Interaction of native and asialo rat sublingual glycoproteins with lectins

The binding properties of the rat sublingual glycoprotein (RSL) and its asialo product with lectins were characterized by quantitative precipitin(QPA) and precipitin inhibition(QPIA) assays. Among twenty lectins tested for QPA, native RSL reacted well only with Artocarpus integrifolia (jacalin), but weakly or not at all with the other lectins. However, its asialo product (asialo-RSL) reacted strongly with many Gal and GalNAc specific lectins-it bound best to three of the GalNAc alpha 1-->Ser/Thr (Tn) and/or Gal beta 1-->4GlcNAc (II) active lectins [jacalin, Wistaria floribunda and Ricinus communis agglutinins] and completely precipitated each of these three lectins. Asialo-RSL also reacted well with Abrus precatorius, Glycine max, Bauhinia purpurea alba, and Maclura pomifera agglutinins, and abrin-a, but not with Arachis hypogeae and Dolichos biflorus agglutinins. The interaction between asialo-RSL and lectins were inhibited by either Gal beta 1-->4GlcNAc, p-NO2-phenyl alpha-GalNAc or both. The mapping of the precipitation and inhibition profiles leads to the conclusion that the asialo rat sublingual glycoprotein provides important ligands for II (Gal beta 1-->4GlcNAc beta 1-->) and Tn (GalNAc alpha 1-->Ser/Thr) active lectins.

Binding studies on the combining site of a GalNAc alpha 1-->-specific lectin with Thomsen-Friedenreich activity prepared from green marine algae Codium fragile subspecies tomentosoides

The combining site of a GalNAc alpha 1-->-specific lectin (CFT) with Thomsen-Friedenreich (T, Gal beta 1-->3-GalNAc alpha 1-->Ser/Thr) activity, purified from the subspecies tomentosoides of green marine algae Codium fragile was studied by quantitative precipitin and precipitin-inhibition assays. Of 27 glycoforms tested, Tn (GalNAc alpha 1-->Ser/Thr) glycoprotein from armadillo submandibular glands, and asialo porcine submandibular glycoprotein, which contains T, Tn and GalNAc alpha 1-->3Gal(A) sequences, completely precipitated the lectin added, and less than 1 microgram glycoprotein was required to precipitate 50% 4.7 micrograms lectin nitrogen. However, CFT precipitated negligibly with Pneumococcus type-XIV polysaccharide and asialo human alpha 1-acid glycoprotein, that contain exclusively the human blood-type-II precursor sequence (II, Gal beta 1-->4GlcNAc) at the nonreducing ends. Among the sugar inhibitors tested, the human blood A-active trisaccharide [Ah, GalNAc alpha 1-->3 (LFuc alpha 1-->2)Gal] was the best inhibitor; it was about twice as active as the T disaccharide. Oligosaccharides without GalNAc alpha 1--> as part of their sequences were inactive, indicating that the acetamido group at C2 of galactose is essential for binding and that GalNAc is the main contributor in the T sequence for binding. From the data provided, it is clear that the combining site of CFT requires an alpha-anomer of GalNAc and recognizes Ah, internal GalNAc alpha 1--> of T and Tn determinants of glycans, but not the blood group I/II (Gal beta 1-->3/4GlcNAc) sequences. Consequently, CFT is a useful reagent for detecting GalNAc alpha 1-->-containing glycoconjugates.

The anchorage function of CipA (CelL), a scaffolding protein of the Clostridium thermocellum cellulosome

Enzymatic cellulose degradation is a heterogeneous reaction requiring binding of soluble cellulase molecules to the solid substrate. Based on our studies of the cellulase complex of Clostridium thermocellum (the cellulosome), we have previously proposed that such binding can be brought about by a special "anchorage subunit." In this "anchor-enzyme" model, CipA (a major subunit of the cellulosome) enhances the activity of CelS (the most abundant catalytic subunit of the cellulosome) by anchoring it to the cellulose surface. We have subsequently reported that CelS contains a conserved duplicated sequence at its C terminus and that CipA contains nine repeated sequences with a cellulose binding domain (CBD) in between the second and third repeats. In this work, we reexamined the anchor-enzyme mechanism by using recombinant CelS (rCelS) and various CipA domains, CBD, R3 (the repeat next to CBD), and CBD/R3, expressed in Escherichia coli. As analyzed by non-denaturing gel electrophoresis, rCelS, through its conserved duplicated sequence, formed a stable complex with R3 or CBD/R3 but not with CBD. Although R3 or CBD alone did not affect the binding of rCelS to cellulose, such binding was dependent on CBD/R3, indicating the anchorage role of CBD/R3. Such anchorage apparently increased the rCelS activity toward crystalline cellulose. These results substantiate the proposed anchor-enzyme model and the expected roles of individual CipA domains and the conserved duplicated sequence of CelS.

Interaction of mistletoe toxic lectin-I with sialoglycoproteins

The binding properties of mistletoe toxic lectin-I (ML-I) with sialo-N- and O-glycans were investigated by quantitative precipitin and precipitin inhibition assays. Human alpha 1-acid glycoprotein reacted strongly with ML-I, precipitating over 82% of the lectin nitrogen tested, while the precipitability of its asialo product decreased by 30%. Native fetuin precipitated 50% of the ML-I added, and its reactivity was reduced by 20% after desialylation. On the contrary, the poor reactivity of rat sublingual sialoglycoprotein with ML-I increased substantially after removal of sialic acid and completely precipitated the lectin added. The glycoprotein-lectin interactions were inhibited by NeuAc alpha 2-->3/alpha 2-->6Gal beta 1-->4Glc and/or Gal beta 1-->4Glc (NAc) residues. From the above results, it is concluded that ML-I is specific for sialic acid. However, sialic acid of some O-glycans also acts as masking molecule as the precipitability of rat sublingual and bovine submandibular glycoproteins with ML-I increased after desialylation.

Fluorogenic fibrinogen and fibrin facilitate macromolecular assembly and dynamic assay of picomolar levels of plasminogen activators under well mixed conditions

Fibrinogen labeled with fluorescein isothiocyanate (FITC) was tested for its ability to serve as a template for macromolecular assembly as well as to provide a fluorogenic signal to allow continuous monitoring of plasminogen activation and fibrinolysis. As dilute solutions of FITC-fibrinogen or FITC-fibrin fiber suspension were degraded during lysis, release of fluorescent fragments abolished proximity-based quenching and resulted in a 2.0- or 3.6-fold increase in fluorescence intensity, respectively. Addition of plasmin at a final concentration of 10 pM to FITC-fibrinogen (10 nM) produced a detectable level of fluorescence dequenching. The assay had sufficient sensitivity to detect plasmin activity in the presence of excess antiplasmin activity, indicating the dissociation of a reversible antiplasmin-plasmin complex. The detection limit of the reaction assay was 20 pM and 200 pM of recombinant tPA and urokinase, using 10 nM FITC-fibrin and 10 nM and 5 nM plasminogen, respectively. The 10-fold greater sensitivity of the assay for tPA was likely due to the molecular assembly of tPA and plasminogen on the FITC-fibrin. Addition of thrombin (1 U/ml) and plasmin (0.1 nM) to 10 nM FITC-fibrinogen produced fluorescence quenching at first due to fibrinogen polymerization followed by dequenching due to fibrinolysis. Addition of 10 mM epsilon-aminocaproic acid to mixtures of thrombin and plasmin allowed the quenching assay of thrombin activity in the presence of active plasmin. FITC-fibrinogen could be copolymerized with recalcified platelet poor plasma (isolated from citrated whole blood) to yield fibrin that was fluorogenic. Dequenching was observed when plasmin was used to degrade the fibrin formed from the platelet poor plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequences of apolipoprotein B 3' hypervariable repeat alleles

