Probing the active site of human manganese superoxide dismutase: the role of glutamine 143

Structural and biochemical characterization of the nonliganding residue glutamine 143 near the manganese of human Mn superoxide dismutase (hMnSOD), a homotetramer of 22 kDa, reveals a functional role for this residue. In the wild-type protein, the side-chain amide group of Gln 143 is about 5 A from the metal and is hydrogen-bonded to Tyr 34, which is a second prominent side chain adjacent to the metal. We have prepared the site-specific mutant of hMnSOD with the conservative replacement of Gln 143 --> Asn (Q143N). The crystal structure of Q143N shows that the side-chain amide nitrogen of residue 143 is 1.7 A more distant from the manganese than in the wild-type enzyme. The Tyr 34 side-chain hydroxyl in Q143N is also moved to become 0.6 A more distant from the metal due to an additional water molecule. Differential scanning calorimetry showed that Q143N is slightly more stable than the wild-type enzyme with Tm for the main unfolding transition increased by 2 degrees C to 90.7 degrees C. Pulse radiolysis and stopped-flow spectrophotometry reveal that unlike wild-type hMnSOD, which is strongly inhibited by peroxide, Q143N MnSOD exhibits no product inhibition even at concentrations of O2. - in the millimolar range, and its catalysis follows Michaelis kinetics with no evidence of cooperativity. However, the overall catalytic activity of this mutant was decreased 2-3 orders of magnitude compared with the wild-type MnSOD, which can account for its lack of product inhibition. Q143N MnSOD lacked the visible absorption spectrum typical of wild-type Mn(III)SOD. Also, unlike the wild-type Mn(III)SOD, which is electron paramagnetic resonance (EPR) silent, Q143N MnSOD has a complex EPR spectrum with many resonances in the region below 2250 G. We conclude that the Gln 143 --> Asn mutation has increased the reduction potential of manganese to stabilize Mn(II), indicating that Gln 143 has a substantial role in maintaining a reduction potential favorable for the oxidation and reduction cycles in the catalytic disproportionation of superoxide. A solvent hydrogen isotope effect near 2 for kcat in catalysis by Q143N hMnSOD indicates rate-contributing proton transfers to form product hydroperoxide anion or hydrogen peroxide. The data demonstrate a prominent role for Gln 143 in maintaining the microenvironment of the manganese and in efficient catalysis of superoxide dismutation to oxygen and hydrogen peroxide.

Reduced expression of hMLH1 and hGTBP/hMSH6: a risk factor for head and neck cancer

Head and neck cancer, like lung cancer, is considered a paradigm of an environmentally induced disease. Genetically determined variation in DNA repair capacity is thought to contribute to susceptibility to tobacco-related cancers. In this molecular epidemiology study, we investigated the association between DNA mismatch-repair (MMR) gene expression and the risk of head and neck cancer. Using our newly developed multiplex reverse transcription-PCR assay, we simultaneously evaluated the relative expression levels of five MMR genes (hMSH2, hMLH1, hPMS1, hPMS2, and hGTBP/hMSH6) in the peripheral blood lymphocytes of 78 patients (mean age = 59.6 +/- 12.4 years) with newly diagnosed head and neck cancer and 86 healthy controls (mean age = 58.2 +/- 12.9 years). The relative MMR gene expression was not correlated with disease stage or tumor site in the cases or with smoking and alcohol use in the controls. The expression levels increased with age in both cases and controls, but the mean expression of hMLH1, hPMS1, and hGTBP/hMSH6 was significantly lower in the cases than in the controls (P < 0.05). Using the median expression level in controls as the cutoff value, significantly increased odds ratios (ORs) were associated only with low expression of hMLH1 (OR = 4.4; 95% confidence interval = 2.1-9.1) and hGTBP/hMSH6 (OR = 2.1; 95% confidence interval = 1.1-4.1) after adjustment for age, sex, ethnicity, smoking status, and alcohol use. The results suggest that low hMLH1 and hGTBP/hMSH6 expression is associated with an increased risk of head and neck cancer. Additional studies with a larger number of subjects are warranted to confirm these findings.

Expression of five selected human mismatch repair genes simultaneously detected in normal and cancer cell lines by a nonradioactive multiplex reverse transcription-polymerase chain reaction

Abnormalities in at least 1 of 5 mismatch repair (MMR) genes (hMSH2, hMLH1, hPMS1, hPMS2 and GTBP/hMSH6) are found in hereditary nonpolyposis colon cancer and sporadic colon cancers. We used a single-reaction multiplex reverse transcription (RT)-polymerase chain reaction (PCR), with the beta-actin gene as an internal control, to simultaneously evaluate expression of these 5 known human MMR genes in normal and tumor cell lines with known or uncharacterized mutations in MMR genes. The relative quantitation of the transcripts is demonstrated by controlling the number of PCR cycles and titrating cDNA with a dose-curve. The 13 normal cell lines tested were derived from normal lymphocytes, skin, thymus, breast, lung, colon, liver and kidney. The 26 cancer cell lines were derived from melanoma and cancers of the brain, breast, lung, colon, pancreas and prostate. All 5 MMR genes were ubiquitously expressed in all normal cell lines tested, suggesting their housekeeping roles. Aberrant MMR gene expression was only observed in the colon cancer cell lines. Two previously uncharacterized colon cancer cell lines did not express hMLH1. These data suggest that this nonradioactive multiplex RT-PCR assay for MMR gene expression may be useful for fast screening for genetic alterations that may affect gene expression and so may aid molecular analysis of MMR-related colon cancer.

