[Evaluation on soil anti-erodibility of soil and water conservation forest]

Indexes including organic matter content, water stable aggregate content, mean weight diameter of water stable aggregate, aggregate degree and disperse coefficient were selected to evaluate soil anti-erodibility of soil and water conservation forests component of different tree species at different ages. The results showed that soil and water conservation forest played an important role in improving soil anti-erodibility, especially to the topsoil. Compared with that of Chinese pine pure forests, Chinese pine-broadleaved mixed forests had higher soil organic matter content, and water stable aggregate content increased by 1.71%-38.53%, and soil anti-erodibility was also increased with increasing stand age.

The value of serum GPDA-F for the diagnosis of primary hepatocellular carcinoma

OBJECTIVE

To investigate the role of glycylproline dipeptidyl aminopeptidase isoenzymes in the diagnosis of primary hepatocellular carcinoma (PHC).

METHODS

We developed a stage gradient polyacrylamide gel electrophoresis system to separate serum GPDA isoenzymes. Total GPDA activities, alpha-fetoprotein, the sizes of tumors and alanine aminotransferase (ALT) activities were also measured simultaneously and the correlation between GPDA-F and these indices was analyzed.

RESULTS

Serum GPDA was separated into two bands, namely fast band (GPDA-F) and slow band (GPDA-S). GPDA-F was negative in all healthy persons as well as in the patients with benign liver filling defects, while it was positive in 85.3% cases of PHC. Liver cirrhosis, chronic hepatitis, extrahepatic carcinoma and metastatic liver carcinoma had low positive rates. GPDA-F was positively correlated with serum total GPDA activities, but had no correlation with AFP and size of the tumors. There was the correlation between GPDA-F and ALT in benign liver diseases, but no correlation between GPDA-F and ALT in PHC. Serial measurements of serum GPDA-F showed that GPDA-F was persistently positive in PHC but might change into negative in benign liver diseases. Dynamic determination of GPDA-F might be helpful to differentiate true positive of PHC from false positive of benign liver diseases.

CONCLUSION

GPDA-F is a new serum marker of PHC. Measurement of serum GPDA-F is of value for the diagnosis of PHC, especially for those at early stage or with negative AFP.

[The clinical application of different brightness and different saturation D-15 tests]

PURPOSE

To compare the clinical application of different brightness and different saturation D-15 tests.

METHODS

Eighteen normal subjects (30 eyes), 19 cases (38 eyes) of congenital color vision defects and 36 cases (59 eyes) of eye diseases were tested with Panel D-15 test, Hann's double D-15 test, middle and low saturation CAS-PI (Psychological Institute, Chinese Academy of Sciences) D-15 tests.

RESULTS

A few of the normal eyes made minor errors in the low saturation D-15 tests. All of the protanopes and deuteranopes could be detected correctly. Protanomalias and deuteranomalias showed normal arrange or some type of abnormal arranges in all of the 5 sets of D-15 tests. In sick eyes, the abnormal rates were the highest in the low saturation D-15 tests and the lowest in Panel D-15 test.

CONCLUSION

The five sets of different brightness and different saturation D-15 tests had similar efficiencies of detecting congenital color vision defects. The abnormal rates of CAS-PI(4/5)D-15 tests and the CAS-PI(2/5)D-15 tests were similar to those of Panel D-15 test and Hann's Double D-15 test. Both tests can be used in the clinical setting.

A case report of frosted branch angiitis and its visual electrophysiology

We reported a 5-years old boy with frosted branch angiitis in both eyes. The visual acuities of the two eyes were suddenly lost to 5/50. The fluorescein angiography, electroretinograms (ERGs) and pattern evoked potentials (PVEPs) had been tested at the acute and the recovery stage of the disease. At the onset of the disease, fluorescein angiography showed obvious dye leakage from dilated retinal veins. The PVEPs and whole field ERGs including rod, maximum, OPs and cone responses were seriously decreased and prolonged, indicating that the visual pathway's and retinal functions were greatly damaged. The patient had an excellent response to systemic prednisone. One month after the treatment, the visual acuities recovered to 60/50 in both eyes. The fluorescein angiography showed that leakage from blood vessels was diminished, but the lesions at macula and optic disc were persisted a longer time even to the end of treatment. Through 6 months medication, nearly all of the electrophysiological abnormalities had been resolved.

