Increased vascular endothelial growth factor peptide and gene expression in hypoplastic lung in nitrofen induced congenital diaphragmatic hernia in rats

Persistent pulmonary hypertension (PPH) in congenital diaphragmatic hernia (CDH) lung has been shown to be associated with structural changes in the pulmonary vasculature, including medial and adventitial thickening. Vascular endothelial growth factor (VEGF) is a potent mitogenic and permeability factor targeting predominantly endothelial cells. mRNA encoding VEGF is detected in all fetal tissues and is most abundant in fetal lung, kidney, and liver. Recently, antenatal dexamethasone (Dex) treatment has been shown to prevent pulmonary-artery structural changes in experimentally-produced CDH. The aim of this study was to investigate mRNA and protein levels of VEGF in CDH lung and to determine whether antenatal Dex treatment has any effect on the production of VEGF. A CDH model was induced in pregnant rats following administration of 100 mg nitrofen on days 9.5 of gestation (term=22 days). Dex 0.25 mg/kg was given on day 18.5 and 19.5. Cesarean section was performed on day 21 of gestation. The fetuses were divided into three groups: normal controls (NC, n=8); nitrofen-induced CDH (CDH, n=8); and nitrofen-induced CDH with antenatal Dex treatment (CDH-Dex, n=8). Protein and mRNA were extracted from the whole lung. VEGF protein was measured by ELISA assay and mRNA expression was evaluated by reverse transcription-polymerase chain reaction. Immunohistochemistry using anti-rat VEGF antibody was also performed in each group. VEGF protein as well as mRNA expression were significantly increased in the CDH group compared to the NC group, which was not affected by antenatal Dex treatment. VEGF immunoreactivity in pulmonary vessel walls was increased in the CDH and CDH-Dex groups compared to the NC group. The enhanced VEGF protein and mRNA expression in CDH lung suggests that increased local synthesis of VEGF may be responsible for the structural changes in the pulmonary vasculature in CDH lung. VEGF expression in CDH lung is not downregulated by antenatal Dex treatment.

Selective neurotrophin deficiency in infantile hypertrophic pyloric stenosis

BACKGROUND/PURPOSE

Increasing evidence suggests that the enteric nervous system is under the control of neurotrophins. Nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4/5 (NT-4/5), promote differentiation, growth, and survival of various central and peripheral nervous system neurons. The biological effects of neurotrophins are mediated by the interactions with high-affinity tyrosine kinase receptors (TrkA, TrkB, TrkC). Recently, abnormalities of intramuscular innervation have been reported in infantile hypertrophic pyloric stenosis (IHPS). To further understand the reported abnormalities in pyloric innervation in IHPS, the authors analyzed the expression of Trk receptors and the neurotrophins content in IHPS.

METHODS

Full-thickness muscle biopsy specimens were obtained from 8 IHPS patients (age range, 23 to 41 days) at pyloromyotomy and from 8 age-matched controls without gastrointestinal disease at autopsy performed within 12 hours after death. Indirect immunohistochemistry was performed using ABC (Avidin Biotin peroxidase Complex) method with anti-Trk specific antibodies (A,B,C). Quantitative analysis was performed using sandwich-type ELISA for NGF, BDNF, NT-3, and NT-4/5.

RESULTS

The intensity of staining of the myenteric plexus for TrkA, TrkB, and TrkC was similar among IHPS and controls. There was a lack of TrkA-positive nerve fibers in IHPS compared with controls. The quantity of total NGF, NT-3, and BDNF in IHPS was significantly lower than in controls.

CONCLUSIONS

The reduced production of neurotrophins in IHPS may be responsible for the delay in the functional and structural maturation of pyloric innervation in IHPS. The lack of TrkA-positive nerve fibers in pyloric muscle may explain the abnormal intramuscular innervation in IHPS.

