Coronary artery bypass surgery without blood transfusion; is it possible?

BACKGROUND: Coronary artery bypass surgery is the most commonly performed cardiac operation and approximately 40-70% of patients require a blood transfusion despite improvements in cardiac surgical techniques. Some preventive perfusion methods to avoid transfusions are described, such as acute normovolemic hemodilution, retrograde autologous priming, and usage of integrated arterial filter oxygenator. AIMS: We combined these three techniques (triple combination technique) to evaluate whether it is possible to avoid blood transfusions in adult patients undergoing coronary artery bypass surgery. MATERIALS AND METHODS: A total of 300 consecutive patients were included in this randomized controlled trial. 150 patients (Group 1) were operated with triple combination technique, The other 150 patients (Group 2) were operated with standard cardiopulmonary bypass technique. The two groups were compared in terms of peroperative and postoperative blood product use. RESULTS: Ninety-two percent (92%) of the patients (Group 1) undergoing coronary artery bypass surgery did not require any blood transfusion. Only 8% of the patients required erythrocyte suspension or fresh frozen plasma transfusion. In Group 2, 58% of patients required blood transfusions. The difference between two groups was statistically significant (p < 0,05). CONCLUSION: Triple combination technique is safe and cost-effective in coronary artery bypass surgery. We think that most of the patients could be operated without blood transfusion with this technique.

Heightened CXCR4 and CXCL12 expression in NF1-associated neurofibromas.

BACKGROUND: Neurofibromatosis type 1 (NF1) is a common autosomal dominantly inherited disorder that affects both the skin and the nervous system. NF1 occurs due to the mutations in the NF1 gene. Neurofibromas are the most common Schwann cell-based tumors in NF1 patients, which are mainly categorized into dermal and plexiform neurofibromas. Studies on different tumor types demonstrate that CXCR4 expression increases in tumor tissues and is linked to metastasis and cancer progression. PURPOSE: In the present study, we aimed to analyze the gene expression of CXCR4, and its ligand CXCL12, in human neurofibromas. METHODS: Eight NF1 patients aged between 5 and 37 (2 males, 6 females) were selected. The patient group comprised 1 plexiform neurofibroma, 1 pheochromocytoma, and 6 dermal neurofibromas. Following pathological examination and diagnosis, tumors were co-stained with antibodies against Schwann cell marker S100 and target molecule CXCR4. CXCR4 expression in Schwann cell-based tumors was detected at the protein level. RNA isolated from the same tumors was used for RT-PCR-based studies to measure the quantitative expression of CXCR4 and CXCL12. RESULTS: CXCR4 gene expression increased 3- to 120-fold and CXCL12 gene expression increased 33- to 512-fold in all human Schwann cell-based tumors. CONCLUSION: In order to validate the role of CXCR4 and its relationship with CXCL12 in NF1, future studies should be performed with additional tumors and different tumor types.

Long-term effect of deslorelin implant on ovarian pre-antral follicles and uterine histology in female rats.

The objective of the present study was to investigate the inhibitory effects of long-term deslorelin implant administration on the ovarian and uterine structures of female rats. A total of 16 non-pregnant female rats were randomly assigned to two groups, each consisting of eight animals. Animals in the implant group (DESL) received subcutaneously (s.c.) a single deslorelin implant (4.7 mg), an analogue of GnRH, while no treatment was applied to the control group (CON). A single adult male rat was introduced into the cages of both the DESL and CON females after 6 weeks of implant administration. After 1 year of implant administration, all animals were killed and follicular structures and volumes of ovaries and uterus were examined using stereological methods. Stereological observations showed that the mean ovarian total volume of the DESL group (0.28 ± 0.07 cm(3)) was lower than that of the CON group (1.55 ± 0.23 cm(3)) (p < 0.001). On the other hand, the total number of pre-antral follicles in the ovaries of DESL (555.32 ± 151.47) females were significantly lower than the control group (1162.96 ± 189.19) (p < 0.001). In the DESL group, the mean volumes of epithelium, endometrium, myometrium and total volume of the uterus were significantly (p < 0.001) lower than in the control groups. In conclusion, these findings indicate that the long-term deslorelin implant (i) interferes with the normal cyclicity of female rats and (ii) affects the pre-antral follicle population. Further studies will be required to determine the effects of long-term deslorelin treatment on the pre-antral follicle numbers and future fertility in other species.

