A voltage- and Ca2+-dependent big conductance K channel in cochlear spiral ligament fibrocytes

Evidence is accruing that spiral ligament fibrocytes (SLFs) play an important role in cochlear K(+) homeostasis, but little direct physiological data is available to support this concept. Here we report the presence and characterization of a voltage- and Ca(2+)-dependent big-conductance K (BK) channel in type I SLFs cultured from the gerbil cochlea. A single-channel conductance of 298+/-5.6 pS (n=28) was measured under symmetrical K(+). Membrane potentials for half-maximal open probability (P(o)) were -67, -45 and 85 mV with cytosolic free-Ca(2+) levels of 0.7 mM, 10 microM and 1 microM, respectively (n=8-14). The Hill coefficient for Ca(2+) affinity was 1.9 at a membrane potential of 60 mV (n=6). The BK channel showed very low activity (P(o)=0.0019, n=5) under normal physiological conditions, suggesting a low resting intracellular free [Ca(2+)]. Pharmacological results fit well with the profile of classic BK channels. The estimated half-maximal inhibitory concentration and Hill coefficient for tetraethylammonium were 0.086+/-0.021 mM and 0.99, respectively (n=4-9). In whole cell recordings, the voltage-activated outward K current was inhibited 85.7+/-4.5% (n=6) by 0.1 microM iberiotoxin. A steady-state kinetic model with two open and two closed stages best described the BK gating process (tau(o1) 0.23+/-0.08 ms, tau(o2) 1.40+/-0.32 ms; tau(c1) 0.26+/-0.09 ms, tau(c2) 3.10+/-1.2 ms; n=11). RT-PCR analyses revealed a splice variant of the BK channel alpha subunit in cultured type I SLFs and freshly isolated spiral ligament tissues. The BK channel is likely to play a major role in regulating the membrane potential of type I SLFs, which may in turn influence K(+) recycling dynamics in the mammalian cochlea.

[Human toll like receptor gene expression in human pulmonary granule epithelial cells and umbilical vein endothelial cells]

OBJECTIVE

To determine whether human Toll like receptors (TLRs) genes are expressed in human lung granule epithelial cells and umbilical vein endothelial cells (UVECs).

METHODS

Specific primers for TLR2 and TLR4 were designed and total RNAs were isolated from human monocyte cell line THP-1, human lung granule epithelial cell line SPC-A-1 and the primary culture of human UVECs. RT-PCR and Northern blotting with digoxin labeling were used for the detection of TLR2 and TLR4 mRNA expression.

RESULTS

TLR4 mRNA expressed in the three types of cells mentioned above. TLR2 mRNA was detected in THP-1 and UVECs, but not in SPC-A-1 cells. By using DNA sequencing, the RT-PCR products were confirmed to be TLR2 and TLR4 cDNAs.

CONCLUSION

This study provided evidence indicating that Toll like receptor genes constitutively express not only in human monocytes but also in human larger vascular endothelial cells and pulmonary granule epithelial cells.

Signalling of GPI-anchored CD157 via focal adhesion kinase in MCA102 fibroblasts

CD157, a glycosylphosphatidylinositol-anchored protein, has previously been shown to mediate tyrosine phosphorylation of a 130 kDa protein (p130) in several cell lines. In this study, we have identified the p130 protein to be focal adhesion kinase (FAK or pp125(FAK)). FAK undergoes phosphorylation at Tyr-397 and Tyr-861 in intact MCA102 cells stably transfected with CD157 (MCA/CD157). MCA/CD157 cells, which displayed a rounded and compact cell morphology, exhibited a dispersed distribution, in contrast to a more closely associated and elongated spindle cell shape in the vector-transfected cells. MCA/CD157 cells proliferated at a rate 20-25% slower than the control cells. Our results demonstrate, for the first time, that FAK is a downstream signalling molecule of CD157.

On relationship inference using gamete identity by descent data

Related individuals are identical by descent (IBD) at a genetic locus if they share the same DNA material from a common ancestor. Continuous gamete IBD data consist of the lengths of (in order) IBD and non-IBD regions along the genomes for gametes segregating from two related individuals and can be used to distinguish different relationships. Under the assumption that the crossovers follow a Poisson process, we show that the exact calculation of the likelihood of a particular relationship for a given gamete IBD datum is tractable. Greatgrandparent--greatgrandchild and cousin relationships are used as examples to illustrate our methods.

Diversity and regulation of plant Ca2+ pumps: insights from expression in yeast

The spatial and temporal regulation of calcium concentration in plant cells depends on the coordinate activities of channels and active transporters located on different organelles and membranes. Several Ca2+ pumps have been identified and characterized by functional expression of plant genes in a yeast mutant (K616). This expression system has opened the way to a genetic and biochemical characterization of the regulatory and catalytic features of diverse Ca2+ pumps. Plant Ca(2+)-ATPases fall into two major types: AtECA1 represents one of four or more members of the type IIA (ER-type) Ca(2+)-ATPases in Arabidopsis, and AtACA2 is one of seven or more members of the type IIB (PM-type) Ca(2+)-ATPases that are regulated by a novel amino terminal domain. Type IIB pumps are widely distributed on membranes, including the PM (plasma membrane), vacuole, and ER (endoplasmic reticulum). The regulatory domain serves multiple functions, including autoinhibition, calmodulin binding, and sites for modification by phosphorylation. This domain, however, is considerably diverse among several type IIB ATPases, suggesting that the pumps are differentially regulated. Understanding of Ca2+ transporters at the molecular level is providing insights into their roles in signaling networks and in regulating fundamental processes of cell biology.

Immunohistochemical localization of WE-14 in the developing porcine sympathoadrenal cell lineage

Immunohistochemical investigation of the post-translational processing of chromogranin A (CgA) to generate WE-14 in the sympathoadrenal cell lineage of the developing porcine fetus (F) detected intense CgA and weak WE-14 immunoreactivity in migrating neuroblast cells of the diffuse sympathetic ganglia adjacent to the dorsal aorta and projecting toward the cortical mass at F24-27. F37-42; WE-14 immunoreactivity was detected in chromaffinoblasts at the periphery of the developing cortex and at F54-56 days gestation WE-14 immunoreactivity was detected in a large population of central medullary cells. From F74 to F76 days and thereafter the number of cells exhibiting intense WE-14 immunostaining decreased, and the majority of chromaffin cells exhibited uniform weak WE-14 immunostaining. At postnatal day 1 (P1) intense WE-14 immunoreactivity was primarily confined to clusters of chromaffin cells with weak immunostaining in the general population. The transitory neuroblasts, chromaffinoblasts, and maturing chromaffin cell population exhibited uniform intense CgA immunostaining through gestation and after birth. Additional observations detected intense CgA and WE-14 immunostaining in extrachromaffin tissue at P1 and in neuronal-like cells in vessels of the aortic arch at F37. This study has demonstrated that CgA is post-translationally processed to generate WE-14 during early fetal development in the migrating progenitor cells of the porcine sympathoadrenal lineage.