Fate of nascent microtubules organized at the M/G1 interface, as visualized by synchronized tobacco BY-2 cells stably expressing GFP-tubulin: time-sequence observations of the reorganization of cortical microtubules in living plant cells

Transgenic BY-2 cells stably expressing a GFP (green fluorescent protein)-tubulin fusion protein (BY-GT16) were subcultured in a modified Linsmaier and Skoog medium. The BY-GT16 cells could be synchronized by aphidicolin and the dynamics of their microtubules (MTs) were monitored by the confocal laser scanning microscopy (CLSM). We have succeeded in investigating the mode of reorganization of cortical MTs at the M/G1 interface. The cortical MTs were initially organized in the perinuclear regions and then they elongated to reach the cell cortex, forming the bright spots there. Subsequently, the first cortical MTs rapidly elongated from the spots and they were oriented parallel to the long axis towards the distal end of the cells. Around the time when the tips of the parallel MTs reached the distal end, the formation of transverse cortical MTs followed in the cortex near the division site, as we had previously suggested [Hasezawa and Nagata (1991) Bot. Acta 104: 206, Nagata et al. (1994) Planta 193: 567]. It was confirmed in independent observations that the appearance of the parallel MTs was followed by the appearance of the transverse MTs in each cell. We found that the transverse MTs spread through the whole cell cortex within about 20-30 min, while the parallel MTs disappeared. The significance of these observations on the mode of cortical MT organization is discussed.

Usefulness of cord-blood harvesting for autologous transfusion in surgical newborns with antenatal diagnosis of congenital anomalies

BACKGROUND/PURPOSE

The risks of homologous transfusion and the effectiveness of predeposit autologous transfusion have been described. The authors examined the clinical usefulness of cord-blood harvesting for autologous transfusion in newborns who had congenital anomalies antenatally diagnosed that would require surgical intervention at or near the time of delivery.

METHODS

Of 112 cases of antenatal diagnosis of congenital anomalies, 50 mothers gave informed consent and enrolled in this study. Cord-blood was withdrawn immediately after clamping of the umbilical cord and was used for autologous transfusion in newborns within the first 3 days postpartum.

RESULTS

A mean of 72 +/- 54 mL of cord-blood was harvested (27 +/- 18 mL/kg). While preserving cord-blood for 3 days at 4 degrees C, no signs of clot formation or hemolysis were observed. The harvested cord-blood included plasma-free Hb ranging from 1 to 68 (13 +/- 18) mg/dL and thrombin-antithrombin III complex ranging from 2 to 273 (18 +/- 50) ng/mL. Bacteriologic examination of the stored cord-blood showed negative cultures, except for samples from 3 newborns after vaginal delivery. A mean of 46 +/- 34 mL of cord-blood was used in 26 patients for autologous transfusion. No significant complications related to cord-blood transfusion were recognized clinically.

CONCLUSIONS

Autologous cord-blood transfusion has the potential to be a useful alternative to homologous transfusion in newborns requiring surgery. Adequate collection and storage techniques for cord-blood must be developed. J Pediatr Surg 36:851-854.

Cell-adhesion molecules and fibroblast growth factor signalling in Hirschsprung's disease