The apolipoprotein B-encoding gene (apoB) 3' end hypervariable repeats contain 11- to 16-bp A+T-rich sequences and are organized tandemly. Sixteen alleles varying in repeat number (26, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55 and 58) were sequenced. Sequencing revealed a gradual extension of the number of bd (5'-TTTTATAATTAAAATA TTTATAATTAAATA) repeats [the fourth and fifth repeat units in variable-number tandem repeat 26 (VNTR26)] from alleles 26 to 58. In addition, four ef (5'-TTTTATAATTAAAATG TTTATAATTACATA) repeats (the eighth to fifteenth repeat units in VNTR26) in alleles 43, 45 and 47, and one ed (5'-TTTTATAATTAAAATG TTTATAATTAAATA) repeat (the sixth and seventh repeat units in VNTR26) in alleles 49, 51, 53 and 55 were deleted. Alleles 43, 45, 47 and alleles 49, 51, 53, 55, 58 also had variations at the 5' end of this repeat region (the first to third repeat units in VNTR26); the 3' end (the 16th to 26th repeat unit of VNTR26) of all alleles was invariant. This molecular event indicates a systemic expansion or contraction in this region.

Tissue plasminogen activator (tPA) inhibits plasmin degradation of fibrin. A mechanism that slows tPA-mediated fibrinolysis but does not require alpha 2-antiplasmin or leakage of intrinsic plasminogen

Thrombolysis is dramatically slower when high concentrations of lytic agent are used. This paradoxical observation, first described as "plasminogen steal," was originally believed to be due to depletion of extrinsic plasminogen and consequent leaching of clot-bound plasminogen. We report that administration of increasing concentrations of recombinant human tissue plasminogen activator (tPA) to fibrin gels resulted in lysis rates that displayed a maximum, with significantly slower rates found at higher tPA, regardless of whether plasminogen was supplied extrinsically or intrinsically. A similar maximum in lysis rates was observed in a system lacking an extrinsic phase when plasminogen was added to fibrin suspensions preincubated with increasing tPA. Thus, intrinsic plasminogen leakage and alpha 2-antiplasmin were not required for the decreased lysis at high tPA. No maximum was observed for increasing concentrations of urokinase. Using fibrin suspensions or gels preincubated with tPA before addition of plasmin, we report that tPA, but not urokinase, caused a dose-dependent inhibition of the fibronolytic action of plasmin. With respect to optimal dosage schemes and the design of novel lytic agents, these findings indicate that (a) there exists a biochemical mechanism against minimizing reperfusion time with increasing tPA dosages and (b) the fibrin affinity of tPA may cause reduced fibrinolysis by plasmin.

[Membrane fusion between Ehrlich ascites of mastocarcinoma cells and liposome induced by proton translocation of transplasma membrane NADH-ferricyanide redox enzymes]

By using resonance energy transfer assay (RET) and fluorescence microscopy we show experimental evidence that membrane fusion of Ehrlich ascites of mastocarcinoma cells with liposomes could be induced by the proton translocation activity associated with NADH-ferricyanide redox enzyme of transplasma membrane of cancer cells. The iodoacetate, an inhibitor of glycolysis, was found to be able to depress the proton translocation activity and also to inhibit the membrane fusion. It is suggested that NADH produced mainly by glycolysis is utilized as the substrate (electron donor) for transmembrane ferricyanide reduction, and the proton pumping activity in the cancer cells is coupled to the transmembrane NADH-ferricyanide redox enzyme system. Experiments also show that membrane fusion extent of cancer cells with liposomes is proportional to the amount of H+ pumped out by the cells and membrane fusion process also exhibits a H+ consuming mode just as in fusion process of mitochondria with liposomes by redox enzyme proton pumps of respiratory chain. All of the results presented in this paper consists with recent reports of this laboratory, which indicated that various types of proton pumping system from different membrane system of cell have a new function in membrane fusion. Therefore, the proton pumping induced membrane fusion may have a more general physiological importance in triggering and modulating fusion process of native membrane in vivo.

Native and asialo-Tamm-Horsfall glycoproteins as important ligands for the detection of GalNAc beta 1-->and Gal beta 1-->4GlcNAc active lectins

The binding properties of human Tamm-Horsfall Sd(a+) urinary glycoprotein(THGP) and asialo-THGP with various applied lectins was investigated by quantitative precipitin and precipitin inhibition assays. Both glycoproteins completely precipitated Abrus precatorius agglutinin(APA). They also reacted well with Wistaria floribunda (WFA), Glycine max (soybean, SBA), and Ricinus communis agglutinins and precipitated over 78% of the lectin nitrogen added, but reacted poorly or weakly with all alpha-anomeric GalNAc specific lectins, such as Helix pomatia (HPA), Phaseolus lunatus (lima bean, LBL), and Maclura pomifera (MPL) lectins. The glycoprotein-lectin interaction was inhibited by GalNAc beta 1-->, Gal beta 1-->4GlcNAc, or by both. The findings suggest that Sd (a+) THGP and asialo-THGP are among the best water-soluble glycoprotein ligands for GalNAc beta 1-->and Gal beta 1-->4GlcNAc active lectins.

Binding sites of ZNC(C)PR, a pentapeptide fragment of argipressin, in rat brain

AIM

To study the binding sites of ZNC (C) PR, a C-terminal pentapeptide fragment of argipressin, in rat brain.

METHODS

Using radioligand assay and radioligand [35S]ZNC(C)PR.

RESULTS

It was found that there exist native binding sites bound ZNC(C)PR with high affinity in a saturable, reversible and specific manner. Scatchard and kinetic analyses showed that these sites were homogeneous with a Kd value of 1.69 +/- 0.16 nmol.L-1 (in the presence of MgCl2 10 mmol.L-1). The binding of ZNC(C)PR to the sites was at a higher level in the brain regions (such as amygdala, cortex,) and was affected by Mg2+.

CONCLUSION

These binding sites represented a new type of receptors and mediated the action of ZNC(C)PR on memory.

