Identification of functional regions of Cbp3p, an enzyme-specific chaperone required for the assembly of ubiquinol-cytochrome c reductase in yeast mitochondria

The Cbp3 protein of Saccharomyces cerevisiae is an enzyme-specific chaperone required for the assembly of ubiquinol-cytochrome c reductase of the mitochondrial respiratory chain. To gain preliminary insight into the role of Cbp3p during assembly, 29 independently isolated mutants were examined to define functional regions of the protein. Mutants were analyzed with respect to respiratory growth, ubiquinol-cytochrome c reductase assembly, and steady state amounts of enzyme subunits and Cbp3p. Three regions essential for Cbp3p activity were identified: regions 1 and 3 were required for Cbp3p function, while region 2 was necessary for protein stability. Mutation of Glu134 in region 1 (Cys124 through Ala140) impaired the ability of the Rieske FeS protein to assemble with the enzyme complex. Mutations targeted to region 3 (Gly223 through Asp229) primarily affected the 14 kDa subunit and cytochrome c(1) assembly. Gly223 was found especially sensitive to mutation and the introduction of charged residues at this site compromised Cbp3p functional activity. Region 2 (Leu167 through Pro175) overlapped the single hydrophobic domain of Cbp3p. Mutations within this area altered the association of Cbp3p with the mitochondrial membrane resulting in enhanced protein turnover. The role of the amino-terminus in Cbp3p activity was investigated using cbp3 deletion strains Delta12-23, Delta24-54, Delta56-96 and Delta12-96. All mutants were respiratory competent, indicating that residues 12-96 were not essential for Cbp3p function, stability or mitochondrial import. Analysis of carboxy-terminal deletion mutants demonstrated that the final 44 residues were not necessary for Cbp3p function; however, alterations in the secondary structure of the extreme carboxy-terminal 17 residues affected assembly protein activity.

Study of an Au colloid self-assembled electrode and its application to the determination of carbon monoxide

A novel electrochemical sensor has been developed for the detection of carbon monoxide. The chemically modified electrode, prepared by reaction of cysteine and then an Au colloid of size approximately 15 nm with a platinum microelectrode, has excellent catalytic activity toward carbon monoxide, with an oxidation potential of +600 mV relative to the Ag/AgCl electrode. The CO gas sensor is based on an Au colloid self-assembled modified electrode as working electrode, an Ag/AgCl electrode as reference electrode, a Pt electrode as counter electrode, and a porous film which is in direct contact with the gas-containing atmosphere. The effects on the determination of CO of different internal electrolyte solutions of perchloric acid, hydrochloric acid, sulfuric acid, nitric acid, and phosphate buffer of different concentrations were also studied. The sensor is characterized by a short response time and highly reproducible detection of CO. This sensor can be used in the field of environmental monitoring and control.

Mercurial sensitivity of aquaporin 1 endofacial loop B residues

The water channel protein aquaporin-1 (AQP1) has two asparagine-proline-alanine (NPA) repeats on loops B and E. From recent structural information, these loops are on opposite sides of the membrane and meet to form a pore. We replaced the mercury-sensitive residue cysteine 189 in AQP1 by serine to obtain a mercury-insensitive template (C189S). Subsequently, we substituted three consecutive cysteines for residues 71-73 near the first NPA repeat (76-78) in intracellular loop B, and investigated whether they were accessible to extracellular mercurials. AQP1 and its mutants were expressed in Xenopus laevis oocytes, and the osmotic permeability (P(f)) of the oocytes was determined. C189S had wild-type P(f) but was not sensitive to HgCl(2). Expression of all three C189S cysteine mutants resulted in increased P(f), and all three mutants regained mercurial sensitivity. These results, especially the inhibitions by the large mercurial p-chloromercunbenzene-sulfonic acid (pCMBS) ( approximately 6A wide), suggest that residues 71-73 at the pore are accessible to extracellular mercurials. A 30-ps molecular dynamics simulation (at 300 K) starting with crystallographic coordinates of AQP1 showed that the width of the pore bottleneck (between Connolly surfaces) can vary (w(avg) = 3.9 A, sigma = 0.75; hydrated AQP1). Thus, although the pore width would be > or = 6 A only for 0.0026 of the time, this might suffice for pCMBS to reach residues 71-73. Alternative explanations such as passage of pCMBS across the AQP1 tetramer center or other unspecified transmembrane pathways cannot be excluded.

