[Synthesis of multifunctional surfactants for elaboration of micellar model systems of enzymes]

In order to provide a closer analogy between micelles and enzymes, the design of functionalized micellar systems have been undertaken. This paper presents the synthesis of surfactant cationic molecules which contains either a free or a protected aldehyde group. An ammonium quaternary surfactant with two functional groups, aldehyde dimethyl acetal and imidazole, has also been synthesized.

The solution structure of a cytotoxic ribonuclease from the oocytes of Rana catesbeiana (bullfrog)

RC-RNase is a pyrimidine-guanine sequence-specific ribonuclease and a lectin possessing potent cell cytotoxicity. It was isolated from the oocytes of Rana catesbeiana (bull frog). From analysis of an extensive set of 1H homonuclear 2D NMR spectra we have completed the resonance assignments. Determination of the three-dimensional structure was carried out with the program X-PLOR using a total of 951 restraints including 814 NMR-derived distances, 61 torsion angles, and 76 hydrogen bond restraints. In the resultant family of 15 best structures, selected from a total of 150 calculated structures, the root-mean-square deviation from the average structure for the backbone heavy-atoms involved in well-defined secondary structure is 0.48 A, while that for all backbone heavy-atoms is 0.91 A. The structure of RC-RNase consists of three alpha-helices and two triple-stranded anti-parallel beta-sheets and folds in a kidney-shape, very similar to the X-ray crystal structure of a homolo gous protein, onconase isolated from Rana pipiens. We have also investigated the interaction between RC-RNase and two inhibitors, cytidylyl(2'-->5')guanosine (2',5'-CpG) and 2'-deoxycytidylyl(3'-->5')-2'-deoxyguanosine (3',5'-dCpdG). Based on the ligand-induced chemical shift changes in RC-RNase and the NOE cross-peaks between RC-RNase and the inhibitors, the key residues involved in protein-inhibitor interaction have been identified. The inhibitors were found to bind in a "retro-binding" mode, with the guanine base bonded to the B1 subsite. The His103 residue was found to occupy the B state with the imidazole ring pointing away from the active site. The structure coordinates and the NMR restraints have been deposited in the Brookhaven Protein Data Bank (1bc4 and 1bc4mr, respectively).

Multinuclear NMR resonance assignments and the secondary structure of Escherichia coli thioesterase/protease I: a member of a new subclass of lipolytic enzymes

Escherichia coli thioesterase/protease I is a 183 amino acid protein with a molecular mass of 20,500. This protein belongs to a new subclass of lipolytic enzymes of the serine protease superfamily, but with a new GDSLS consensus motif, of which no structure has yet been determined. The protein forms a tetramer at pH values above 6.5 and exists as a monomer at lower pH values. Both monomer and tetramer are catalytically active. From analysis of a set of heteronuclear multidimensional NMR spectra with uniform and specific amino acid labeled protein samples, we have obtained near-complete resonance assignments of the backbone 1H, 13C and 15N nuclei (BMRB databank accession number 4060). The secondary structure of E. coli thioesterase/protease I was further deduced from the consensus chemical shift indices, backbone short- and medium-range NOEs, and amide proton exchange rates. The protein was found to consist of four beta-strands and seven alpha-helices, arranged in alternate order. The four beta-strands were shown to form a parallel beta-sheet. The topological arrangement of the beta-strands of -1x, +2x, +1x appears to resemble that of the core region of the alpha beta hydrolase superfamily, typically found in common lipases and esterases. However, substantial differences, such as the number of beta-strands and the location of the catalytic triad residues, make it difficult to give a definitive classification of the structure of E. coli thioesterase/protease I at present.

Differentiating turkey postvaccination isolants of Pasteurella multocida using arbitrarily primed polymerase chain reaction

The chromosomal DNA of 29 field isolants of Pasteurella multocida from commercial turkey farms in Missouri and the avirulent Clemson University (CU) and M-9 vaccine strains of P. multocida were tested using the arbitrarily primed polymerase chain reaction (AP-PCR) in combination with 32P-labeled deoxycytidine triphosphate (dCTP) and high-resolution gel electrophoresis. The 29 field isolants of P. multocida were isolated from outbreaks of fowl cholera in turkey flocks in which vaccination with the CU vaccine had been performed within 2 weeks of the isolation, and it was suspected that the outbreak could have been due to the use of the live CU vaccine. The results of this study showed that: 1) the use of the live CU vaccine can lead to the isolation of the vaccine strain if the outbreak occurs within 2 weeks of vaccination; 2) a higher proportion of field isolants collected during 1983 and 1984, when the usage of the CU vaccine strain was highest on Missouri turkey farms, had PCR-amplified product profiles similar or identical to those of the CU vaccine strain compared with the period between 1987 and 1992, when its use was less; and 3) there was no relationship between the PCR-amplified product profiles and the serotype.