[A study on processing of the root of Astragalus membranaceus Bge. by HPLC]

The paper presents a study on the drug-processing of the root of Astragalus membranaceus. A HPLC method for the determination of astragaloside IV in its processed products has been established. The recovery is 96.1% and the RSD is 2.15%.

[The orthogonal design study on tumor-inhibition and cancer-block role of Chinese medicinal 1023 co]

OBJECTIVE

To study the effect of Chinese herb medicine on the inhibition of tumor formation and block of malignant transformation.

METHODS

The Chinese medicine 1023 co. was given by intubation feeding started simultaneously with the painting of 0.5% DMBA on the hamster's cheek mucosa.

RESULTS

The tumor formation in 1023 co. group was delayed for 12 days comparing with the control group and the incidence of dysplasia and cancer in 1023 co. group was lower significantly than that of the control group (P < 0.01).

CONCLUSION

The 1023 co. is effective in inhibiting tumor formation and blocking cancerous transformation. By orthogonal design we find the proper prescription is A2 B2 C2 D1.

Expression of peroxisome proliferator-activated receptors in urinary tract of rabbits and humans

Peroxisome proliferator-activated receptors (PPARs, alpha, beta/delta, and gamma) are members of the nuclear receptor superfamily of ligand-activated transcription factors. PPARs regulate the expression of genes involved in lipid metabolism. 8(S)-hydroxyeicosatetraenoic acid (8-S-HETE), leukotriene B4 (LTB4), and hypolipidemic fibrates activate PPAR alpha, whereas PPAR gamma is activated by prostaglandin metabolites. The present studies examined the intrarenal and tissue distribution of rabbit and human PPAR alpha, -beta/delta, and -gamma mRNAs. Nuclease protection showed PPAR alpha predominated in liver, heart, and kidney, whereas PPAR gamma, a putative adipose-specific transcription factor, was in white adipose tissue, bladder, and ileum, followed by kidney and spleen. Lower expression levels of PPAR beta/delta were observed in several tissues. In situ hybridization of kidney showed PPAR alpha mRNA predominated in proximal tubules and medullary thick ascending limbs of both rabbit and human. PPAR gamma was exclusively expressed in medullary collecting duct and papillary urothelium. Immunoblot confirmed the expression of PPAR gamma protein in freshly isolated inner medullary collecting ducts. mRNAs for all the PPARs were expressed in the ureter and bladder in both rabbit and human, but PPAR gamma expression was greatest. This distinct distribution of PPAR isoforms has important implications for lipid-activated gene transcription in urinary epithelia.

[Experimental study on prevention of pneumoconiosis complicating with tuberculosis by Mycobacterium vaccae]

OBJECTIVE

To explore the role of Mycobacterium vaccae in prevention of pneumoconiosis complicating with tuberculosis.

METHOD

Mycobacterium vaccae was injected into rats which had been exposed to quartz for 2 weeks, and H37Rv was injected into their tail veins 1 month later. All the rats were killed 3 months later. Indexes for evaluation in the study included tuberculous lesion pathological change index, Mycobacterium tuberculosis culture in a fixed amount in lung tissues, count of Mycobacterium tuberculosis and histopathological changes in alveolar macrophages.

RESULT

Tuberculous lesion pathological change index, Mycobacterium tuberculosis culture in a fixed amount in lung tissues and count of Mycobacterium tuberculosis in alveolar macrophages were 2.6 +/- 0.5, (4.40 +/- 4.00) x 10(4) CFU and 7.2 +/- 3.2 respectively in pneumoconiosis complicated with tuberculosis and injecting Mycobacterium vaccae group, while 3.1 +/- 0.3, (18.9 +/- 18.2) x 10(4) CFU and 12.5 +/- 6.3 respectively in the control group. And statistically significant differences were found between the two groups (P < 0.05, 0.01, 0.05 respectively). The histopathological analysis revealed that proliferative and lymphoid nodules were predominant in the pneumoconiosis complicated with tuberculosis and injecting Mycobacterium vaccae group, while necrotic nodules in the control group.

CONCLUSION

Mycobacterium vaccae might play a role in prevention of pneumoconiosis complicating with tuberculosis.

[Lecture of principles and applications of capillary electrophoresis (V) Applications of capillary electrophoresis in pharmaceutical analysis and clinical chemistry]

A review with 68 references is presented on the application and new developments of CE in pharmaceutical analysis, clinical chemistry and single cell analysis etc. The pharmaceutical analysis includes main component assay, determination of drug-related impurities, stoichiometric determination and quantitative determinations. The Chinese herb analysis includes determinations of main components and prescriptions of Chinese herb. The chiral separation includes separation mechanism and some new chiral selectors. The application of CE in clinical chemistry includes determinations of serum and protein, monitoring of drug metabolism, etc. Single cell analysis includes determinations of component in neurocells and human erythrocyte.

Experimental polyneuropathy produced in guinea-pigs immunized against sulfatide

Antibodies to sulfatide are associated with polyneuropathy. To investigate the role of anti-sulfatide antibodies in this neurological disorder, guinea-pigs were immunized with sulfatide, and their behavior, serology and pathology were compared with animals injected with simple Freund's adjuvant. Eleven of 13 guinea-pigs that developed raised serum anti-sulfatide antibodies after five injections of sulfatide showed definite motor weakness. Demyelination of peripheral nerves and immunoglobulin deposits at peripheral nerve myelin sheath were found in symptomatic animals only. Functional impairment of the animals was significantly correlated with serum anti-sulfatide IgG levels and pathological findings in nerve fiber studies. Control animals and animals that received 1-3 injections of sulfatide were behaviorally and pathologically normal.

