Structural insights into the mechanism of intramolecular proteolysis

A variety of proteins, including glycosylasparaginase, have recently been found to activate functions by self-catalyzed peptide bond rearrangements from single-chain precursors. Here we present the 1.9 A crystal structures of glycosylasparaginase precursors that are able to autoproteolyze via an N --> O acyl shift. Several conserved residues are aligned around the scissile peptide bond that is in a highly strained trans peptide bond configuration. The structure illustrates how a nucleophilic side chain may attack the scissile peptide bond at the immediate upstream backbone carbonyl and provides an understanding of the structural basis for peptide bond cleavage via an N --> O or N --> S acyl shift that is used by various groups of intramolecular autoprocessing proteins.

[Evaluation of N staging of cervical lymph nodes with positive palpation in laryngeal carcinoma]

OBJECTIVE

To evaluate N staging of cervical lymph nodes with positive palpation objectively.

METHOD

Serial sections of lymph nodes of neck dissections with transparent methods were observed under light microscope.

RESULT

81 lymph nodes with pathological metastases were verified in 100 patients with 114 palpation positive lymph nodes. The correspondent rate was 71.1%. The correspondent rate of clinical N via pathological N staging was N1 35.6%, N2a 25.0%, N2b 58.3%, N2c 75.0%, N3 100.0% respectively.

CONCLUSION

N staging judged only by palpation is not sufficient in clinic. It should be combined with other examinations.

Rainbow holography with large image depth

A synthetic slit method is used to record the rainbow hologram of a three-dimensional diffused object directly, without any lens. By controlling the position of the synthetic slit, we use this method to produce the reconstructed image of a hologram with much larger image depth than without such control.

[Comparative study on livertaxis of lactosaminated human growth hormone and galactosyl-human growth hormone]

This study was conducted to compare the livertaxis of lactosaminated human growth hormone (hGH-L) with that of galactosyl human growth hormone (hGH-Gal), using radioactive tracer technique. hGH-L and hGH-Gal were first prepared. After hGH-L, hGH-Gal and hGH were labelled with 131I or 125I, the data on biodistribution in mice, imaging in rabbits and chicken were obtained. hGH-L and hGH-Gal had remarkable livertaxis and their percentages for uptake in liver were 68.83%-74.65% and 68.18%-74% respectively, which were about two times as high as that of hGH. All of the hepatic bindings were receptor-mediated. But, the synthesizing of hGH-L was more easy-to-do, more mild in reaction conditions, and more economical of raw material as compared with the synthesizing of hGH-Gal. Therefore, hGH-L is a more potential receptor-mediated hepatic targeting secreting somatomedian drug for treating dwarfism.

[Pathologic feature of occult lymphatic metastasis in supraglottic carcinoma]

OBJECTIVE

To study the pathologic features of occult lymphatic metastasis in patients with supraglottic carcinoma and its implication in treatment.

METHODS

Serial sections of 153 neck dissection specimens in 100 patients with supraglottic carcinoma were studied under microscope.

RESULTS

Clinically negative nodes had been proved histologically positive in 58 specimens (38%) and 51 occult nodes, size ranged from 0.5 cm to 2.6 cm with average of 1.1 cm. The distribution of metastastic lymph nodes was 1 in level I (2%), 37 in level II (73%), 12 in level III(23%) and 1 in level IV(2%). Among the 51 nodes, 21(41%) were in early stage, 18 (35%) in growth stage, 7(14%) in full stage, 5(10%) were extracapsular.

CONCLUSION

Occult metastasis rate of supraglottic carcinoma is as high as 38%, selective neck dissection is recommended for the surgical treatment of this disease.

Large-viewable-angle rainbow holography

A new, to our knowledge, method for recording rainbow holograms of three-dimensional diffused objects in one step without the use of slits is proposed. No lens is needed for recording in this kind of holography; instead, multiple synthetic slits are created by displacement and multiple exposure of an object to expand the horizontal and the vertical viewing angles of the hologram.