Hirschsprung's disease (HD) is characterised by the absence of ganglion cells and the presence of hypertrophic nerve trunks in the distal bowel. It has been suggested that aganglionosis may be caused by failure of differentiation as a result of microenvironmental change after neuronal migration has occurred. Recently, it was reported that cell-adhesion molecules (CAMs) and fibroblast growth factors (FGFs) stimulate neurite outgrowth through activation of FGF receptors (FGFRs) in neurons. The aim of this study was to investigate the expression of CAMs FGFs, and FGFRs in ganglionic (NG) and aganglionic (AG) segments of HD in order to understand the role of CAM-FGF signalling in the pathogenesis of HD. Specimens from NG and AG segments of bowel from 11 patients with HD were obtained at the time of definitive pull-through operation, snap-frozen in OCT compound, and stored at -70 degrees C. Aganglionosis was confirmed by Haematoxylin and eosin staining and acetylcholinesterase histochemistry; 8-micron cryosections were immunostained using the standard streptavidinbiotin-immunoperoxidase method. The following antibodies were used as the first antibody; FGF2 and FGF7 for FGFs, FGFR1 and FGFR2 for FGFRs, NCAM, L1CAM, and N-cadherin for CAMs. FGF2, FGF7, and FGFR2 were expressed in neuronal tissue of NG segments as well as in hypertrophic nerves of AG segments. There was a lack of FGFRI expression in neuronal tissue of both NG and AG bowel. Immunoreactivity with all three CAMs was detected in ganglion cells in NG bowel and in hypertrophic nerve trunks in AG bowel. In contrast the numbers of CAM-positive nerve fibres in muscle layers were markedly decreased in AG bowel compared to NG bowel. The markedly decreased expression of CAMs on nerve fibres within the muscle of AG bowel suggests that CAM-FGF signalling is altered in HD, resulting in failure of enteric neuroblast migration.

Internal anal sphincter achalasia: outcome after internal sphincter myectomy

BACKGROUND

Internal anal sphincter achalasia (IASA), also referred to as ultrashort segment Hirschsprung's disease (HD), is a clinical condition with presentation similar to HD, but with the presence of ganglion cells on rectal biopsy. The diagnosis of IASA is made on anorectal manometry, which shows the absence of rectosphincteric reflex on rectal balloon inflation. Altered intramuscular innervation has been reported in IASA. The purpose of this study was to review the outcome after internal sphincter myectomy in patients with IASA.

METHODS

Fifteen consecutive patients (age range, 2 years to 12 years) with IASA underwent posterior internal sphincter myectomy. All patients presented with severe constipation with or without soiling. The diagnosis of IASA was made by anorectal manometry. HD was excluded in these cases by the presence of ganglion cells and normal acetylcholinesterase activity on suction rectal biopsies. Internal sphincter (IS) specimens were examined using immunohistochemistry for the general neuronal marker PGP 9.5 and synapsin 1 (a presynaptic marker) and using general histochemistry for NADPH-diaphorase. All patients underwent follow-up for periods from 2 years to 6 years.

RESULTS

PGP 9.5, synapsin 1 and NADPH-diaphorase positive nerve fibers were either absent or markedly reduced in IASA specimens compared with controls, confirming previous reports of defective intramuscular innervation in IASA. At the time of follow-up, 7 patients have regular bowel motions and are not on any laxatives. Six patients have normal bowel habits but are on small doses of laxatives. One patient is able to stay clean with regular enema regimen. One patient required resection of dilated and redundant sigmoid colon and now has normal bowel habits with laxatives.

CONCLUSION

The majority of patients with internal anal sphincter achalasia can be treated successfully by internal sphincter myectomy.

Angiotensin-converting enzyme genotype distribution in familial vesicoureteral reflux

Vesicoureteric reflux (VUR) is known to occur in families. In siblings of index patients with VUR, there is a much higher incidence (16% to 46%) than in the general population. The renin-angiotensin system plays an important role in renal development. Recently, it has been reported that angiotensin-converting enzyme (ACE) I/D gene polymorphism is a risk factor for renal parenchymal damage in patients with congenital urological abnormalities. The aim of this study was to investigate the ACE I/D genotype pattern in familial VUR patients. Blood samples were obtained from 86 families in which two or more members had VUR. Samples of DNA were extracted from 407 blood samples (183 affected patients and 224 non-affected family members). To detect ACE I/D polymorphism, polymerase chain reaction (PCR) amplification was performed using specific primers for the ACE gene. PCR products were electrophoresed with 2% agarose gel containing ethidium bromide. Among 224 non-affected family members the ACE genotype distribution of DD, ID, and II was 23%; 56% and 21%, respectively. The ACE genotype distribution of 183 affected patients was 28%, 47% and 25%, respectively. There was no significant difference in ACE I/D distribution between affected patients and their non-affected families. Both the ACE genotype distribution of affected patients and that of non-affected family members were not significantly different from the previously reported genotype distribution of the normal Caucasian population. This study demonstrates that ACE genotype frequencies are similar in index patients with VUR and their unaffected siblings, thus suggesting that the ACE gene is not involved in the development of familial VUR.