Prediction of early postoperative atrial fibrillation after cardiac surgery: is it possible?

BACKGROUND: Postoperative atrial fibrillation is common after cardiac surgery. In this study, we aimed to investigate the value of interatrial conduction time for the prediction of early postoperative atrial fibrillation, using intra-operative transoesophageal echocardiography. METHODS: A total of 65 patients undergoing cardiac surgery in our hospital between January and March 2007 were prospectively evaluated, and 59 patients with sinus rhythm were included in the study. We performed transoesophageal echocardiography on all patients, and intra-operatively measured the interatrial conduction time, as recently described. The patients with episodes of atrial fibrillation during the postsurgery hospitalisation period were defined as group 1 and those without episodes were defined as group 2. RESULTS: Mean interatrial conduction time was 74 ± 15.9 ms in group 1 and 54 ± 7.9 ms in group 2. The difference in interatrial conduction time between the two groups was statistically significant (p < 0.05). In this study we found a statistically significant interatrial conduction delay between the groups. Postoperative atrial fibrillation was more frequent in patients with a longer interatrial conduction time. CONCLUSION: Increased interatrial conduction time may cause postoperative atrial fibrillation and it can be measured intraoperatively by transoesophageal echocardiography.

Laboratory diagnostics in the urine of young and pregnant ewes.

OBJECTIVE: The purpose of this study was to identify values for net acid base excretion (NABE) which are significant indicators of the acid-base equilibrium in pregnant and young ewes and to show its relationship with other parameters (base, acid, ammonium [NH4], base-acid quotient, sodium [Na], potassium [K], calcium [Ca]) in ovine urine. In contrast to dairy cows, data are rare on these parameters in ewes. MATERIAL AND METHODS: A total of 99 animals were used in the study, consisting of 56 young (average of 5.6±1.1 months) and 43 pregnant ewes (average of 35.2±18.8 months). Measurement of fractional NABE in urine samples was carried out according to the method reported by Kutas. The pH value of the urine was measured with a laboratory pH meter. Na, K and total Ca were measured with a flame photometer. RESULTS: For all values except Na significant differences occurred between urine samples of pregnant ewes and young ewes (p<0.001). Base, acid, NH4, NABE, K and Ca values were significantly higher in the urine of the youngs than in pregnant ewes. In young ewes, a strong correlation was found between NABE and base values while a weak correlation could be observed between pH and base values. In pregnant ewes, strong NABE-base, NABE-K, K-acid and K-base correlations were found as well as weak NH4-base, NH4-NABE and NH4-K correlations. There was a strongly positive correlation between NABE and NH4 in pregnant ewes, while a weak negative correlation between those values was observed in young ewes. CONCLUSION: For the first time, we established values for NABE and certain other parameters in urine of pregnant ewes and young ewes. It was shown that the acid-base balance in pregnant ewes and young ewes can be evaluated by measuring NABE and certain trace elements in urine like in cattle.

Characterization of oestrous induction response, oestrous duration, fecundity and fertility in Awassi ewes during the non-breeding season utilizing both CIDR and intravaginal sponge treatments.

The aim of this study was to investigate characterization of oestrous response, onset of induced oestrus, oestrous duration, fecundity and fertility in Awassi ewes treatment with intravaginal sponges and Controlled Intravaginal Drug Release (CIDR) devices in combination with pregnant mare serum gonadotropin (PMSG) under local environmental conditions during the non-breeding season. A total of 62 ewes were divided into three groups. Group CIDR (n = 20) was treated with CIDR devices for 12 days and 400 IU PMSG was injected upon removal of the CIDR. For ewes in Group Sponge (SP) (n = 24), 30 mg fluorogestone acetate was administered to the sheep for 12 days and 400 IU PMSG was injected upon withdrawal of the sponge. Group Control (CON) (n = 18) served as a control group and received no treatment. Adult, intact and sexually experienced Awassi rams were introduced to all groups at the time when the intravaginal devices were removed. There were no significant differences in terms of oestrous response (CIDR: 90%, SP: 87.5%), time to onset of oestrus and duration of induced oestrus between the CIDR and SP groups. The oestrous response of treatment groups was significantly greater (p < 0.05) than in the control ewes. There were no significant differences in pregnancy (CIDR: 70%, SP: 70.8%), lambing (CIDR: 85%, SP: 79.2%) and fecundity rates between ewes treated with CIDR and those treated with sponges. However, pregnancy and lambing rates were significantly (p < 0.05) higher in ewes treated with CIDR or sponges when compared with those in the control group. It was concluded that it is possible to induce fertile oestrus, successful pregnancy and lambing with the treatment of either CIDR or intravaginal sponge in combination with PMSG in Awassi ewes during the non-breeding season.