Regulation of polar auxin transport by AtPIN1 in Arabidopsis vascular tissue

Polar auxin transport controls multiple developmental processes in plants, including the formation of vascular tissue. Mutations affecting the PIN-FORMED (PIN1) gene diminish polar auxin transport in Arabidopsis thaliana inflorescence axes. The AtPIN1gene was found to encode a 67-kilodalton protein with similarity to bacterial and eukaryotic carrier proteins, and the AtPIN1 protein was detected at the basal end of auxin transport-competent cells in vascular tissue. AtPIN1 may act as a transmembrane component of the auxin efflux carrier.

AtPIN2 defines a locus of Arabidopsis for root gravitropism control

The molecular mechanisms underlying gravity perception and signal transduction which control asymmetric plant growth responses are as yet unknown, but are likely to depend on the directional flux of the plant hormone auxin. We have isolated an Arabidopsis mutant of the AtPIN2 gene using transposon mutagenesis. Roots of the Atpin2::En701 null-mutant were agravitropic and showed altered auxin sensitivity, a phenotype characteristic of the agravitropic wav6-52 mutant. The AtPIN2 gene was mapped to chromosome 5 (115.3 cM) corresponding to the WAV6 locus and subsequent genetic analysis indicated that wav6-52 and Atpin2::En701 were allelic. The AtPIN2 gene consists of nine exons defining an open reading frame of 1944 bp which encodes a 69 kDa protein with 10 putative transmembrane domains interrupted by a central hydrophilic loop. The topology of AtPIN2p was found to be similar to members of the major facilitator superfamily of transport proteins. We have shown that the AtPIN2 gene was expressed in root tips. The AtPIN2 protein was localized in membranes of root cortical and epidermal cells in the meristematic and elongation zones revealing a polar localization. These results suggest that AtPIN2 plays an important role in control of gravitropism regulating the redistribution of auxin from the stele towards the elongation zone of roots.

Crystal structures of Flavobacterium glycosylasparaginase. An N-terminal nucleophile hydrolase activated by intramolecular proteolysis

Glycosylasparaginase (GA) is a member of a novel family of N-terminal nucleophile hydrolases that catalytically use an N-terminal residue as both a polarizing base and a nucleophile. These enzymes are activated from a single chain precursor by intramolecular autoproteolysis to yield the N-terminal nucleophile. A deficiency of GA results in the human genetic disorder known as aspartylglycosaminuria. In this study, we report the crystal structure of recombinant GA from Flavobacterium meningosepticum. Similar to the human structure, the bacterial GA forms an alphabetabetaalpha sandwich. However, some significant differences are observed between the Flavobacterium and human structures. The active site of Flavobacterium glycosylasparaginase is in an open conformation when compared with the human structure. We also describe the structure of a mutant wherein the N-terminal nucleophile Thr152 is substituted by a cysteine. In the bacterial GA crystals, we observe a heterotetrameric structure similar to that found in the human structure, as well as that observed in solution for eukaryotic glycosylasparaginases. The results confirm the suitability of the bacterial enzyme as a model to study the consequences of mutations in aspartylglycosaminuria patients. They also suggest that further studies are necessary to understand the detail mechanism of this enzyme. The presence of the heterotetrameric structure in the crystals is significant because dimerization of precursors has been suggested in the human enzyme to be a prerequisite to trigger autoproteolysis.

[Significance of pathological type in cervical lymph metastasis of laryngeal cancer]

To research significance of pathological type in cervical lymph metastasis of laryngeal cancer. Observing metastasis lymph nodes in serial sections of 55 cases neck dissection specimens with microscope. Single type 21 cases, 90% of them were occult metastasis, three-year survival rate was 90%. Multiple types 10 cases, 70% of them were occult metastasis, three-year survival rate was 70%. Gathering type 24 cases, 92% of them can be palpated by physician, three-year survival rate was 54%. It is suitable that cervical metastasis lymph nodes of laryngeal cancer were divided into three types in pathology. It is significance for treatment and prognosis.

