake of Hg2+ in the olfactory neurons from the blood, may lead to considerable concentrations of the metal in the olfactory bulbs.

Animals↗
PubMed2002

Variation of systolic blood pressure in rats exposed to cadmium and nickel.

This research was intended to verify separate and combined effects of cadmium and nickel on blood pressure in rats. After cadmium chloride (CdCl(2)) and nickel chloride (NiCl(2)) were administered individually and combined by intraperitoneal injection to rats daily for a week, systolic blood pressure of the tails were measured at 1, 5, 10, 20, and 30 days after administration. Each substance was injected into rats with 0.1 mg/kg x bw and 1.0 mg/kg x bw concentrations. After 0.1 mg/kg x bw CdCl(2) was injected, statistically significant differences from the control group (only saline) were found at 1, 5, and 10 days. After 0.1 mg/kg x bw NiCl(2) was injected, no statistically significant differences from the control group were found. After 0.1 mg/kg x bw CdCl(2) and 0.1 mg/kg x bw NiCl(2) were injected combined simultaneously, statistically significant differences from the control group were found at 1, 5, and 10 days, compared with the 0.1 mg/kg x bw CdCl(2) group after 5 days and the 0.1 mg/kg x bw NiCl(2) group after 5 and 10 days. After 1.0 mg/kg x bw CdCl(2) was injected, statistically significant differences from the control group were found at 1, 5, 10, and 20 days. After 1.0 mg/kg x bw NiCl(2) was injected, statistically significant differences from the control group were found at 1 and 5 days. After 1.0 mg/kg x bw CdCl(2) and 1.0 mg/kg x bw NiCl(2) were injected combined, statistically significant differences were found at 1, 5, 10, 20, and 30 days, compared with 1.0 mg/kg x bw CdCl(2) at 10, 20, and 30 days and 1.0 mg/kg x bw NiCl(2) at 5, 10, 20, and 30 days. It was found that the effect of CdCl(2) on blood pressure was much more than that of NiCl(2) and the combination of CdCl(2) and NiCl(2) in high concentration delayed recovery of blood pressure.

Animals↗
PubMed1997

Alterations in the reproductive patterns of female mice exposed to xenobiotics.

Chemicals, by virtue of their varied interactions with biological molecules, are expected to differ in the way they may alter female reproduction. Reproductive toxicity may reflect effects either on the female germ cells or on various maternal processes such as ovulation, implantation, pregnancy, and parturition. In either case, the ultimate manifestation of chemical toxicity on female reproduction is a decrease in the number of normal young born. Very little information is available on the effects of chemicals that are nonhormonal in nature on the long-term ability of treated females to produce offspring. This report presents the results of long-term female total reproductive capacity (TRC) tests on 29 chemicals, including pharmaceuticals, pesticides, and alkylating and industrial agents. For each chemical, the minimum test involved an evaluation of the maximum tolerated dose administered as a single intraperitoneal injection. Females were single-pair mated with an untreated male for most of the female's reproductive life span (a minimum of 347 days posttreatment) and scored for the number of live births produced during this period. Confirmatory dominant lethal experiments or histological examinations for numbers of small follicles were carried out when mutagenic effects or cytotoxicity, respectively, were suspected as the basis for reduced fertility. Of the 29 chemicals studied, 17 had reproductive effects which may be grouped into one of three classes: (1) those that reduced the total number of young and litters per female, (2) those that reduced the total number of young but not of litters, and (3) those that had no significant effect on the total number of young produced but reduced the size of the first and/or second litters. The TRC provides a capacity for detecting a range of toxic insults upon female reproduction. Many of the chemicals were indeed shown to affect the reproductive performance of females through mutagenic and/or cytotoxic effects on follicles. In some cases, however, no causative mechanism could be identified for the observed reduction in reproductive performance. Nevertheless, with this report the number of chemicals tested by this TRC procedure has been quadrupled and the categories of chemicals tested have been substantially broadened.