Exoglucanase activities of the recombinant Clostridium thermocellum CelS, a major cellulosome component

The recombinant CelS (rCelS), the most abundant catalytic subunit of the Clostridium thermocellum cellulosome, displayed typical exoglucanase characteristics, including (i) a preference for amorphous or crystalline cellulose over carboxymethyl cellulose, (ii) an inability to reduce the viscosity of a carboxymethyl cellulose solution, and (iii) the production of few bound reducing ends on the solid substrate. The hydrolysis products from crystalline cellulose were cellobiose and cellotriose at a ratio of 5:1. The rCelS activity on amorphous cellulose was optimal at 70 degrees C and at pH 5 to 6. Its thermostability was increased by Ca2+. Sulfhydryl reagents had only a mild adverse effect on the rCelS activity. Cellotetraose was the smallest oligosaccharide substrate for rCelS, and the hydrolysis rate increased with the substrate chain length. Many of these properties were consistent with those of the cellulosome, indicating a key role for CelS.

Fraction A of armadillo submandibular glycoprotein and its desialylated product as sialyl-Tn and Tn receptors for lectins

Fraction A of the armadillo submandibular glycoprotein (ASG-A) is one of the simplest glycoproteins among mammalian salivary mucins. The carbohydrate side chains of this mucous glycoprotein have one-third of the NeuAc alpha 2-->6GalNAc (sialyl-Tn) sequence and two thirds of Tn (GalNAc alpha-->Ser/Thr) residues. Those of the desialylated product (ASG-Tn) are almost exclusively unsubstituted GalNAc residues (Tn determinant). When the binding properties of these glycoproteins were tested by a precipitin assay with Gal, GalNAc and GlcNAc specific lectins, it was found that ASG-Tn reacted strongly with all of the Tn-active lectins and completely precipitated Vicia villosa (VVL both B4 and mixture of A and B), Maclura pomifera (MPA), and Artocarpus integrifolia (jacalin) lectins. However, it precipitated poorly or negligibly with Ricinus communis (RCA1); Dolichos biflorus (DBA); Viscum album, ML-I; Arachis hypogaea (PNA), and Triticum vulgaris (WGA). The reactivity of ASG-A (sialyl-Tn) was as active as that of ASG-Tn with MPA and less or slightly less active than that of ASG-Tn with VVL-A+B, VVL-B4, HPA, WFA, and jacalin, as one-third of its Tn was sialylated. These findings indicate that ASG-A and its desialylated product (ASG-Tn) are highly useful reagents for the differentiation of Tn, T (Gal beta 1-->3GalNAc), A (GalNAc alpha 1-->3Gal) or Gal specific lectins and monoclonal antibodies against such epitopes.

A sheep hydatid cyst glycoprotein as receptors for three toxic lectins, as well as Abrus precatorius and Ricinus communis agglutinins

The binding properties of a glycoprotein with blood group P1 specificity isolated from sheep hydatid cyst fluid with Gal and GalNAc specific lectins was investigated by quantitative precipitin and precipitin inhibition assays. The glycoprotein completely precipitated Ricinus communis agglutinin (RCA1), Abrus precatorius agglutinin (APA) and Mistletoe toxic lectin-I (ML-I). Only 1.0 microgram of P1 glycoprotein was required to precipitate 50% of 5.1 micrograms ML-I nitrogen. It also reacted well with abrin-a and ricin, precipitating over 73% of the lectin nitrogen added, but poorly or weakly with Dolichos biflorus (DBL), Vicia villosa (VVL, a mixture of A4, A2B2 and B4), VVL-B4, Arachis hypogaea (PNA), Maclura pomifera (MPL), Bauchinia purpurea alba (BPL) and Wistaria floribunda (WFL) lectins. When an inhibition assay in the range of 5.1 micrograms N to 5.9 micrograms N of lectins (ML-I, abrin-a; ricin, RCA1, and APA, and 10 micrograms P1 active glycoprotein interaction was performed; from 76 to 100% of the precipitations were inhibited by 0.44 and 0.52 mumol of Gal alpha 1-->4Gal and Gal beta 1-->4GlcNAc, respectively, but not or insignificantly with 1.72 mumol of GlcNAc. The Gal alpha 1-->4Gal disaccharide found in this P1 active glycoprotein is a frequently occurring sequence of many glycosphingolipids located at the surface of mammalian cell membranes, especially human erythrocytes and intestinal cells for ligand binding and microbial toxin attachment. The present finding suggests that the Gal alpha 1-->4Gal beta 1-->4GlcNAc sequence in this P1 active glycoprotein is one of the best glycoprotein receptors for three toxic lectins (ricin, abrin-a, and ML-I) as well as for APA, and RCA1, and the result of inhibition assay implies that these lectins are recognizing part or all of the Gal alpha 1-->4Gal beta 1-->4GlcNAc sequence in the P1 active glycoprotein.

Multilineal hematopoiesis in a three-dimensional murine long-term bone marrow culture

The highly packed cell density and the three-dimensional structure in the hematopoietic compartment of bone marrow facilitate cell-to-cell and cell-to-matrix interactions known to be important for hematopoietic activities. To provide a similar environment in vitro, we developed a long-term bone marrow culture (LTBMC) system, continuously perfused with Dexter's medium, employing packed, highly porous bovine collagen microspheres as the matrix support for marrow cell growth. Using murine bone marrow as a model, we found that the culture system differed from the conventional flask culture in the following ways: 1) as revealed by the electron microscopy, the bone marrow cells in the culture system grew in a three-dimensional configuration, similar to that in vivo, 2) the cell output from the culture system at 37 degrees C was virtually the same as that at 33 degrees C, and 3) in the absence of exogenous growth factors, except those in the serum, the culture system produced lymphoid cells and all stages of committed cells (i.e., erythrocytes, granulocytes, macrophages, and megakaryocytes), thus indicating multilineal differentiation of the hematopoietic stem cells. Furthermore, cell clusters resembling erythroblastic islands were observed in the absence of exogenous erythropoietin (Epo). The culture system appears to provide a different microenvironment than that of the flask culture and may be used as an alternative model for hematopoiesis.

A fluorescence quench and dequench assay of fibrinogen polymerization, fibrinogenolysis, or fibrinolysis

We present a kinetic assay based on the use of fluorescein isothiocyanate (FITC)-labeled fibrinogen as a fluoroactive substrate. The multiple FITCs bound to fibrinogen experienced quenching due to their close proximity. The thrombin-induced polymerization of FITC-fibrinogen led to additional fluorescence quenching due to enhanced neighbor-neighbor interactions in protofibrils and protofibril aggregates. The initial rate of quenching was directly dependent on the thrombin concentration at either low or high ionic strength. The final extent of quenching during polymerization with thrombin could be modulated by prevailing ionic strength and thrombin concentration suggesting that the quenching was due to fibril extension as well as aggregation. The full extent of quenching was greatly reduced by addition to the reaction of unlabeled fibrinogen or Gly-Pro-Arg-Pro, as expected for quenching due to neighbor-neighbor interactions. In contrast to polymerization, cleavage of fibrinogen by plasmin released FITC-labeled fragments free of proximity-based quenching that resulted in a large intensity increase as lysis proceeded--a process termed dequenching. The majority of the dequenching signal during fibrinogenolysis occurred during the generation of fragment X which proceeded as a first-order process with respect to fibrinogen-bound plasmin with kcat = 0.479 s-1. The Kd of active plasmin to fibrinogen was calculated to be 0.42 microM. Addition of epsilon-aminocaproic acid (epsilon ACA)-plasmin complex to FITC-fibrinogen produced little dequenching, demonstrating a requirement for binding in order to initiate lysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Cloning and expression of the Clostridium thermocellum celS gene in Escherichia coli