[Cytogenetics and clinical studies of hematologic malignancies with 11q23 abnormalities in China]

OBJECTIVE

To evaluate the association between 11q23 abnormalities and the clinical, hematologic, prognostic aspects of hematologic malignancies.

METHODS

A total of 6000 cases of hematologic malignancies from our hospital and near regions in China were investigated between October 1985 and November 1998. Chromosome preparations were made on bone marrow cells by using direct method and/or unstimulated short-term cultures. Karyotypes were analyzed by R-banding technique and expressed according to ISCN(1995).

RESULTS

11q23 abnormalities were found in 28 of 6000 cases with hematologic malignancies(0.47%). It may be separated into seven cytonetic categories: t(4;11)(q21;q23)(ten cases), t(11;19)(q23;p13)(five cases), t(9;11)(p12;q23)(two cases), t(10;11)(p15;q23)(two cases), t(6;11)(q27;q23) (one case), del(11)(q23)(seven cases), and t(11;?)(q23;?)(one case). The diagnoses included acute myeloid leukemia in 14 cases (M(2a), three; M(4), two; M(5a), one; M(5b), eight), acute lymphoblastic leukemia(ALL) in 10 cases, myelodysplastic syndrome in three cases and malignant histiocytosis in one case. All 10 cases with t(4;11) anomaly were ALL. Follow-up data were available for 22 of them. Their median survival was 113 days. The patients may be grouped according to the presence or absence of additional abnormalities and/or normal karyotype. The median survival was 75 days for five patients with 11q23 anomaly only, 18 days for two patients with 11q23 and additional abnormalities, 135 days for 10 patients with 11q23 anomaly, additional abnormalities and normal karyotype, and 150 days for 5 patients with 11q23 anomaly and normal karyotype.

CONCLUSION

11q23 abnormalities were mainly seen in ALL and acute monocytic leukemia. Their prognosis was very poor. Both additional abnormalities and lack of normal karyotype had adverse effects on the survival of patients. Thus, they represent a unique clinical-cytogenetic association. 11q23 abnormality; hematologic malignancy; acute monocytic leukemia; acute lymphoblastic leukemia; prognosis

A study of toxic effect of mitomycin C on cultured bovine trabecular meshwork cells

PURPOSE

To explore the toxicity of Mitomycin C (MMC) on trabecular meshwork cells.

METHODS

Bovine trabecular meshwork cells were cultured in vitro and exposed to MMC of different concentrations. The cellular morphology, ultrastructure, mortality and phagocytosis was studied with light microscopy, transmission electron microscopy and methods of Wright's stain, etc.

RESULTS

It was found that the toxic effect of MMC on the cells was in a dose-dependent mode. 1 x 10(-2) and 1 x 10(-3) mg/ml of MMC caused a large part of cells dead, 1 x 10(-4) and 1 x 10(-5) mg/ml of the drug had remarkable killing effect on the cells. 1 x 10(-6) mg/ml of MMC had still a mild toxicity, while 1 x 10(-7) mg/ml of MMC had not any influence on cellular morphology, mortality, and phagocytosis, etc. The safe concentration on bovine trabecular meshwork cells was 1 x 10(-7) mg/ml and the LD50 was between 1 x 10(-3) and 1 x 10(-4) mg/ml.

CONCLUSIONS

Refering to previous data, we conclude that conventional clinical-application of MMC might do harm to trabecular meshwork cells.

Anchoring an extended HTLV-1 Rex peptide within an RNA major groove containing junctional base triples

BACKGROUND

The Rex protein of the human T cell leukemia virus type 1 (HTLV-1) belongs to a family of proteins that use arginine-rich motifs (ARMs) to recognize their RNA targets. Previously, an in vitro selected RNA aptamer sequence was identified that mediates mRNA transport in vivo when placed in the primary binding site on stem-loop IID of the Rex response element. We present the solution structure of the HTLV-1 arginine-rich Rex peptide bound to its RNA aptamer target determined by multidimensional heteronuclear NMR spectroscopy.