Signaling mechanisms underlying strain-dependent brain natriuretic peptide gene transcription

Activation of brain natriuretic peptide (BNP) gene promoter activity represents one of the earliest and most reliable markers of ventricular cardiac myocyte hypertrophy. We recently demonstrated that mechanical strain increases immunoreactive BNP secretion, steady-state BNP mRNA levels and BNP gene transcriptional activity in neonatal rat myocyte cultures. We have also shown that strain-dependent BNP gene transcription is critically dependent on the functional integrity of a number of integrins (specfically beta1, beta3, and alpha(v)beta5 integrins) present on the surface of cardiac myocytes. When used alone, each of these antibodies resulted in a significant reduction in strain-dependent activation of a transfected hBNP-luciferase reporter and inhibition of a number of signaling pathways that have been linked to stimulation of this reporter (e.g., extracellular signal regulated kinase and c-Jun amino terminal kinase). The present study shows that combinations of these antibodies resulted in further reductions in hBNP gene promoter activity and inhibition of the relevant signaling cascades. These studies provide further support for the importance of integrin-matrix interactions in promoting strain-dependent changes in cardiac myocyte gene transcription.

Synthesis, nicotinic acetylcholine receptor binding, and antinociceptive properties of 2-exo-2-(2'-substituted 5'-pyridinyl)-7-azabicyclo[2.2.1]heptanes. Epibatidine analogues

A convenient, high-yield synthesis of 7-tert-butoxycarbonyl-7-azabicyclo[2.2.1]hept-2-ene (5), which involved the addition of tributyltin hydride to 7-tert-butoxycarbonyl-2-p-toluenesulfonyl-7-azabicyclo[2.2.1]hept-2-ene (4) followed by elimination of the tributyltin and p-tolylsulfonyl groups using tetrabutylammonium fluoride was developed. The addition of 2-amino-5-iodopyridine to 5 under reductive Heck conditions provided 7-tert-butoxycarbonyl-2-exo-(2'-amino-5'-pyridinyl)-7-azabicyclo[2.2.1]heptane (6). Compound 6 was the key intermediate used to prepare epibatidine analogues where the 2'-chloro group on the pyridine ring was replaced with a fluorine (1b), bromine (1c), iodine (1d), hydroxy (1e), amino (1f), dimethylamino (1g), trifluoromethanesulfonate (1h), and hydrogen (1i) group. (+)- and (-)-Epibatidine and compounds 1b-d and 1i all possess similar binding affinities at the alpha(4)beta(2) nAChR receptors labeled by [(3)H]epibatidine. Compound 1f has affinity similar to nicotine, whereas compounds 1e, 1g, and 1h have much lower affinity. The binding affinity appears to be dependent upon the electronic nature of the substituent. However, other factors are also involved. None of the compounds possesses appreciable affinity for the alpha(7) nAChR labeled by [(125)I]iodo-MLA. With the exception of 1f and 1g, all the epibatidine analogues are full agonists (tail flick test) in producing antinociception after intrathecal injection in mice.

Coupling of agonist-induced AMPA receptor internalization with receptor recycling

Excitatory post-synaptic currents in the CNS are primarily mediated by alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) receptors in response to glutamate. Internalization of cell-surface receptors has been shown to be one mechanism by which to control receptor function. To test for agonist control of AMPA receptor plasma membrane expression we used biochemical assays to study AMPA receptor internalization and insertion processes. In heterologous cells, we observed a slow constitutive internalization and a rapid agonist-induced internalization of AMPA receptors. To our surprise, however, agonist treatment had no effect on the steady-state levels of AMPA receptors on the cell surface. To examine whether this could be explained by an agonist-induced increase in the insertion rate of AMPA receptors into the plasma membrane we developed an assay to independently measure receptor insertion. Remarkably, agonist treatment of cells also dramatically increased AMPA receptor plasma membrane insertion rates. In addition, using an assay to measure recycling of internalized pools we found that internalized receptors are rapidly recycled to the cell surface. These results suggest that agonist-induced receptor internalization is coupled to increases in receptor recycling. This increase in receptor flux through intracellular pools may allow for rapid changes in receptor surface expression by independent regulatory control of internalization and insertion.

Sequence evaluation of four pooled-tissue normalized bovine cDNA libraries and construction of a gene index for cattle

An essential component of functional genomics studies is the sequence of DNA expressed in tissues of interest. To provide a resource of bovine-specific expressed sequence data and facilitate this powerful approach in cattle research, four normalized cDNA libraries were produced and arrayed for high-throughput sequencing. The libraries were made with RNA pooled from multiple tissues to increase efficiency of normalization and maximize the number of independent genes for which sequence data were obtained. Target tissues included those with highest likelihood to have impact on production parameters of animal health, growth, reproductive efficiency, and carcass merit. Success of normalization and inter- and intralibrary redundancy were assessed by collecting 6000-23,000 sequences from each of the libraries (68,520 total sequences deposited in GenBank). Sequence comparison and assembly of these sequences was performed in combination with 56,500 other bovine EST sequences present in the GenBank dbEST database to construct a cattle Gene Index (available from The Institute for Genomic Research at http://www.tigr.org/tdb/tgi.shtml). The 124,381 bovine ESTs present in GenBank at the time of the analysis form 16,740 assemblies that are listed and annotated on the Web site. Analysis of individual library sequence data indicates that the pooled-tissue approach was highly effective in preparing libraries for efficient deep sequencing.

Hepatocellular carcinoma and aflatoxin exposure in Zhuqing Village, Fusui County, People's Republic of China

Hepatocellular carcinoma (HCC) is a common cause of cancer morbidity and mortality in Asia and Africa. Epidemiological studies have found that dietary exposure to aflatoxin B1 (AFB1) and chronic infection with hepatitis B virus are two major risk factors for HCC. We have collated the incidence and mortality data of malignant tumors from 1973 to 1999 in Zhuqing Village, Fusui County, an area with very high HCC rates, and found that this cancer accounted for 64% of the total cancer incidence. Dietary intake of AFB1 was monitored for 1 week in a study group consisting of 15 males and 14 females from different households in this village. Four of 29 participants (13.8%) and 3 of 15 (20%) male participants were hepatitis B virus surface antigen positive. AFB1 was detectable in 76.7% (23 of 30) of ground corn samples (range, 0.4-128.1 ppb), 66.7% (20 of 30) of cooking peanut oil samples (range, 0.1-52.5 ppb), and 23.3% (7 of 30) of rice samples (range, 0.3-2.0 ppb) collected from each household. Mean levels of serum AFB1-albumin adducts in this group were 1.24 +/- 0.31 pmol/mg of albumin at the beginning of the study and 1.21 +/- 0.19 pmol/mg of albumin at the end of the period. Urinary AFB1 metabolites were detectable in 88.9% (24 of 27) samples (range, 0.9-3569.7 ng/24-h urine). These data provide the exposure and disease risk information for establishing intervention studies to diminish the impact of aflatoxin exposure in this high-risk population.