Effects of CIDR-G and melatonin implants, and their combination on the efficacy of oestrus induction and fertility of Kilis goats.

The objective of this study was to compare the efficiency of oestrus induction protocols on Kilis dairy goats kept on a goat farm situated close to Kilis, Turkey. Eighty goats were assigned randomly into four groups of 20 animals each in a factorial arrangement: (i) untreated control (CON), (ii) melatonin implant (MEL), (iii) CIDR-G (CIDR) and (iv) melatonin implant plus CIDR-G (MC). Experiments were performed in mid-anoestrus season under natural photoperiod environment. The differences among treatment groups in oestrus response were significant. Oestrus response was higher in the MC group than in other groups (p < 0.05). A significant difference was observed in the time interval from cessation of treatment to the onset of oestrus among treatments. The CIDR-G treatment reduced intervals from buck introduction to oestrus. The time to onset of oestrus in both the MC and CIDR groups was significantly shorter, compared with the MEL and CON groups (p < 0.05). The number of does kidding and fertility were not different among treatment groups (p > 0.05). Fecundity was similar among goats in all groups. Prolificacy and twining rates showed similar trends as fecundity rates, with no differences (p > 0.05) between treatments. The results of this study showed that oestrus in Kilis does can be effectively induced by using melatonin and CIDR combined treatment, and fertility will not be adversely affected. However, this treatment did not improve fecundity, prolificacy and twining rates.

Expression of genes in the canine pre-implantation uterus and embryo: implications for an active role of the embryo before and during invasion.

The aim of the present study was to assess genes expressed in maternal uterine tissue and pre-implantation embryos which are presumably involved in maternal recognition and establishment of canine pregnancy. For this purpose, 10 pregnant bitches were ovariohysterectomized between days 10 and 12 after mating. Four non-pregnant bitches served as controls. Early pregnancy was verified by flushing the uterine horns with PBS solution. The collected embryos (n = 60) were stored deep-frozen (-80 degrees C). Uterine tissue was excised, snaps frozen in liquid nitrogen and homogenized using TRI Reagent. All embryos from one litter were thawed together and also homogenized in TRI Reagent. RT-PCR was performed to prove mRNA expression of progesterone receptor, key enzymes of the prostaglandin synthesis pathway, selected growth factors, cytokines, immune cell receptors, major histocompatibility complex (MHC) and matrix-metalloproteinases (MMP). Only pregnant uteri revealed the presence of mRNA for interferon (IFN)-gamma, IL-4 and CD-8, which resembles the milieu in humans and other mammalians. Similarly, in day 10 embryos, mRNA for transforming growth factor-beta, insulin-like growth factor-1,-2, hepatocyte growth factor, leukaemia inhibitor factor, tumour necrosis factor-alpha, interleukin-1beta,-6,-8, cyclooxygenase-2, CD4(+) cells, and MMP-2 and -9 were detected, but not MHC-I or -II. We therefore suppose that the canine embryo, like its human counterpart, actively initiates measures to prevent attacks from the maternal immune system to prepare its own adhesion, nidation, growth and further development.

Cervical leiomyoma in a dairy cow during pregnancy.

In the present report we describe a case of cervical leiomyoma that was diagnosed at parturition in a Holstein cow. The tumor mass, which measured 25.5 cm x 21.5 cm x 14.5 cm in size and weighed 4.5 kg, was removed surgically. The tumor was solid, well circumscribed, whitish-pink colored, and encapsulated. The tumor was diagnosed as leiomyoma. The leiomyoma had no adverse effects on pregnancy. This is the first report of a bovine cervical leiomyoma during parturition.

Comparison of the harmonic scalpel and the ultrasonic surgical aspirator in subsegmental lung resections: an experimental study.