Clostridium thermocellum ATCC 27405 produces an extremely complicated multi-component cellulase aggregate (cellulosome) highly active on crystalline cellulose. From the cellulosome, two subunits, CelS (or Ss; M(r) = 82,000) and CelL (or SL, CipA; M(r) = 250,000), have been identified as essential for crystalline cellulose degradation [Wu et al. (1988) Biochemistry 27:1703]. We have determined the DNA sequence of the celS gene from four cloned DNA fragments encompassing this gene [Wang et al. (1993) J Bacteriol 175:1293]. To express the entire celS gene in Escherichia coli, the celS structural gene was amplified by the polymerase chain reaction (PCR) employing the PCR primers corresponding to sequences flanking the desired gene. This PCR product (2.1 x 10(3) bases; 2.1 kb) was cloned into an E. coli expression vector pRSET B. Subsequent expression of the cloned gene resulted in a fusion protein (rCelS; M(r) = 86,000) as inclusion bodies. The rCelS protein was recognized specifically by an anti-CelS antiserum in a Western blot analysis. The inclusion bodies were purified and solubilized in 5 M urea. The refolded rCelS produced very little reducing sugar from carboxymethylcellulose. However, it showed a higher activity on the crystalline cellulose (Avicel) and an even higher activity on phosphoric-acid-swollen Avicel. These results indicate that the CelS is an exoglucanase.

The biotin/avidin-mediated microtiter plate lectin assay with the use of chemically modified glycoprotein ligand

The conditions of a simple and sensitive microtiter plate lectin assay with biotinylated TF- and/or Tn-reactive lectins and ExtrAvidin/alkaline phosphatase conjugate are described. As ligand for lectin binding, chemically modified glycophorin A from human erythrocytes was used. The TF and Tn receptors present in glycophorin A in cryptic form were exposed by desialylation under mild acidic conditions (TF) and by removing galactose residues from asialoglycophorin by Smith degradation (Tn). These modifications can be performed either in solution or on the plate coated with untreated glycophorin. It was demonstrated with six lectins that their biotinylation via lectin amino groups gave products of higher binding activity than biotinylation via periodate-oxidized carbohydrate residues of lectins. The first step in the binding assay requires the selection of the proper concentration of the glycoprotein used for coating the plate, since the lectins tested showed a maximal binding at an optimal glycophorin concentration, and in many cases the binding was distinctly lower when a higher ligand concentration was used for coating. The inhibition of binding of Tn-reactive lectins to plates coated with asialo-agalactoglycophorin (Tn antigen) was performed using low- and high-molecular-weight inhibitors (1-2 micrograms lectin was used for each inhibition curve) and concentrations of inhibitors required for 50% inhibition of lectin binding were compared. The results were in agreement with the known specificity of the lectins tested. In conclusion, the method described is simple, sensitive, and versatile, enabling the characterization of lectin specificity with a broad spectrum of inhibitors using microgram quantities of lectin only.

Transport phenomena and clot dissolving therapy: an experimental investigation of diffusion-controlled and permeation-enhanced fibrinolysis

We have investigated the effects of diffusive and convective transport on fibrinolysis. Using a constant pressure drop (delta P/L) from 0 to 3.7 mmHg/cm-clot to drive fluid permeation, various regimes of lytic agents were delivered into fine and coarse fibrin gels (3 mg/ml) and whole blood clots. Using plasmin (1 microM) delivered into pure fibrin or urokinase (1 microM) delivered into glu-plasminogen (2.2 microM)-laden fibrin, the velocity at which a lysis front moved across fibrin was greatly enhanced by increasing delta P/L. Lysis of fine and coarse fibrin clots by 1 microM plasmin at delta P/L of 3.67 and 1.835 mmHg/cm-clot, respectively, led to a 12-fold and 16-fold enhancement of the lysis front velocity compared to lysis without pressure-driven permeation. For uPA-mediated lysis of coarse fibrin at delta P/L = 3.67 mmHg/cm-clot, the velocity of the lysis front was 25-fold faster than the lysis front velocity measured in the absence of permeation. Similar permeation-enhanced phenomenon was seen for the lysis of whole blood clots. Without permeation, the placement of a lytic agent adjacent to a clot boundary led to a reaction front that moved at a velocity dependent on the concentration of plasmin or uPA used. Overall, these studies suggest that transport phenomena within the clot can play a major role in determining the time needed for reperfusion during fibrinolysis.

Increased frequency of apolipoprotein B signal peptide sp24/24 in patients with coronary artery disease. General allele survey in the population of Taiwan and comparison with Caucasians

Apolipoprotein B (apoB) signal peptide (sp) polymorphism was characterized by polymerase chain reaction in blood samples of 58 coronary artery disease (CAD) patients and 319 control individuals of Chinese Han ethnic origin in Taiwan. In the CAD group, 77% of the observed alleles were sp27 (sp with 27 amino acids), and the remaining 23% sp24 (sp with 24 amino acids). The frequency distributions of the apoB sp allele in the control group were 0.81 for sp27 and 0.19 for sp24. The genotype distributions were 0.64 sp27/27, 0.26 sp27/24 and 0.10 sp24/24 in the CAD group; 0.64 sp27/27, 0.33 sp27/24 and 0.03 sp24/24 in the control group. The frequency of sp24/24 was significantly higher (p = 0.012) in the CAD group than in the control group. Several studies have shown that the frequency of sp24/24 is higher in hyperlipidemic than in normolipidemic groups. This marker is probably in linkage disequilibrium with some other atherogenic genes. Our study shows that the differences in both apoB signal peptide alleles and sp27/27 and sp27/24 genotype distributions are statistically significant between the Taiwanese and Caucasians.