Manometric characteristics of the upper esophageal sphincter recorded with a microsleeve

OBJECTIVES

We compared manometric recordings of the upper esophageal sphincter (UES) recorded with a miniature sleeve to those obtained using standard manometry.

METHODS

The UES pressure of eight volunteer subjects was measured by station pull-through (SPT), by rapid pull-through (RPT), and with a microsleeve sensor for 30 min, followed by 15 min of esophageal acid infusion. Deglutitive UES relaxation recorded with a microsleeve and solid state sensor were compared.

RESULTS

The UES pressure recorded with the microsleeve (25+/-9 mm Hg) was significantly less than that by SPT (114+/-18 mm Hg) or RPT (152+/-19 mm Hg), and was unaffected by acid infusion. Periods of low UES pressure were observed during long interswallow intervals (11+/-4, range 6-18 mm Hg). Deglutitive relaxation duration and intrabolus pressure measured with the microsleeve were less than those recorded by the solid state transducer.

CONCLUSIONS

"Normal" UES pressure is heavily dependent on measurement technique; pressures obtained with a miniature sleeve are a fraction of those obtained by SPT or RPT. During periods of relative comfort with minimal swallowing, UES tone is approximately 10 mm Hg, similar to that during sleep. Volume modulation of deglutitive UES relaxation is demonstrable with a microsleeve, albeit with less precision than with a solid-state transducer.

Bisubstrate analogue inhibitors of 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase: synthesis and biochemical and crystallographic studies

6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) catalyzes the transfer of pyrophosphate from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP), leading to the biosynthesis of folate cofactors. Like other enzymes in the folate pathway, HPPK is an ideal target for the development of antimicrobial agents because the enzyme is essential for microorganisms but is absent from human and animals. Three bisubstrate analogues have been synthesized for HPPK and characterized by biochemical and X-ray crystallographic analyses. All three bisubstrate analogues consist of a pterin, an adenosine moiety, and a link composed of 2-4 phosphoryl groups. P(1)-(6-Hydroxymethylpterin)-P(2)-(5'-adenosyl)diphosphate (HP(2)A, 5) shows little affinity and inhibitory activity for E. coli HPPK. P(1)-(6-Hydroxymethylpterin)-P(3)-(5'-adenosyl)triphosphate (HP(3)A, 6) shows moderate affinity and inhibitory activity with K(d) = 4.25 microM in the presence of Mg(2+) and IC(50) = 1.27 microM. P(1)-(6-Hydroxymethylpterin)-P(4)-(5'-adenosyl)tetraphosphate (HP(4)A, 7) shows the highest affinity and inhibitory activity with K(d) = 0.47 microM in the presence of Mg(2+) and IC(50) = 0.44 microM. The affinity of MgHP(4)A for HPPK is approximately 116 and 76 times higher than that of MgADP and 6-hydroxymethylpterin, respectively. The crystal structure of HPPK in complex with 7 (HPPK.MgHP(4)A) has been determined at 1.85 A resolution with a crystallographic R factor of 0.185. The crystal structure shows that 7 occupies both HP- and ATP-binding sites and induces significant conformational changes in HPPK. The biochemical and structural studies of the bisubstrate analogues indicate that the bisubstrate analogue approach can produce more potent inhibitors for HPPK and the minimum length of the link for a bisubstrate analogue is approximately 7 A.

[Expression of rasp21, C-myc, C-erbB-2, and AFP in 2-FAA induced experimental hepatocarcinogenesis]

OBJECTIVE

To investigate the distribution of oncogenes and their relationships in 2-FAA induced experimental hepatocarcinogenesis.

METHODS

Rasp21, C-myc, C-erbB-2, and AFP were detected and analyzed by the SP method of immunohistochemistry.

RESULTS

Some cells expressed rasp21, C-myc, and AFP in peripheral liver lobules and alternated hepatocyte foci in the early stage of the experiment. And with the formation and progression of hyperplastic hepatocytic nodules, expressed cells increased and often accompanied each other. Expression of C-erbB-2 appeared in the middle stage of the hepatocarcinogenesis.