RESULTS

The Rex peptide in a predominantly extended conformation threads through a channel formed by the shallow and widened RNA major groove and a looped out guanine. The RNA aptamer contains three stems separated by a pair of two-base bulges, and adopts an unanticipated fold in which both junctional sites are anchored through base triple formation. Binding specificity is associated with intermolecular hydrogen bonding between guanidinium groups of three non-adjacent arginines and the guanine base edges of three adjacent G.C pairs.

CONCLUSIONS

The extended S-shaped conformation of the Rex peptide, together with previous demonstrations of a beta-hairpin conformation for the bovine immunodeficiency virus (BIV) Tat peptide and an alpha-helical conformation for the human immunodeficiency virus (HIV) Rev peptide in complex with their respective RNA targets, expands our understanding of the strategies employed by ARMs for adaptive recognition and highlights the importance of RNA tertiary structure in accommodating minimalist elements of protein secondary structure.

Expression and purification of the transcription factor NtcA from the cyanobacterium Anabaena PCC 7120

The transcription factor NtcA from the cyanobacterium Anabaena PCC 7120 was heterologously expressed in Escherichia coli. In order to optimize the expression of NtcA, random silent mutations were introduced at the 5' end of the DNA encoding the protein. To get as high a yield of pure protein as possible, different strategies of expression as well as purification conditions were used. Under optimal expression conditions, a high-level expression clone of NtcA was coexpressed with GroEL-ES at 37 degrees C. A hexahistidine tag was added to the N-terminus of the protein in order to allow purification on an IMAC affinity column. Expression followed by one purification step using IMAC affinity chromatography gave a yield of 30-40 mg pure NtcA protein per liter of bacterial culture. Gel-shift experiments showed that the recombinant NtcA was active in binding a DNA sequence containing an NtcA-specific site.

Residential magnetic fields predicted from wiring configurations: II. Relationships To childhood leukemia

Case-control data on childhood leukemia in Los Angeles County were reanalyzed with residential magnetic fields predicted from the wiring configurations of nearby transmission and distribution lines. As described in a companion paper, the 24-h means of the magnetic field's magnitude in subjects' homes were predicted by a physically based regression model that had been fitted to 24-h measurements and wiring data. In addition, magnetic field exposures were adjusted for the most likely form of exposure assessment errors: classic errors for the 24-h measurements and Berkson errors for the predictions from wire configurations. Although the measured fields had no association with childhood leukemia (P for trend=.88), the risks were significant for predicted magnetic fields above 1.25 mG (odds ratio=2.00, 95% confidence interval=1.03-3.89), and a significant dose-response was seen (P for trend=.02). When exposures were determined by a combination of predictions and measurements that corrects for errors, the odds ratio (odd ratio=2.19, 95% confidence interval=1.12-4.31) and the trend (p =.007) showed somewhat greater significance. These findings support the hypothesis that magnetic fields from electrical lines are causally related to childhood leukemia but that this association has been inconsistent among epidemiologic studies due to different types of exposure assessment error. In these data, the leukemia risks from a child's residential magnetic field exposure appears to be better assessed by wire configurations than by 24-h area measurements. However, the predicted fields only partially account for the effect of the Wertheimer-Leeper wire code in a multivariate analysis and do not completely explain why these wire codes have been so often associated with childhood leukemia. The most plausible explanation for our findings is that the causal factor is another magnetic field exposure metric correlated to both wire code and the field's time-averaged magnitude.

Residential magnetic fields predicted from wiring configurations: I. Exposure model

A physically based model for residential magnetic fields from electric transmission and distribution wiring was developed to reanalyze the Los Angeles study of childhood leukemia by London et al. For this exposure model, magnetic field measurements were fitted to a function of wire configuration attributes that was derived from a multipole expansion of the Law of Biot and Savart. The model parameters were determined by nonlinear regression techniques, using wiring data, distances, and the geometric mean of the ELF magnetic field magnitude from 24-h bedroom measurements taken at 288 homes during the epidemiologic study. The best fit to the measurement data was obtained with separate models for the two major utilities serving Los Angeles County. This model's predictions produced a correlation of 0.40 with the measured fields, an improvement on the 0.27 correlation obtained with the Wertheimer-Leeper (WL) wire code. For the leukemia risk analysis in a companion paper, the regression model predicts exposures to the 24-h geometric mean of the ELF magnetic fields in Los Angeles homes where only wiring data and distances have been obtained. Since these input parameters for the exposure model usually do not change for many years, the predicted magnetic fields will be stable over long time periods, just like the WL code. If the geometric mean is not the exposure metric associated with cancer, this regression technique could be used to estimate long-term exposures to temporal variability metrics and other characteristics of the ELF magnetic field which may be cancer risk factors.