Interaction of hamster submaxillary sialyl-Tn and Tn glycoproteins with Gal, GalNAc and GlcNAc specific lectins

Hamster submaxillary glycoprotein (HSM), one of the simplest glycoproteins among mammalian salivary mucins, is composed of approximately equivalent amounts of protein, hexosamine and sialic acid. The Thr and Ser residues in the protein core account for more than half of all of the amino acid residues, while Lys, Glu, Pro and Ala are the major components of the remaining portion of amino acids. The carbohydrate side chains of this mucous glycoprotein have mainly the NeuAc-GalNAc-(sialyl-Tn) sequence (HSM), and those of the desialylated product (HSM-Tn) are almost exclusively unsubstituted GalNAc residues (Tn determinants). The binding properties of sialyl-Tn (HSM) and asialo-HSM (HSM-Tn) glycoproteins were tested by precipitin assay with Gal, GalNAc and GlcNAc specific lectins. The HSM-Tn completely precipitated Vicia villosa (VVL both B4 and mixture of A and B), Maclura pomifera (MPL), and Artocarpus integrifolia (Jacalin) lectins; less than 2 micrograms of HSM-Tn were required for precipitating 50% of 5.0-6.3 micrograms lectin nitrogen added. HSM-Tn also reacted well with Helix pomatia lectin (HPL), Wistaria floribunda lectin (WFL) and Abrus precatorius agglutinin (APA) and precipitated in each case over 81% of the lectin nitrogen added. The reactivity of HSM-Tn with other lectins (Ricinus communis, RCA1; Dolichol biflorus, DBL; Viscum album, ML-I; Arachis hypogaea, PNA, and Triticum vulgaris, WGA) was weak or negligible. The activity of sialyl-Tn (HSM) was more restricted; HSM reacted well with Jacalin, moderately with MPL and VVL-B4, but was inactive or only weakly with the other lectins used. These findings indicate that HSM and its desialylated product (HSM-Tn) are highly useful reagents for the differentiation of Tn and T/Gal specific lectins and for anti-T, Tn and Af monoclonal antibodies.

Product-activation of Escherichia coli membrane-bound H(+)-ATPase (F1F0-ATPase) connected with epsilon-subunit at alkaline pH

Mutant strain AN1518 or AN2387 (Gly48-->Asp in epsilon-subunit) and partial revertant strain AN2540 (Gly48-->Asp, Pro47-->Ser in epsilon-subunit) of E. coli were used in a kinetic study of membrane-bound H(+)-ATPase. It was found that at pH 9.0 mutant strain AN1518 or AN2387 and partial revertant strain AN2540 gave a low initial rate, which increased with time until linearity was reached after 1-2 min. This phenomenon was prominent in mutant strains, but was not so obvious in wild-type AN346 of E. coli; this property is similar to F1-ATPase reported by Cox [1]. The mechanism of the slow activation of membrane-bound H(+)-ATPase was further investigated in this paper. The experimental results indicated that the hydrolytic rate of E. coli F1F0-ATPase that increased with time was membrane protein concentration- and pH-dependent, and that the product ADP produced during ATP hydrolysis is the factor causing the slow activation. Preincubation of the hydrolytic product ADP with a concentration comparable to that produced in the assay (20 microM) caused initial activation of ATP hydrolysis and abolished the slow activation. On the other hand, with the removal of ADP during the progress of the hydrolytic reaction it could be seen that the slow activation was abolished as well. In order to test the relationship between the epsilon-subunit and ADP involved in the slow activation, trypsin treatment was carried out on the membrane-bound H(+)-ATPase of various strains. The activation observed after trypsin treatment was on the order of AN1518 > AN2540 > AN346. The activation effects of ADP and trypsin were not found to be additive. This implies that ADP acted in a similar way to trypsin, i.e., to cause removal of the epsilon-subunit. A tentative mechanism of the slow activation was proposed that ADP, a product of ATP hydrolysis, could induce conformational changes of F1F0 at alkaline pH 9.0, thus weakening the binding strength between the epsilon-subunit and other subunits of F1F0, and resulting in removal or partial removal of the epsilon-subunit. This further impaired the coupling of F1 and F0 in the mutant strains; as a consequence the rate of ATP hydrolysis was increased.

[Study on the influence of enzymatic digestion upon tumor-infiltrating lymphocytes]

To get a long-term culture of tumor-infiltrating lymphocytes (TILs) is very difficult. The authors have investigated some suitable enzymes, their digestive conditions such as time and temperature, which may influence the viability and cytotoxicity of TILs. The results showed that collagenase II and IV could keep viability of TILs much longer than those treated with trypsin or hyaluronidase. The digestion with collagenase II or IV at 4 degrees C for 24 hours was much less damage to viability of TILs than those treated at 37 degrees C for one hour. The TILs, which digested at 4 degrees C for 24 hours, still had cytotoxicity against autologous tumor cells as long as sixty to seventy-five days.

Interaction of a novel Tn (GalNAc alpha 1-->Ser/Thr) glycoprotein with Gal, GalNAc and GlcNAc specific lectins

A naturally occurring Tn glycoprotein (Native ASG-Tn) with GalNAc alpha 1-->Ser/Thr as the only carbohydrate side chains, has been prepared from armadillo submandibular glands. In a quantitative precipitin assay, this glycoprotein completely precipitated Maclura pomifera (MPA), Vicia villosa B4 (VVL-B4) and Artocarpus integrifolia (Jacalin, AIL). It also reacted well with Helix pomatia (HPL) and Wistaria floribunda (WFL) and precipitated over 75% of the lectin nitrogen added, but poorly with Ricinus communis agglutinin (RCA1), ricin, peanut (Arachis hypogaea, PNA), Abrus precatorius agglutinin (APA) and Triticum vulgaris (WGA). This finding suggests that this novel Tn-glycoprotein may serve as a useful reagent for differentiating Tn and T specific monoclonal antibodies and lectins.

Effects of hyaluronan on collagen fibrillar matrix contraction by fibroblasts

Hyaluronan, found in high concentrations in fetal tissues, appears to have a major role in preventing scar formation in fetal wounds. Nevertheless, its role in inhibiting wound contractures associated with scar formation has not been clearly demonstrated. Our current study evaluated the effects of hyaluronan using an in vitro floating collagen fibrillar matrix (CFM) contraction model. The results demonstrated that the contraction of CFM by fibroblasts was significantly reduced when high concentrations (> 1 mg/mL) of hyaluronan were present in the media. This phenomenon is unique to hyaluronan, because chondroitin sulfate was ineffective in this connection. Fibroblast migration and proliferation studies indicated that high concentrations of hyaluronan stimulated cell migration and had no cytotoxic effects. Some possible mechanisms by which high concentrations of hyaluronan reduced CFM contraction by fibroblasts were proposed. Because the viscosity of a hyaluronan solution is much greater than that of chondroitin sulfate, and this increases with concentration, we investigated whether this property in itself was an important factor in inhibiting CFM contraction. No direct correlation was found between the viscosity of glycosaminoglycans and their ability to reduce CFM contraction.

Characterization of binding sites of a memory-enhancing peptide AVP(4-8) in rat cortical synaptosomal membranes

The pentapeptide pGlu-Asn-Cyt-Pro-Arg [AVP(4-8), termed ZNC(C)PR in this article] has been found as a metabolite of arginine-vasopressin (AVP) in rat brain and has been shown to have potent memory-enhancing activity and to yield a series of biochemical events in brain tissues. [35S]ZNC(C)PR was chemically synthesized with high specific activity (232 Ci/mmol), and specific binding sites for ZNC(C)PR were located in synaptosomal membrane preparations of rat brain. We identified a specific binding site for ZNC(C)PR with a Kd of 3.12 nM and Bmax of 31 fmol/mg protein in anterior cortical synaptosomal membranes in the presence of 5 mM Ni2+. A comparison of synthetic analogues of ZNC(C)PR competing with [35S]ZNC(C)PR for binding to anterior cortical receptor are presented. ZDC(C)PR, a 2-aspartyl substitute of the 2-asparaginyl residue in ZNC(C)PR, had the most potent competition, but AVP did not show significant ability to compete for the receptor with ZNC(C)PR.