CONCLUSIONS

Expression of rasp21, C-myc, and AFP in the experimental hepatocarcinogenesis is an early molecule change, which may relate to the initiation of hepatocarcinogenesis and be considered to be one of the molecular bases for the morphogenesis of hepatocarcinogenesis. During the development of lesion, C-erbB-2 may have promoting effects. It is also clear that malignant transformation of hepatocyte needs the cooperation of multiple oncogenes.

A novel procedure for pre-embedding double immunogold-silver labeling at the ultrastructural level

Pre-embedding double immunogold-silver labeling using two ultrasmall gold conjugates has not been attempted previously because a means of distinguishing labels by conjugates of identical sizes was lacking. This study investigated the feasibility of creating a particle size segregation between two ultrasmall gold conjugates through sequential immunogold incubations and silver enhancements. Two primary antibodies, mouse anti-synaptophysin and rabbit anti-glial fibrillary acidic protein (GFAP), were used in the model system. Differentiation of the double labeling was achieved by incubating with one ultrasmall gold conjugate, followed by silver enhancement, and then incubating with the second ultrasmall gold conjugate, followed by additional silver enhancement. This resulted in two groups of silver-enhanced particles: smaller particles enhanced once and larger particles enhanced twice. Electron microscopic examination revealed two readily distinguished populations of gold-silver particles within the appropriate structures, with very little size overlap. The quality of the ultrastructure permitted identification of most subcellular organelles. This procedure provides for the first time a pre-embedding immunogold-silver labeling protocol that allows the precise subcellular co-localization of multiple antigens.

Manometric heterogeneity in patients with idiopathic achalasia

BACKGROUND & AIMS

In certain cases of achalasia, particularly those in early stages with minimal endoscopic or radiographic abnormalities, the diagnosis may rely on manometry, which is the most sensitive test for the disease. The aim of this study was to critically evaluate the manometric criteria in a population of patients with idiopathic achalasia.

METHODS

Clinical histories and manometric recordings of 58 patients with idiopathic achalasia and 43 control subjects were analyzed with regard to esophageal body contraction amplitude, peristaltic effectiveness in terms of both completeness and propagation velocity, lower esophageal sphincter (LES) resting pressure, LES relaxation pressure, and intraesophageal-intragastric pressure gradient. Variants of achalasia were defined by finding manometric features that significantly differed from the remainder of achalasia patients, such that the diagnosis might be questioned.

RESULTS

Four manometrically distinct variants were identified. These variants were characterized by (1) the presence of high amplitude esophageal body contractions, (2) a short segment of esophageal body aperistalsis, (3) retained complete deglutitive LES relaxation, and (4) intact transient LES relaxation. In each instance, the most extreme variant is discussed and compared with the remainder of the achalasia population and with controls.

CONCLUSIONS

The significance in defining these variants of achalasia lies in the recognition that these sometimes confusing manometric findings are consistent with achalasia when combined with additional clinical data supportive of the diagnosis. Furthermore, such variants provide important clues into the pathophysiology of this rare disorder.

[Expression of the gene encoding human leukocyte differentiation antigen 5D4]

OBJECTIVE

To make sure that 5D4 cDNA is a full length cDNA and to prepare antigens to make monoclonal antibodies against different epitopes in 5D4 protein.

METHODS

Recombinant expression vectors pGEX-5X-3-5D4 (full length) and pGEX-5X-3-5D4 (5'fragment) were constructed. 5D4 polypeptides were expressed in Escherichia coli DH5 alpha. 5D4 mRNA expression was detected in various tissues and cell lines with Northern blot assay and RT-PCR.

RESULTS

Northern blot demonstrated five mRNA transcripts of 1.9, 2.4, 3.9, 4.5, and 10.0 kb in length existing and expressing of various extent in various tissues. The 1.9 kb mRNA transcript was observed only in the spleen and the small intestinal tissues. The expression of 5D4 mRNA was different in various cell lines. 5D4 polypeptides were expressed in Escherichia coli DH5 alpha.

CONCLUSION

The 1,846 bp 5D4 cDNA is a full length cDNA. A full length 5D4 protein and a 5D4 polypeptide which is the NH2 side to the transmembrane region fused with GST with a molecular weight of 66,000 and 60,000 expressing in Escherichia coli DH5 alpha.