Engineering neoglycoproteins with multiple O-glycans using repetitive pentapeptide glycosylation units

Controlled protein remodeling with O-linked glycans has been limited by our incomplete understanding of the process of glycosylation. Here we describe a secretable fibroblast growth factor (FGF) with multiple mucin-type O-glycans produced by introducing a minimum pentapeptide glycosylation unit in a decarepeat format at its N- or C-terminus. Expressed in Chinese hamster ovary cells, chemical and biochemical analyses of the resultant proteins (Nm10-FGF and Cm10-FGF, respectively) demonstrated that all O-glycosylation units were glycosylated and the dominant structure was sialylated Gal[beta1-3]GalNAc. This indicates that minimum O-glycosylation unit in multirepeat format serves as a remarkably efficient acceptor in CHO cells. The Nm10-FGF and Cm10-FGF proteins maintained the mitogenic activity to vascular endothelial cells. In addition, intact Cm10-FGF and its desialylated form interacted with several lectins in the same way as mucin-type glycoproteins. The intact Cm10-FGF with multiple sialylated O-glycans exhibited a longer lifetime in circulating blood, whereas the Cm10-FGF with desialylated O-glycans exhibited a shorter lifetime than the deglycosylated form of Cm10-FGF. Our approach would thus appear to be highly effective for engineering neoglycoproteins, the characteristics of which are determined by their multiple mucin-type O-glycans.

Molecular cloning of mouse alpha-1,6-fucosyltransferase and expression of its mRNA in the developing cerebrum

Complementary DNA encoding mouse alpha-1,6-fucosyltransferase (FUT) was cloned. The deduced primary structure consisted of 575 amino acids and had 96.0% and 93.0% identity with alpha-1,6-FUT of human and porcine origin, respectively. Quantitative analysis of alpha-1,6-FUT mRNA expression during selected developmental stages of the cerebrum showed that the expression increased during later embryonic stages and was highest in the early postnatal stages (P1 to P7), after which it declined somewhat but still remained relatively high in the mature adult. The expression profile suggests important roles of FUT in the developing central nervous system.

Three-dimensional morphology of gut innervation in total intestinal aganglionosis using whole-mount preparation

BACKGROUND

Total intestinal aganglionosis (TIA) is a rare form of Hirschsprung's disease (HD). The aim of this study was to examine the 3-dimensional morphology of the myentric plexus of the entire gastrointestinal tract in a newborn with total intestinal aganglionosis.

METHODS

Whole-mount preparations were made of the entire gastrointestinal tract using NADPH-diaphorase histochemistry and c-kit (a marker of interstitial cells of Cajal) immunohistochemistry.

RESULTS

Whole-mount preparations of the esophagus, stomach, and duodenum showed 3-dimensional morphology of the myenteric plexus forming a meshlike network of nerve fibers, connected to each other and to ganglia. There were large numbers of NADPH-diaphrase-positive nerve fibers between the muscle fibers in the circular muscle layer. In esophagus, stomach, and duodenum, c-kit-positive interstitial cells of Cajal (ICC) formed a 3-dimensional network between the two muscle layers and also were abundant within the circular muscle layer. In the jejunum, ileum, and colon, the myenteric plexus was absent and was replaced by hypertrophic nerve bundles that stained weakly with NADPH-diaphrase. Circular muscle layer completely lacked NADPH-diaphrase-positive nerve fibers. The c-kit-positive ICCs in the jejunum, ileum, and colon were sparse and localized mainly around the nerve trunks between the circular and longitudinal muscle layers.