Longevity-determining genes in Caenorhabditis elegans: chromosomal mapping of multiple noninteractive loci

We have used chromosome mapping with polymorphic markers to define genetic components governing life span in the nematode Caenorhabditis elegans. A complex recombinant-inbred population was derived from an interstrain cross, yielding > 1000 genotypes, each a composite of homozygous segments from the two parental strains. Genotypes were analyzed for the last-surviving 1-5% of worms in aging cohorts, and for young controls, by multiplex polymerase chain reaction using polymorphic markers to distinguish the parental alleles. We identified five regions of the genome at which one parental allele was significantly enriched in long-lived subpopulations. At four of five loci, the same alleles were selected in aging cohorts maintained under two different conditions, implying that these genes determine life span in differing environments.

Structural features of the Clostridium thermocellum cellulase SS gene

The Clostridium thermocellum cellulase SS is a subunit of the extracellular cellulase complex (cellulosome). It has previously been shown that SS, hydrolyzes crystalline cellulose synergistically with another subunit, SL. To study this synergism further, the authors cloned the gene coding for SS (celS) and compared its sequence to other known cel genes. The celS, although unique in its DNA sequence, has many structural features similar to those found in other cel genes. These features include a ribosome biding site, signal peptide sequence, the existence of a conserved reiterated amino acid sequence, and a palindromic structure downstream from its open reading frame.

DNA polymorphisms of apolipoprotein B in the population of Taiwan

Four apolipoprotein B (apoB) genetic polymorphisms, the AluI, XbaI, MspI and EcoRI restriction fragment length polymorphisms (RFLPs), were analyzed for 162 individuals in Taiwan by polymerase chain reaction. Allele frequency determination revealed that this population has 0.86 AluI- (A-), 0.99 XbaI- (X-), 1.0 MspI+ (M+), and 0.98 EcoRI+ (E+) alleles. Major genotypes were A-/A- (0.75), X-/X- (0.98), M+/M+ (1.0) and E+/E+ (0.96). There were 0.22 A-/A+, 0.02 X-/X+ and 0.04 E+/E- heterozygous genotypes and one minor homozygous A+/A+ (0.03) genotype. The XbaI allele frequency is similar to that found in the Japanese population (XbaI- 0.96), but is significantly different from that in Caucasians (XbaI- 0.31-0.54). Significant differences (p < 0.001) between the Taiwanese and Caucasians were also observed for the AluI, EcoRI and MspI RFLP alleles of the apoB gene. More heterozygous genotypes are observed in Caucasians than in the Taiwanese.

Cloning and DNA sequence of the gene coding for Clostridium thermocellum cellulase Ss (CelS), a major cellulosome component

Clostridium thermocellum ATCC 27405 produces an extracellular cellulase system capable of hydrolyzing crystalline cellulose. The enzyme system involves a multicomponent protein aggregate (the cellulosome) with a total molecular weight in the millions, impeding mechanistic studies. However, two major components of the aggregate, SS (M(r) = 82,000) and SL (M(r) = 250,000), which act synergistically to hydrolyze crystalline cellulose, have been identified (J. H. D. Wu, W. H. Orme-Johnson, and A. L. Demain, Biochemistry 27:1703-1709, 1988). To further study this synergism, we cloned and sequenced the gene (celS) coding for the SS (CelS) protein by using a degenerate, inosine-containing oligonucleotide probe whose sequence was derived from the N-terminal amino acid sequence of the CelS protein. The open reading frame of celS consisted of 2,241 bp encoding 741 amino acid residues. It encoded the N-terminal amino acid sequence and two internal peptide sequences determined for the native CelS protein. A putative ribosome binding site was identified at the 5' end of the gene. A putative signal peptide of 27 amino acid residues was adjacent to the N terminus of the CelS protein. The predicted molecular weight of the secreted protein was 80,670. The celS gene contained a conserved reiterated sequence encoding 24 amino acid residues found in proteins encoded by many other clostridial cel or xyn genes. A palindromic structure was found downstream from the open reading frame. The celS gene is unique among the known cel genes of C. thermocellum. However, it is highly homologous to the partial open reading frame found in C. cellulolyticum and in Caldocellum saccharolyticum, indicating that these genes belong to a new family of cel genes.

Defining carbohydrate specificity of Ricinus communis agglutinin as Gal beta 1-->4GlcNAc (II) > Gal beta 1-->3GlcNAc (I) > Gal alpha 1-->3Gal (B) > Gal beta 1-->3GalNAc (T)

To define carbohydrate specificity of Ricinus communis agglutinin (RCA1), the combining site of RCA1 was further characterized by quantitative precipitin (QPA) and precipitin-inhibition assays (QPIA). Among the oligosaccharides tested for QPIA, Gal beta 1-->4GlcNAc (II, human blood group type II precursor sequence) was found to be 7.1 times more active than Gal beta 1-->3GalNAc (T, Thomsen-Friedenreich sequence) and about 1.7 times more active than the other three disaccharides tested--Gal beta 1-->4Man, Gal beta 1-->3DAra and Gal beta 1-->6GalNAc. Gal alpha 1-->4Gal, the receptor of the uropathogenic E. coli ligand was 3.6 times less active than the II sequence. These results indicate that the beta 1-->4 linkage of the terminal Gal to subterminal GlcNAc is important as this beta 1-->4GlcNAc sequence is at least 1.6 times more active than other types of disaccharides. Among the glycoproteins examined for QPA, native and desialized bovine submandibular glycoproteins, native and desialized human plasma alpha 1-acid glycoproteins, as well as crude hog stomach mucin and its three mild acid hydrolyzed products reacted well with the lectin. These glycoproteins precipitated over 75% of the lectin nitrogen added indicating that RCA1 has the ability to recognize Gal beta 1-->4/3GlcNAc and/or the related residues at the non-reducing ends and at positions in the interior of the chains. However, Tn (GalNAc alpha 1-->Ser/Thr sequence) rich glycoproteins such as desialized ovine submandibular glycoprotein and desialized armadillo salivary glycoprotein, in which over 90% of the carbohydrate side chains are Tn determinants with none or only a trace of I/II or T determinants, precipitated poorly with RCA1. From the present and previous results obtained, the carbohydrate specificity of RCA1 can be constructed and summarized in decreasing order by lectin determinants as follows: II (Gal beta 1-->4GlcNAc) > I (Gal beta 1-->3GlcNAc) > E (Gal alpha 1-->4Gal) and B (Gal alpha 1-->3Gal) > T (Gal beta 1-->3GalNAc), while Tn (GalNAc alpha 1-->Ser/Thr) is a poor inhibitor.