Alkylating Agents↗
PubMed2001

Effect of dietary beta-1,3 glucan on immune responses and disease resistance of healthy and aflatoxin B1-induced immunocompromised rohu (Labeo rohita Hamilton).

The immunostimulant beta-1,3 glucan was fed at 0.1% in feed for 7 days to healthy and aflatoxin B1 (AFB1)-induced immunocompromised fish, Labeo rohita (one of the major tropical carp species), in a 60 day trial. The effects of AFB1, glucan and their interactions on non-specific and specific immunity levels and disease resistance of fish were studied. A single intraperitoneal injection of AFB1 at 1.25 mg kg(-1) body weight) caused a significant (P < 0.05) reduction in non-specific immunity as measured through neutrophil phagocytic indices, serum bactericidal activity, and specific immunity as measured through bacterial agglutination titre against Edwardsiella tarda, as well as reduced protection against Aeromonas hydrophila challenge in comparison to control fish which were exposed neither to aflatoxin nor to glucan. Feeding of glucan to healthy fish raised the non-specific and specific immunity level and protection against bacterial infection compared with the control. Feeding of glucan to AFB1-induced immunocompromised fish for 7 days significantly raised the degree of resistance against A. hydrophila challenge and the non-specific immunity level in comparison to non-treated AFB1 exposed fish. Although feeding of glucan was able to increase specific immunity, all measured through haemagglutination titre against sheep red blood cells, and bacterial (E. tarda) agglutination titre in healthy fish in comparison to all other groups, no significant increase in specific immunity to the aflatoxin-exposed group was seen.

Adjuvants, Immunologic↗
PubMed2002

The effects of 3-methylcholanthrene on macrophage respiratory burst and biotransformation activities in the common carp (Cyprinus carpio L.).

The sensitivity of phagocytic cell function as a bioindicator of pollution stress by polycyclic aromatic hydrocarbons was evaluated in the common carp (Cyprinus carpio L). The time course response of the head-kidney macrophage respiratory burst was measured 1, 2, 3, 5 and 7 days after intraperitoneal injection of a prototypical Cyp 1A inducer (3-methylcholanthrene). This immune activity was compared to the rate of induction of total cytochrome P450, ethoxyresorufin O-deethylase activity (EROD) and glutathione S-transferase activity (GST) in the liver and head-kidney. 3-methylcholanthrene (40 mg kg(-1)) caused a rapid increase in the macrophage respiratory burst. This response was maximal at day 3 post exposure and coincided with maximum induction of cytochrome P450 and EROD activity in liver and head-kidney. Moreover, alpha-naphtoflavone, which functions as both an Ah receptor antagonist and an inhibitor of cytochrome P450 1A activity, reversed the 3-methylcholanthrene induction of immune and enzymatic parameters measured, suggesting metabolic processes. Taken together these results suggest that the induction of macrophage oxidative function may be an equally sensitive marker of exposure to polycyclic aromatic hydrocarbon as the induction of biotransformation activities and confirm that responses mediated by the Ah receptor are similar, if not identical, to those of mammals.

Animals↗
PubMed2002

Temperature dependent activation of leucocyte populations of rainbow trout, Oncorhynchus mykiss, after intraperitoneal immunisation with Aeromonas salmonicida.