[Analysis of fusion points in hybrid genes and gene deletion for congenital red-green color vision defects]

OBJECTIVE

To investigate gene deletion and the fusion points of hybrid genes in congenital red-green color vision defects.

METHODS

Genomic DNA was collected from 11 protans, 19 deutans and 5 normal controls. Promoter and exons 2-5 of the red and green pigment genes in these subjects were analyzed by using PCR-Heteroduplex-SSCP analysis. The origin and component of each individual gene were determined by comparison with the patterns of known sequence of the red and green visual pigment genes.

RESULTS

Fourteen out of the 30 patients with red-green color vision defects were found to have hybrid gene. The fusion points of the hybrid gene were located in exon 1-intron 1(4 cases), introns 2-3(5 cases) and intron 4 (5 cases).

CONCLUSION

The fusion point of a hybrid gene may occur in exon 1-intron 1 and intron 4 as well as in introns 2-3(including exon 3).

Cholinergic prejunctional inhibition of nitrergic neurotransmission in the guinea-pig isolated basilar artery

1. The effects of endogenous and exogenous acetylcholine (ACh) on nitrergic relaxations elicited by electrical field stimulation (EFS) were studied in guinea-pig endothelium-denuded basilar artery preparations precontracted with 1 micromol/L prostaglandin F(2 alpha) and a possible role of K+ channels in mediating the effects was investigated. 2. Acetylcholine (3 micromol/L) and physostigmine (10 micromol/L) produced small, yet statistically significant, inhibitions of EFS-induced nitrergic relaxations, while atropine (1 micromol/L) slightly enhanced the nitrergic response. The ACh-induced inhibition was atropine sensitive. Acetylcholine or atropine did not affect relaxations induced by sodium nitroprusside. 3. The inhibition of nitrergic relaxations by 3 micromol/L ACh was prevented by the K+ channel blockers tetraethylammonium and 4-aminopyridine, but was not changed by iberiotoxin, apamin or glibenclamide. 4. Neither vasoactive intestinal polypeptide nor the alpha2-adrenoceptor agonists noradrenaline and clonidine modulated nitrergic neurotransmission in the guinea-pig basilar artery. 5. The findings show that ACh acts on prejunctional muscarinic receptors of nitrergic nerves to inhibit nitrergic neurotransmission. It is suggested that endogenous ACh may have this effect; however, the physiological significance of this prejunctional modulation is not clear due to the relatively small effect produced. The prejunctional inhibitory action of ACh may involve opening of neuronal K+ channels.

Ciliary neurotrophic factor induces expression of the IGF type I receptor and FGF receptor 1 mRNAs in adult rat brain oligodendrocytes

Ciliary neurotrophic factor (CNTF) is produced and released in response to injury in the central nervous system (CNS). While CNTF initially was characterized as a trophic factor for neurons, more recent evidence supports roles for this factor in survival, proliferation, and maturation of oligodendrocyte lineage cells. Evidence is emerging to support the hypothesis that CNTF's actions may include enhancing other growth and trophic factors. Here we tested the hypothesis that CNTF can induce expression of receptors on oligodendrocytes for factors that are known to promote their generation, maturation, and survival. Specifically, we used an in vivo paradigm to test whether CNTF, when injected stereotactically into forebrain white matter of adult rats, could induce mRNA expression for the insulin-like growth factor (IGF) type I receptor (IGF-IR), fibroblast growth factor (FGF) receptor (FGFR)-1, FGFR3, and platelet-derived growth factor (PDGF) receptor-alpha (PDGFRalpha). We determined that CNTF injection increased expression of IGF-IR and FGFR1 mRNAs in adult white matter to 200-250% of control levels. Cellular analysis indicated that these receptor mRNAs were induced in interfascicular oligodendrocytes. In contrast, CNTF had no effect on levels of FGFR3 and PDGFRalpha mRNAs. These results suggest that CNTF enhances the sensitivity of oligodendrocytes to other mitogens and trophic factors via induction of their receptors.