BACKGROUND: In this study, we evaluated the effectiveness of two devices using ultrasonic energy for dissection of lung parenchyma in an experimental animal model by comparing the two methods with each other. METHODS: Twenty New Zealand rabbits were used. One-lung ventilation was obtained under direct vision and the left lung was collapsed. The rabbits were ventilated with pressure-controlled ventilation during the experiment, beginning with a pressure level of 10 cmH(2)O. After a 1 x 1-cm pulmonary wedge resection of part of the collapsed left lung using a harmonic scalpel (group A) or an ultrasonic surgical aspirator (group B), the left lung was inflated and the pressure level was increased by 5 cmH(2)O every five minutes. The pressure level which caused an air leak from the resection surface was recorded. The morphological damage to the lung parenchyma was evaluated under light microscopy. RESULTS: The mean value of airway pressure levels that resulted in an air leak from the resection surface was 32.5 +/- 9.2 cmH(2)O for group A and 24.5 +/- 2.9 cmH(2)O for group B, and the difference between the two groups was statistically significant. The mean level of coagulation necrosis was 558.6 +/- 380.8 microns (133 - 1064 microns) for group A. No tissue damage to pulmonary parenchyma was observed in group B. CONCLUSION: The harmonic scalpel can be safely used in peripheral lung resections without needing any other method to ensure hemostasis and air tightness. The ultrasonic surgical aspirator can be used for the dissection and resection of deeper lesions and preserves more lung tissue but requires additional interventions for control of the air leak from the resection surface.

Experimental use of N-butyl cyanoacrylate tissue adhesive on lung parenchyma after pulmonary resection.

BACKGROUND: The aim of this study was to investigate the effectiveness of N-butyl cyanoacrylate tissue adhesive for the prevention of air leak together with the morphological changes to lung parenchyma. METHODS: Twelve New Zealand rabbits were used. The rabbits were ventilated with pressure-controlled ventilation during the experiment, beginning with a pressure level of 10 cm H (2)O. After a 2 x 2-cm pulmonary wedge resection, the resection surface was sealed with N-butyl cyanoacrylate and the pressure level was increased every five minutes in 5-cm H (2)O increments. The pressure level which caused an air leak from the resection surface was recorded. The morphological damage to the lung parenchyma was evaluated under light microscopy. RESULTS: The mean value of the pressure levels that caused air leak was 43.3 +/- 8.8 cm H (2)O. No tissue damage to lung parenchyma was recorded after histopathological examination. CONCLUSION: N-butyl cyanoacrylate was effective in preventing air leak from the pulmonary resection surface even with high airway pressure levels. It could be used as an aid for pulmonary resection lines or to control the air leak from pulmonary parenchyma.

True vaginal prolapse in a bitch.

Frequently, vaginal fold prolapse is the protrusion of edematous vaginal tissue into and through the opening of the vulva occurring during proestrus and estrus stages of the sexual cycle. True vaginal prolapse may occur near parturition, as the concentration of serum progesterone declines and the concentration of serum oestrogen increases. In the bitch, this type of true vaginal prolapse is a very rare condition. This short communication describes a 5-year-old female, cross-breed dog in moderate condition, weighing 33 kg, with distocia and true vaginal prolapse. Abdominal palpation and transabdominal ultrasonography revealed live and dead foetuses in the uterine horns. One dead and four live fetuses were removed from uterus by cesarean section. The ovariohysterectomy was performed after repositioning the vaginal wall with a combination of traction from within the abdomen and external manipulation through the vulva. Re-occurrence of a vaginal prolapse was not observed and the bitch recovered completely after the surgical therapy. Compared to other vaginal disorders, vaginal prolapse is an uncommon condition in the bitch. In the present case, extreme tenesmus arising from distocia may have predisposed to the vaginal prolapse. The cause of dystocia was probably the disposition of the first foetus. We concluded that the vaginal prolapse was the result of dystocia in the present case.

Cytotoxicity of Fusarium mycotoxins to mammalian cell cultures as determined by the MTT bioassay.