[Effect of 6A8 alpha-mannosidase expression on the proliferative response of human B cell line 3D5]

OBJECTIVE

To study the effect of 6A8 alpha-mannosidase expression on the proliferative response of human B cell 3D5.

METHODS

Recombination of adeno-associated virus vector(rAAV) mediated delivery of sense 6A8 DNA or antisense 6A8 DNA into 3D5 cells, and monoclonal antibody 6A8 alpha staining and Con A binding assay for determination of the change of 6A8 alpha-mannosidase expression, MTT assay for proliferation detection of 3D5 cells driven by Staphylococcus aureus crude cell suspension formalin-fixed (SAC), lower molecular weight B cell growth factor (LMW-BCGF), or rIL-6.

RESULTS

The expression of 6A8 alpha-mannosidase was enhanced in sense 6A8-transduced cells and reduced in antisense 6A8-transduced cells. In comparison with the wild type and the mock-transduced cells, the proliferative response of the sense 6A8-transduced cells to SAC stimulation was enhanced (P < 0.05). However, transduction with antisense 6A8 did not affect the response. In addition, transduction with either sense or antisense 6A8 had no effect on proliferation of 3D5 cells induced by LMW-BCGF or IL-6.

CONCLUSION

The proliferative response to SAC stimulation was enhanced in the 3D5 cells with enhanced expression of 6A8 alpha-mannosidase. Either enhancement or reduction of 6A8 alpha-mannosidase expression had no effect on proliferation induced by LMW-BCGF or IL-6.

Catalytic center assembly of HPPK as revealed by the crystal structure of a ternary complex at 1.25 A resolution

BACKGROUND

Folates are essential for life. Unlike mammals, most microorganisms must synthesize folates de novo. 6-Hydroxymethyl-7, 8-dihydropterin pyrophosphokinase (HPPK) catalyzes pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP), the first reaction in the folate pathway, and therefore is an ideal target for developing novel antimicrobial agents. HPPK from Escherichia coli is a 158-residue thermostable protein that provides a convenient model system for mechanistic studies. Crystal structures have been reported for HPPK without bound ligand, containing an HP analog, and complexed with an HP analog, two Mg(2+) ions, and ATP.

RESULTS

We present the 1.25 A crystal structure of HPPK in complex with HP, two Mg(2+) ions, and AMPCPP (an ATP analog that inhibits the enzymatic reaction). This structure demonstrates that the enzyme seals the active center where the reaction occurs. The comparison with unligated HPPK reveals dramatic conformational changes of three flexible loops and many sidechains. The coordination of Mg(2+) ions has been defined and the roles of 26 residues have been derived.

CONCLUSIONS

HPPK-HP-MgAMPCPP mimics most closely the natural ternary complex of HPPK and provides details of protein-substrate interactions. The coordination of the two Mg(2+) ions helps create the correct geometry for the one-step reaction of pyrophosphoryl transfer, for which we suggest an in-line single displacement mechanism with some associative character in the transition state. The rigidity of the adenine-binding pocket and hydrogen bonds are responsible for adenosine specificity. The nonconserved residues that interact with the substrate might be responsible for the species-dependent properties of an isozyme.

[Identification of high-lying odd energy levels of uranium by resonant ionization mass spectrometry]

Single-colour and two-colour multiphoton resonant ionization spectra of uranium atom were studied extensively with a Nd:YAG laser-pumped dye laser atomic beam apparatus time-of-flight mass spectrometer in our laboratory. The energy locations of high-lying odd-parity levels in the region 33,003-34,264 cm-1, measured by a two-colour three-step ionization technique, were reported here. The angular momentum quantum number J was uniquely assigned for these levels by using angular momentum selection rules.

Bolus transit assessed by an esophageal stress test in postfundoplication dysphagia

INTRODUCTION

Dysphagia is common after Nissen fundoplication but the relationship between dysphagia and bolus transit is poorly defined. This study compared bolus transit of fundoplication patients to normal individuals.