Characterization and functional analysis of the cis-autoproteolysis active center of glycosylasparaginase

Glycosylasparaginase is an N-terminal nucleophile hydrolase and is activated by intramolecular autoproteolytic processing. This cis-autoproteolysis possesses unique kinetics characterized by a reversible N-O acyl rearrangement step in the processing. Arg-180 and Asp-183, involved in binding of the substrate in the mature enzyme, are also involved in binding of free amino acids in the partially formed substrate pocket on certain mutant precursors. This binding site is sequestered in the wild-type precursor. Binding of free amino acids on mutant precursors can either inhibit or accelerate their processing, depending on the individual mutants and amino acids. The polypeptide sequence at the processing site, which is highly conserved, adopts a special conformation. Asp-151 is essential for maintaining this conformation, possibly by anchoring its side chain into the partially formed substrate pocket through interaction with Arg-180. The reactive nucleophile Thr-152 is activated not only by deprotonation by His-150 but also by interaction with Thr-170, suggesting a His-Thr-Thr active triad for the autoproteolysis.

Site-directed mutagenesis of essential residues involved in the mechanism of bacterial glycosylasparaginase

Flavobacterium glycosylasparaginase was cloned in an Escherichia coli expression system. Site-directed mutagenesis was performed at residues suggested to be important in the catalytic mechanism based on the crystal structure of the human enzyme and other biochemical studies. In vitro autoproteolysis allowed the mutant enzymes to be activated, including those that were slow to self-cleave. Based on the activity of the mutant enzymes, six catalytically essential amino acids were identified: Trp-11, Asp-66, Thr-152, Thr-170, Arg-180, and Asp-183. Kinetic analysis of each mutant further defined the function of these residues in substrate specificity and reaction rate. Mutagenesis of the N-terminal nucleophile residue Thr-152 confirmed the key function of its side-chain hydroxyl group. Partial activities of mutants T152S/C were in agreement with the general mechanism of N-terminal nucleophile (Ntn)-amidohydrolases. The side-chain hydroxyl of Thr-170 contributes to the reaction rate based on studies of mutants T170S/C/A. Residues Asp-183 and Arg-180 were found to H-bond, respectively, with the charged alpha-amino and alpha-carboxyl group of the substrate (Asn-GlcNAc). Mutants R180Q/L and D183E/N had greatly decreased substrate affinity and reduced reaction rates. Kinetic studies also showed that Trp-11 is involved in regulation of the enzyme reaction rate, contradictory to a previous suggestion that this residue is involved in substrate binding. Asp-66 is a new residue found to be important in enzyme activity. The overall active site structure involving these catalytic residues resembles the glutaminase domain of glucosamine 6-phosphate synthase, another member of the Ntn-amidohydrolase family of enzymes.

Crystal structure of glycosylasparaginase from Flavobacterium meningosepticum

The crystal structure of recombinant glycosylasparaginase from Flavobacterium meningosepticum has been determined at 2.32 angstroms resolution. This enzyme is a glycoamidase that cleaves the link between the asparagine and the N-acetylglucosamine of N-linked oligosaccharides and plays a major role in the degradation of glycoproteins. The three-dimensional structure of the bacterial enzyme is very similar to that of the human enzyme, although it lacks the four disulfide bridges found in the human enzyme. The main difference is the absence of a small random coil domain at the end of the alpha-chain that forms part of the substrate binding cleft and that has a role in the stabilization of the tetramer of the human enzyme. The bacterial glycosylasparaginase is observed as an (alphabeta)2-tetramer in the crystal, despite being a dimer in solution. The study of the structure of the bacterial enzyme allows further evaluation of the effects of disease-causing mutations in the human enzyme and confirms the suitability of the bacterial enzyme as a model for functional analysis.

[Clinical and pathological study on cervical lymph node metastasis of supraglottic cancer]

AIM

To study pathological features of cervical lymph node metastasis and the relationship between supraglottic cancer and cervical lymph node metastasis.

METHOD

Observation of 100 whole-organ serial sections of the larynges and 170 sides of the radical neck dissection specimens.

RESULTS

1. Cervical lymph node metastasis 55 cases, metastatic rate 55%; 2. Four series of cervical metastasis: clinico-pathologic metastases (29 cases), pathologic metastases (26 cases), clinical metastases (5 cases), no metastasis (40 cases). 3. Four stages of metastatic lymphnode: early stage, growth stage, fullness stage and capsular perforative stage; 4. Three types of metastases: single type (21 cases), multiple type (10 cases) and aggregated (24 cases) type. 5. Metastatic rates of supraglottic cancer of different regions: aryepiglottic fold 85.7%, arytenoid cartilage area 66.6%, epiglotto-ventricular fold 56.8%, epiglottic 46.4%, ventricular fold 45.4%. 6. When the tumour spread to the perilaryngeal region, the metastatic rate was 80% to 84%.