Cloning, expression, and regulation of rabbit cyclooxygenase-2 in renal medullary interstitial cells

Prostaglandin synthesis requires cyclooxygenase-1 (COX1) or -2 (COX2), which mediate the conversion of arachidonate to prostaglandin H2. COX1 is the predominant constitutive isoform, whereas COX2 expression is typically low. In the present studies we cloned rabbit COX2 and determined its distribution in unstimulated tissues. Screening rabbit eye and uterine libraries yielded two cDNAs containing identical inserts with a 1,812-nucleotide open-reading frame. This encoded a 604-amino acid polypeptide, 90% identical to human, rat, and mouse COX2. Expression of the rabbit COX2 in HEK-293 cells enhanced prostanoid synthesis. Constitutive COX2 mRNA expression was highest in kidney and urinary bladder. COX2 expression was primarily in renal outer medullary interstitial cells with cortical expression in macula densa. In cultured medullary interstitial cells, COX2 mRNA predominated, with little COX1 expression. Interstitial cell COX2 mRNA but not COX1 was induced by phorbol ester and epidermal growth factor but suppressed by dexamethasone. Phorbol ester also upregulated immunoreactive COX2. Constitutive COX2 in these tissues has important implications for side effects of COX2-selective inhibitors.

[Preliminary study on planar two-dimensional capillary electrophoresis]

Capillary Electrophoresis (CE) system with rectangular cross section columns is integrated on quartz monocrystal plate. Because of its high surface-to-volume ratio and excellent heat conductivity of quartz, rectangular capillary is extremely efficient in dissipating heat compared to conventional circular capillaries. Comparative study showed that much higher electric field strength can be applied to this system without bubble formation. Another advantage of rectangular geometry channel is better detection ability because of the elimination of optical path distortion. The effectiveness of the planar CE has been demonstrated by comparing the separation of two solutes in phosphate buffer between rectangular and circular cross section column with same area. We also found that the separation efficiency can be improved dramatically by decreasing the channel dimension, which underlies the miniaturization of planar CE. In addition, injection by micro injector eliminate sample biasing and increase reproductivity. A simple manifold of rectangular flow channels are fabricated on quartz substrate. By use of electroosmotic pumping it is possible to control the direction of fluid flow in the manifold of intersecting channels without the use of valves. The experimental results proved that the band dispersion after the valveless switching is almost negligible, showing that the two dimensional separation is possible. The main contribution to band-broadening in our capillary electrophoresis is longitudinal diffusion, injection delay time and wall adsorption. In some cases the wall adsorption make the most contribution. Optimum efficiency depends on minimization of these unavoidable sources causing band broadening.

[Subtype and sequence analysis of the C2-V3 region of gp120 genes among human immunodeficiency virus infected IDUs in Ruili epidemic area of Yunnan Province of China]

DNA fragments of HIV-1 env gene were amplified by nested-PCR from 17 uncultured peripheral blood mononuclear cells (PBMCs) obtained from HIV-1 seropositive intravenous drug users (IDUs) in Ruili city of Yunnan Province. The C2-V3 region (about 450 bp) of them were sequenced. Sequence analysis showed that there exists two HIV-1 subtypes, B and C, with 5.8% and 2.2% gene divergence inside each subtype. The 12 subtype B strains, were closely related to those found in Thailand, Myanma and Ruili city of Yunnan, and the nucleotide sequence divergence between them ranged from 4.4% to 4.9%; meanwhile, the 5 subtype C strains were most close to those found in India as well as Ruili city, all with a genetic distance of 1.9%. The small divergence among Ruili HIV-1 subtype C strains suggests a recent epidemic. The analysis of V3 loop amino sequence of 12 subtype B HIV-1 reveals that V3-tip motif of 6 samples (50%) is GPGQ and that of 3 samples (25%) is GPGR. In addition, the codon of arginine (R) of all the strains is CGA instead of AGA. This result is in accordance with our previous hypothesis that there is a drift in vivo from GPGR to GPGQ motif on the tipof V3-loop of HIV-1 subtype B strain in this arm with the elapse of time.

Vibrational analysis of nucleic acids. IV. Normal modes of the DNA phosphodiester structure modeled by diethyl phosphate

Raman and ir spectra are reported for diethyl phosphate [(CH3CH2O)2PO2-] and diethyl phosphate isotopomers incorporating carbon-13 at methylene group sites [(CH313CH2O)2PO2-] and deuterium substituents on methyl and methylene carbons [(CH3CD2O)2PO2-, (CD3CH2O)2PO2-, (CD3CD2O)2PO2-]. The vibrational spectra are analyzed to develop a consistent set of assignments for the C-C-O-P(O2-)-O-C-C network, which serves as a model for the nucleic acid phosphodiester backbone. The present study resolves previously conflicting vibrational assignments for the phosphodiester skeleton and provides a firm empirical basis for interpreting conformationally sensitive modes of DNA and RNA. Ab initio vibrational analyses have also been conducted on the above isotopomers of diethyl phosphate in the trans-gauche-gauche-trans conformation, optimized using the 3-21+G* basis set at the restricted Hartree-Fock level. The ab initio calculations are in good agreement with the empirical results, thus strengthening the proposed assignment scheme for Raman and infrared spectra. The present study provides a basis for improvement of empirical force fields utilized in previous normal coordinate analyses of the nucleic acid phosphodiester group.