The role of protein kinase Calpha in U-87 glioma invasion

To investigate the hypothesis that protein kinase Calpha (PKCalpha) is functional glial tumor cell invasion, stable PKCalpha sense and antisense transfected U-87 cell lines were established and PKCalpha expression characterized by Western blot and PKC activity assays. Invasion assays including barrier migration (Koochekpour et al., Extracellular matrix proteins inhibit proliferation, upregulate migration and induce morphological changes in human glioma lines. Eur. J. Cancer, 1995, 31, 375-380; Merzak et al., CD44 mediates human glioma cell adhesion and invasion in vitro. Cancer Res., 1994, 54, 3988-3992; Merzak et al., Cell surface gangliosides are involved in the control of human glioma cell invasion in vitro. Neurosci. Lett., 1994, 177, 11-16), and spheroid confrontation were used to study the relationship between PKCalpha expression and invasiveness. PKCalpha overexpressing clones show increased barrier migration (1.5x) relative to the control transfected clones. PKCalpha inhibited clones exhibited reduced invasiveness, to < 50%. In coculture with PKCalpha overexpressing clones, the remaining normal fetal rat brain aggregate volume was significantly decreased (up to 200%) but 90% of the initial brain volume was left in PKCalpha inhibited clone in the rat brain aggregate tumor spheroid confrontation. This effect was not associated with significant growth inhibition. We conclude that expression of PKCalpha in glioma-derived cell lines appears to be central to glioma invasion in vitro.

Probing the kinetic mechanism and coenzyme specificity of glutathione reductase from the cyanobacterium Anabaena PCC 7120 by redesign of the pyridine-nucleotide-binding site

Glutathione reductase from the cyanobacterium Anabaena PCC 7120 contains a pyridine-nucleotide-binding motif differing from that of the enzyme from other sources and an insertion of 10 amino acid residues. Homology modeling was used to obtain a model of the enzyme structure. It revealed that in the Anabaena enzyme Lys(203) replaces Arg, found to interact with the 2'-phosphate of NADP(H) in the enzyme from other sources, and that it has an extra loop near the entrance of the pyridine-nucleotide-binding site. The steady-state and preequilibrium kinetic properties were characterized for the wild-type enzyme, a K203R, and a loop deletion mutant. All enzyme forms had higher catalytic efficiency with NADPH than with NADH, although the difference was less than for glutathione reductase from other sources. The specificity was most pronounced in the formation of the charge-transfer complex between the pyridine nucleotide and oxidized enzyme-bound FAD, as compared to later steps in the reaction. Unexpectedly, by replacing Lys(203) with Arg, the specificity for NADPH was diminished in the complete redox reaction. Ser(174) appears to interact with the 2'-phosphate of NADPH and introduction of arginine instead of lysine, therefore, has little effect on the interaction with this coenzyme. However, the efficiency in forming the charge-transfer complex between the pyridine nucleotide and oxidized enzyme-bound FAD was increased in the K203R mutant using NADPH but not with NADH. The lack of affinity toward 2',5'-ADP-Sepharose by the wild-type enzyme was not changed by replacing Lys(203) with Arg but deletion of the loop resulted in an enzyme that bound to the immobilized ligand. Removal of the loop increased the efficiency of the enzyme in the reductive half-reaction with both pyridine-nucleotides as well as in the overall catalytic mechanism.

Prognostic value of genomic alterations in invasive cervical squamous cell carcinoma of clinical stage IB detected by comparative genomic hybridization

The clinical behavior of invasive cervical carcinoma of clinical stage IB varies considerably in tumors presenting without regional lymph node metastases. The early identification of patients at higher risk for poor outcome may prove useful because these patients would benefit from aggressive adjuvant treatments. In this study, comparative genomic hybridization was applied to evaluate whether genomic aberrations have prognostic significance in cervical carcinoma. Genomic alterations were evaluated in 62 cervical carcinomas of clinical stage IB. DNA sequence losses were most prevalent at chromosomes 4q (53%), 3p (52%), 13q (45%), 4p (44%), Xq (44%), 5q (40%), 18q (37%), and 6q (35%). Several genomic alterations were associated with poor clinical outcome or metastasis. The total number of DNA aberrations/tumor (P < 0.02) and the number of DNA sequence losses/tumor (P < 0.04) were associated with disease-specific survival. 9p deletions were significantly more frequent in carcinomas with lymph node metastasis than in node-negative tumors (P < 0.03). Losses of chromosome 11p (P < 0.0001) and 18q (P < 0.01) were associated with poor prognosis in cervical carcinomas without lymph node metastasis. These data suggest that inactivation of tumor suppressor genes on chromosomes 9p, 11p, and 18q may play a role in the progression of cervical carcinoma.