CONCLUSION

Metastatic rate of cervical lymph node is higher in supraglottic cancers, the aggregated type and capsular perforative stage are more in metastasis lymph nodes. Analysis the original sites of supraglottic cancer is conductive to the prediction of the cervical lymph node metastasis.

Cloning and biochemical characterization of an anionic peroxidase from Zea mays

We have isolated, cloned and characterized a cDNA from Zea mays L., denoted ZmAP1, coding for an anionic peroxidase. The open reading frame of ZmAP1 starting 72 residues from the 5' end of the cDNA predicts a 37,778 dalton protein of 356 amino acid residues. The protein has high similarity to other peroxidases and contains two peroxidase motifs that carry two highly conserved histidines in the active center. We expressed recombinant ZmAP1 protein in E. coli as a fusion with maltose-binding protein. The fusion protein was biochemically active after addition of hemin to the apoprotein. The maize peroxidase ZmAP1 has a pH optimum at pH 4.0 and a Km of 0.2 mM for the substrate 2,2'-azino-bis-(3-ethyl-benzothiazolin-6-sulfonic acid) at this pH. In maize seedlings the ZmAP1 gene is expressed predominantly in roots, the mesocotyl, the coleoptile and to a lower extent in the node, whereas no expression in the primary leaf was found. In situ hybridization shows that the expression of ZmAP1 in the young maize root is confined to the epidermis, hypodermis and the pericycle.

A nodule-specific gene family from Alnus glutinosa encodes glycine- and histidine-rich proteins expressed in the early stages of actinorhizal nodule development

Two cDNAs representing different members (agNt84 and ag164) of a gene family encoding glycine- and histidine-rich proteins have been isolated from cDNA libraries from Alnus glutinosa root nodules. Expression of the corresponding genes could only be detected in nodules. With in situ hybridization, the expression in nodules was found to occur in young, infected cells of the prefixation zone (zone 2). The encoded proteins contain putative signal peptides for targeting to the endomembrane system, sharing sequence similarity with signal peptides from plant glycine-rich proteins, among them nodulin 24, a nodule-specific protein from soybean. This similarity suggests that, analogous to nodulin-24, proteins encoded by agNt84/ag164 may be located at the interface between the host plant membrane and the matrix surrounding the endosymbiont. The 3' untranslated regions of the cDNAs contain unusual poly(AT)n stretches that may play a role in the regulation of RNA stability. The protein encoded by agNt84 cDNA was expressed in Escherichia coli as a fusion with maltose-binding protein, and was shown to have the ability to bind to a nickel-chelating resin, indicating that it may function as a metal-binding protein.

Nitrogen metabolism in actinorhizal nodules of Alnus glutinosa: expression of glutamine synthetase and acetylornithine transaminase

Two nodule cDNA clones representing genes involved in Alnus glutinosa nitrogen metabolism were analysed. ag11 encoded glutamine synthetase (GS), the enzyme responsible for ammonium assimilation, while ag118 encoded acetylornithine transaminase (AOTA), an enzyme involved in the biosynthesis of citrulline, the nitrogen transport form in Alnus. GS mRNA was found at highest levels in root nodules, where it was present in the infected cells as well as in the cells of the pericycle of the vascular system. AOTA transcripts were found at high levels in nodules, confined to the infected cells, suggesting that in nodules of A. glutinosa, citrulline biosynthesis takes place mainly in the infected cells.