Vibrational analysis of nucleic acids. IV. Normal modes of the DNA phosphodiester structure modeled by diethyl phosphate

Raman and ir spectra are reported for diethyl phosphate [(CH3CH2O)2PO2-] and diethyl phosphate isotopomers incorporating carbon-13 at methylene group sites [(CH313CH2O)2PO2-] and deuterium substituents on methyl and methylene carbons [(CH3CD2O)2PO2-, (CD3CH2O)2PO2-, (CD3CD2O)2PO2-]. The vibrational spectra are analyzed to develop a consistent set of assignments for the C-C-O-P(O2-)-O-C-C network, which serves as a model for the nucleic acid phosphodiester backbone. The present study resolves previously conflicting vibrational assignments for the phosphodiester skeleton and provides a firm empirical basis for interpreting conformationally sensitive modes of DNA and RNA. Ab initio vibrational analyses have also been conducted on the above isotopomers of diethyl phosphate in the trans-gauche-gauche-trans conformation, optimized using the 3-21+G* basis set at the restricted Hartree-Fock level. The ab initio calculations are in good agreement with the empirical results, thus strengthening the proposed assignment scheme for Raman and infrared spectra. The present study provides a basis for improvement of empirical force fields utilized in previous normal coordinate analyses of the nucleic acid phosphodiester group.

Drosophila rosA gene, which when mutant causes aberrant photoreceptor oscillation, encodes a novel neurotransmitter transporter homologue

The Drosophila receptor oscillation A (rosA) mutations, which cause electroretinogram (ERG) defects, including oscillations, were localized to the 24F4-25A2 region of chromosome 2L. Genomic fragments from this region, isolated from bacteriophage P1 clones, included those that detect transcriptional defects in rosA mutants in RNA blot experiments. One of these genomic fragments was used to screen a head cDNA library. The largest cDNA clone (3.6 kb) isolated was shown to rescue a rosA mutant in P element-germline transformation experiments. The ROSA protein deduced from the open reading frame in the 3.6 kb rosA cDNA is 943 amino acids long and is 36-41% identical to members of the superfamily of Na+/Cl(-)-dependent neurotransmitter transporters, with no indication of higher sequence identity to any one subgroup within the superfamily. RNA blot experiments revealed multiple transcripts in various developmental stages, the most abundant one being a 3.7 kb transcript, particularly in the adult head. Tissue in situ experiments identified the rosA transcript to be localized to many tissues, with higher levels of hybridization in the nervous system and digestive tract. The results demonstrate that the rosA gene encodes a novel Na+/Cl(-)-dependent transporter important for normal response properties of the photoreceptor.

Emergence of avian H1N1 influenza viruses in pigs in China

Avian influenza A viruses from Asia are recognized as the source of genes that reassorted with human viral genes to generate the Asian/57 (H2N2) and Hong Kong/68 (H3N2) pandemic strains earlier in this century. Here we report the genetic analysis of avian influenza A H1N1 viruses recently isolated from pigs in southern China, a host suspected to generate new pandemic strains through gene reassortment events. Each of the eight gene segments was of avian origin. Phylogenetic analysis indicates that these genes form an Asian sublineage of the Eurasian avian lineage, suggesting that these viruses are an independent introduction into pigs in Asia. The presence of avian influenza viruses in pigs in China places them in an optimal position for transmission to humans and may serve as an early warning of the emergence of the next human influenza virus pandemic.

Vibrational analysis of nucleic acids. V. Force field and conformation-dependent modes of the phosphodiester backbone modeled by diethyl phosphate

A generalized valence force field is derived for the diethyl phosphate anion [(CH3CH2O)2PO2-] and its deuterium [(CH3CD2O)2PO2-, (CD3CH2O)2PO2- and (CD3CD2O)2PO2-] and carbon-13 [(CH3 13CH2O)2PO2-] derivatives in the stable trans-gauche-gauche-trans conformation. Normal coordinate analysis of the trans-gauche-gauche-trans conformer, which serves as a structural analog of the nucleic acid phosphodiester group, is based on comprehensive infrared and Raman spectroscopic data and vibrational assignments obtained for the diethyl phosphate anion. The generalized valence force field is in good agreement with the scaled ab initio force field of diethyl phosphate and represents significant improvement over earlier modeling of the phosphodiester moiety with dimethyl phosphate. The conformational dependence of skeletal C-C-O-P(O2-)-O-C-C stretching vibrations is also explored. Starting with the trans-gauche-gauche-trans conformation, the frequency dependence of skeletal stretching modes has been obtained by stepwise rotation of the torsion angles of the P-O and C-O bonds corresponding to nucleic acid torsions alpha (P-O5'), beta (O5'-C5'), epsilon (C3'-O3'), and zeta (O3'-P). Both symmetric and antisymmetric phosphoester stretching modes are highly sensitive to P-O and C-O torsions, whereas symmetric and antisymmetric phosphodioxy (PO2-) stretching modes are less sensitive. The present results provide an improved structural basis for understanding previously developed empirical correlations between vibrational marker bands and nucleic acid backbone conformation.