Coronary artery disease risk predicted by plasma concentrations of high-density lipoprotein cholesterol, apolipoprotein AI, apolipoprotein B, and lipoprotein(a) in a general Chinese population

We measured lipid and lipoprotein concentrations in blood samples from control subjects and patients with coronary artery disease (CAD) in Taiwan. We found significant differences (P < 0.01) in the concentrations of high-density lipoprotein cholesterol (HDLC), apolipoprotein AI (ApoAI), apolipoprotein B (ApoB), and lipoprotein(a) [Lp(a)]. Concentrations of HDLC < 350 mg/L, ApoAI < 900 mg/L, ApoB > 800 mg/L, and Lp(a) > 200 mg/L occurred, respectively, 2.8, 5.2, 1.7, and 2.3 times more frequently in the patients than in the control group. If one considers HDLC at < 350 mg/L, ApoAI at < 900 mg/L, ApoB at > 800 mg/L, and Lp(a) at > 200 mg/L as separate risk factors for CAD, the ratio of individual patients to control subjects having 4, 3, 2, 1, or 0 risk factors was [symbol: see text] 9.4, 2.1, 0.2, 0.2, respectively. Individuals displaying three or more risk factors were found 15 times more frequently in the CAD group than in the control group. These risk factors may be used clinically for the prediction and prevention of CAD in the general population.

Coronary artery disease risk predicted by plasma concentrations of high-density lipoprotein cholesterol, apolipoprotein AI, apolipoprotein B, and lipoprotein(a) in a general Chinese population

We measured lipid and lipoprotein concentrations in blood samples from control subjects and patients with coronary artery disease (CAD) in Taiwan. We found significant differences (P &lt; 0.01) in the concentrations of high-density lipoprotein cholesterol (HDLC), apolipoprotein AI (ApoAI), apolipoprotein B (ApoB), and lipoprotein(a) [Lp(a)]. Concentrations of HDLC &lt; 350 mg/L, ApoAI &lt; 900 mg/L, ApoB &gt; 800 mg/L, and Lp(a) &gt; 200 mg/L occurred, respectively, 2.8, 5.2, 1.7, and 2.3 times more frequently in the patients than in the control group. If one considers HDLC at &lt; 350 mg/L, ApoAI at &lt; 900 mg/L, ApoB at &gt; 800 mg/L, and Lp(a) at &gt; 200 mg/L as separate risk factors for CAD, the ratio of individual patients to control subjects having 4, 3, 2, 1, or 0 risk factors was [symbol: see text] 9.4, 2.1, 0.2, 0.2, respectively. Individuals displaying three or more risk factors were found 15 times more frequently in the CAD group than in the control group. These risk factors may be used clinically for the prediction and prevention of CAD in the general population.

Intrathoracic extramedullary hematopoietic tumor in hemoglobin H disease

We report a Chinese patient with hemoglobin H (Hb H) disease who developed intrathoracic extramedullary hematopoiesis (EMH) 17 years following splenectomy for a blunt abdominal injury. The patient initially presented with extreme hyperbilirubinemia and multiple intrathoracic tumors. Hb H disease was diagnosed after investigation, and the marked jaundice, which declined gradually after supportive treatment, was attributed to his chronic hemolysis superimposed on an acute hepatitis C virus infection. A biopsy of the intrathoracic tumors revealed an EMH. Intrathoracic EMH, which is usually encountered in patients with beta-thalassemia and hereditary spherocytosis, has never been reported in Hb H disease. In areas where thalassemia is prevalent, EMH should be considered in the differential diagnosis of patients who have chronic anemia with asymptomatic intrathoracic tumor to avoid unnecessary surgical interventions.

Hair casts: a clinical and electron microscopic study

Hair casts were seen in 22 girls ranging in age from 4 to 13 years. They were localized to the frontal, vertex, and temporal areas. The number of affected hairs varied from one-tenth to one-third. Twenty of the 22 girls styled their hair in ponytails or pigtails. Compound root sheath casts were present in six of nine patients using 1% 4-dimethylaminocinamaldehyde stain. A mass of large polymorphous scales and solitary or clumped spores was seen on the surface of hair casts using scanning and transmission electron microscopy. Energy-dispersive x-ray microanalysis showed that elements of silicon, aluminum, and molybdenum were uniquely present in hair casts. We assume that tightly drawn braids, by causing local circulatory disturbances and inflammation of the scalp, may be one etiologic factor in the disorder.

Characterization of the F-plasmid conjugative transfer gene traU

We characterized the traU gene of the Escherichia coli K-12 conjugative plasmid F. Plasmids carrying segments of the F transfer operon were tested for their capacity to complement F lac traU526. The protein products of TraU+ clones were identified, and the nucleotide sequence of traU was determined. traU mapped between traW and trbC. It encodes a 330-amino-acid, Mr36,786 polypeptide that is processed. Ethanol caused accumulation of a precursor polypeptide; removal of ethanol permitted processing of the protein to occur. Because F lac traU526 strains appear to be resistant to F-pilus-specific phages, traU has been considered an F-pilus assembly gene. However, electron microscopic analysis indicated that the traU526 amber mutation caused only a 50% reduction in F-piliation. Since F lac traU526 strains also retain considerable transfer proficiency, new traU mutations were constructed by replacing a segment of traU with a kanamycin resistance gene. Introduction of these mutations into a transfer-proficient plasmid caused a drastic reduction in transfer proficiency, but pilus filaments remained visible at approximately 20% of the wild-type frequency. Like traU526 strains, such mutants were unable to plaque F-pilus-specific phages but exhibited a slight sensitivity on spot tests. Complementation with a TraU+ plasmid restored the wild-type transfer and phage sensitivity phenotypes. Thus, an intact traU product appears to be more essential to conjugal DNA transfer than to assembly of pilus filaments.

Apolipoprotein B mRNA editing. Validation of a sensitive assay and developmental biology of RNA editing in the rat

Apolipoprotein B (apoB) 48 mRNA is the product of a C----U conversion of the first base of the codon CAA for Gln-2153 in apoB-100 mRNA, changing it to an in-frame stop codon (UAA). Methods for measuring the ratio of apoB-48 to apoB-100 mRNA that have been authenticated with standard mixtures of the two apoB mRNA species have not been described. Using RNA mixtures consisting of known proportions of in vitro transcripts of apoB-100 and apoB-48, we directly compared four different assays. We found that a procedure based on the polymerase chain reaction, cDNA cloning, and oligonucleotide colony hybridization was the most sensitive and accurate assay. Total RNAs isolated from adult rat small intestine, adult liver, Day 15 and term placentas, and term fetal membranes were found to contain apoB mRNA in the following relative amounts: 100, 59.8, 0.9, 6.96, and 1087, respectively. They all contained both apoB-48 and apoB-100 mRNAs, with the former constituting 95.8, 59.2, 4.6, 1.3, and 0.8%, respectively, of the apoB mRNA. We examined the ontogeny of apoB-48 mRNA biogenesis in the liver and intestine in the rat prenatally on Days 17, 19, and 20 of gestation, and postnatally on Days 1, 3, 7, 13, 20, 24, and 37 after birth. Slot-blot hybridization demonstrated that apoB mRNA showed a peak at birth (Days 1-3 in the liver and Days 1-7 in the small intestine) and then decreased on Days 7 (in the liver) and 13 (in the intestine) before it increased again on Day 20 toward the adult level. Quantitation of the ratio of apoB-48 to apoB-100 mRNA at the different time points showed that RNA editing became highly competent prenatally on Day 19 of gestation in the small intestine, but postnatally on Day 24 after birth in the liver. The asynchronous nature for this developmentally regulated process in the liver and small intestine of the rat has implications for the mechanism of RNA editing and lipid homeostasis in this animal.