Fusarium mycotoxins occur worldwide in cereal grains and animal feeds and cause outbreaks of Fusarium mycotoxicoses in humans and animals. In this study mammalian cell cultures were used to screen the cytotoxicity of the most common Fusarium mycotoxins; deoxynivalenol (DON), zearalenone (ZEN), fumonisin B(1) (FB(1)) and moniliformin (MON). The most sensitive cell line for each Fusarium mycotoxin was determined for further toxicological investigations as an alternative to whole animal testing. Chinese hamster ovary cells (CHO-K1) were found to be the most sensitive for DON and FB(1) with IC(50) values of 0.27 and 85.5 microg/ml, respectively, after 48-h exposure. The hepatocellular carcinoma cells (HepG2) showed the highest sensitivity to MON with IC(50) values of 39.5 for 48 h and 26.8 microg/ml for 72-h exposure. Balb/c mice keratinocyte cell line (C5-O) was found to be the most sensitive to ZEN with IC(50) of 24.1 microg/ml after 72-h exposure. DON was found the most cytotoxic to the cell cultures of all the mycotoxins tested, followed by MON, ZEN, and FB(1). The results indicated that CHO-K1, C5-O, and HepG2 cells were found to be the sensitive cell lines for preliminary screening of DON, ZEN and MON contaminated feed and food extracts, respectively.

The iron-regulatory peptide hormone hepcidin: expression and cellular localization in the mammalian kidney.

It is generally accepted that iron homeostasis is mainly controlled in the gastrointestinal tract by absorption of dietary iron. However, recent studies have shown that the kidneys are also involved in iron metabolism. Since the iron-regulatory and antimicrobial peptide hormone hepcidin was originally isolated from human urine we have investigated the expression as well as the zonal and cellular localization of hepcidin in the mammalian kidney and developed an ELISA assay to analyze hepcidin concentrations in serum and urine. The expression of hepcidin was shown by RT-PCR and immunoblot experiments; its cellular localization was studied by immunocytochemistry in human, mouse and rat kidney, which revealed similar patterns of immunoreactivity. Hepcidin expression was absent from the proximal tubule and descending and ascending thin limbs. There was strong expression in the thick ascending limb of the cortex and in connecting tubules. Moderate expression was noted in the thick ascending limb and collecting ducts of the medulla and in collecting ducts of the papilla. Importantly, the cells of the macula densa were unstained. At the cellular level, hepcidin was localized to the apical cell pole of the renal epithelial cells. Based on its presence in urine, hepcidin may be released apically into the urine. Enhanced levels of hepcidin were determined in patients with chronic renal insuffciency (156.8 ng/ml, controls 104.2 ng/ml) indicating that the kidneys may metabolize and/or eliminate the circulating peptide. From the expression of hepcidin in the mammalian kidney, we have concluded that the iron-regulatory hormone is an intrinsic renal peptide which is not only eliminated by the kidney but is also synthesized in the kidney tubular system. Localization of hepcidin in the kidney implicates an iron-regulatory role of this peptide hormone in the renal tubular system, possibly in connection with the iron transporter divalent metal transporter-1.

Ontogeny of guanylin-immunoreactive cells in rat salivary glands.

Guanylin-like peptides regulate electrolyte/water transport through the epithelia. Moreover, these peptides possess antiproliferative activity and regulate the turnover of epithelial cells. In an earlier study we localized guanylin immunoreactivity in secretory ducts of adult rodent salivary glands. In this study we investigated the appearance and distribution pattern of this peptide during the development of rat salivary glands. Guanylin immunoreactivity appeared at the beginning of cell differentiation from solid bud, on embryonic day 17 in the submandibular and sublingual glands and after day 18 in the parotid gland. Guanylin immunoreactivity appeared first in ductal and acinar anlage: its cell distribution pattern and fate differed in these two compartments. In the duct cells guanylin immunoreactivity spread after the duct system developed, whereas in acinar cells it disappeared after cell differentiation. The guanylin immunoreactivity we detected in adult salivary duct cells accords with guanylin's role in regulating electrolyte and water transport through the various epithelia. It does so by activating guanylate cyclase-C receptor, increasing intracellular cGMP concentration, and phosphorylating the cystic fibrosis transmembrane conductance regulator (CFTR) protein by the cGMP-dependent protein kinase II. This signaling cascade couples to the ductal electrolyte/water secretion and modulates finally the electrolyte composition of the saliva. On the other hand, CFTR is also involved in mechanisms of cell growth, by regulating apoptosis, and promoting cell differentiation. The early diffuse guanylin immunoreactivity we observed in ducts and acinar anlage, before the secretory set is operative, suggests guanylin has a role in cell differentiation.