Crystal structure of the cyclin-specific ubiquitin-conjugating enzyme from clam, E2-C, at 2.0 A resolution

The destruction of the cyclin B protein is necessary for the cell to exit from mitosis. The destruction of cyclin B occurs via the ubiquitin/proteasome system and involves a specific ubiquitin-conjugating enzyme (Ubc) that donates ubiquitin to cyclin B. Here we present the crystal structure of the cyclin-specific Ubc from clam, E2-C, determined at 2.0 A resolution. The E2-C enzyme contains an N-terminal extension in addition to the Ubc core domain. The N-terminal extension is disordered, perhaps reflecting a need for flexibility as it interacts with various partners in the ubiquitination system. The overall structure of the E2-C core domain is quite similar to those in previously determined Ubc proteins. The interaction between particular pairs of E2-C proteins in the crystal has some of the hallmarks of a functional dimer, though solution studies suggest that the E2-C protein exists as a monomer. Comparison of the E2-C structure with that of the other available Ubc structures indicates conserved surface residues that may interact with common components of the ubiquitination system. Such comparison also reveals a remarkable spine of conserved hydrophobic residues in the center of the protein that may drive the protein to fold and stabilize the protein once folded. Comparison of residues conserved only among E2-C and its homologues indicates surface areas that may be involved in mitotic-specific ubiquitination.

Inferring tree models for oncogenesis from comparative genome hybridization data

Comparative genome hybridization (CGH) is a laboratory method to measure gains and losses of chromosomal regions in tumor cells. It is believed that DNA gains and losses in tumor cells do not occur entirely at random, but partly through some flow of causality. Models that relate tumor progression to the occurrence of DNA gains and losses could be very useful in hunting cancer genes and in cancer diagnosis. We lay some mathematical foundations for inferring a model of tumor progression from a CGH data set. We consider a class of tree models that are more general than a path model that has been developed for colorectal cancer. We derive a tree model inference algorithm based on the idea of a maximum-weight branching in a graph, and we show that under plausible assumptions our algorithm infers the correct tree. We have implemented our methods in software, and we illustrate with a CGH data set for renal cancer.

Cholinergic prejunctional inhibition of nitrergic neurotransmission in the guinea-pig isolated basilar artery

1. The effects of endogenous and exogenous acetylcholine (ACh) on nitrergic relaxations elicited by electrical field stimulation (EFS) were studied in guinea-pig endothelium-denuded basilar artery preparations precontracted with 1 mumol/L prostaglandin F2 alpha and a possible role of K+ channels in mediating the effects was investigated. 2. Acetylcholine (3 mmol/L) and physostigmine (10 mumol/L) produced small, yet statistically significant, inhibitions of EFS-induced nitrergic relaxations, while atropine (1 mumol/L) slightly enhanced the nitrergic response. The ACh-induced inhibition was atropine sensitive. Acetylcholine or atropine did not affect relaxations induced by sodium nitroprusside. 3. The inhibition of nitrergic relaxations by 3 mumol/L ACh was prevented by the K+ channel blockers tetraethylammonium and 4-aminopyridine, but was not changed by iberiotoxin, apamin or glibenclamide. 4. Neither vasoactive intestinal polypeptide nor the alpha 2-adrenoceptor agonists noradrenaline and clonidine modulated nitrergic neurotransmission in the guinea-pig basilar artery. 5. The findings show that ACh acts on prejunctional muscarinic receptors of nitrergic nerves to inhibit nitrergic neurotransmission. It is suggested that endogenous ACh may have this effect; however, the physiological significance of this prejunctional modulation is not clear due to the relatively small effect produced. The prejunctional inhibitory action of ACh may involve opening of neuronal K+ channels.