METHODS

Twelve fundoplication patients and 20 healthy volunteers rated their ability to swallow eight bolus consistencies from no difficulty (0) to extreme difficulty (3) to compute a dysphagia score (range = 0-24). A 16-lumen manometric assembly was positioned across the esophagogastric junction (EGJ) and subjects were imaged fluoroscopically in a supine posture while swallowing 5 cc liquid barium and a 5-cc marshmallow-like viscoelastic barium bolus. Videofluoroscopic images were analyzed for total esophageal transit time and the fraction of time required to cross the EGJ. Manometric tracings were analyzed for the intrabolus pressure proximal to the EGJ, intragastric pressure, and distal peristaltic amplitude for each bolus.

RESULTS

Dysphagia scores for fundoplication patients were significantly higher (7.3 +/- 5.1, range = 1-17) than for normals (0.5 +/- 0.6, range = 0-2). This correlated with longer total transit times for liquids and solids (r = 0.60, P < 0.01) and a greater percentage of transit time attributable to the EGJ transit. Retrograde flow at the EGJ (escape of bolus proximally up the esophagus) and peristaltic dysfunction were more frequent in fundoplication patients. However, no differences existed in manometric parameters between groups.

CONCLUSIONS

Fundoplication impairs both liquid and solid esophageal bolus transit. Dysphagia perceived by fundoplication patients correlated with increased transit time, particularly across the EGJ. Combined quantitative evaluation with manometry and fluoroscopy reveals functional defects in fundoplication subjects, which are not evident by either modality alone.

[Effect of 5,7-dihydroxytryptamine on the distribution pattern of calcitonin gene-related peptide in different motoneuron pools]

OBJECTIVE

The effect of 5,7-dihydroxytryptamine (5,7-DHT) on distribution pattern of calcitonin gene-related peptide (CGRP) in different motoneuron pools was studied in rats.

METHODS

Cholera toxin B subunit coupled with colloidal gold (CB-Au) retrograde labeling combined with CGRP immunocytochemistry technique was mainly used.

RESULTS

In control group, there was a different distribution pattern of CGRP-LI content in soleus motoneuron (SOL-Mn) and extensor digitorum longus motoneuron (EDL-Mn) pools. SOL-Mn pools had a higher ratio of neurons lacking CGRP-LI/weak CGRP-LI and a lower proportion of strongly CGRP-LI labeled ones. Comparing with control, there was a marked shift to increasing of CGRP-LI content in SOL-Mn pool and slight decrease in EDL-Mn pools 14 days after 5,7-DHT. All the SOL-Mns were CGRP-LI positive and the ratio of CGRP-LI strongly positive Mns significantly increased (P < 0.001) while 5,7-DHT did not increase the ratio of CGRP-LI strongly positive Mn in EDL-Mn pool.

CONCLUSIONS

Except muscular motor activity, the different distribution pattern of CGRP-LI content in SOL-Mn and EDL-Mn pools is related to different 5-HT inputs. SOL-Mns may receive more 5-HT inputs.

Dissecting the nucleotide binding properties of Escherichia coli 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase with fluorescent 3'(2)'-o-anthraniloyladenosine 5'-triphosphate

6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) catalyzes the transfer of pyrophosphate from ATP to 6-hydroxymethyl-7, 8-dihydropterin, the first reaction in the folate biosynthetic pathway. Like other enzymes in the folate pathway, HPPK is an ideal target for development of antimicrobial agents because the enzyme is essential for microorganisms but is absent from humans and animals. Using 3'(2')-o-anthraniloyladenosine 5'-triphosphate as a fluorescent probe, a fluorometric competitive binding assay has been developed for measuring the dissociation constants of various compounds that bind to the ATP site of HPPK. The fluorometric assay has been used to determine the nucleotide specificity and dissect the energetics of the binding of MgATP. The order of affinity of various nucleoside triphosphates for HPPK is MgATP>MgGTP>MgITP>MgXTP approximately MgUTP approximately MgCTP. The affinity of MgATP for HPPK (K(d)=2.6+/-0.06 microM) is 260-fold higher than that of MgGTP and more than 1000-fold higher than those of the other nucleoside triphosphates, indicating that HPPK is highly specific with respect to the base moiety of the nucleotide. The affinity of ATP for HPPK in the presence of Mg(2+) is 15 times that in the absence of Mg(2+), indicating that the metal ion is important for the binding of the nucleotide. Removal of the gamma-phosphate from MgATP reduces its affinity for HPPK by a factor of approximately 21. The affinity of AMP for HPPK is about one third that of ADP and almost the same as that of adenosine. The result suggests that among the three phosphoryl groups of MgATP, the gamma-phosphoryl group is most critical for binding to HPPK and the alpha-phosphoryl group contributes little to the binding of the nucleotide. The affinity of MgATP is 18 times that of MgdATP, indicating that the 2'-hydroxyl group of MgATP is also important for binding. van't Hoff analysis suggests that binding of MgATP is mainly driven by enthalpy at 25 degrees C and the entropy of binding is also in favor of the formation of the HPPK.MgATP complex.