Functional interaction of NF-Y and Sp1 is required for type a natriuretic peptide receptor gene transcription

The vasorelaxant and anti-mitogenic activities of the atrial and brain natriuretic peptides depend upon their binding to the type A natriuretic peptide receptor (NPR-A) expressed on the surface of vascular cells. Intervention strategies aimed at controlling NPR-A expression are limited by the paucity of studies in this area. Here we identify a sequence CCAAT between -141 and -137 of the NPR-A promoter that, when mutated, reduces promoter activity by 90% in rat aortic smooth muscle (RASM) cells. Protein/DNA cross-linking and immunoperturbation of electrophoretically shifted complexes formed between RASM nuclear extracts and an oligonucleotide surrounding the CCAAT sequence indicates that the heterotrimeric transcription factor NF-Y binds specifically to the wild-type, but not mutated, CCAAT element. Cotransfection of a dominant negative mutant of the NF-YA subunit results in a concentration-dependent decrease in the activity of the NPR-A promoter in RASM cells confirming that endogenous NF-Y is an activator of the promoter. Mutation of the CCAAT element, in conjunction with mutation of all three Sp1 sites previously shown to be involved in NPR-A promoter regulation, virtually eliminates NPR-A promoter activity in RASM cells. Coexpression of all three NF-Y subunits together with Sp1 in Drosophila cells deficient in these factors indicates that NF-Y and Sp1 act synergistically to reconstitute NPR-A promoter activity. A direct physical association between NF-Y and Sp1 can be demonstrated both in vitro by glutathione S-transferase pull-down assay and in the intact cell by coimmunoprecipitation and functional studies. Together, these studies show that NPR-A promoter activity is dominantly regulated through functional, and possibly physical, interactions of NF-Y and Sp1.

[Preparation of novel magnetic dextran affinity adsorbents and their application to purify urokinase]

The reverse phase suspension and embedment technique were adopted to prepare magnetic dextran microsphere (MDMS). The dispersion medium was mixture of some organic solvents. Span-80 was used as stabilizer. The aqueous dextran with magnetic fluid was suspended in dispersion medium with epichlorohydrin as cross-linking reagent. The mixture was stirred for 30 minutes at room temperature and then heated at 70 degrees C for 4 hours, MDMS was thus obtained. MDMS was activated by epichlorohydrin on which 6-aminohexanoic acid, glycine or ethylene diamine was bonded as spacers. Then it was coupled with p-aminobenzamide, L-arginine methyl ester or guanidohexanoic acid and five magnetic affinity adsorbents were prepared. The MDMS was polydisperse particles with the size of 50-300 meshes and the content of Fe3O4 was about 6.2 per cent in the MDMS. Influence of some parameters such as viscosity and density of organic phase, the volume ratio of organic and aqueous phase, the quantity of surfactant and stirring speed on preparing MDMS was studied. Magnetic affinity adsorbents were used to purify crude urokinase in a bath mode and the effect of coupling reagents and ligands on results of purification was discussed. The bioactivity recovery was 40.0 to 60.7 per cent, the purification-fold was between 14.9 and 32.8, and the adsorptive capacity varies from 89 mg to 121 mg per milliliter of adsorbent.

The TIGR Gene Indices: analysis of gene transcript sequences in highly sampled eukaryotic species

While genome sequencing projects are advancing rapidly, EST sequencing and analysis remains a primary research tool for the identification and categorization of gene sequences in a wide variety of species and an important resource for annotation of genomic sequence. The TIGR Gene Indices (http://www.tigr.org/tdb/tgi. shtml) are a collection of species-specific databases that use a highly refined protocol to analyze EST sequences in an attempt to identify the genes represented by that data and to provide additional information regarding those genes. Gene Indices are constructed by first clustering, then assembling EST and annotated gene sequences from GenBank for the targeted species. This process produces a set of unique, high-fidelity virtual transcripts, or Tentative Consensus (TC) sequences. The TC sequences can be used to provide putative genes with functional annotation, to link the transcripts to mapping and genomic sequence data, to provide links between orthologous and paralogous genes and as a resource for comparative sequence analysis.

The occ1 gene is preferentially expressed in the primary visual cortex in an activity-dependent manner: a pattern of gene expression related to the cytoarchitectonic area in adult macaque neocortex

Marker molecules to visualize specific subsets of neurons are useful for studying the functional organization of the neocortex. One approach to identify such molecular markers is to examine the differences in molecular properties among morphologically and physiologically distinct neuronal cell types. We used differential display to compare mRNA expression in the anatomically and functionally distinct areas of the adult macaque neocortex. We found that a gene, designated occ1, was preferentially transcribed in the posterior region of the neocortex, especially in area 17. Complete sequence analysis revealed that occ1 encodes a macaque homolog of a secretable protein, TSC-36/follistatin-related protein (FRP). In situ hybridization histochemistry confirmed the characteristic neocortical expression pattern of occ1 and showed that occ1 transcription is high in layers II, III, IVA and IVC of area 17. In addition, occ1 transcription was observed selectively in cells of the magnocellular layers in the lateral geniculate nucleus (LGN). Dual labeling immunohistochemistry showed that the occ1-positive neurons in area 17 include both gamma-aminobutyric acid (GABA)-positive aspiny inhibitory cells and the alpha-subunit of type II calcium/calmodulin-dependent protein kinase (CaMKII alpha)-positive spiny excitatory cells. With brief periods of monocular deprivation, the occ1 mRNA level decreased markedly in deprived ocular dominance columns of area 17. From this we conclude that the expression of occ1 mRNA is present in a subset of neurons that are preferentially localized in particular laminae of area 17 and consist of various morphological and physiological neuronal types, and, furthermore, occ1 transcription is subject to visually driven activity-dependent regulation.

Regulation of AMPA receptor GluR1 subunit surface expression by a 4. 1N-linked actin cytoskeletal association

The synaptic localization, clustering, and immobilization of neurotransmitter receptors and ion channels play important roles in synapse formation and synaptic transmission. Although several proteins have been identified that interact with AMPA receptors and that may regulate their synaptic targeting, little is known about the interaction of AMPA receptors with the cytoskeleton. In studies examining the interaction of the AMPA receptor GluR1 subunit with neuronal proteins, we determined that GluR1 interacts with the 4.1G and 4.1N proteins, homologs of the erythrocyte membrane cytoskeletal protein 4.1. Using the yeast two-hybrid system and a heterologous cell system, we demonstrated that both 4.1G and 4.1N bind to a membrane proximal region of the GluR1 C terminus, and that a region within the C-terminal domain of 4.1G or 4.1N is sufficient to mediate the interaction. We also found that 4.1N can associate with GluR1 in vivo and colocalizes with AMPA receptors at excitatory synapses. Disruption of the interaction of GluR1 with 4.1N or disruption of actin filaments decreased the surface expression of GluR1 in heterologous cells. Moreover, disruption of actin filaments in cultured cortical neurons dramatically reduced the level of surface AMPA receptors. These results suggest that protein 4.1N may link AMPA receptors to the actin cytoskeleton.