Identification of somatostatin receptor subtypes 1, 2A, 3, and 5 in neuroendocrine tumours with subtype specific antibodies.

BACKGROUND AND AIMS: Recently, novel somatostatin receptor (sstr) subtype specific ligand analogues have been developed for medical treatment of neuroendocrine tumours expressing different sstrs (sstr1-5). At present, individual expression patterns of sstr subtypes are based on methods such as in situ hybridisation and polymerase chain reaction at the transcriptional level. Therefore, we generated subtype specific antibodies against sstr1, 2A, 3, and 5 and analysed their presence, cellular localisation, distribution, and expression pattern in 33 gastrinomas, 36 insulinomas, and 35 tumours associated with a carcinoid syndrome by immunohistochemistry at the translational level. METHODS: Western blotting experiments were performed in the normal human pancreas used as a reference organ and in tumour tissues; at the cellular level, sstrs were localised by immunohistochemistry in tissue paraffin sections. RESULTS: In western blot analyses, the antibodies identified the respective receptors in their correct molecular range in extracts of the pancreas and neuroendocrine tumours. Using immunohistochemistry and immunofluorescence, the antibodies specifically detected the receptors in islet cells of the normal pancreas. Immunohistochemistry in the tumours revealed that all investigated sstr subtypes were highly expressed in the different tumour types. The frequency and expression pattern of the individual sstr subtypes varied considerably not only between the different tumour types but also in each patient. CONCLUSIONS: We conclude that immunohistochemistry with subtype specific antibodies can be used in clinical routine work to analyse sstr expression patterns for each patient before treatment and to facilitate well directed individual medical therapy by administering subtype specific somatostatin analogues.

Guanylin in the human pancreas: a novel luminocrine regulatory pathway of electrolyte secretion via cGMP and CFTR in the ductal system.

Cystic fibrosis transmembrane conductance regulator (CFTR) is a channel and regulator protein that is crucially involved in transepithelial ion transport. In the exocrine pancreas, the CFTR-mediated secretion of an electrolyte-rich fluid is a major but as yet incompletely understood function. We show here that the peptide guanylin is a specific activator of CFTR function in the human pancreas implicating regulation of pancreatic electrolyte secretion. Guanylin and its affiliated signaling and effector proteins including guanylate cyclase C, cGMP-dependent protein kinase II, CFTR, and the epithelial Cl-/HCO3- exchanger, anion exchanger 2, are highly expressed in the human pancreas. Guanylin is localized specifically to the typical centroacinar cells and proximal duct cells which, based on its additional presence in the pancreatic juice, is obviously released luminally into the pancreatic ducts. The guanylin receptor and the respective functional downstream proteins are all confined to the apical membrane of the duct cells implicating an as yet unknown route of luminal regulatory pathway of electrolyte secretion in the ductal system. Functional studies in two different human pancreatic duct cell lines expressing the CFTR Cl- channel that is functionally intact in CAPAN-1 cells but defective (delta F508) in CFPAC-1 cells clearly identify guanylin as a specific regulator of pancreatic CFTR channel function. Whole-cell patch-clamp recordings in CAPAN-1 cells revealed that forskolin induces an increase of Cl- conductance mediated by cAMP. In contrast, guanylin increased Cl- conductance in the same cells via cGMP but not cAMP; the respective membrane current was largely blockable by the sulfonylurea glibenclamide. In CFPAC-1 cells, however, neither guanylin nor forskolin produced a current activation. Based on the present findings we conclude that guanylin is an intrinsic pancreatic regulator of Cl- current activation in pancreatic duct cells via cGMP and CFTR. Remarkably, in the pancreas guanylin may exert its function through an intriguing luminocrine mode via the pancreatic juice.

Guanylin and uroguanylin in the parotid and submandibular glands: potential intrinsic regulators of electrolyte secretion in salivary glands.