The temperature dependence of in vivo activation of rainbow trout Oncorhynchus mykiss, leucocyte populations after intraperitoneal injection (i.p.) of fish with a T-cell independent antigen Aeromonas salmonicida (strain MT423) was investigated using a proliferation assay and flow cytometric analysis with mab specific for trout leucocyte surface markers. In trout kept at 15-17 degrees C a prominent activation of blood and spleen leucocytes was found. Also, drastic changes of the percentage of the leucocyte populations in blood and spleen occurred: the amount of monocytes in the blood increased between day 2 and day 7 post injection (p.i.), whereas in spleen the amount of monocytes stayed at a high level (approximately 35%) after a depression between day 4 and day 7 p.i. The percentage of B-lymphocytes was increased first in spleen and then in blood. The percentage of granulocytes in blood was elevated during the whole experiment compared to control fish. In trout kept at 10-12 degrees C only blood leucocytes showed a weak activation after i.p. injection of A. salmonicida, whereas spleen leucocytes showed nearly no reaction. Only the percentage of granulocytes in the blood (day 2-14 p.i.) and of monocytes in the spleen (day 2 and day 8 p.i.) was changed compared to phosphate buffered saline (PBS)-injected fish. However, the development of A. salmonicida specific antibodies was contrary to the cellular reaction. Whereas antibodies could first be detected after 16-18 days p.i. in both groups the amount of antibodies was significantly higher in sera of trout kept at 10-12 degrees C at day 22 and day 28 p.i. than in sera of trout kept at 15-17 degrees C. These results indicate stronger A. salmonicida induced activation of monocytes, granulocytes and B-lymphocytes at higher temperature. However, the development of a specific antibody response against A. salmonicida seemed to be more effective at lower temperatures.

Aeromonas↗
PubMed2002

Efficacy of different administration routes for vaccination against Vibrio anguillarum in Atlantic halibut (Hippoglossus hippoglossus L.).

Atlantic halibut (Hippoglossus hippoglossus L.) is a potentially important new species to cold-water aquaculture. Development of a viable industrial farming technique has been hampered by continued pathogen problems within the rearing cycle and there are several reports that indicated how susceptible juvenile halibut are to bacterial and viral diseases. Interest has been expressed, within the industry, over the possibility of vaccinating suitably sized animals to protect against the more common aquaculture pathogens. Vibrio spp. are of particular concern due to their ubiquitous nature and the relatively frequent occurrence of these pathogens within marine aquaculture. We have previously investigated the susceptibility of Atlantic halibut to infection by Vibrio anguillarum and the efficacy of intraperitoneal injected delivery of a commercial vaccine in protecting against the disease. Given the very high rate of protection offered by immunisation we wanted to investigate the effect of alternate routes of administration on the efficacy of the vaccine.

Administration, Oral↗
PubMed2003

In vivo effects of beta-glucan and LPS on regulation of lysozyme activity and mRNA expression in Atlantic salmon (Salmo salar L.).

The present study was undertaken to compare the effects of intraperitoneally injected bacterial lipopolysaccharide (LPS) and yeast beta-glucan on lysozyme activity in Atlantic salmon, and to explore what organ(s) are responsible for the increase in plasma lysozyme activity induced by the compounds. The results indicated that LPS stimulates plasma lysozyme activity at least as efficiently as beta-glucan. The lysozyme gene was shown to be transcribed in head kidney, spleen, liver and intestine, and accumulation of transcript was demonstrated in response to both beta-glucan and LPS in all of these organs. Intracellular lysozyme activity was detected in the same organs and in isolated blood polymorphonuclear cells (PMN) and lymphocytes. Increased lysozyme activity in response to both beta-glucan and LPS was demonstrated in blood PMN and cells isolated from head kidney and intestine. In spleen and liver on the other hand, there was no increase in lysozyme activity in response to the stimulants. Based on previous work and the present results it is suggested that plasma lysozyme induced by LPS and beta-glucan originate from macrophages in the different organs. The head kidney is likely to be the main supplier of plasma lysozyme considering its high contents of macrophages. This work supports the notion that microbial compounds containing phylogenetically conserved structures (beta-glucan and LPS) are able to stimulate the non-specific defence of animals against infection by enhancing the lysozyme expression.

Animals↗
PubMed1993

Actions of goldfish neuropeptide Y on the secretion of growth hormone and gonadotropin-II in female goldfish.