[A study of the relevant factors of removal of common bile duct stones with endoscopic mechanical lithotripsy]

Endoscopic mechanical lithotripsy (EML) was attempted in 41 patients with common bile duct stones unable to be removed by endoscopic sphincterotomy. These patients had altogether 89 stones with stone size ranged from 5 to 30 mm (mean transverse diameter 16.6 +/- 6.0 mm and mean longitudinal diameter 20.0 +/- 7.1 mm). 31 patients had 34 stones greater than or equal to 20 mm in transverse diameter. The overall stone removal rate was 97.6%. The rate of complete removal of the stone fragments with EML at one time was 78.6% (11/14) for large, 58.8% (10/17) for middle and 0 (0/5) for small incision of the sphincter. In patients with diameter of the distal common bile duct greater than or equal to 14 mm and less than 9 mm the rate was 83.3% and 30.8% respectively and the difference was of significance (P < 0.05). The rate of complete removal for using basket and balloon catheter was 6/10 and 4/9 separately and that for combined used of these two methods 83.3% (10/12). The rate of spontaneous passage of the stone (within one week) was 1/5. It is concluded that complete removal of the stone fragments was related mainly to the length of the incision, diameter of distal common bile duct and methods of removing stone fragments after the crush with lithotripsy basket; when the stone is large and there is the no space around the stone for lithotripsy basket manipulation, a large amount of diluted contrast material is injected into the bile duct so as to increase the space and facilitate the ensonaring of the stone with lithotripsy basket. Hard stones can not be crushed easily, so they constitute one of the reasons of failure.

[Preparation of galactosyl-cytochrome C and studies on its hepatic targeting property]

This paper reports the preparation of the coupling compound between thiogalactose and cytochrome C(Cyt-C). The binding tests of this compound to asialoglycoprotein receptor have also been carried out in vivo. The results show that the pharmacokinetics of this compound is in accordance with the basic characteristic of receptor induced binding. The highest uptake of liver reaches to 32.9% and at the same time the conjugate remains 78.6% the biological activity of Cyt-C. It is possibly a hepatic targeting drug or a hepatic targeting carrier.

[The preparation of hepatic receptor imaging agent 99mTc-DTPA-NGA]

The method of preparation and the character of the hepatic receptor imaging agent 99mTc-DTPA-NGA have been presented. The radio-chemical purity of the imaging agent is higher than 95% and the stability of the imaging agent is more than 6 hours in vitro and in human blood. The agent is able to tend to liver and has the character of receptor-intervene-conduct binding. Our comparative study of 99mTc-DTPA-NGA versus 99mTc-NGA reveals, the stability of the former in vitro and in human blood is better than that of the latter. The imaging in rabbits shows that the imaging quality of the former is higher than that of the latter. The radioactive metabolites in urine have been examined. The former does not fall off 99mTc in vivo, but the latter falls off 99mTc clearly. 10 clinical hepatic imagings have had satisfactory results.

Activation of glycosylasparaginase. Formation of active N-terminal threonine by intramolecular autoproteolysis

The activation mechanism of glycosylasparaginase of Flavobacterium meningosepticum has been analyzed by site-directed mutagenesis and activation of purified precursors in vitro. Mutation of Thr-152 to Ser or Cys leads to gene products that are not activated in vivo but are activated in vitro because processing of the mutant precursors is inhibited by certain amino acids in the cell. Kinetic studies reveal that activation is an intramolecular autoproteolytic process. The involvement of His-150 and Thr/Ser/Cys-152 in activation suggests that autoproteolysis resembles proteolysis by serine/cysteine proteases. Multiple functions of the highly conserved active threonine residue are implicated.

Active site and oligosaccharide recognition residues of peptide-N4-(N-acetyl-beta-D-glucosaminyl)asparagine amidase F

Crystallographic analysis and site-directed mutagenesis have been used to identify the catalytic and oligosaccharide recognition residues of peptide-N4-(N-acetyl-beta-D-glucosaminyl)asparagine amidase F (PNGase F), an amidohydrolase that removes intact asparagine-linked oligosaccharide chains from glycoproteins and glycopeptides. Mutagenesis has shown that three acidic residues, Asp-60, Glu-206, and Glu-118, that are located in a cleft at the interface between the two domains of the protein are essential for activity. The D60N mutant has no detectable activity, while E206Q and E118Q have less than 0.01 and 0.1% of the wild-type activity, respectively. Crystallographic analysis, at 2.0-A resolution, of the complex of the wild-type enzyme with the product, N,N'-diacetylchitobiose, shows that Asp-60 is in direct contact with the substrate at the cleavage site, while Glu-206 makes contact through a bridging water molecule. This indicates that Asp-60 is the primary catalytic residue, while Glu-206 probably is important for stabilization of reaction intermediates. Glu-118 forms a hydrogen bond with O6 of the second N-acetylglucosamine residue of the substrate and the low activity of the E118Q mutant results from its reduced ability to bind the oligosaccharide. This analysis also suggests that the mechanism of action of PNGase F differs from those of L-asparaginase and glycosylasparaginase, which involve a threonine residue as the nucleophile.