CONCLUSIONS

Whole-mount preparation is an elegant 3-dimensional technique in which the relationship of branching and interconnecting nerve fibers to each other and to muscle can be seen clearly. Absence of myenteric plexus, lack of nitrergic innervation, and depletion of interstitial cells of Cajal in the bowel wall throughout the small and large bowel contribute to the inability of the smooth muscle to relax, thereby causing lack of peristalsis in TIA.

Observation of untreated patients with neuroblastoma detected by mass screening: a "wait and see" pilot study

BACKGROUND

Recent studies have indicated that mass screening for neuroblastoma detects tumors that otherwise would have regressed spontaneously without recognition. Therefore, we started an observation program for these patients to determine how frequently spontaneous regression occurs.

PROCEDURE

Eighteen patients were detected by mass screening between June 1994 and December 1996. Eight of these cases matched the following criteria and entered the observation program: Stage I or II, less than 5 cm in diameter; no involvement of large vessels or organs; not difficult to resect; informed consent. If there were an increase in tumor size, an elevation of tumor markers, or evidence of metastasis, the tumor would be immediately resected.

RESULTS

Five of the eight cases showed spontaneous regression. Although the remaining three tumors were resected 6-10 months after diagnosis, all patients survived without evidence of recurrence.

CONCLUSIONS

At least 60% of neuroblastoma cases who entered our observation program regressed spontaneously.

The changes in glycosylation after partial hepatectomy enhance collagen binding of vitronectin in plasma

Vitronectin is a multifunctional glycoprotein present in the extracellular matrix and plasma. Changes in rat vitronectin were studied during liver regeneration after partial hepatectomy. Carbohydrate concentrations of vitronectin decreased to 2/3 of sham-operated rats at 24 h after partial hepatectomy. Carbohydrate composition and lectin reactivity indicated that N-glycosylation and sialylation of vitronectin changed markedly after partial hepatectomy, while amino acid composition did not change significantly. We previously showed that deN-glycosylation of vitronectin in vitro affects collagen binding among various ligands (Yoneda et al., Biochemistry (1998) 37, 6351-6360). Vitronectins from partially hepatectomized rats at 24 h were found to exhibit markedly enhanced binding to type I collagen. The effect of sialylation on collagen binding was further examined using enzymatically deglycosylated vitronectin of nonoperated rats. Collagen binding increased by 1.2 times after deN-glycosylation of vitronectin, while it increased more than 2.9 times after desialylation. Various glycosyltransferases in liver are known to change after partial hepatectomy, including the attenuation of N-oligosaccharide transferase. The findings therefore suggest that the collagen binding of vitronectin is modulated by the alteration of peptide glycosylation caused by postoperative physiological changes of glycosyltransferases and that the change may contribute to tissue remodeling processes.

Simultaneous determination of trichothecene mycotoxins and zearalenone in cereals by gas chromatography-mass spectrometry

Trichothecene mycotoxins are commonly distributed in crop fields in the world, and zearalenone has been found in cereals. Rapid and accurate methods for the determination of these mycotoxins is required to prevent the intoxication of humans, and to contribute to the supply of safe foods and feeds for human and livestock. Gas chromatography-mass spectrometry (GC-MS) is a useful method for the determination of these toxins. We describe here our current GC-MS analysis for the simultaneous determination of trichothecenes and zearalenone contaminants in cereals.