Optimized heterologous expression of glutathione reductase from Cyanobacterium anabaena PCC 7120 and characterization of the recombinant protein

Glutathione reductase (GR) from the cyanobacterium Anabaena PCC 7120 was heterologously expressed in Escherichia coli SG5. Silent random mutations were introduced in the 5' region of DNA encoding the enzyme in order to generate a high-level expression clone. To maximize protein expression, the culture conditions were also optimized. In the high-level expression clones selected, E. coli-preferred codons were selectively used at certain positions. Under the optimal expression conditions, a yield of 17 mg recombinant protein per liter was obtained, which is about 10-fold higher than that of the wild-type enzyme. A hexahistidine tag was added at the C-terminal of the protein in order to allow IMAC affinity purification. This strategy simplified the purification process and provided a homogeneous enzyme for functional characterization. Anabaena GR uses NADPH as a coenzyme, like most of the GRs from other sources, but the KM values for NADPH and GSSG are higher than those of enzymes previously studied. The Anabaena enzyme also shows significant activity when NADH is used as a reductant.

Efficient and stable transduction of cardiomyocytes after intramyocardial injection or intracoronary perfusion with recombinant adeno-associated virus vectors

BACKGROUND

The delivery of recombinant genes to cardiomyocytes holds promise for the treatment of a variety of cardiovascular diseases. Previous gene transfer approaches that used direct injection of plasmid DNA or replication-defective adenovirus vectors have been limited by low transduction frequencies and transient transgene expression due to immune responses, respectively. In this report, we have tested the feasibility of using intramyocardial injection or intracoronary infusions of recombinant adeno-associated virus (rAAV) vectors to program transgene expression in murine cardiomyocytes in vivo.

METHODS AND RESULTS

We constructed an rAAV containing the LacZ gene under the transcriptional control of the cytomegalovirus (CMV) promoter (AAVCMV-LacZ). We then injected 1x10(8) infectious units (IU) of this virus into the left ventricular myocardium of adult CD-1 mice. Control hearts were injected with the AdCMV-LacZ adenovirus vector. Hearts harvested 2, 4, and 8 weeks after AAVCMV-LacZ injection demonstrated stable beta-galactosidase (beta-gal) expression in large numbers of cardiomyocytes without evidence of myocardial inflammation or myocyte necrosis. In contrast, the AdCMV-LacZ-injected hearts displayed transient beta-gal expression, which was undetectable by 4 weeks after injection. Explanted C57BL/6 mouse hearts were also perfused via the coronary arteries with 1.5x10(9) IU of AAVCMV-LacZ and assayed 2, 4, and 8 weeks later for beta-gal expression. beta-Gal expression was detected in <1% of cardiomyocytes at 2 weeks after perfusion but was detected in up to 50% of cardiomyocytes 4 to 8 weeks after perfusion.

CONCLUSIONS

Direct intramyocardial injection or coronary artery perfusion with rAAV vectors can be used to program stable transgene expression in cardiomyocytes in vivo. rAAV appears to represent a useful vector for the delivery of therapeutic genes to the myocardium.

Effects of hydrostatic pressure on cultured bovine trabecular meshwork cells

In order to explore the effects of pressure on trabecular meshwork cells, bovine trabecular meshwork cells were cultured in vitro and subjected to different levels of hydrostatic pressure. The cellular morphology, ultrastructure and phagocytosis were studied with inverted phase-contrast microscopy, light microscopy and transmission electron microscopy, etc. It was found that the cells subjected to 2.0 kPa or 2.67 kPa for 48 h had no remarkable difference as compared with the controls in terms of parameters observed. Those under 4.0 kPa for 24 h showed slight changes in structure and a mild decrease in phagocytic function. The damage appeared more severe if the pressure was higher or lasted longer. From the above we conclude that trabecular meshwork cells can only bear pressure below a certain level. They may be destroyed structurally or impaired functionally by pressure over this level.