pH measurement of root canal sealers

The purpose of this study was to compare the surface pH level of three different type sealers after mixing at various time intervals in vitro. The cements were mixed according to the manufacturer's instructions. They were incubated to set in 100% humidity at 37 degrees C for 1 h, 24 h, 5 days, 8 days, 2 wk, 3 wk, 4 wk, 5 wk, and 7 wk. pH was calculated by a Twin pH meter. The pH levels of the three sealers were different at various time intervals (p < 0.0001). The resin-based cement had a acid pH level (pH < 7.0). The calcium hydroxide-based cement showed a higher alkalinity pH level (pH > 7.0). The zinc oxide-eugenol-based cement showed a similar pH level to the calcium hydroxide cement at the end of the measurement. We postulated that, in endodontic therapy when those healing is needed, the alkaline-based sealer is the choice.

Fibrillogenesis of Alzheimer Abeta peptides studied by fluorescence energy transfer

Pathogenesis of Alzheimer's disease is associated with the polymerization of the Abeta peptide into fibrils that accumulate to form plaques. One strategy for therapy is the targeting of inhibitors against fibrillogenesis; however, prior to the formulation of specific tactics, a thorough understanding of the polymerization mechanism is essential. We have applied the principle of fluorescence energy transfer to monitor fibrillogenesis. In theory, this method is capable of measuring fibrillogenesis at physiological concentrations of peptide. Using this assay, we have determined that: fibril formation by Abeta(9-25) is reversible and cooperative, there are two imidazole-carboxylate salt bridges per monomer, monomers are in free exchange with fibrils, and the exchange process displays measurable kinetics.

Identification of DNA methylation markers for human breast carcinomas using the methylation-sensitive restriction fingerprinting technique

We have developed a PCR-based method, called methylation-sensitive restriction fingerprinting (MSRF), to screen changes in DNA methylation in breast carcinomas. Two hypermethylation-containing fragments, HBC-1 (for "hypermethylation in breast cancer") and HBC-2, were identified in the amplified breast tumor DNA relative to the amplified normal breast DNA of a patient. Nucleotide sequence analysis revealed no significant matches between the sequence of HBC-1 and the known sequences in the GenBank database, whereas the sequence of HBC-2 matched the upstream region of an antisense WT1 (Wilms' tumor suppressor gene) promoter. The methylation status in the breast tumor DNA from this patient was confirmed by Southern hybridization using HBC-1 and HBC-2 as probes, respectively. Further analysis showed that HBC-1 was methylated aberrantly in 90% (17 of 19 patients) of the primary breast carcinomas examined. This study demonstrates that MSRF provides a useful means for screening aberrant changes in DNA methylation during tumorigenesis. The commonly methylated fragments identified by MSRF could potentially supplement pathological markers currently used for cancers and additionally lead to the discovery of novel methylated tumor suppressor genes.

The arc index in evaluation of Class III malocclusion

Lateral cephalometric radiographs were obtained for 46 individuals (18 men and 28 women) aged 20 to 30 years. The sample consisted of Taiwanese with Class III malocclusions and prognathic facial profiles. A modification of the Sassouni arch analysis was used to evaluate this group. All parameters were compared with the norms for adult Taiwanese. The facial pattern of the Class III group was similar to that reported in other studies. The maxilla was in a retrusive position; the lengths of the maxilla and the mandible were significantly different from those in the normal group; the mandibular central incisor was retroinclined; and the total gonial angle, upper gonial angle, and lower gonial angle in the Class III group were significantly different from those angles in the normal group in both sexes. The arc index represented the maxillomandibular positional relationship. There was a statistically significant difference between the mean arc indexes of the Class III and the normal groups. The results indicated that the more negative the arc index, the greater the Class III tendency.