Does the route of feeding modify gastric emptying in rats?

BACKGROUND

It has been shown that the pattern of previous nutrient intake can influence gastric emptying. However, the effect of the absence of enteral stimulation in the setting of a normal energy supply on gastric emptying has not been examined. The aim of this study was to determine whether the absence of enteral stimulation during total parenteral nutrition (TPN) could modify gastric emptying in rats.

METHODS

Two experiments were performed. First, gastric emptying of a peptone meal was compared between rats receiving TPN, oral liquid diet (same solution as TPN), or regular diet (control group) for 10 days. In the second experiment, gastric emptying of two test meals (40% peptone and 25% glucose) was studied before and after rats received TPN or intragastric nutrition (same solution as TPN) for 10 to 12 days.

RESULTS

In experiment 1, gastric emptying of 40% peptone in the TPN and liquid diet groups was slower than that in the control group. This difference was significant between the TPN group and the control group (p < .01) but not between the liquid diet and control groups (p = .076). Gastric emptying of this meal in the TPN and liquid diet groups was similar. In experiment 2, no difference in gastric emptying of 40% peptone or 25% glucose was found between rats receiving TPN and those receiving intragastric nutrition for 10 to 12 days.

CONCLUSIONS

The composition of diet not the route of feeding is important in the modification of gastric emptying by the pattern of previous nutrient intake.

Increased frequency of transient lower esophageal sphincter relaxation induced by gastric distention in reflux patients with hiatal hernia

BACKGROUND & AIMS

This study aimed to determine if hiatal hernia influences vulnerability to reflux and transient lower esophageal sphincter relaxation (tLESR) during gastric distention in patients with gastroesophageal reflux disease (GERD).

METHODS

Eight normal subjects and 15 patients with GERD were studied. A metal clip attached to the squamocolumnar junction (SCJ) was beneath the hiatus in all control subjects. Eight GERD patients with >/=1-cm SCJ-hiatus separation were considered hernia patients, and 7 with <1-cm separation were considered nonhernia patients. Manometry and esophageal pH were recorded for 30 minutes, after which the stomach was loaded with acid dextrose and the recording continued for 2 hours with intragastric air infusion of 15 mL/min.

RESULTS

Baseline reflux was comparable among groups. Gastric distention increased the frequency of reflux by the tLESR mechanism in all groups. Controls and nonhernia patients had median increases of 4.0 and 4.5 in tLESR frequency, respectively, and hernia patients had a median increase of 9.5/h. tLESR frequency was highly correlated with the SCJ-hiatus separation (r = 0.76; P < 0.001).

CONCLUSIONS

Gastric air infusion was a potent stimulus for tLESR and reflux. The resultant tLESR frequency was directly proportional to the separation between the SCJ and hiatus, suggesting that the perturbed anatomy associated with hiatal hernia predisposed to eliciting tLESRs in patients with GERD.

[The multicolour three-photon resonant ionization spectrum studies in uranium atom]

The multicolour three-photon resonant ionization spectra of 238U were measured by using the pulsed dye lasers system synchronously pumped by a frequency doubled Nd:YAG-laser 532 nm output(operated at 10 Hz), a device for atomic beam of U, time-of-flight mass spectrometer and boxcar integrator. The dye laser pulses have a 6 ns duration. Beams from the dye lasers, which have the same polarization direction and are focused by lenses, entered an interaction chamber through opposite windows on a common axis and spatially overlapped the U atomic beam. The optical pulse from dye laser DL2 was delayed to arrive at the interaction region 8 ns after the pulse from dye laser DL1; in the same way, the pulse from DL3 was delayed 8 ns after from DL2. The atomic beam device was made from stainless steel. We generated the U vapor by heating solid U in a graphite crucible by e-type electron-field on first excited states were studied in uranium atom. The question how to determine single-colour, two-colour and three-colour three-photon resonant ionization peak in the three-colour three-photon resonant ionization spectra diagram were solved.