Anchoring of rice BAC clones to the rice genetic map in silico

A wealth of molecular resources have been developed for rice genomics, including dense genetic maps, expressed sequence tags (ESTs), yeast artificial chromosome maps, bacterial artificial chromosome (BAC) libraries and BAC end sequence databases. Integration of genetic and physical maps involves labor-intensive empirical experiments. To accelerate the integration of the bacterial clone resources with the genetic map for the International Rice Genome Sequencing Project, we cleaned and filtered the available EST and BAC end sequences for repetitive sequences and then searched all available rice genetic markers with our filtered databases. We identified 418 genetic markers that aligned with at least one BAC end sequence with >95% sequence identity, providing a set of large insert clones with an average separation of 1 Mb that can serve as nucleation points for the sequencing phase of the International Rice Genome Sequencing Project.

An optimized protocol for analysis of EST sequences

The vast body of Expressed Sequence Tag (EST) data in the public databases provide an important resource for comparative and functional genomics studies and an invaluable tool for the annotation of genomic sequences. We have developed a rigorous protocol for reconstructing the sequences of transcribed genes from EST and gene sequence fragments. A key element in developing this protocol has been the evaluation of a number of sequence assembly programs to determine which most faithfully reproduce transcript sequences from EST data. The TIGR Gene Indices constructed using this protocol for human, mouse, rat and a variety of other plant and animal models have demonstrated their utility in a variety of applications and are freely available to the scientific research community.

Integrin dependence of brain natriuretic peptide gene promoter activation by mechanical strain

Expression of the brain natriuretic peptide (BNP) gene in cultured neonatal rat ventricular myocytes is activated by mechanical strain in vitro. We explored the role of cell-matrix contacts in initiating the strain-dependent increment in human BNP (hBNP) promoter activity. Coating the culture surface with fibronectin effected a dose-dependent increase in basal hBNP luciferase activity and amplification of the response to strain. Preincubation of myocytes with an RGD peptide (GRGDSP) or with soluble fibronectin, each of which would be predicted to compete for cell-matrix interactions, resulted in a dose-dependent reduction in strain-dependent hBNP promoter activity. A functionally inert RGE peptide (GRGESP) was without effect. Using fluorescence-activated cell sorting, we demonstrated the presence of beta(1), beta(3), and alpha(v)beta(5) integrins in myocytes as well as non-myocytes and alpha1 only in non-myocytes in our cultures. Inclusion of antibodies directed against beta(1), beta(3), or alpha(v)beta(5), but not alpha(1), alpha(2), or cadherin, was effective in blocking the BNP promoter response to mechanical strain. These same antibodies (anti-beta(3), -beta(1), and -alpha(v)beta(5)) had a similar inhibitory effect on strain-stimulated ERK, p38 MAPK, and, to a lesser extent, JNK activities in these cells. Cotransfection with chimeric integrin receptors capable of acting as dominant-negative inhibitors of integrin function demonstrated suppression of strain-dependent BNP promoter activity when vectors encoding beta(1) or beta(3), but not beta(5), alpha(5), or a carboxyl-terminal deletion mutant of beta(3) (beta(3)B), were employed. These studies underscore the importance of cell-matrix interactions in controlling cardiac gene expression and suggest a potentially important role for these interactions in signaling responses to mechanical stimuli within the myocardium.

Gene index analysis of the human genome estimates approximately 120,000 genes

Although sequencing of the human genome will soon be completed, gene identification and annotation remains a challenge. Early estimates suggested that there might be 60,000-100,000 (ref. 1) human genes, but recent analyses of the available data from EST sequencing projects have estimated as few as 45,000 (ref. 2) or as many as 140, 000 (ref. 3) distinct genes. The Chromosome 22 Sequencing Consortium estimated a minimum of 45,000 genes based on their annotation of the complete chromosome, although their data suggests there may be additional genes. The nearly 2,000,000 human ESTs in dbEST provide an important resource for gene identification and genome annotation, but these single-pass sequences must be carefully analysed to remove contaminating sequences, including those from genomic DNA, spurious transcription, and vector and bacterial sequences. We have developed a highly refined and rigorously tested protocol for cleaning, clustering and assembling EST sequences to produce high-fidelity consensus sequences for the represented genes (F.L. et al., manuscript submitted) and used this to create the TIGR Gene Indices-databases of expressed genes for human, mouse, rat and other species (http://www.tigr.org/tdb/tgi.html). Using highly refined and tested algorithms for EST analysis, we have arrived at two independent estimates indicating the human genome contains approximately 120,000 genes.

[Abdominal aortic aneurysm treated by endovascular stent-graft and conventional surgical repair: a comparison]

OBJECTIVE

To evaluate the feasibility of abdominal aortic aneurysm (AAA) treated by endovascular stent-graft.

METHODS

The clinical data of 52 patients with AAA treated by endovascular stent-graft (n = 20) and conventional surgical repair (n = 32) were analysed retrospectively. Patients conditions, operative hours, blood loss, function recovery and complications were compared.

RESULTS

No significant difference was observed in sex, age, other disease, anesthesia risk category, aneurysm type, aneurysm diameter, technical success rate, and mortality rate between the groups (P > 0.05). The patients who underwent intraluminal treatment had significant reductions in operative time, blood loss, intensive care unit and hospitalization. But there was a high complication rate in the endovascular stent-graft group. All complications were connected with the interventional technique; endo-leak was the chief complication after operation.

CONCLUSIONS

Endovascular treatment has marked merits such as reduced trauma, short hospitalization stays, and early functional recovery. It is suitable for the patients who can't undergo open surgical repair. But the complications caused by this technique needs further study.

Immunohistochemical examination of the lungs in infant death cases using antibodies against milk components

To examine the use of immunohistochemical staining with antibodies against milk components for detection of aspirated milk on lung sections, eighteen infant death cases were investigated. Immunostaining was performed with anti-human alpha lactalbumin, anti-human IgA, anti-human milk fat globulin 1, and anti-cow whey antibody. Reactivity with each antibody was examined, and semi-quantitative examinations were performed to compare the amount of aspirated milk using anti-human alpha lactalbumin antibody. Materials in the alveoli or bronchioli on lung sections suspected to be aspirated milk showed the most sensitive and clearest reaction with anti-human alpha lactalbumin antibody. Of the eighteen cases, ten cases showed positive reaction with this antibody. The amount of aspirated milk varied widely in each case. In conclusion, immunohistochemical staining with antibodies against human milk components, especially anti-human alpha lactalbumin antibody, can detect small amounts of milk. Using this method, we were able to compare the relative amount of aspirated milk among cases.

[Endoluminal stent-graft repair of aortic aneurysms]

OBJECTIVE

To study the clinical value of the treatment of aortic aneurysms with endovascular stent-graft prosthesis.

METHODS

After a unilateral surgical arteriotomy, Talent, Vanguard and Chinese stent-graft were advanced through the femoral arteries and placed in the proper position of the aneurysm sac under X-ray fluoroscopic guidance.

RESULTS

Four patients with descending aneurysm, 1 patient with abdominal aortic aneurysm (AAA) involving the renal artery, superior mesenteric artery and celiac artery, and 1 patient with right common iliac artery aneurysm received straight stent-grafts. Five patients with infrarenal AAA received bifurcated stent-grafts. CT and MRA were performed during a follow-up of 3 - 19 months. Aortic aneurysms were completely excluded from the circulation. Five patients prolonged fever was noted and 1 patient was found to have a leakage 3 months later, and hemiplegia in 1 after procedure.