Dynamics of trimethoprim bound to dihydrofolate reductase--a deuterium NMR study

We have employed deuterium NMR techniques to determine the dynamics of trimethoprim (TMP) in a binary complex with dihydrofolate reductase (DHFR) or in a ternary complex with DHFR and cofactor NADP+ in the fully hydrated state. TMP was deuterated at the following positions: (2',6'-D2)TMP, (3'-Ome-D3)TMP and (3',4'-Ome-D6)TMP. Dynamics of TMP were deduced from lineshape simulation and relaxation measurements of the deuterium NMR powder spectra of the three samples obtained at various temperatures. The results showed that in the polycrystalline state the TMP molecule is very rigid. The only detectable motion is the methyl group rotation at a rate of 10(10) s-1 at 25 degrees C, as determined from simulation of the partially relaxed powder patterns. When bound to DHFR a residual deuterium quadrupole splitting of 140 kHz was observed for (2',6'-D2)TMP at temperatures up to 30 degrees C, suggesting that the benzyl ring in the bound state is also very rigid. In contrast, in the binary complex with DHFR the methoxyl groups of TMP undergo librational motion of 10(7) s-1 about the C3-O bond at an amplitude of 54 degrees for the meta methoxyl group and about the C4-O bond at an amplitude of 70 degrees and similar rate for the para methoxyl group at 30 degrees C. The presence of the cofactor, NADP+, appears to tighten up the binding pocket such that the motion freedom of TMP is more restricted. The rigidity of TMP in a protein complex as revealed by our deuterium NMR results is in accord with the tight binding of TMP to DHFR.

Repression by a differentiation-specific factor of the human cytomegalovirus enhancer

We detected a novel nuclear protein, MRF, that binds to multiple sites on the modulator which is located upstream of the human cytomegalovirus major immediate early gene enhancer. The expression of MRF is differentiation specific; the DNA binding activity is present in nuclear extracts from undifferentiated Tera-2 and THP-1 cells, but significantly reduced after these cells are induced to differentiate. In undifferentiated cells the enhancer activity is repressed by the modulator and upon differentiation the enhancer becomes active. Competitive binding assays demonstrate that MRF requires the presence of multiple A+T stretches for binding to DNA, rather than binding to a specific DNA sequence. Mutations of these stretches in the modulator reduce the binding activity of MRF, as well as the repressing activity on the enhancer. These results suggest that MRF may act as a repressor of enhancer function. We propose that MRF binds over the entire modulator and exerts repressor activity.

Structural analysis of a biologically active echistatin analogue des(46-49)-[Ala8,37]-echistatin gamma with three disulfide bonds by 2D-NMR and computer graphics

An echistatin analogue, designated as des(46-49)-[Ala8,37]-echistatin gamma, was synthesized chemically by solid-phase peptide synthesis. The analogue was made by replacing Cys8 and Cys37 residues with two alanines and the deletion of C-terminal peptide 46-49 of echistatin gamma, resulting in an artificial polypeptide of 45 amino acids with three disulfide bonds. In the platelet aggregation assay, the analogue exhibits almost the same activity as echistatin gamma, indicating that the linear sequence of des(46-49)-[Ala8,37]-echistatin gamma contains all of the primary-structure information that is required for proper folding of this synthetic polypeptide. The tertiary structure of the analogue, as determined from high-resolution nuclear magnetic resonance (NMR) coupled with dynamic simulated annealing, is very similar to that of echistatin alpha1 which differs from echistatin gamma by 8 residues. In particular the two important sites of the Arg-Gly-Asp (RGD) loop and the C-terminal Lys45, both of which show some degree of disorder, are maintained in similar spatial orientation and proximity as those in echistatin alpha 1 even without the constraint provided by the disulfide bond of the (Cys8-Cys37) pair. These results provide new insights in further defining distinct structural features of echistatin gamma, which are involved in supporting the active polypeptide conformation to achieve biological activity in the absence of one pair of disulfide bonds.