Neuropeptide Y (NPY) has been recently characterized in the goldfish and the sequence deduced from goldfish brain cDNA clones reveals that goldfish NPY (gNPY) has over 86% identity with human NPY (hNPY) (Blomqvist et al., 1992, Proc. Natl. Acad. Sci. USA 89, 2350-2354). In the present study, we used synthetic gNPY to investigate the role of NPY in the regulation of growth hormone (GH) and gonadotropin-II (GtH-II) in the goldfish. The dose-response relationships of gNPY on GH and GtH-II release were first tested using an in vitro perifusion system for pituitary fragments. It was found that gNPY stimulated both GH and GtH-II release in a dose-dependent manner, with ED50 values of 1.89 +/- 0.9 nM for GH and 4.19 +/- 2.9 nM for GtH-II. In addition, the C-terminal fragment gNPY (18-36) stimulated the release of both GH and GtH-II, but with lower potency than did the intact molecule. These results confirm our previous findings using hNPY. The interactions of gNPY and other GH and GtH-II regulators were also examined in the present studies. Prolonged infusion of sGnRH induced initial peak releases of GH and GtH-II, followed by a second phase of sustained hormone release at a reduced level. Application of a 5-min pulse of gNPY during the second phase of sGnRH action further stimulated GH and GtH-II release, but only to the levels similar to those induced by gNPY alone. Prolonged infusion with gNPY induced a rapid desensitization of GH and GtH-II release; the hormone levels returned to basal within 25 min in the continued presence of gNPY. Administration of 5-min pulse of sGnRH during the desensitization phase of continuous gNPY perfusion induced a similar GH response to that induced by sGnRH alone, whereas the GtH-II responses to sGnRH given during gNPY infusion were smaller than the responses to sGnRH alone, suggesting that the mechanisms of gNPY stimulation on GH and GtH-II release may be somewhat different. The gNPY-induced GH release was blocked by somatostatin, a known GH inhibitor; the gNPY-induced GtH-II release was reduced by dopamine, a known inhibitor for GtH-II. Finally, intraperitoneal injection of gNPY induced time- and dose-dependent increases in serum GH and GtH-II levels. Together, these results suggest that NPY may play a physiological role in the regulation of GH and GtH-II secretion in the goldfish.

Animals↗
PubMed1993

1,25(OH)2 vitamin D3 increases ionized plasma calcium concentrations in the immature Atlantic cod Gadus morhua.

Intraperitoneal injections of 1,25(OH)2 vitamin D3 (1,25(OH)2D3) produced hypercalcemia in the marine teleost the Atlantic cod (Gadus morhua) with increased plasma concentrations of ionized calcium (CaI) while the total plasma calcium concentrations (CaT) were unaffected. A single injection of 10 micrograms kg bw-1 of 1,25(OH)2D3 increased CaI concentrations from 1.74 +/- 0.03 mM to 1.8 +/- 0.01 mM after 24 hr in Experiment 1 and from 1.67 +/- 0.03 mM to 1.82 +/- 0.06 mM after 72 hr in Experiment 2. This hypercalcemic effect was sustained by daily injections for 5 but not 7 days. Daily injections of a lower dose of 1,25(OH)2D3, 1 microgram kg bw-1, caused hypercalcemia after 5 days (CaI increased from 1.68 +/- 0.01 mM to 1.76 +/- 0.02 mM). Plasma calcium concentrations were not affected by any of the other seco-steroids (vitamin D3, (25(OH)), vitamin D3 (25(OH)D3), or 24,25(OH)2 vitamin D3 (24,25(OH)2D3), except for a decrease in CaT concentrations after 7 daily in injections of 25(OH)D3 (2 micrograms kg bw-1). Plasma phosphate concentrations were not changed by any of the seco-steroids. It is concluded that 1,25(OH)2D3 is hypercalcemic in the marine Atlantic cod.

Animals↗
PubMed1996

Evidence that cortisol may protect against the immediate effects of stress on circulating leukocytes in the trout.