[Study of an ancient corpse of the Warring States period unearthed from Tomb No. 1 at Guo-Jia Gang in Jingmen City (A comprehensive study)]

An ancient female corpse excavated from the robbed tomb No. 1 at Guo-Jia-Gang in Jingmen city of Hubei Province was studied. It was confirmed that the corpse was buried more than 2,300 years ago, namely at the middle stage of the Warring States period and is the earliest one of the ancient coffin corpses unearthed in China so far. It is of the same type as the ancient corpses of Weatern Han Dynasty excavated from tomb No. 1 at Ma-Wang-Dui in Changsha City and from the tomb No. 168 at Phoenix Hill in Jinagling City respectively. The collagenous fibers of connective tissue from all parts in the corpse were well preserved, showing fine ultrastructure with clear periodical cross banding, and a lot of bacterial spores were found between them. In addition, a large number of eggs of clonorchis sinensis and trichuris trichiura were found in the content of the bowel. The level and the cause of good preservation were discussed and it was believed that the good preservation may result from the combined effect of the internal and external environmental factors around the corpse.

Clonal stability of blood cell lineages indicated by X-chromosomal transcriptional polymorphism

The idea that stem cells oscillate between a state of activity and dormancy, thereby giving rise to differentiating progeny either randomly or in orderly clonal succession, has important implications for understanding normal hematopoiesis and blood cell dyscrasias. The degree of clonal stability in individuals also has practical implications for the evaluation of clonal lymphomyeloproliferative diseases. To evaluate the clonality pattern of the different types of blood cells as a function of time we have validated the applicability, sensitivity, and reproducibility of a thermostable ligase reaction to detect transcripts of the G6PD allele on the active X-chromosome in normal heterozygous females. While the ratio of the two X-chromosome-derived allelic transcripts varied widely among hemopoietic tissues in a given individual, this allelic ratio was virtually identical in all types of mature myeloid and lymphoid cells. Longitudinal studies indicated constancy of the G6PD allelic ratio in blood cells over a 912-d period of observation in healthy females. The individual variability observed in this allelic ratio suggests that the progeny of a relatively small number of original embryonic hemopoietic stem cells, approximately eight, contribute to the sustained production of all types of blood cells in healthy individuals.

[Correction of the secondary nasal deformity in bilateral cleft lip with a new technique]

Bilateral cleft lip often has nasal deformities of various degrees. It is not enough to elongate the nasal columella for such deformities. Based on the thoughts that secondary deformities of the nose and lip should be treated as a whole, the authors introduced a new technique, in which five aspects of the deformities were considered and treated at the same time. Thirteen patients have undergone surgical correction with satisfactory results.

Yishou jiangzhi (de-blood-lipid) tablets in the treatment of hyperlipemia

The Yishoujiangzhi (de-blood-lipid) tablets (composed of Radix Polygori Multiflori, Rhizoma Polygonati, Fructus Lycii, Crataegus Pinnatifida and Cassia Tora) were used in the treatment of 130 cases of hyperlipemia, achieving an effective rate of 87.0% in lowering serum cholesterol and 80.8% in lowering triglyceride.

[Correction of unilateral cleft lip nasal deformity with modified Bardach's technique]

Twenty-nine cases of unilateral cleft lip nasal deformities were corrected with modified Bardach's technique. Overall results were satisfactory. The key to a successful and stable correction of the nasal deformity is to lengthen the columella on the cleft side and to mobilize alar cartilage from its surrounding tissue, creating a symmetric shape and length. The major advantages of the technique are lengthening of the cleft columella and creation of a symmetric and well-projected nasal tip. The surgical technique is described in details. Some considerations before and during operation were discussed.

Primary familial polycythemia: a frameshift mutation in the erythropoietin receptor gene and increased sensitivity of erythroid progenitors to erythropoietin

Primary familial and congenital polycythemia (PFCP) is characterized by erythrocytosis with normal arterial PO2, blood P50, and serum erythropoietin (EPO) levels. In two PFCP families EPO receptor (EPOR) polymorphisms cosegregated with PFCP. A heterozygous insertion of G at EPOR nucleotide 5975 was identified in genomic DNA from polycythemic members of family no. 2. 5974insG shifts the reading frame at codon 430, predicting amino acid substitutions and truncation of the last 64 amino acids. Wild-type and mutant EPOR transcripts were detected in erythroid progenitors from affected individuals. Burst-forming units-erythroid from patients exhibited increased colony size and sensitivity to EPO. Transfected Ba/F3 cells expressing EPOR 5974insG exhibited increased EPO sensitivity compared with cells expressing wild-type EPOR. The functional effect of this EPOR mutation was directly compared with the other C-terminal mutations reported in unrelated PFCP families by expression in Ba/F3 cells. The transfected cells with another primary polycythemia associated EPOR mutant construct (G6002A) also exhibited increased sensitivity to EPO.

Cloning and characterization of a dihydrolipoamide acetyltransferase (E2) subunit of the pyruvate dehydrogenase complex from Arabidopsis thaliana

A cDNA encoding a dihydrolipoamide acetyltransferase (E2) subunit of the pyruvate dehydrogenase complex has been isolated from Arabidopsis thaliana. A cell culture cDNA expression library was screened with a monoclonal antibody (JIM 63) raised against nuclear matrix proteins, and four clones were isolated. One of these was 2175 base pairs in length, and it contained an open reading frame with an amino acid sequence and domain structure with strong similarity to the E2s of other eukaryotic and prokaryotic organisms. The organization and number of functional domains within the Arabidopsis protein are identical to those of the human E2, although the amino acid sequences within these domains are equally similar to those of the yeast and human proteins. The predicted amino acid sequence reveals the presence of a putative amino-terminal leader sequence with characteristics similar to those of other proteins, which are targeted to the plant mitochondrial matrix. The cross-reactivities of plant mitochondrial matrix proteins with JIM 63 and antibodies raised against the E2 and protein X components of eukaryotic pyruvate dehydrogenase complexes are consistent with the clone encoding a mitochondrial form of E2 and not the smaller protein X. The E2 mRNA of 2.2 kilobases was expressed in a range of Arabidopsis and Brassica napus tissues.