CONCLUSIONS

Endovascular treatment of aortic aneurysm is technically feasible and can effectively exclude aortic aneurysms from the circulation. Endoluminal repair may serve as an interventional strategy to treat aneurysm, especially in patients at high surgical risk, but long term effect needs further study.

[Study on the packings of affinity chromatography for the separation of urokinase]

Two kinds of affinity chromatographic packings for the separation of urokinase were synthesized by coupling of p-amino benzamidine (p-ABZ) to commercially available sepharose and polyepoxypropyl methacrylate (PEPMA). Then they were applied for separating crude urokinase. It was found that the average recovery of bioactivity on sepharose was higher than that on PEPMA, resulting in 108.3% and 43.4% respectively. The high rigidity of PEPMA permits fast flow of protein solutions and operation by higher-pressure affinity chromatography. The average purification times were 36.9 folds for PEPMA column and nine-folds for Sepharose column. The purification of crude urokinase described in this paper demonstrates that PEPMA column is effective for purifying biological products in a large scale.

[The survey of HIV prevalence among drug users in Guangxi, China]

OBJECTIVE

To understand the distribution and related risk factors of HIV infection among drug users in Guangxi.

METHOD

Three hundred and twenty five drug users were tested for serum HIV antibody, with enzyme linked immunosorbent assay.

RESULTS

One hundred and sixteen drug users (35.7%) were found to be HIV positive. The main risk factors associated with HIV infection were intravenous drug users and needle sharing among drug users. The HIV prevalence was 40.9% (114/279) among IDUs, and only 4.3% (2/46) among oral drug users. The phenomenon of sharing injecting equipment (76.7%) among intravenous drug users in Guangxi represents a very serious problem.

CONCLUSION

There is a high risk of HIV infection among drug users in Guangxi. Prevention programs urgently need to be implemented.

Differential expression of gamma-aminobutyric acid type B receptor-1a and -1b mRNA variants in GABA and non-GABAergic neurons of the rat brain

To understand the heterogeneity of gamma-aminobutyric acid type B receptor (GABABR)-mediated events, we investigated expression of GABABR1a and 1b mRNA variants in GABA and non-GABAergic neurons of the rat central nervous system (CNS), by using nonradioactive in situ hybridization histochemistry and, in combination with GABA immunocytochemistry, double labeling. In situ hybridization with a pan probe, which recognizes a common sequence of both GABABR1a and GABABR1b mRNA variants, demonstrated widespread expression of GABABR1 mRNA at various levels in the CNS. Both GABABR1a and GABABR1b were expressed in the neocortex, hippocampus, dorsal thalamus, habenula, and septum, but only GABABR1a was detected in cerebellar granule cells, in caudate putamen, and most hindbrain structures. A majority of GABA neurons in cerebral cortex showed hybridization signals for both GABABR1a and GABABR1b, whereas those in most subcortical structures expressed either or neither of the two. GABA neurons in thalamic reticular nucleus and caudate putamen hybridized primarily for GABABR1a. Purkinje cells in the cerebellar cortex expressed predominantly GABABR1b. GABA neurons in dorsal lateral geniculate nucleus did not display significant levels of either GABABR1a or GABABR1b mRNAs. These data suggested widespread availability of GABABR-mediated inhibition in the CNS. The differential but overlapping expression of GABABR1 mRNA variants in different neurons and brain structures may contribute to the heterogeneity of GABABR-mediated inhibition. Some GABA neurons possessed, but others might lack the molecular machinery for GABABR-mediated disinhibition, autoinhibition, or both.

The TIGR gene indices: reconstruction and representation of expressed gene sequences

Expressed sequence tags (ESTs) have provided a first glimpse of the collection of transcribed sequences in a variety of organisms. However, a careful analysis of this sequence data can provide significant additional functional, structural and evolutionary information. Our analysis of the public EST sequences, available through the TIGR Gene Indices (TGI; http://www.tigr.org/tdb/tdb.html ), is an attempt to identify the genes represented by that data and to provide additional information regarding those genes. Gene Indices are constructed for selected organisms by first clustering, then assembling EST and annotated gene sequences from GenBank. This process produces a set of unique, high-fidelity virtual transcripts, or tentative consensus (TC) sequences. The TC sequences can be used to provide putative genes with functional annotation, to link the transcripts to mapping and genomic sequence data, and to provide links between orthologous and paralogous genes.

Calmodulin activation of an endoplasmic reticulum-located calcium pump involves an interaction with the N-terminal autoinhibitory domain

To investigate how calmodulin regulates a unique subfamily of Ca(2+) pumps found in plants, we examined the kinetic properties of isoform ACA2 identified in Arabidopsis. A recombinant ACA2 was expressed in a yeast K616 mutant deficient in two endogenous Ca(2+) pumps. Orthovanadate-sensitive (45)Ca(2+) transport into vesicles isolated from transformants demonstrated that ACA2 is a Ca(2+) pump. Ca(2+) pumping by the full-length protein (ACA2-1) was 4- to 10-fold lower than that of the N-terminal truncated ACA2-2 (Delta2-80), indicating that the N-terminal domain normally acts to inhibit the pump. An inhibitory sequence (IC(50) = 4 microM) was localized to a region within valine-20 to leucine-44, because a peptide corresponding to this sequence lowered the V(max) and increased the K(m) for Ca(2+) of the constitutively active ACA2-2 to values comparable to the full-length pump. The peptide also blocked the activity (IC(50) = 7 microM) of a Ca(2+) pump (AtECA1) belonging to a second family of Ca(2+) pumps. This inhibitory sequence appears to overlap with a calmodulin-binding site in ACA2, previously mapped between aspartate-19 and arginine-36 (J.F. Harper, B. Hong, I. Hwang, H.Q. Guo, R. Stoddard, J.F. Huang, M.G. Palmgren, H. Sze ¿1998 J Biol Chem 273: 1099-1106). These results support a model in which the pump is kept "unactivated" by an intramolecular interaction between an autoinhibitory sequence located between residues 20 and 44 and a site in the Ca(2+) pump core that is highly conserved between different Ca(2+) pump families. Results further support a model in which activation occurs as a result of Ca(2+)-induced binding of calmodulin to a site overlapping or immediately adjacent to the autoinhibitory sequence.

Endothelin-dependent and -independent components of strain-activated brain natriuretic peptide gene transcription require extracellular signal regulated kinase and p38 mitogen-activated protein kinase

The application of mechanical strain to cultured cardiac myocytes in vitro leads to activation of the brain natriuretic peptide (BNP) gene promoter, a marker of cardiac hypertrophy. We have previously shown that this activation results from both a direct mechanostimulatory event and an indirect autocrine/paracrine stimulation involving the sequential production of angiotensin II and endothelin (ET). In the present study, we examined the role of p38 mitogen-activated protein kinase (MAPK) and extracellular signal regulated kinase (ERK) in signaling the increase in promoter activity trafficking through each of these pathways. ET was shown to stimulate both p38 MAPK and ERK activity in these cultures and to activate human BNP (hBNP) promoter activity. Activation of the promoter was inhibited approximately 45% by SB-203580, a p38 MAPK inhibitor, and approximately 70% by PD98059, an inhibitor of the ERK-activating kinase MAPK kinase. The ET-independent (ie, direct) stimulation of the hBNP promoter by mechanical strain was inhibited approximately 70% by SB-203580 and approximately 60% by PD98059, implying that similar signaling circuitry is used, albeit to different degrees, by the direct and indirect pathways. The p38 MAPK component of both the ET-dependent and the ET-independent responses to strain appears to operate through a series of nuclear factor-kappaB binding, shear stress response element-like structures in the hBNP gene promoter. Collectively, these data suggest that activation of the BNP promoter by hypertrophic stimuli involves the participation of several independent signaling pathways. Such redundancy would help to guarantee generation of the full hypertrophic phenotype independently of the nature of the hypertrophic stimulus.