Rainbow trout stressed by an intraperitonal injection of saline displayed reduced phagocytic activity of their spleen and head-kidney macrophages within 3 hr. Phagocytic activity was similarly depressed by injecting noradrenalin, but was maintained in fish injected with the adrenergic blocking agent phentolamine, suggesting that endogenous catecholamines are involved in this stress response. Since stress may increase the number of circulating granulocytes, it is proposed that noradrenalin, released during stress, causes the liberation of active macrophages from the lymphocytic tissue, the remaining macrophages therefore showing a lowered phagocytic index. Cortisol injection, like phentolamine, prevented the depressive effect of stress on the phagocytic index but did not antagonize the depressive effect of exogenous noradrenalin. It is suggested that the stress-induced release of endogenous catecholamines may be prevented by cortisol. Injection stress caused a decline in the number of circulating lymphocytes/thrombocytes, indicating their retrafficking into some other tissue. This was opposed by cortisol and by high doses of noradrenalin. It is proposed that cortisol or noradrenalin may oppose, directly or indirectly, the expression of adhesion molecules which are normally induced after stress.

Adrenergic alpha-Agonists↗
PubMed1996

A radioimmunoassay for African catfish growth hormone: validation and effects of substances modulating the release of growth hormone.

A highly sensitive radioimmunoassay has been developed for measuring plasma growth hormone (GH) concentrations in the African catfish (Clarias gariepinus). The lower detection limit of the assay was 0.1 ng/ml and the standard curve had an ED50 value of 0.5 ng/ml. The validity of the assay was established and the effects of several neurotransmitters on the release of GH were examined. In vitro experiments, using a static culture system for dispersed pituitary cells, demonstrated that the GH release in African catfish was affected by growth hormone-releasing hormone and somatostatin. Single intraperitoneal injections with a dopamine agonist, apomorphine, produced significant and dose-dependent increases in plasma GH levels. Unlike carp, goldfish, and tilapia, a super-active analogue of salmon gonadotrophin-releasing hormone did not alter plasma GH levels in African catfish.

Animals↗
PubMed1996

Melatonin influences gonadotropin II secretion in the Atlantic croaker (Micropogonias undulatus).

The role of melatonin in the control of gonadotropin II (GtH II) secretion was investigated in Atlantic croaker (Micropogonias undulatus) during different phases of the day-night cycle and seasonal reproductive cycle. Intraperitoneal injection of melatonin during the late-light phase of the day-night cycle elicited a significant elevation in plasma GtH II levels in croaker with fully developed gonads. The increase in GtH II levels was observed 30 min postinjection; the levels remained elevated for 1 hr and started to decline at the 2-hr sampling time. The stimulatory effect of melatonin was dose-dependent over the range 5 to 500 ng/g body weight. Circulating GtH II levels in fish with fully developed gonads showed significant diurnal variation, with elevated levels during the dark phase. The GtH II secretion in response to stimulation by a LHRH analog (LHRHa) also varied during the day-night cycle, with the maximum levels during the early-dark phase. Interestingly, melatonin stimulated GtH II release during the late-light and early- and mid-dark phases. The increased gonadotropic response to melatonin preceded (late-light phase) or corresponded to the period of elevated circulating GtH II levels and increased responsiveness to stimulation by LHRHa during the dark phase, suggesting that melatonin may be involved in the control of daily GtH II cycles in this species. Melatonin inhibited LHRHa-induced GtH II release during the mid-dark phase of the day-night cycle in a dose-dependent manner; the physiological significance of this inhibitory influence is not understood at present. No significant effect of melatonin on basal or LHRHa-induced GtH II release was observed in regressed croaker. Melatonin injection (1 or 10 ng/g body weight) into the third ventricle in the preoptic anterior hypothalamic area (POAH) of croaker with fully developed gonads resulted in an elevation in plasma GtH II concentrations. In addition, a low concentration (0.2 ng/ml) of melatonin stimulated in vitro GtH II release from the pituitary fragments of fish with fully developed gonads. These results suggest that melatonin can influence GtH II secretion by acting at the level of POAH and also directly at the pituitary to stimulate GtH II release.

Adaptation, Physiological↗
PubMed2002

Hematological effects of high dose of cortisol on the carp (Cyprinus carpio L.): cortisol effect on the carp blood.