Electrostatic potential distribution of the gene V protein from Ff phage facilitates cooperative DNA binding: a model of the GVP-ssDNA complex

The crystal structure of the gene V protein (GVP) from the Ff filamentous phages (M13, fl, fd) has been solved for the wild-type and two mutant (Y41F and Y41H) proteins at high resolution. The Y41H mutant crystal structure revealed crystal packing interactions, which suggested a plausible scheme for constructing the polymeric protein shell of the GVP-single-stranded DNA (ssDNA) complex (Guan Y, et al., 1994, Biochemistry 33:7768-7778). The electrostatic potentials of the isolated and the cooperatively formed protein shell have been calculated using the program GRASP and they revealed a highly asymmetric pattern of the electrostatic charge distribution. The inner surface of the putative DNA-binding channel is positively charged, whereas the opposite outer surface is nearly neutral. The electrostatic calculation further demonstrated that the formation of the helical protein shell enhanced the asymmetry of the electrostatic distribution. A model of the GVP-ssDNA complex with the n = 4 DNA-binding mode could be built with only minor conformational perturbation to the GVP protein shell. The model is consistent with existing biochemical and biophysical data and provides clues to the properties of GVP, including the high cooperatively of the protein binding to ssDNA. The two antiparallel ssDNA strands form a helical ribbon with the sugar-phosphate backbones at the middle and the bases pointing away from each other. The bases are stacked and the Phe 73 residue is intercalated between two bases. The optimum binding to a tetranucleotide unit requires the participation of four GVP dimers, which may explain the cooperativity of the GVP binding to DNA.

Crystal structures of Y41H and Y41F mutants of gene V protein from Ff phage suggest possible protein-protein interactions in the GVP-ssDNA complex

Gene V protein (GVP) encoded by the filamentous phage Ff (M13, fl, fd) is a homodimeric protein of 87 amino acids that binds to single-stranded DNA (ssDNA) nonspecifically and cooperatively. The structure (monoclinic C2 form) of the wild-type protein has been determined and refined at 1.8-A resolution [Skinner et al. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 2071-2075]. The monomer structure consists of a somewhat distorted five-stranded beta-barrel core with three prominent loops: a DNA-binding loop, a dyad loop, and a dimer contact loop. The amino acid residue at position 41 plays an important role in the dimer-dimer interactions of the protein-ssDNA complex. Two Y41 mutant structures have been studied by X-ray crystallography. The Y41F GVP structure has been refined to an R-factor of 0.180 at 2.2-A resolution and is very similar to the wild-type (wt) structure (rmsd of all C alpha atoms = 0.30 A). In contrast, Y41H GVP forms a new crystal lattice in the space group P2(1)2(1)2(1) with a = 77.18 A, b = 84.17 A, and c = 28.62 A. Its structure has been solved by the molecular replacement method and refined to an R-factor of 0.170 at 2.5-A resolution. The two monomers of Y41H are crystallographically independent, and their structures remain similar to wt-GVP but with significant differences, particularly in the DNA-binding hairpin region. In both crystals, the loop (residues 36-43) that contains the Y41 residue is involved in the crystal dimer packings but in a different manner. The dimer-dimer contacts found in the wt-GVP crystal may be important for GVP aggregation in the absence of DNA. In the presence of DNA, the dimer-dimer contacts may switch to the type found in the Y41H crystal, allowing the GVP-ssDNA complex to form cooperatively. A model of the complex, consistent with existing biochemical and biophysical data, has been constructed from those crystal packing data.

E. coli penicillin acylase isolation by selective release, aqueous two-phase partitioning and ultrafiltration

A procedure has been developed for the purification of penicillin acylase from E. coli fermentation broths. The method described is based primarily on selective release from biomass, charge-directed partitioning in an aqueous two-phase system, and the use of ultrafiltration membranes to recycle the modified polyethylene glycol required and to further purify the enzyme. Each step has been discussed and comparisons have been made with other approaches, where possible. Suggestions have been made for optimisation in process engineering. The approach developed may be applicable to other beta-lactam antibiotic acylases or more generally to some of the other E. coli periplasmic proteins.

Structure of the gene V protein of bacteriophage f1 determined by multiwavelength x-ray diffraction on the selenomethionyl protein

The crystal structure of the dimeric gene V protein of bacteriophage f1 was determined using multiwavelength anomalous diffraction on the selenomethionine-containing wild-type and isoleucine-47-->methionine mutant proteins with x-ray diffraction data phased to 2.5 A resolution. The structure of the wild-type protein has been refined to an R factor of 19.2% using native data to 1.8 A resolution. The structure of the gene V protein was used to obtain a model for the protein portion of the gene V protein-single-stranded DNA complex.