Characterization of the structure and melting behavior of the loop I fragment of ColE1 RNA I

We have synthesized two RNA fragments: a 42-mer corresponding to the full loop I sequence of the loop I region of ColE1 antisense RNA (RNA I), plus three additional Gs at the 5'-end, and a 31-mer which has 11 5'-end nucleotides (G(-2)-U9) deleted. The secondary structure of the 42-mer, deduced from one- and two-dimensional NMR spectra, consists of a stem of 11 base-pairs which contains a U-U base-pair and a bulged C base, a 7 nucleotide loop, and a single-stranded 5' end of 12 nucleotides. The UV-melting study of the 42-mer further revealed a multi-step melting behavior with transition temperatures 32 degrees C and 71 degrees C clearly discernible. In conjunction with NMR melting study the major transition at 71 degrees C is assigned to the overall melting of the stem region and the 32 degrees C transition is assigned to the opening of the loop region. The deduced secondary structure agrees with that proposed for the intact RNA I and provides structural bases for understanding the specificity of RNase E.

Assignment of the human fast skeletal troponin T gene (TNNT3) to chromosome 11p15.5: evidence for the presence of 11pter in a monochromosome 9 somatic cell hybrid in NIGMS mapping panel 2

Human fast skeletal troponin T (TnTf), the tropomyosin binding component of the multisubunit troponin complex, plays an important role in the Ca2+ regulation of striated muscle contraction. Specific primers designed from the 3' end of human TnTf cDNA were used to amplify an intronic region by polymerase chain reaction (PCR). This TnTf-specific PCR product was detected from two somatic cell hybrids containing human chromosomes 9 and 11, respectively, in NIGMS mapping panel 2. However, further studies with other somatic hybrid cell lines (Bios Laboratory) localized the TnTf gene (HGMW-approved symbol TNNT3) only to chromosome 11. This observation was further confirmed by fluorescence in situ hybridization with a 12-kb TnTf genomic probe generated by extended PCR, showing the sublocalization of the gene to band p15.5 on chromosome 11. This locus is of specific interest, as Beckwith-Wiedemann syndrome and various childhood and adult tumor-related abnormalities have been mapped to this region. The study also indicates the presence of an 11pter region in the NIGMS cell hybrid GM10611, which has previously been reported to contain only human chromosome 9.

Determination of three-dimensional solution structure of waglerin I, a toxin from Trimeresurus wagleri, using 2D-NMR and molecular dynamics simulation

The solution conformation of a synthetic snake venom toxin waglerin I, has been determined by using proton nuclear magnetic resonance spectroscopy. By a combination of various two-dimensional NMR techniques, the 1H-NMR spectrum of waglerin I was completely assigned. A set of 247 interproton distance restraints was derived from nuclear Overhauser enhancement (NOE) measurements. These NOE constraints, in addition to the 2 dihedral angle restraints (from coupling constant measurements) and 7 omega torsion angel restraints for prolines, formed the basis of three-dimensional structure determined by molecular dynamics techniques. The 19 structures that were obtained satisfy the experimental restraints, and display small deviation from idealized covalent geometry. Analysis of converged structures indicates that the toxin has no special secondary structure. In the solution structure of waglerin I, the central ring region is well defined but the N- and C-termini possesses more disorder.

Generation Times and Modeling of Enterotoxin-Positive and Enterotoxin-Negative Strains of Clostridium perfringens in Laboratory Media and Ground Beef

The growth of two enterotoxin-positive (ent⁺) and two enterotoxin-negative (ent^-) strains of Clostridium perfringens were examined in two laboratory media, fluid thioglycollate and fluid thioglycollate with beef, and in autoclaved ground beef stored at 37, 41, 43, 46, and 48°C. There was no association between enterotoxigenicity and optimum growth temperature, which varied depending on strain and medium. Experimentally obtained values for generation times at 43°C were as low as 8.7 and 6.3 min in thioglycollate both for ent⁺ and ent^- strains respectively. In autoclaved ground beef the shortest generation times, 7.1 min and 9.2 min, were obtained at 41 and 46°C for two ent⁺ strains. For ent^- strains in autoclaved ground beef a generation time of 6.6 min was observed at 43°C. Temperature optima obtained experimentally were the same as those obtained by the Gompertz model. The rapid growth of the ent⁺ strains between 41 and 46°C underlines previous recommendations for proper holding and cooling of protein foods such as meat and poultry known to support the growth of this organism.

Conformation of the propeptide domain of factor IX

The propeptide domain in the precursor forms of blood clotting proteins contains the recognition sequences for gamma-carboxylase. In hemophilia B, several point mutations in this propeptide domain are responsible for the inherited disease. A peptide containing the propeptide sequence of factor IX was synthesized by solid phase methods. Two dimensional 1H-NMR and CD studies indicate that this peptide motif adopts an alpha-helical structure in a 40% trifluoroethanol-containing aqueous solution. The results suggest that the amphipathic alpha-helix within the propeptide domain of factor IX could create a recognition surface for gamma-carboxylase. The influences of mutations and their relationship with the alpha-helical structure are discussed.