[Endoluminal stent-graft for aortic aneurysms: a report of six cases]

OBJECTIVE

To explore the clinical value of the treatment of aortic aneurysms with endovascular stent-graft prostheses.

METHODS

Six patients were included in the study. 4 patients with infrorenal abdominal aneurysms involving the aortic bifurcation and the common iliac arteries received bifurcated stent-grafts; 1 patient with descending and abdominal aortic aneurysm received straight stent-graft; and 1 patient with right common iliac artery aneurysm received straight stent-graft. After a unilateral surgical arteriotomy, the endoprostheses were advanced through the femoral arteries and placed under the guidance of fluoroscope. CT and MRI were perfomed during the follow-up of 2-16 months.

RESULTS

All patients got a primary success. The aortic aneurysms were completely excluded from the circulation. Two cases had a prolonged fever; 1 case was found a leakage 3 months later.

CONCLUSION

Our results suggest that endovascular treatment of aortic aneurysm is technically feasible and it can effectively exclude aortic aneurysms from the circulation. With further refinement, endoluminal repair may emerge as an interventional strategy to treat infrarenal aortic aneurysm, especially for patients at high surgical risk.

[Auditory neuropathy]

OBJECTIVE

To study the clinical feature and audiological and electrophysiological characteristics of auditory neuropathy.

METHODS

The history, audiometry, stapedial reflex, electrocochleogram, auditory brainstem response, promontory stimulation tests, otoacoustic emissions (OAE) and its contralateral supression tests were studied in 17 cases of auditory neuropathy.

RESULTS

The patients were predominently female teenagers with a history of gradual onset of bilateral hearing loss, pure tone auditometry revealed symmetric ascending audiograms with moderate hearing loss at frequencies below 1 kHz, but relatively normal hearing at 2 kHz and above. Speech reception thresholds were between 40 to 85 dB HL, discrimination score was from 29% to 68%. Stapedial reflex, auditory brainstem response and compound action potentials were absent or threshold elevated disproportionately to the pure tone threshold. All of the patients had normal cochlear microphonics and robust spontaneously and transiently evoked otoacoustic emissions (SOAE and TEOAE), the TEOAE showed no contralateral suppression effects as seen in normal subjects.

CONCLUSION

The diagnosis of the disease depends on the discrepancies between subjective and objective hearing and pre-neural and neural responses. The crossed olivocochlear bundle function testing in terms of contralateral acoustic stimulation induced otoacoustic emission reduction is specific for differential diagnosis. There is a need for more awareness of the disease among otolaryngologists and neurologists.

Mechanical strain activates BNP gene transcription through a p38/NF-kappaB-dependent mechanism

Application of mechanical strain to neonatal rat ventricular myocytes in culture evokes changes in gene expression reminiscent of those that occur with hypertrophy in vivo, such as stimulation of brain natriuretic peptide (BNP) gene expression. Here, we show that a major component of strain-dependent BNP promoter activation results from stimulation of p38 mitogen-activated protein kinase (MAPK) in the cardiac myocyte. Strain increased p38 activity in a time-dependent fashion. The p38 inhibitor SB203580 led to a reduction of approximately 60% in strain-activated human BNP (hBNP) promoter activity. Cotransfection of wild-type p38 increased both basal and strain-dependent promoter activity, while cotransfection with MKK6AL, a dominant-negative inhibitor of p38 MAPK kinase, resulted in partial inhibition of either p38- or strain-activated hBNP promoter activity. p38 MAPK increased hBNP promoter activity through activation of the transcription factor NF-kappaB. Activation of the hBNP promoter by either p38 or strain was mediated by DNA elements present in the 5' flanking sequence of the gene. Mechanical strain promoted assembly of NF-kappaB components on these DNA elements in vitro. Thus, induction of the hBNP promoter by mechanical strain depends, at least in part, on stimulation of p38 and subsequent activation of NF-kappaB. This activation may play an important role in signaling the increased BNP gene expression that accompanies hemodynamic overload and cardiac hypertrophy in vivo.

Urothelial hinge as a highly specialized membrane: detergent-insolubility, urohingin association, and in vitro formation

Urothelial surface is covered by numerous plaques (consisting of asymmetric unit membranes or AUM) that are interconnected by ordinary looking hinge membranes. We describe an improved method for purifying bovine urothelial plaques using 2% sarkosyl and 25 mM NaOH to remove contaminating membrane and peripheral proteins selectively. Highly purified plaques interconnected by intact hinge areas were obtained, indicating that the hinges are as detergent-insoluble as the plaques. These plaque/hinge preparations contained uroplakins, an as yet uncharacterized 18-kDa plaque-associated protein, plus an 85-kDa glycoprotein that is known to be hinge-associated in situ. Examination of the isolated, in vitro-resealed bovine AUM vesicles by quick-freeze deep-etch showed that each AUM particle consists of a 16-nm, luminally exposed "head" anchored to the lipid bilayer via a 9-mm transmembranous "tail", and that an AUM plaque can break forming several smaller plaques separated by newly formed particle-free, hinge-like areas. These data lend support to our recently proposed three-dimensional model of mouse urothelial plaques. In addition, our findings suggest that urothelial plaques are dynamic structures that can rearrange giving rise to new plaques with intervening hinges; that the entire urothelial apical surface (both plaque and hinge areas) is highly specialized; and that these two membrane domains may be equally important in fulfilling some of the urothelial functions.

[Atomic/ionic fluorescence in microwave plasma torch discharge excited by high current microsecond pulsed hollow cathode lamp-europium atomic/ionic fluorescence spectrometry]

Eu atomic and ionic fluorescence spectrometry in microwave plasma torch discharge excited by high current microsecond pulsed hollow cathode lamp (HCMP HCL-MPT AFS/IFS) was studied. Operating conditions were optimized. The best detection limits for AFS and IFS obtained with a desolvated ultrasonic nebulization system were 42.0 ng/mL for Eu I 462.7 nm and 21.8 ng/mL for Eu II 381.97 nm, respectively, both were better than those given by the instruction manual of a Baird ICP AFS-2000 spectrometer using pneumatic concentric nebulizer with desolvation for AFS, but were significantly higher than those obtained by using the Baird spectrometer with a mini-monochromator and a ultrasonic nebulzer system.

[Cerebral protective effects of some compounds isolated from traditional Chinese herbs]

OBJECTIVE

To study the cerebral protective effects of some compounds isolated from traditional Chinese herbs.