The intestinal peptides guanylin and uroguanylin regulate the electrolyte/water transport in the gastrointestinal epithelium via activation of cystic fibrosis transmembrane conductance regulator (CFTR), the cystic fibrosis gene product. Because a major but incompletely understood function of the salivary glands is the CFTR-mediated secretion of an electrolyte-rich fluid, we investigated the rat and guinea pig parotid and submandibular glands for expression, cellular distribution, and subcellular localization of guanylin and uroguanylin. RT-PCR analyses with guanylin and uroguanylin-specific primers revealed that both peptides are highly expressed in the parotid and submandibular glands. At the translational level, western blotting analyses with peptide-specific guanylin and uroguanylin antibodies identified the expected 12.5-kDa immunoreactive peptides in these organs. At the cellular level, guanylin and uroguanylin were exclusively confined to epithelial cells of the intralobular and interlobular ducts. At the subcellular level, the immunoreactivities were localized by preembedding immunoelectron microscopy to small vesicles which were concentrated at the apical part of the secretory epithelial cells. The expression and cell-specific localization of guanylin and uroguanylin in the salivary glands indicate that these peptides may be specifically involved in the regulation of CFTR-mediated electrolyte/water secretion in the salivary gland ductal system.

Uroguanylin and guanylate cyclase C in the human pancreas: expression and mutuality of ligand/receptor localization as indicators of intercellular paracrine signaling pathways.

The intestinal peptide hormone uroguanylin regulates electrolyte/fluid transport in the gastrointestinal epithelium by binding to its receptor, guanylate cyclase C (GC-C), and thus specifically coupling to activation of cystic fibrosis transmembrane conductance regulator (CFTR). Since CFTR is crucially involved in pancreatic electrolyte secretion, we investigated the human pancreas for expression and cell-specific localization of uroguanylin and guanylate cyclase C as potential regulatory components of pancreatic electrolyte secretion. RT-PCR analyses with specific primers revealed that uroguanylin and GC-C are expressed in the human pancreas (and in the duodenum, used as positive control); at the translational level, western blotting analyses with peptide- and region-specific antibodies identified the presence of 12.5 kDa uroguanylin and 130 kDa GC-C in both human pancreatic and intestinal extracts. At the cellular level, uroguanylin and GC-C immunoreactivities were absent from the islets of Langerhans but were exclusively confined to the exocrine parenchyma. Hence, uroguanylin was localized to the centroacinar cells typical of the pancreas, and also to epithelial cells of the intercalated, intralobular and interlobular ducts where the peptide was primarily concentrated adluminally to the apical portion of the respective cells. Coincidently, correlative studies localized the GC-C receptor to the epithelial cells of the ductal network, where it was confined exclusively to the apical cell membrane that evidently represents the functionally relevant target membrane domain for the regulatory peptide. In view of the fact that CFTR is highly expressed in pancreatic ductal cells where uroguanylin and its receptor are also localized, we assume that uroguanylin, an intrinsic pancreatic peptide, is involved in the regulation of electrolyte/water secretion in the ductal system via GC-C and CFTR. The particular cellular expression of uroguanylin in duct cells and the localization of GC-C to the duct cell apical membrane domain predict a novel route of intercellular signaling and luminal activation of GC-C via the pancreatic juice.

Expression and cell-specific and membrane-specific localization of NHE-3 in the human and guinea pig upper gastrointestinal tract.

Na+/H+ exchangers (NHEs) are vital transmembrane transport proteins mediating the electroneutral exchange of Na+ and H+ ions in mammalian cells. In the epithelium of the lower intestine, the isoform NHE-3 is apparently involved in Na+ absorption; however, its presence and cellular localization in the duodenum and particularly in the stomach remain largely unclear. Therefore, we studied the human and guinea pig stomach and duodenum for the expression, regional and mucosal distribution pattern, and membrane-specific localization of NHE-3. Reverse transcription/polymerase chain reaction analyses revealed strong expression of NHE-3 in the stomach and duodenum, where it was identified as a 85-kDa immunoreactive protein by Western blotting experiments. Whereas NHE-3 was localized to the basolateral membrane of surface mucous cells of the stomach, it was exclusively confined to the brush border membrane of epithelial cells in the duodenum. We conclude that the basolateral NHE-3 in the stomach protects the mucosa by secreting protons that diffuse into the mucous cells. In the duodenum, the localization of NHE-3 to the apical membrane of enterocytes suggests a resorptive function by directional Na+ transport. These findings indicate that NHE-3 may be involved in various segment-specific functions in the upper gastrointestinal tract.