Cardiolipin synthase expression is essential for growth at elevated temperature and is regulated by factors affecting mitochondrial development

Cardiolipin (CL) is a unique dimeric phospholipid localized primarily in the mitochondrial membrane. In eukaryotes, the enzyme CL synthase catalyses the synthesis of CL from two lipid substrates, CDP-diacylglycerol and phosphatidylglycerol. In earlier studies, we reported the purification of CL synthase from Saccharomyces cerevisiae and the cloning of the gene CRD1 (previously called CLS1) that encodes the enzyme. Because CL is an important component of the mitochondrial membrane, knowledge of its regulation will provide insight into the biogenesis of this organelle. To understand how CL synthesis is regulated, we analysed CRD1 expression by Northern blot analysis of RNA extracted from cells under a variety of growth conditions. CRD1 expression is regulated by mitochondrial development factors. CRD1 levels were 7- to 10-fold greater in stationary than in logarithmic growth phase, and threefold greater in wild-type than in rho 0 mutants. Expression was somewhat elevated during growth in glycerol/ethanol versus glucose media. In contrast, CRD1 expression was not regulated by the phospholipid precursors inositol and choline, and was not altered in the regulatory mutants ino2, ino4 and opi1. Mutations in cytochrome oxidase assembly, which led to reduced Crd1p enzyme activity, did not affect CRD1 expression. The crd1 null mutant makes a truncated CRD1 message. Although the null mutant can grow on both fermentable and non-fermentable carbon sources at lower temperatures, it cannot form colonies at 37 degrees C. In conclusion, CRD1 expression is controlled by factors affecting mitochondrial development, but not by the phospholipid precursors inositol and choline. Expression of CRD1 is essential for growth at elevated temperatures, suggesting that either CL or Crd1p is required for an essential cellular function.

[Loss of heterozygosity and microsatellite instability in the region including BRCA1 of breast cancer in Chinese]

OBJECTIVE

To shed light on the relationship between BRCA1 gene and breast cancer in Chinese Han women.

METHODS

Four microsatellites DNA (D17S855, D17S579, D17S1327 and THRA1) within the BRCA1 gene were used as polymorphic markers. A study of loss of heterozygosity(LOH) and microsatellite instability(MSI) at the above- mentioned 4 microsatellites of 50 breast cancer patients was conducted by using PCR -PAUGE-DNA silver staining (polymerase chain reaction-polyacrylamide urea gel electrophoresis) method.

RESULTS

Twenty-nine or 58% of the informative cases showed LOH; 35.71%, 15. 38%, 18.18%, and 26.19% of the informative cases showed positive LOH at the D17S855, D17S579, D17S1327 and THRA1 loci respectively. The rate of MSI was 46%, and the rates of MSI at the four loci were 16%, 18%, 18% and 12% respectively. Further study on the associations between the phenomena of LOH and MSI and different clinical stages revealed that MSI was an early event in mammary tumorigenesis while LOH occurred at a later stage.

CONCLUSION

All of these suggest that breast cancer in Chinese be somehow linked to BRCA1.

GATA6 regulates HNF4 and is required for differentiation of visceral endoderm in the mouse embryo

GATA6 belongs to a family of zinc finger transcription factors that play important roles in transducing nuclear events that regulate cellular differentiation and embryonic morphogenesis in vertebrate species. To examine the function of GATA6 during embryonic development, gene targeting was used to generate GATA6-deficient (GATA6(-/-)) ES cells and mice harboring a null mutation in GATA6. Differentiated embryoid bodies derived from GATA6(-/-) ES cells lack a covering layer of visceral endoderm and severely attenuate, or fail to express, genes encoding early and late endodermal markers, including HNF4, GATA4, alpha-fetoprotein (AFP), and HNF3beta. Homozygous GATA6(-/-) mice died between embryonic day (E) 6.5 and E7. 5 and exhibited a specific defect in endoderm differentiation including severely down-regulated expression of GATA4 and absence of HNF4 gene expression. Moreover, widespread programmed cell death was observed within the embryonic ectoderm of GATA6-deficient embryos, a finding also observed in HNF4-deficient embryos. Consistent with these data, forced expression of GATA6 activated the HNF4 promoter in nonendodermal cells. Finally, to examine the function of GATA6 during later embryonic development, GATA6(-/-)-C57BL/6 chimeric mice were generated. lacZ-tagged GATA6(-/-) ES cells contributed to all embryonic tissues with the exception of the endodermally derived bronchial epithelium. Taken together, these data suggest a model in which GATA6 lies upstream of HNF4 in a transcriptional cascade that regulates differentiation of the visceral endoderm. In addition, these data demonstrate that GATA6 is required for establishment of the endodermally derived bronchial epithelium.