Hypoplastic left heart syndrome with male pseudohermaphroditism and bicornuate uterus bicollis

A 39-week-old phenotypically female infant was born with hypoplastic left heart syndrome and expired on the third day of life. An autopsy revealed the patient to also have male pseudohermaphroditism and uterus bicornis bicollis. The association of hypoplastic left heart syndrome and male pseudohermaphroditism has been reported in only two previous patients.

[Microdialysis sampling and microbore liquid chromatography with electrochemical detection for determination of serotonin in rat brain striatum]

AIM

To develop a sensitive method for determination of serotonin in biological samples.

METHODS

A combination of microdialysis sampling and microbore liquid chromatography with electrochemical detection (LCEC) was established.

RESULTS

Changes of serotonin in fg or pg in microdialysates from brain striatum of the free moving rat were easily determined.

CONCLUSION

This developed method was useful for living animal research. Serotonin level in corpus striatum healthy rats was quite stable.

The solution structure of the active domain of CAP18--a lipopolysaccharide binding protein from rabbit leukocytes

We have employed the circular dichroism (CD) technique to characterize the solution structure of CAP18(106-137), a lipopolysaccharide (LPS) binding, antimicrobial protein, and its interaction with lipid A. Our results revealed that CAP18(106-137) may exist in at least three lipid A concentration-dependent, primarily helix conformations. The 'model' structure of CAP18(106-137) in 30% (v/v) TFE, determined by nuclear magnetic resonance (NMR) technique, was found to be a complete and very rigid helix. In this conformation, the cationic and hydrophobic groups of CAP18(106-137) are separated into patches and stripes in such a way that it can favorably interact with lipid A through either coulombic interaction with the diphosphoryl groups or hydrophobic interaction with the fatty acyl chains.

Genetic alterations of microsatellites on chromosome 18 in human breast carcinoma

Allelic alterations of chromosome 18 microsatellites were determined using normal and tumor DNA pairs from 29 patients with infiltrating ductal carcinoma of the breast. Loss of heterozygosity was detected in 62% (18 of 29 patients) of the tumors at one or more of these microsatellites. Eight of the 18 patients exhibited deletions in the region at 18q21.1. This chromosomal band is known to contain a tumor suppressor gene (DCC) whose expression is frequently inactivated in several types of cancer. Ten other patients had deletions in regions not included in the DCC locus. Five of these patients revealed a common deletion at the D18S50 locus (18q23), and the other five patients had deletions in various other regions of the chromosome. No apparent correlation between loss of heterozygosity of chromosome 18 microsatellites and the clinical stage was found in this series. The results indicate that, in addition to the DCC locus, the 18q23 region is likely to contain a second tumor suppressor gene relevant to breast carcinogenesis. Four percent of all microsatellites tested in these patients showed allelic differences in the sizes of repeat units between tumor and the corresponding constitutional DNAs. The pattern of allele instability observed in breast carcinoma differed from that originally reported in a hereditary type of colorectal carcinoma. The observation suggests that this phenomenon is not a mechanism specific to neoplastic processes in breast carcinoma.

The craniofacial morphologic structures of the adult with Class III malocclusion

The morphologic study of adults with true Class III malocclusion has seldom been reported. Tracings of lateral cephalograms of 51 Taiwanese adults with true Class III malocclusion were subjected to quadrilateral analysis. Means and standard deviations, t test, correlation analysis, and regressive analysis were used to compare the differences between this group and a reference population of adults with normal occlusion. The results indicated that the maxillary base is shorter and in a more retrusive position in adults with Class III malocclusion. Furthermore, the mandible is in a more protrusive position. The pattern of growth in the Class III malocclusion was found to be horizontal, that is hypodivergent. In diagnosis of the abnormality, the rule of the quadrilateral can provide assistance. That is, the maxillary base length, mandibular base length, anterior lower facial height, and posterior lower facial height can be used to evaluate the abnormality. In postural relationships the sagittal angle, vertical sagittal ratio, and horizontal sagittal ratio can be used as a reference.