Engineering of an FGF-proteoglycan fusion protein with heparin-independent, mitogenic activity

In the absence of heparan sulfate (HS) on the surface of target cells, or free heparin (HP) in the vicinity of their receptors, fibroblast growth factor (FGF) family members cannot exert their biological activity and are easily damaged by proteolysis. This limits the utility of FGFs in a variety of applications including treatment of surgical, burn, and periodontal tissue wounds, gastric ulcers, segmental bony defects, ligament and spinal cord injury. Here we describe an FGF analog engineered to overcome this limitation by fusing FGF-1 with HS proteoglycan (PG) core protein. The fusion protein (PG-FGF-1), which was expressed in Chinese hamster ovary cells and collected from the conditioned medium, possessed both HS and chondroitin sulfate sugar chains. After fractionation, intact PG-FGF-1 proteins with little affinity to immobilized HP and high-level HS modification, but not their heparitinase or heparinase digests, exerted mitogenic activity independent of exogenous HP toward HS-free Ba/F3 transfectants expressing FGF receptor. Although PG-FGF-1 was resistant to tryptic digestion, its physiological degradation with a combination of heparitinase and trypsin augmented its mitogenic activity toward human endothelial cells. The same treatment abolished the activity of simple FGF-1 protein. By constructing a biologically active proteoglycan-FGF-1 fusion protein, we have demonstrated an approach that may prove effective for engineering not only FGF family members, but other HP-binding molecules as well.

Muscarinic acetylcholine receptor expression in aganglionic bowel

In Hirschsprung's disease (HD) there exists an overabundance of acetylcholine (ACh), which in turn stimulates excessive production of the enzyme acetylcholinesterase. Muscarinic ACh receptors (mAChRs) play an important role in smooth-muscle contraction. Recent studies have indicated five different subtypes of mAChRs encoded by five different genes, ml to m5. The purpose of this study was to investigate the expression of each mAChR subtype in aganglionic (AG) colon to further understand the pathophysiology of HD. Entire colon resected at the time of pull-through operation for HD was obtained from 14 patients. Specimens obtained at autopsy from 8 age-matched patients without gastrointestinal disease acted as controls. Frozen sections were used for indirect immunohistochemistry as well as in-situ hybridization. Immunohistochemistry was performed using specific antiserum against each mAChR subtype and in-situ hybridization was performed using specific oligonucleotide probes against ml to m5 subtypes. Messenger RNA (mRNA) was extracted from normoganglionic (NG) and AG bowel of HD patients and normal control bowel. Reverse transcription-polymerase chain reaction was performed to evaluate mRNA levels of each mAChR subtype. To adjust the levels of mRNA expression, a housekeeping gene G3PDH, known to be expressed normally, was used as an internal control. Strong m2 and m3 immunoreactivity was observed in the mucosal layer, smooth-muscle layers, and myenteric plexus of NG bowel, whereas ml immunoreactivity was only detected in the mucosal layer. The most striking finding was the abundance of m3-immunoreactive fibers in muscle layers of NG bowel while there was a total lack of m3 fibers in smooth-muscle of AG bowel. Intense mRNA signals encoding m2 and m3 and to a lesser degree ml were detected in NG bowel, and these signals were weak in AG bowel. Immunoreactivity and mRNA expression of m4 and m5 was not detected in NG or AG bowel. The lack of m3-immunoreactive fibers in the smooth-muscle layers of AG bowel and decreased m2 and m3 mRNA expression in AG bowel may be responsible for the motility dysfunction in the aganglionic segment.

Congenital diaphragmatic hernia in identical twins

The authors present a pair of identical twins with congenital diaphragmatic hernia (CDH) diagnosed prenatally, who underwent successful surgical repair. They were diagnosed as having CDH at 32 weeks' gestation and showed respiratory distress soon after cesarean section at 33 weeks' gestation. Both survived after scheduled perinatal management followed by surgery, for which the prenatal diagnosis of CDH was valuable.

Tracheal agenesis in a child who survived for 6 years

The authors report on a child with tracheal agenesis who survived for 6 years and 10 months. A female infant was born with respiratory distress and an absence of audible cry. With mask ventilation, gastrostomy and division of the esophagus was performed just after birth. She was well ventilated with an endotracheal tube inserted through the cervical esophagostomy after thoracic esophageal banding. An accidental extubation caused her anoxic encephalopathy at 9 months of age. She had been alive without artificial ventilatory support until she died of acute esophageal bleeding.