METHOD

Laser microcirculation dynamic analyzer and cultured rat cortical neurons were used.

RESULT

Pueraria lobata flavonoids(LPF), Panax notoginseng saponins(PNS), oxymatrine, anisodamine and berberine could dilate microvessels and increase the cerebral blood flow of anesthetized mice's meninges. LPF, PNS, oxymatrine, and anisodamine also accelerated the flow of blood. Oxymatrine, like anisodamine, increased quantities of erythrocytes in high frequency movements. PNS could protect cultured rat cortical neurons from glutamate neurotoxicity.

CONCLUSION

LPF, PNS, oxymatrine, anisodamine and berberine have certain protective effects on brain, but differ in mechanisms of action.

Sp1 dependence of natriuretic peptide receptor A gene transcription in rat aortic smooth muscle cells

The atrial natriuretic peptide receptor (NPR-A) Is expressed in smooth muscle cells of the vasculature, where it is thought to signal the vasodilatory properties of the peptide. Despite its important role as a regulator of cardiovascular homeostasis, relatively little is known of the genomic factors governing expression of this gene. We show here that NPR-A promoter activity is reduced by 50-75% when any of three GC-rich sites are mutated. Simultaneous mutation of all three leads to a >90% reduction in NPR-A promoter activity. Transfection of wild-type, but not mutant, decoy oliogonucleotides encoding any one of the sites reduces NPR-A activity, presumably reflecting competition for a common transcription factor. Gel shift analyses show that each of the wild-type, but not the mutant, sites interferes with the formation of selected DNA-protein complexes on the other sites. These complexes share similar electrophoretic mobility. Immunoperturbation studies show that one of these shared complexes contains Sp1, whereas two others contain Sp3. Overexpression of either Sp1 or Sp3 in a cell type containing very low levels of these transcription factors (i.e. Drosophila Schneider cells) leads to induction of the wild-type, but not the mutant, NPR-A promoter. The data suggest that the Sp1 family of transcription factors plays a central role in NPR-A gene transcription. The association of Sp1 family members with transcriptional regulation of a number of genes involved in hemodynamic control will be discussed.

The processing of secretogranin II in the peripheral nervous system: release of secretoneurin from porcine sympathetic nerve terminals

The distribution of secretoneurin (SN), a peptide derived from secretogranin II (SgII), in the coeliac ganglion, the splenic nerve and the spleen was examined by immunohistochemistry. In the ganglion, SN immunoreactivity (IR) was unevenly distributed. Positive nerve terminals densely surrounded some postganglionic perikarya in which also intense SN-IR was present. In the crushed splenic nerves, intense immunoreactivities appeared proximal (but to a less extent also distal) to the crush of the nerve. Analysis by cytofluorimetric scanning (CFS) demonstrated that SN-IR and neuropeptide Y immunoreactivity (NPY-IR) were predominant in the axons proximal to the crush representing anterogradely transported components. Using radioimmunoassay (RIA) we demonstrated that upon electrical stimulation (10 Hz, 1 min) of the splenic nerve, significant amounts of SN-IR (64.2+/-2.3 fmol) were released together with NA (4. 1x106+/-0.2 fmol) and NPY (330.0+/-7.2 fmol) from the isolated perfused porcine spleen. To evaluate the processing of SgII in sympathetic neurons, boiled tissue extracts (coeliac ganglia and splenic nerve) and boiled spleen perfusate (used as a suitable source for vesicle derived peptides) were analysed by gel filtration chromatography followed by SN-RIA. In all cases immunoreactivity was present solely as SN, indicating that SgII was fully processed to the free peptide. The evidence that SN is transported to the nerve terminals and is released from the porcine spleen upon nerve stimulation, suggests that it may modulate adrenergic neurotransmission and may also play a role in the neuroimmune communication.

Three-dimensional analysis of the 16 nm urothelial plaque particle: luminal surface exposure, preferential head-to-head interaction, and hinge formation

The luminal surface of mouse urothelium in contact with the urine is almost entirely covered with plaques consisting of uroplakin-containing particles that form p6 hexagonal crystals with a center-to-center distance of 16 nm. A combination of quick-freeze/deep-etch images and our previous negative staining data indicate that the head domain of the uroplakin particle, which is exposed without an extensive glycocalyx shield, interacts closely with the head domains of the neighboring particles, while the membrane-embedded tail domains are farther apart; and that urothelial particles and plaques are not rigid structures as they can change their configuration in response to mechanical perturbations. Based on these data, we have constructed three-dimensional models depicting the structural organization of urothelial particles and plaques. Our models suggest that the head-to-head interaction may play a key role in determining the shape and size of the urothelial plaques. These models can explain many properties of urothelial plaques including their unique shape, detergent-insolubility, and morphological changes during vesicle maturation.

Pig splenic nerve: peptides derived from chromogranins by proteolytic processing during axonal transport

We have investigated the proteolytic processing of chromogranin A, chromogranin B and NESP55 (a novel chromogranin-like protein) during axonal transport using pig splenic nerve as a model. We have also studied the presence of chromogranin-derived peptides in the perfusate during electrical stimulation of this nerve. High-performance gel filtration chromatography followed by radioimmunoassay (RIA) revealed that chromogranins are proteolytically processed to varying degrees during axonal transport. For chromogranin A and NESP55, the precursor is still present in the proximal part of the nerve, whereas in the distal part and nerve terminals, intermediate-sized peptides and the free peptides GE-25 and GAIPIRRH dominate, respectively. For chromogranin B, the precursor has already been processed to an intermediate-sized peptide in the proximal part of the nerve, which is also present in the distal parts together with the free peptide PE-11. For chromogranin B and NESP55, only the free peptides PE-11 and GAIPIRRH, or in the case of chromogranin A, the free peptide GE-25 plus an intermediate-sized one, are released from the terminals into the splenic perfusate. These results demonstrate that chromogranins are processed to smaller peptides during axonal transport.

A high-affinity Ca2+ pump, ECA1, from the endoplasmic reticulum is inhibited by cyclopiazonic acid but not by thapsigargin

To identify and characterize individual Ca2+ pumps, we have expressed an Arabidopsis ECA1 gene encoding an endoplasmic reticulum-type Ca2+-ATPase homolog in the yeast (Saccharomyces cerevisiae) mutant K616. The mutant (pmc1pmr1cnb1) lacks a Golgi and a vacuolar membrane Ca2+ pump and grows very poorly on Ca2+-depleted medium. Membranes isolated from the mutant showed high H+/Ca2+-antiport but no Ca2+-pump activity. Expression of ECA1 in endomembranes increased mutant growth by 10- to 20-fold in Ca2+-depleted medium. 45Ca2+ pumping into vesicles from ECA1 transformants was detected after the H+/Ca2+-antiport activity was eliminated with bafilomycin A1 and gramicidin D. The pump had a high affinity for Ca2+ (Km = 30 nM) and displayed two affinities for ATP (Km of 20 and 235 microM). Cyclopiazonic acid, a specific blocker of animal sarcoplasmic/endoplasmic reticulum Ca2+-ATPase, inhibited Ca2+ transport (50% inhibition dose = 3 nmol/mg protein), but thapsigargin (3 microM) did not. Transport was insensitive to calmodulin. These results suggest that this endoplasmic reticulum-type Ca2+-ATPase could support cell growth in plants as in yeast by maintaining submicromolar levels of cytosolic Ca2+ and replenishing Ca2+ in endomembrane compartments. This study demonstrates that the yeast K616 mutant provides a powerful expression system to study the structure/function relationships of Ca2+ pumps from eukaryotes.