RNA editing of apolipoprotein B mRNA. Sequence specificity determined by in vitro coupled transcription editing

Apolipoprotein (apo) B-48 mRNA is produced by in vivo RNA editing which involves a C----U conversion of the first base of the codon CAA for Gln-2153, changing it to UAA, an in-frame stop codon. We have reproduced the editing reaction in vitro using nuclear extracts. Efficient RNA editing was demonstrated by using apoB mRNA segments as substrate or in a coupled transcription-editing reaction using apoB minigenes as template. ApoB minigenes were constructed by ligating the adenovirus major late promoter to a fragment of apoB-100 DNA containing the editing site and used for the transcription-editing reaction. We defined the sequence specificity of the editing reaction using site-specific single and multiple base mutants constructed by the polymerase chain reaction. Among 22 different mutant apoB-100 minigene constructs containing mutations in the bases immediately flanking the edited C-6666, 20 were edited in the coupled transcription-editing reaction. The results suggest a relatively lax sequence specificity for apoB mRNA editing. Our observation may have important implications for apoB-48 biogenesis as well as for the editing process as a general biologic regulatory mechanism.

The elastic modular changes of the rat uterine cervix under different physiological conditions

In this paper, the elastic moduli of the rat uterine cervix were measured under different physiological conditions. It was found that the moduli significantly changed with the sex cycle, being higher in diestrus than in estrus, and highest in early pregnancy. The results suggest that active changes occur in the function of the uterine cervix under the modulation of hormones.

Nucleotide sequence of traQ and adjacent loci in the Escherichia coli K-12 F-plasmid transfer operon

The F tra operon region that includes genes trbA, traQ, and trbB was analyzed. Determination of the DNA sequence showed that on the tra operon strand, the trbA gene begins 19 nucleotides (nt) distal to traF and encodes a 115-amino-acid, Mr-12,946 protein. The traQ gene begins 399 nt distal to trbA and encodes a 94-amino-acid, Mr-10,867 protein. The trbB gene, which encodes a 179-amino-acid, Mr-19,507 protein, was found to overlap slightly with traQ; its start codon begins 11 nt before the traQ stop codon. Protein analysis and subcellular fractionation of the products expressed by these genes indicated that the trbB product was processed and that the mature form of this protein accumulated in the periplasm. In contrast, the protein products of trbA and traQ appeared to be unprocessed, membrane-associated proteins. The DNA sequence also revealed the presence of a previously unsuspected locus, artA, in the region between trbA and traQ. The artA open reading frame was found to lie on the DNA strand complementary to that of the F tra operon and could encode a 104-amino-acid, 12,132-dalton polypeptide. Since this sequence would not be expressed as part of the tra operon, the activity of a potential artA promoter region was assessed in a galK fusion vector system. In vivo utilization of the artA promoter and translational start sites was also examined by testing expression of an artA-beta-galactosidase fusion protein. These results indicated that the artA gene is expressed from its own promoter.

HLA and Chinese IgA nephropathy in Taiwan

No HLA-A, B, C, DR, DQ association was found in 80 Chinese IgA nephropathy patients. In addition, no prognostic genetic marker was discovered. The subgroup of those with gross hematuria was immunogenetically distinct from the subgroup of those without gross hematuria.

Fetal sex identification and prenatal bonding

This study explored the relation between expectant parents' knowledge of fetal sex and their attachment to their fetuses. During a routine 18-wk. prenatal visit, 126 expectant couples from an HMO population independently completed a background questionnaire and Fetal Attachment Scales of Cranky. During a routine 34-wk. obstetrical ultrasound examination those who chose to know were informed of the fetal sex. Total attachment scales were readministered during the 37th week. Parents' sex, knowledge of fetal sex, and the passage of time significantly affected attachment scores. Both parents' scores increased over time. Mothers' scores increased at a greater rate than the fathers'. Those parents who knew the fetal sex had significantly lower scores than those who did not. Whether the sex of the fetus was the preferred sex was nonsignificant. Results were derived from a double multivariate analysis of variance which controlled the within-couple and within-subject effects.

The product of the F plasmid transfer operon gene, traF, is a periplasmic protein

The products of clones carrying the F plasmid transfer operon gene, traF, were analyzed. Proteins expressed in maxicells were labeled with [35S]methionine and examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Clones carrying the wild-type traF gene expressed two polypeptide products that were not products of clones containing the traF13 amber mutation. These migrated with apparent molecular weights (Ma) of 27,000 and 25,000. A pulse-chase experiment suggested that the larger product was a precursor of the smaller one. In the presence of ethanol, the Ma-27,000 polypeptide accumulated and the Ma-25,000 product was not expressed. These results indicated that the traF protein undergoes proteolytic processing associated with export. Cell fractionation experiments further indicated that the greatest concentration of the mature (Ma 25,000) TraF protein was located in the periplasm. The DNA sequence of traF and the position of the transition mutation in traF13 DNA were also determined. Sequence analysis suggested that traF would be expressed as a 247-amino-acid, Mr-28,006 polypeptide. The 19 amino acids at the amino terminus of this polypeptide appear to constitute a typical membrane leader peptide, while the remainder of the molecule (Mr 25,942) is predicted to be primarily hydrophilic in character.

Metabolic changes in women using a long-acting monthly oral contraceptive and return of ovulation on discontinuation

Metabolic changes were investigated in two groups of women using oral contraceptives for 5 to 16 years. Blood samples were taken during the last cycle of oral contraceptive use and three months post-treatment. One group had used a monthly oral contraceptive (MOC, 3mg quinestrol and 10mg 16-methylene chlormadinone acetate) and the second group a daily oral contraceptive (DOC, 35 micrograms ethynylestradiol and 0.625 mg norethisterone). During treatment there were increases in serum total cholesterol and triglycerides but not HDL-C, in plasma total cortisol but not in renin activity, angiotensin II or urinary free cortisol excretion, in hemoglobin and some coagulation factors but not Factor X or antithrombin III, platelet function or fibrinolysis. The area under the blood glucose concentration-time curve, but not that for serum insulin, was slightly increased and there was no change in fasting blood sugar concentrations. All metabolic parameters, except plasma cortisol, which had shown an increase on treatment, had decreased to control levels within 3 months. Ovulation returned promptly in all women, the mean time being 70 days for Group MOC and 44 days for Group DOC. Thus, in spite of the long duration of use of the oral contraceptives, metabolic changes were minor.