Introduction of an N-glycosylation cassette into proteins at random sites: expression of neoglycosylated FGF

We developed a method for introducing an N-glycosylation cassette into proteins at random sites by constructing cDNAs and expressing it in mammalian cells. The protocol entails four steps: (i) generation of cDNAs that contain single, randomly-located blunt end cuts; (ii) ligation of N-glycosylation cassettes into the blunt end cuts in three-frame formats; (iii) selection of the cDNA clones encoding N-glycosylated proteins; and (iv) subcloning into an expression vector for transfection and expression in mammalian cells. This method was evaluated using secreted fibroblast growth factor (FGF) as a model protein. Several secreted FGF cDNA clones, each containing an AsnLeuSer-coding sequence at a random site, were obtained. When these clones were expressed in mammalian cells, some of the secreted FGFs were found to be N-glycosylated. The method described here should also be applicable for random introduction of functional oligopeptide/polypeptide cassettes into virtually any protein of interest.

Use of a Palmaz stent for tracheomalacia: case report of an infant with esophageal atresia

A male infant with congenital cardiac anomalies and esophageal atresia with tracheoesophageal fistula (EA-TEF) showed intractable respiratory symptoms after delayed primary repair of EA-TEF. Computed tomography demonstrated that the trachea was compressed by the enlarged aorta. Artificial ventilation was necessary even after aortopexy performed at 2 months of age. At 140 days of age, an expandable metallic stent (Palmaz stent) was inserted through a rigid bronchoscope into the trachea underfluoroscopic control. His respiratory status improved dramatically, and he was extubated in 18 hours. Although the follow-up period has been 9 months, the short-term result is satisfactory. The expandable metallic stent placement should be considered in patients with EA-TEF who show intractable respiratory symptoms caused by tracheomalacia.

The AATPAP sequence is a very efficient signal for O-glycosylation in CHO cells

The peptide signal sequence for protein O-glycosylation is not fully characterized, although a recent in vitro study proposed that the sequence motif, XTPXP, serves as a signal for mucin-type O-glycosylation. Here, we show that the AATPAP sequence acts as an efficient O-glycosylation signal, in vivo. A secreted fibroblast growth factor (secFGF) was used as a model to analyze glycosylation and its effects on the biological activity of FGF. Two constructs encoding [AATPAP]secFGF in which AATPAP was introduced at the N- or C-terminus of secFGF were constructed in an eukaryotic expression vector. [AATPAP]secFGF proteins were then expressed in Chinese hamster ovary (CHO) cells and secreted into the surrounding medium, primarily as modified forms sensitive to sialidase but not to peptide N-glycosidase F. The modifying groups were not seen when the AATPAP sequence was converted to AAAPAP or when [AATPAP]secFGF was expressed in mutant cells incapable of UDP-GalNAc biosynthesis. The results indicate that the modifying groups were mucin-type O-glycans and that the AATPAP served as an efficient O-glycosylation signal sequence. The O-glycosylated forms of [AATPAP]secFGF were as mitogenic toward human vascular endothelial cells as unmodified secFGF, suggesting that introduction of the signal into biologically active polypeptides is a promising approach with which O-glycosylation may be achieved without affecting original activity.

Silver and thallium(I) complexation with dibenzo-16-crown-4

Dibenzo-16-crown-4 (1) indicates high silver and thallium(I) ion selectivity over sodium, potassium, and rubidium ion evaluated from the solvent extraction of metal picrates, while its cation-binding ability is lower than those of dibenzo-18-crown-6 (2) and dibenzo-22-crown-6 (3). Taking account of the highest thallium(I) ion selectivity for 1 obtained from extraction experiments, PVC membrane thallium(I)-selective electrodes based on 1 are prepared. The electrode shows the best potentiometric selectivity coefficients for thallium(I) over potassium and rubidium than those of 2 and 3, and commercially available bis(crown ether)s (4).