Reciprocal up- and down-regulation of BDNF mRNA in tetanus toxin-induced epileptic focus and inhibitory surround in cerebral cortex

Chronic focal epilepsy is associated with synaptic plasticity and growth of new connections. Brain-derived neurotrophic factor (BDNF) is associated with each of these processes in normal brain and shows acute up-regulation in models of generalized epilepsy. Here, using an experimental model of focal epilepsy, we show persistent up-regulation of BDNF mRNA, independent of that of other growth factors, in association with the development and persistence of chronic seizures. In situ hybridization histochemistry revealed that rats perfused within 2-3 days after seizure onset had widespread increases in BDNF mRNA levels in the neocortex. Rats perfused at later times, however, showed focal up-regulation of BDNF mRNA at the injection site and down-regulation in a surrounding cortical zone. Nerve growth factor and neurotrophin-3 mRNAs were not significantly altered. These reciprocal changes in BDNF gene expression in the epileptic focus and the cortical surround may contribute to plastic changes in epileptic neuronal circuits that accompany the transition from acute to chronic epilepsy. BDNF down-regulation in the surround is likely to be associated with the inhibitory surround that hampers seizure spread, but facilitates the persistence of a chronic epileptic focus.

Autocrine/paracrine determinants of strain-activated brain natriuretic peptide gene expression in cultured cardiac myocytes

The application of mechanical strain leads to activation of human brain natriuretic peptide gene promoter activity, a marker of hypertrophy, in cultured neonatal rat ventricular myocytes. We have used a combination of transient transfection analysis and reverse transcriptase-polymerase chain reaction to examine the role of locally produced factors in contributing to this activation. Conditioned media from strained, but not static, cultures led to a dose-dependent increase in human brain natriuretic peptide gene promoter activity. This increase was completely blocked by losartan or BQ-123, implying a role for angiotensin and endothelin as autocrine/paracrine mediators of the response to strain. Inclusion of the same antagonists in the cultures themselves led to only partial inhibition (approximately 60%), whereas inclusion of exogenous endothelin or angiotensin II resulted in amplification of the strain response. Angiotensin II and endothelin appear to be arrayed in series in the regulatory circuitry; the angiotensin response was blocked by BQ-123, whereas the endothelin response was unaffected by losartan. Mechanical strain was also shown to stimulate expression of the endogenous angiotensinogen, angiotensin-converting enzyme, and endothelin genes in this system. Collectively, these data indicate that locally generated angiotensin II and endothelin, acting in series, play an important autocrine/paracrine role in mediating strain-dependent activation of cardiac-specific gene expression.

[An etiological and serological study on Dengue epidemic in Guangdong Province]

In 1978-1995, Dengue fever epidemics(serotype 1-4) occurred in Guangdong Province. Among 9 species of mosquitoes found in the epidemic areas, the positive rate of virus isolation in Aedes albopictus was 20.69%, in Aedes aegypti 18.95%, in Culex quinquefasciatus 10.29%, Dengue viruses were not isolated in other 6 species of mosquitoes. The positive rate of virus isolation in the three species showed no significant differences (chi 2 = 2.77 P > 0.05). Aedes aegypti was the main transmitting vector in Hainan Island and Zhanjiang District, whereas Aedes albopictus was in the other epidemic areas. The positive rate of virus isolation within 3 days of disease onset was between 73.58% and 82.05%, but the virus could still be isolated on the 8th day of disease onset. The highest antibody positive rate from the patients' paired-sera was 93.89% and the lowest was 33.71%. IgM antibody could be detected 5 days after the disease onset in some cases, even on the 33rd day of disease onset. These results suggest that virus isolation by collecting patient's blood within 1-4 days of disease onset, or IgM antibody detection after 5 days of disease onset can be used as method for early and rapid diagnosis of the disease.

[Major blood vessel excision and reconstruction in the treatment of retroperitoneal neoplasms]

OBJECTIVE

To summarize the experience in the treatment of retroperitoneal tumors involving major blood vessels.

METHODS

Twenty five cases with retroperitoneal tumors involving major blood vessels were treated by excision of the tumor and the major blood vessel involved followed by vascular reconstruction.

RESULTS

After a careful preoperative evaluation and necessary preparation, the tumor together with the involved blood vessels in all patients are successfully resected and the severed major blood vessels reconstructed. There was no operative death.

CONCLUSION

Retroperitoneal neoplasm involving major blood vessels is not a contraindication for surgical resection. The tumor and the involved vessel can be removed en bloc followed by vascular reconstruction. The risk of local tumor recurrence can thus be minimized and better survival achieved.

Homology-directed repair is a major double-strand break repair pathway in mammalian cells

Mammalian cells have been presumed to repair potentially lethal chromosomal double-strand breaks (DSBs) in large part by processes that do not require homology to the break site. This contrasts with Saccharomyces cerevisiae where the major DSB repair pathway is homologous recombination. Recently, it has been determined that DSBs in genomic DNA in mammalian cells can stimulate homologous recombination as much as 3 or 4 orders of magnitude, suggesting that homology-directed repair may play an important role in the repair of chromosomal breaks. To determine whether mammalian cells use recombinational repair at a significant level, we have analyzed the spectrum of repair events at a defined chromosomal break by using direct physical analysis of repair products. When an endonuclease-generated DSB is introduced into one of two direct repeats, homologous repair is found to account for 30-50% of observed repair events. Both noncrossover and deletional homologous repair products are detected, at approximately a 1:3 ratio. These results demonstrate the importance of homologous recombination in the repair of DSBs in mammalian cells. In the remaining observed repair events, DSBs are repaired by nonhomologous processes. The nonhomologous repair events generally result in small deletions or insertions at the break site, although a small fraction of events result in larger chromosomal rearrangements. Interestingly, in two insertions, GT repeats were integrated at one of the broken chromosome ends, suggesting that DSB repair can contribute to the spread of microsatellite sequences in mammalian genomes.

[Reoperative treatment of recurrent retroperitoneal tumor]

OBJECTIVE

To improve the resection rate and survival rate for recurrent retroperitoneal tumor (RRT).

METHOD

We analysed 34 patients with RRT who were treated in our hospital from 1987 to 1995. One patient had benign tumor, the others malignant. Because 7 patients were operated on over one time, we performed 53 operations including complete resection in 42 patients, palliative resection 8 and biopsy 3.

RESULT

The 1-and 2-year survival rates for complete resection cases were 71.2% and 65.3%. The patients who received palliative resection and biopsy died within one year.

CONCLUSION

The diagnosis, preoperative preparation and intraoperative management of RRT are important to operative safety and survival rate. We emphasize the importance of reoperation and complete resection for RRT.