The level of circulating cortisol and peripheral blood parameters were determined in carp age 2 years (K(2)) 24, 72, and 216 h after a single intraperitoneal injection of a high dose (200 mg x kg(-1) body wt) of hydrocortisone. The most striking effect of cortisol was manifest as a significant change in the percentage composition of leukocytes, whose number per unit volume of blood remained relatively constant. A profound lymphopenia and eosinopenia were compensated for in the general balance by an increased number of circulating promyelocytes and myelocytes as well as metamyelocytes and mature polymorphonuclear neutrophilic granulocytes. The results and their possible reasons are discussed on the background of literature data.

Animals↗
PubMed2002

Isolation and characterization of a homologue of mammalian prolactin-releasing peptide from the tilapia brain and its effect on prolactin release from the tilapia pituitary.

In the tilapia (Oreochromis mossambicus), as in many teleosts, prolactin (PRL) plays a major role in osmoregulation in freshwater. Recently, PRL-releasing peptides (PrRPs) have been characterized in mammals. Independently, a novel C-terminal RF (arginine-phenylalanine) amide peptide (Carrasius RF amide; C-RFa), which is structurally related to mammalian PrRPs, has been isolated from the brain of the Japanese crucian carp. The putative PrRP was purified from an acid extract of tilapia brain by affinity chromatography with antibody against synthetic C-RFa and HPLC on a reverse-phase ODS-120 column. The tilapia PrRP cDNA was subsequently cloned by polymerase chain reaction. The cDNA consists of 619 bp encoding a preprohormone of 117 amino acids. Sequence comparison of the isolated peptide and the preprohormone revealed that tilapia PrRP contains 20 amino acids and is identical to C-RFa. Incubation of the tilapia pituitary with synthetic C-RFa (100 nM) significantly stimulated the release of two forms of tilapia PRL (PRL188 and PRL177). However, the effect of C-RFa was less pronounced than the marked increase in PRL release in response to hyposmotic medium. The ability of C-RFa to stimulate PRL release appears to be specific, since C-RFa failed to stimulate growth hormone release from the pituitary in organ culture. In contrast, rat and human PrRPs had no effect on PRL release. C-RFa was equipotent with chicken GnRH in stimulating PRL release in the pituitary preincubated with estradiol 17beta. Circulating levels of PRL were significantly increased 1 h after intraperitoneal injection of 0.1 microg/g of C-RFa in female tilapia in freshwater but not in males. These results suggest that C-RFa is physiologically involved in the control of PRL secretion in tilapia.

Amino Acid Sequence↗
PubMed1996

Adhesion prevention with ancrod released via a tissue-adherent hydrogel.

The objective of this investigation was to evaluate the effect of ancrod, a fibrinogenolytic protease from Malayan pit viper venom, locally delivered through a photopolymerized biodegradable hydrogel in preventing postoperative adhesions. The experimental model involved ischemic and serosal injury to the uterine horns of rats with measurement of adhesions 7 days after injury. Ancrod was delivered intravenously for 5 days preoperatively through 3 days postoperatively, intraperitoneally for 5 days preoperatively, intraperitoneally for 3 days postoperatively, and locally via the hydrogel formed upon the uterine horns by photopolymerization of an aqueous precursor solution. Systemic defibrinogenation by intravenous administration pre-through postoperatively reduced the extent of adhesions by 63% without dose sensitivity from 5 to 20 units/kg/day. Preoperative defibrinogenation by intraperitoneal administration reduced adhesion extent by up to 57%, while postoperative administration was more effective, reducing adhesions by up to 84% with a dose-dependent response from 5 to 20 units/kg/day. Administration of ancrod by local release from a tissue-adherent hydrogel was more effective than either the hydrogel alone or the same amount of ancrod administered by postoperative intraperitoneal injection. Adhesions were reduced by 82% at a local dose of 10 units/kg, compared to a reduction of 68% due to the barrier properties of the gel alone (P < 0.01) and of 19% due to the same amount of drug given at the time of surgery (P < 0.001). Local delivery of ancrod from a tissue-adherent hydrogel barrier thus provided an efficacious prevention to postoperative adhesions while permitting administration of a low total dose of the protease.

Abdomen↗