Esophagogastric junction pressure topography after fundoplication

OBJECTIVES

This study compared the pressure topography after laparoscopic Nissen fundoplication to that of normal subjects and patients with hiatal hernia and reflux disease.

METHODS

Seven patients with fundoplication, 7 normal subjects and 7 patients with hiatal hernia, were studied. The squamocolumnar junction and intragastric margin of the esophagogastric junction (EGJ) were marked with metal clips. Axial and radial characteristics of EGJ pressure were mapped relative to the hernia and clipped during concurrent fluoroscopy and manometry. Responses to inspiration and abdominal compression were also analyzed.

RESULTS

Fundoplication modifies the EGJ by restoration of the hiatal component of EGJ pressure and elongation of the subdiaphragmatic component. Maximal EGJ pressure after fundoplication is mainly dependent on the extrinsic effect of the hiatal canal that compresses the esophagus; the resultant length of the EGJ reflects the length of the fundic wrap. Integrity of the EGJ after fundoplication is independent of the intrinsic lower esophageal sphincter itself.

CONCLUSIONS

Fundoplication alters the pressure topography of the EGJ by reducing the hiatal hernia, tightening the hiatal orifice, and constructing a subdiaphragmatic wrap of variable length. Each effect depends on different technical aspects of the surgery with the potential of substantial variability in the resultant pressure topography.

[6A8 cDNA encodes A type of alpha-mannosidase]

OBJECTIVE

To find the nature of the protein encoded by 6A8 cDNA.

METHODS

In the light of that the ligand of Con A is mannoses and that the function of alpha-mannosidase is trimming of mannoses in the oligosaccharide chains of glycoproteins, COS-7 cells and CNE-2L2 cells, a cloned cell line of human nasopharyngeal carcinoma, were transfected with pRc/CMV-sense 6A8 cDNA or pRc/CMV-antisense 6A8 cDNA and the Con A binding to the cells was examined upon a lazer scan confocal microscope.

RESULTS

The data demonstrated that with transfection of pRc/CMV-sense 6A8 cDNA the binding of Con A to the cells was decreased, but the staining of the cells with mAb 6A8 was enhanced, and vise versa for the cells with transfection of pRc/CMV-antisense 6A8 cDNA.

CONCLUSIONS

The protein encoded by 6A8 cDNA might be a type of alpha-mannosidase recognized by mAb 6A8.

[A light and scanning electron microscopic study of primary teeth in hypophosphatasia]

OBJECTIVE

To investigate the features of primary tooth structure in hypophosphatasia.

METHODS

Three primary teeth from two patients at age of 3 yr-6 month and 4 yr-2 month, who were diagnosed hypophosphatasia. The structural changes of these teeth were examined by light microscopy, polarizing microscopy and scanning electron microscopy.

RESULTS

The complete absence of cementum was a prominent feature in all the teeth, three small island-shape cementun areas were found in scanning electron microscopy. A large number of resorptions were found on the root surfaces, particularly near apical portions of roots. The main findings included disturbances of dentin mineralization, hypoplasia or aplasia of root cementum and external resorption of root dentin.

CONCLUSION

The hypoplasia or aplasia of root cementum was thought to be the prime etiological factor in the early loss of primary teeth.

[Simultaneous determination of tungsten, molybdenum and titanium by k-factor dual-wavelength standard addition method]

In this paper, a new method for simultaneous spectropthotometric determination of tungsten, molybdenum and titanium is proposed. The method is based on the difference of absorption spectra of the three elements forming coloured complexes with PF in acidic medium and in the presence of nonionic surfactant Tween-80. The absorbance of sample was measured at wavelengths of 503, 530 and 560 nm, and the data were treated by the principle of the k coefficients and dual-wavelength standard addition method. The method has been applied to the determination of tungsten, molybdenum and titanium in steels, and satisfactory results were obtained.