Crystal structure of endo-beta-N-acetylglucosaminidase H at 1.9 A resolution: active-site geometry and substrate recognition

BACKGROUND

Endo-beta-N-acetylglucosaminidase H (Endo H), an endoglycosidase secreted by Streptomyces plicatus, hydrolyzes the glycosidic bond between the core N-acetyglucosamine residues of asparagine-linked high-mannose oligosaccharides. Endo H is a commonly used reagent in glycobiology research, including the characterization of oligosaccharides in glycoproteins. On-going crystallographic studies of Endo H and related endoglycosidases are aimed at identifying the molecular features that determine the different substrate specificities of these enzymes.

RESULTS

The three-dimensional structure of Endo H has been determined to 1.9 A resolution. The overall fold of the enzyme is that of an irregular (alpha/beta)8-barrel comprising eight beta-strand/loop/alpha-helix units. Units 5 and 6 have very short loop sections at the top of the molecule and their alpha-helices are replaced by sections of extended geometry. The loop of unit 2 includes a small two-stranded antiparallel beta-sheet. A shallow curved cleft runs across the surface of the molecule from the area of units 5 and 6, over the core of the beta-barrel to the area of the beta-sheet of loop 2. This cleft contains the putative catalytic residues Asp130 and Glu132 above the core of the beta-barrel. These residues are surrounded by several aromatic residues. The loop 2 area of the cleft is formed by neutral polar residues, mostly asparagines.

CONCLUSIONS

The structure of Endo H is very similar to that of Endo F1, a closely related endoglycosidase secreted by Flavobacterium meningosepticum. Detailed comparison of the structures of Endo H and Endo F1 supports the model previously proposed for substate binding and recognition, in which the area of loop 2 determines the substrate specificity and the alpha-helices of units 5 and 6 are missing to accommodate the protein moiety of the substrate.

[Single high-dose and fractionated low dose cisplatin in the EP protocol for advanced NSCLC--a prospective randomized trial on 72 patients]

A prospective randomized trial on 72 patients (12 cases in stage III and 60 cases in stage IV) suffering from non-small cell lung cancer (NSCLC) was carried out from January 1993 to March 1994 to assess the immediate results of single high dose DDP and fractionated low doses DDP in the EP (Etoposide and Cisplatin, DDP) protocol. The response rate to the former regimen was 47.1% (16/34) as compared with 39.5% (15/38) of the latter. The difference between these two regimens were not statistically significant (P > 0.10). The former regimen had higher incedence of delayed vomiting (P < 0.01), but the latter had more severe bone marrow suppression (P < 0.05). Without significant difference in renal toxicity (P > 0.10). The authors suggest that, the EP protocol consisting of fractionated doses of DDP, may be more preferrable due to its mild gastro-intestinal toxic reaction and less expensive in the treatment of advanced NSCLC patients. Yet, it is necessary to guard against its renal toxicity and myelosuppression.

[Analysis of 100 cases of precancerous laryngeal lesions]

Hundred cases of precancerous laryngeal lesions were analysed on the basis of clinical pathology. The results showed that there was close relationship between the precancerous laryngeal lesions and voice abuse and long-term heavy smoking. The pathology showed epithelial hyperplasis and mild to severe atypical hyperplasia (heterotype). Scanning electronmicroscopy revealed that the more severe the degree of the epithelial heterotype, the more pleomorphic the shape of cell morphology, margin. Twenty cases had malignant changes later, and the rate of malignant change was high in those with atypical hyperplasia. Some lesions which were taken for polyps clinically and pathologycally could also have malignant changes, so more attention should be paid to these lesions during clinical management.