Vibrational analysis of nucleic acids. I. The phosphodiester group in dimethyl phosphate model compounds: (CH3O)2PO2-, (CD3O)2PO2-, and (13CH3O)2PO2-

Normal coordinate analyses and vibrational assignments are presented for the dimethyl phosphate anion [(CH3O)2PO2-] and its deuteriomethyl [(CD3O)2PO2-] and carbon-13 [(13CH3O)2PO2-] derivatives in the gauche-gauche conformation. The dimethyl phosphate anion, which is the simplest model for the nucleic acid phosphodiester moiety, exhibits many of the spectral complexities of DNA and RNA and has previously resisted a complete and consistent vibrational analysis. In the present study we make use of new experimental data on the dimethyl phosphate isotopomers, including Raman depolarization measurements, to develop a consistent valence force field for normal modes of the C--O--P--O--C phosphodiester network and its hydrogenic substituents, as well as for stretching and bending modes of the O--P--O network of the anionic phosphodioxy group (PO2-). The force field established for dimethyl phosphate incorporates one significant nonbonded force constant, introduced from ab initio calculations, to account for interaction between the two ester C--O bonds. This study resolves previous problematic assignments for conformation-sensitive symmetric (in-phase) and asymmetric (out-of-phase) skeletal stretching modes of the ester linkages and demonstrates substantial anharmonicity in the hydrogen-stretching vibrations of the methyl substituents. New assignments are proposed for Raman bands of the phosphodioxy group, which may serve as potential indicators of structure and interaction of the DNA phosphates.

Molecular structure of cyclic diguanylic acid at 1 A resolution of two crystal forms: self-association, interactions with metal ion/planar dyes and modeling studies

Cyclic ribodiguanylic acid, c-(GpGp), is the endogenous effector regulator of cellulose synthase. Its three dimensional structure from two different crystal forms (tetragonal and trigonal) has been determined by x-ray diffraction analysis at 1 A resolution. Both structures were solved by direct methods and refined by block-matrix least squares refinement to R-factors of 0.112 (tetragonal) and 0.119 (trigonal). In both crystal forms, two independent c-(GpGp) molecules associate with each other to form a self-intercalated dimer. All four c-(GpGp) molecules have very similar backbone conformation. The riboses are in the C3'-endo pucker with pseudorotation angles ranging from -7.2 degrees to 16.5 degrees and the bases have anti glycosyl chi angles (-175.5 degrees to 179.7 degrees). In the tetragonal form, a hydrated cobalt ion is found to coordinate to two N7 atoms of adjacent guanines, forcing these two guanines to destack with a large dihedral angle (33 degrees). This metal coordination mechanism has been noted previously in other Pt- or Co-GMP complexes and may be relevant to the binding of the anticancer drug cisplatin to a GpG sequence in DNA. A model of the adduct between cisplatin and a d(CAATGGATTG) duplex has been constructed in which the induced bending of the DNA helix at the Pt crosslinking site is 33 degrees, consistent with earlier electrophoretic analyses. Moreover, c-(GpGp) exhibits unusual spectral properties not seen in other cyclic dinucleotides. It interacts with planar organic intercalator molecules in ways similar to double helical DNA. We propose a cage-like model consisting of a tetrameric c-(GpGp) aggregate in which a large cavity (host molecule) is generated to afford a binding site for certain planar intercalators (guests molecules). The aggregate likely uses a hydrogen bonding scheme the same as that found in the G-quartet molecules, e.g., telomere DNA. The conformation of c-(GpGp) also suggests that certain nearest-neighbor intercalators may be synthesized on the basis of its unique molecular framework. Modeling studies have been carried out to test this hypothesis.

Protective effects of silybin and tetrandrine on the outcome of spontaneously hypertensive rats subjected to acute coronary artery occlusion

The effects of silybin and tetrandrine on the survival of spontaneously hypertensive rats subjected to acute coronary artery occlusion were investigated. The mortality after acute coronary occlusion in spontaneously hypertensive rats (66.7%) was higher than that of control Wistar-Kyoto rats (20%, P < 0.05). Oral administration of silybin (300 mg/kg daily) for 8-12 days reduced mortality in spontaneously hypertensive rats (0, P < 0.01 in comparison with untreated spontaneously hypertensive rats). Administration of tetrandrine 40 mg/kg daily for 8-12 days reduced the mortality to some extent (22.2%, P = 0.051, as compared with control rats). Silybin reduced blood pressure and the incidence of post-occlusion arrhythmias in spontaneously hypertensive rats to the same extent as tetrandrine. Both silybin and tetrandrine decreased the severity of ventricular hypertrophy. Although there were significant decreases in risk zone and infarct zone in silybin- and tetrandrine-treated rats, the ratio of infarct to risk zone was not changed. The results implies that silybin may be beneficial when used in hypertensive patients who develop acute myocardial infarction.

[A study on the relationship between Helicobacter pylori and chronic gastritis and peptic ulcer by the case-control method and sequential analysis]

The association between Helicobacter pylori and the chronic gastritis and peptic ulcer was investigated by the case-control method, 1:1 matched study and sequential analysis. The results of three methods showed that the degree of association between Helicobacter pylori and the chronic gastritis and peptic ulcer was significant (chi 2 = 22.70, P < 0.001, OR = 15.63, 95% CI of OR was 5.05, 48.43), especially that between Helicobacter pylori and active chronic gastritis (OR = 20.92). The results indicate that Helicobacter pylori might be an etiological factor for patients with chronic gastritis and peptic ulcer.

Molecular and crystal structures of ecteinascidins: potent antitumor compounds from the Caribbean tunicate Ecteinascidia turbinata

Some members of marine alkaloid ecteinascidins (Et's), isolated from the Caribbean tunicate Ecteinascidia turbinata, exhibit potent anticancer activity. The three dimensional structures of the N12-formyl derivative of Et729 1a and the natural N12-oxide of Et743 2 have been determined by x-ray crystallography at 0.9 A resolution. Compounds 1a and 2 crystallize in the space groups P2(1)2(1)2(1) (a = 23.214(9) A, b = 28.541(10) A and c = 13.303(9) A) and P2(1) (a = 11.720(5) A, b = 13.230(4) A, c = 28.557(5) A, beta = 90.22(2) degrees), respectively. Their crystal structures have been solved by the Patterson search method, which located the sulfur atoms permitting the phase extension. The final crystallographic R-factors are 0.059 and 0.069 for 1a and 2, respectively. There are two independent molecules, associated as a dimer, in the asymmetric unit of crystals of both 1a and 2. The structure determination allows an unequivocal assignment of the relative configuration of all the chiral centers. Assuming that ecteinascidins and safracin C (whose absolute configuration is known) have the same absolute configuration at C1 position, then the absolute configurations of various chiral positions in Ets are C1(R), N2(R), C3(R), C4(R), C11(R), C13(S), C21(S) and C22(R), respectively. The four independent Et molecules adopt two conformations in which the position of ring C relative to rings A & B is different. The molecules have a compact shape and they are conformationally strained due to a severe van der Waals clash between the sulfur atom and the aromatic ring A. By analogy to the related saframycin, the potent biological activity of Et's may be associated with their ability to form a covalent adduct to DNA using the reactive carbinolamine group. The covalent binding interaction between the Et and the N2 of guanine in the minor groove of the DNA double helix has been studied by computer modelling which suggests that rings A and B "stack" against the DNA backbone. While the bulky drug molecule makes numerous contacts with DNA, it does not significantly distort the conformation of the DNA double helix.

Additional antitumor ecteinascidins from a Caribbean tunicate: crystal structures and activities in vivo

Ecteinascidins (Ets), isolated from the Caribbean tunicate Ecteinascidia turbinata, protect mice in vivo against P388 lymphoma, B16 melanoma, M5076 ovarian sarcoma, Lewis lung carcinoma, and the LX-1 human lung and MX-1 human mammary carcinoma xenografts. Crystal structures of two tris(tetrahydroisoquinoline) Ets were investigated with single crystals of the 21-O-methyl-N12-formyl derivative of Et 729 and the natural N12-oxide of Et 743. Representatives of an additional class of Ets, Et 722 and Et 736, isolated from the same organism, were assigned tetrahydro-beta-carboline-substituted bis(tetrahydroisoquinoline) structures by NMR and fast atom bombardment MS spectra.

Location-dependent variations in the material properties of the anterior cruciate ligament

Our recent anterior drawer studies in human cadaveric knees [Guan and Butler, Adv. Bioengng 17, 5 (1990); Guan et al., Trans. orthop. Res. Soc. 16, 589 (1991)] have suggested that anterior bundles of the anterior cruciate ligament (ACL) develop higher load-related material properties than posterior bundles. This was confirmed when we reevaluated the axial failure data for these bundle-bone specimens from an earlier study [Butler et al., J. Biomechanics 19, 425-432 (1986)]. The purpose of this study was to determine, in a larger data set, if anteromedial and anterolateral bundles of the anterior cruciate ligament exhibit significantly larger load-related material properties than the posterior ligament bundles. Seven ACL-bone units from seven donors (the three tissues from the original study plus four new ones) were subdivided into three subunits, preserving the bone insertions. The subunits were failed in tension at a constant strain rate (100% s-1) and four material properties were compared within and between donors. The anterior bundles developed significantly larger moduli, maximum stresses, and strain energy densities to maximum stress than the posterior subunits. Moduli for the anterior vs posterior subunits averaged 284 MPa vs 155 MPa, maximum stresses averaged 38 MPa vs 15 MPa, and strain energy densities averaged 2.7 N m cc-1 vs 1.1 N m cc-1, respectively. No significant differences were found, however, among strains to maximum stress or between any of the other properties for the two anterior subunits. These results are important to the design of ligament replacements and suggest new experiments designed to distinguish in vivo force levels in these ACL bands, a possible reason for the material differences.

Membrane affinity chromatography used for the separation of trypsin inhibitor

Polysulphone (PS) was chemically modified by acrylation-amination and by chloromethylation-amination, respectively. An ultrafiltration membrane of chemically modified polysulphone (CMPS) was prepared by the phase inversion method. Trypsin was then covalently bonded onto the CMPS membrane by diazotization. The activity of immobilized trypsin reaches up to 10200 U/g; 15 mg trypsin was immobilized on 1 g CMPS membrane. Separation of soybean trypsin inhibitor was carried out on the affinity membrane, yielding 6.5 mg pure trypsin inhibitor in one run. The enzyme membrane has good activity and stability.

[Reaction between monoclonal antibodies to porcine zona pellucida and human and porcine ovary in vitro]

Reaction between monoclonal antibodies to porcine zona pellucida (LPD8, LPC4) and human and porcine ovaries was studied by ABC immunohistochemistry technique in vitro. When slices of human and porcine ovaries were stained with ABC, not only the zona pellucida but also the ovum cytoplasm was stained. Other regions of the ovary, such as granulosa cell, theca cell and connective tissue, could not be stained. These results suggest that the monoclonal antibodies to porcine zona pellucida probably have no direct effect on the endocrine function of ovary, but they may combine with ovum cytoplasm and inhibit follicular growth, so that the number of follicles reduces and endocrine function of the ovary decreases. We do not think that the prospects of continual study on LPD8, LPC4 are good.

[Clinical analysis of surgical repair in 21 cases of transverse facial cleft]

The paper introduced 6 surgical procedures for repairing the transverse facial cleft. To assess the advantages and disadvantages of these procedures, the observation and comparison about the postoperative long-term results were made. A new method called lower lip triangular flap method which was designed by the author was introduced in details. The selection of these surgical procedures and the essential parts of the operation were also discussed.