Crystallization and preliminary crystallographic analysis of two endo-beta-N-acetylglucosaminidases, endo H and endo F1

Endo H and F1 are endoglycosidases that cleave the oligosaccharide moiety of asparagine-linked glycoproteins by hydrolysis of the glycosidic bond in the N,N'-diacetylchitobiose core. The two enzymes are specific for high-mannose oligosaccharides. Here, we report the crystallization and preliminary crystallographic analysis of Endo H and Endo F1. Crystals were grown by hanging drop vapor diffusion methods. Both proteins crystallize from crystallization buffers containing polyethyleneglycol 8000 and zinc acetate as precipitating agents in cacodylate buffer. The crystals of Endo H belong to the tetragonal space group P4(1)2(1)2 (or P4(3)2(1)2) with cell dimensions: a = 85.22 A, c = 89.41 A. The crystals of Endo F1 belong to the hexagonal space group P6(1) (or P6(5)) with cell dimensions: a = 70.61 A, c = 100.32 A. Crystals of both proteins diffract to at least 1.8 A resolution.

[Characterization of receptor-mediated binding of 99mTc-NGA in vitro]

This paper reports results of an assay of the binding of 99mTc-galactosylneoglycoalbumin (NGA) and plasma membranes of the rat liver in vitro. The data showed that 99mTc-NGA could be bound to the membrane receptor with high affinity. Specificity and saturability, and that the amount of membrane-bound 99mTc-NGA varied linearly with the amount of membrane within each reaction tube. The biphasic curve of scatchard plot revealed that 99mTc-NGA was bound to two sites of the receptor with different affinity and concentration (K1 8.4089 x 10(9) L/mol, R1 1.7350 x 10(-12) mol/mg); K2 2.0827 x 10(8) L/mol, R2 6.9530 x 10(-12) mol/mg). Therefore, the authors consider that 99mTc-NGA is a promising hepatic receptor agent for imaging.

One-step rainbow holography using a dual lens with no slit

In this paper one-step rainbow holography that uses a dual lens for recording a three-dimensional diffuse object is discussed. During the exposure process, only one of the lenses is moved so that a synthetic slit formed at the observation position. Both of the lenses can have a shorter focal length, which has the effect of expanding the visual field and narrowing the synthetic slit. This method simplifies the experimental technique needed for synthetic-slit holography.

[The preparation of 99mTc-NGA instant lyophilized kit for hepatic imaging]

The preparation of one-step kit for the 99mTc labelled galactosyl-neo-glycoalbumin (NGA) using SnCl2 reduced method was reported in this paper. We developed a method of quality control and established the optimum scheme of technetium labelling on the basis of exploring the effects of varied labelled conditions on radiochemical purity. Our data indicates : (a) the kit is sterile, pyrogen-free and no toxic effects; (b) the operation is simple and fast; (c) its period of validity lasts no less than 3 months; (d) the radiochemical purity > 95%; (e) the stability of 99mTc-NGA in vitro > 4 hours; (f) the results of animal imaging and clinical probation are satisfactory.

[Pharmacokinetic studies on 99mTc-NGA in human]

Two normal subjects and three patients with hepatic disease were intravenously injected each with a single dose of 99mTc-NGA (galactosyl-neoglycoalbumin), a liver receptor imaging agent. The results showed that pharmacokinetics of 99mTc-NGA accorded with the two compartment open model. In the normal subjects, T1/2 alpha and T1/2 beta averaged 1.65 and 19.39 min respectively, indicating a rapid distribution process and a slow elimination process. There were significant differences in pharmacokinetics of 99mTc-NGA between the normal subjects and the patients with hepatic disease, and therefore the relevant parameters are of importance for the evaluation of hepatic function.

Rainbow holography using a large aperture lens for a full object beam

A method of making rainbow holograms by using a full object beam is described. In this technique we simultaneously use a moving object and a moving imaging lens, instead of using a slit during the exposure process. The position of the synthetic slit is independent of the position of the imaging lens and its focal length. Using this method, a one-step rainbow holographic image with a large visual field and high resolution can be obtained. A theoretical analysis and some experimental results are presented.